Vertical characterization of soil contamination using multi-way modeling--a case study.

PubMed

Singh, Kunwar P; Malik, Amrita; Basant, Ankita; Ojha, Priyanka

2008-11-01

This study describes application of chemometric multi-way modeling approach to analyze the dataset pertaining to soils of industrial area with a view to assess the soil/sub-soil contamination, accumulation pathways and mobility of contaminants in the soil profiles. The three-way (sampling depths, chemical variables, sampling sites) dataset on heavy metals in soil samples collected from three different sites in an industrial area, up to a depth of 60 m each was analyzed using three-way Tucker3 model validated for stability and goodness of fit. A two component Tucker3 model, explaining 66.6% of data variance, allowed interpretation of the data information in all the three modes. The interpretation of core elements revealing interactions among the components of different modes (depth, variables, sites) allowed inferring more realistic information about the contamination pattern of soils both along the horizontal and vertical coordinates, contamination pathways, and mobility of contaminants through soil profiles, as compared to the traditional data analysis techniques. It concluded that soils at site-1 and site-2 are relatively more contaminated with heavy metals of both the natural as well as anthropogenic origins, as compared to the soil of site-3. Moreover, the accumulation pathways of metals for upper shallow layers and deeper layers of soils in the area were differentiated. The information generated would be helpful in developing strategies for remediation of the contaminated soils for reducing the subsequent risk of ground-water contamination in the study region.

Spatial and taxonomic variation in trace element bioaccumulation in two herbivores from a coal combustion waste contaminated stream.

PubMed

Fletcher, Dean E; Lindell, Angela H; Stillings, Garrett K; Mills, Gary L; Blas, Susan A; Vaun McArthur, J

2014-03-01

Dissimilarities in habitat use, feeding habits, life histories, and physiology can result in syntopic aquatic taxa of similar trophic position bioaccumulating trace elements in vastly different patterns. We compared bioaccumulation in a clam, Corbicula fluminea and mayfly nymph Maccaffertium modestum from a coal combustion waste contaminated stream. Collection sites differed in distance to contaminant sources, incision, floodplain activity, and sources of flood event water and organic matter. Contaminants variably accumulated in both sediment and biofilm. Bioaccumulation differed between species and sites with C. fluminea accumulating higher concentrations of Hg, Cs, Sr, Se, As, Be, and Cu, but M. modestum higher Pb and V. Stable isotope analyses suggested both spatial and taxonomic differences in resource use with greater variability and overlap between species in the more physically disturbed site. The complex but essential interactions between organismal biology, divergence in resource use, and bioaccumulation as related to stream habitat requires further studies essential to understand impacts of metal pollution on stream systems. Copyright © 2014 Elsevier Inc. All rights reserved.

Variability of pesticide exposure in a stream mesocosm system: macrophyte-dominated vs. non-vegetated sections.

PubMed

Beketov, Mikhail A; Liess, Matthias

2008-12-01

For flowing water bodies no information is available about patterns of contaminant distribution in flowing water compared to macrophyte-dominated structures. The aim of the study was to examine temporal dynamic and spatial cross-channel variability of pulse exposure of the insecticide thiacloprid in outdoor stream mesocosms. Two distinct cross-channel sections have been considered: macrophyte-dominated littoral and non-vegetated midstream. Median disappearance time ranged from 17 to 43 h (water phase, midstream). We showed that during the exposure pulse (10h) thiacloprid concentrations in the macrophyte-dominated section were 20-60% lower than those in the non-vegetated section. This suggests that spatial variability in contaminant concentrations, particularly in streams containing macrophytes, should be taken into account to enable a more realistic assessment of (i) exposure and associated effects and (ii) mass transport of pesticides and other chemicals into river systems (e.g. losses with surface runoff).

Geomorphological assessment of sediment contamination in an urban stream system

USGS Publications Warehouse

Rhoads, B.L.; Cahill, R.A.

1999-01-01

Little is known about the influence of fluvial-geomorphological features on the dispersal of sediment-related contaminants in urban drainage systems. This study investigates the relation between reach-scale geomorphological conditions and network-scale patterns of trace-element concentrations in a partially urbanized stream system in East-Central Illinois, USA Robust statistical analysis of bulk sediment samples reveals levels of Cr, Cu, Pb, Ni, and Zn exceed contamination thresholds in the portion of the watershed in close proximity to potential sources of pollution-in this case storm-sewer outfalls. Although trace-element concentrations decrease rapidly downstream from these sources, substantial local variability in metal levels exists within contaminated reaches. This local variability is related to reach-scale variation in fluvial-geomorphic conditions, which in turn produces variation in the degree of sorting and organic-matter content of bed material. Metal concentrations at contaminated sites also exhibit considerable variability over time. Analytical tests on specific size fractions of material collected at a highly contaminated site indicate that Cr and Ni are concentrated in the 0.063 to 0.250 mm fraction of the sediment. This fraction also has elevated concentration of Zr. SEM analysis shows that the fine sand fraction contains shards of stainless steel within a matrix of zircon sand, an industrial material associated with a nearby alloy casting operation. Samples of suspended load and bedload at the contaminated site also have elevated amounts of trace metals, but concentrations of Ni and Cr in the bedload are less than concentrations in the bed material, suggesting that these trace elements are relatively immobile. Off the other hand, amounts of CU and Zn in the bedload exceed concentrations in the bed material, implying that these trace metals are preferentially mobilized during transport events.

Use of a moss biomonitoring method to compile emission inventories for small-scale industries.

PubMed

Varela, Z; Aboal, J R; Carballeira, A; Real, C; Fernández, J A

2014-06-30

We used a method of detecting small-scale pollution sources (DSSP) that involves measurement of the concentrations of elements in moss tissues, with the following aims: (i) to determine any common qualitative patterns of contaminant emissions for individual industrial sectors, (ii) to compare any such patterns with previously described patterns, and (iii) to compile an inventory of the metals and metalloids emitted by the industries considered. Cluster analysis revealed that there were no common patterns of emission associated with the industrial sectors, probably because of differences in production processes and in the types of fuel and raw materials. However, when these variables were shared by different factories, the concentrations of the elements in moss tissues enabled the factories to be grouped according to their emissions. We compiled a list of the metals and metalloids emitted by the factories under study and found that the DSSP method was satisfactory for this purpose in most cases (53 of 56). The method appears to be a useful tool for compiling contaminant inventories; it may also be useful for determining the efficacy of technical improvements aimed at reducing the industrial emission of contaminants and could be incorporated in environmental monitoring and control programmes. Copyright © 2014 Elsevier B.V. All rights reserved.

Influences of climate on aflatoxin producing fungi and aflatoxin contamination.

PubMed

Cotty, Peter J; Jaime-Garcia, Ramon

2007-10-20

Aflatoxins are potent mycotoxins that cause developmental and immune system suppression, cancer, and death. As a result of regulations intended to reduce human exposure, crop contamination with aflatoxins causes significant economic loss for producers, marketers, and processors of diverse susceptible crops. Aflatoxin contamination occurs when specific fungi in the genus Aspergillus infect crops. Many industries frequently affected by aflatoxin contamination know from experience and anecdote that fluctuations in climate impact the extent of contamination. Climate influences contamination, in part, by direct effects on the causative fungi. As climate shifts, so do the complex communities of aflatoxin-producing fungi. This includes changes in the quantity of aflatoxin-producers in the environment and alterations to fungal community structure. Fluctuations in climate also influence predisposition of hosts to contamination by altering crop development and by affecting insects that create wounds on which aflatoxin-producers proliferate. Aflatoxin contamination is prevalent both in warm humid climates and in irrigated hot deserts. In temperate regions, contamination may be severe during drought. The contamination process is frequently broken down into two phases with the first phase occurring on the developing crop and the second phase affecting the crop after maturation. Rain and temperature influence the phases differently with dry, hot conditions favoring the first and warm, wet conditions favoring the second. Contamination varies with climate both temporally and spatially. Geostatistics and multiple regression analyses have shed light on influences of weather on contamination. Geostatistical analyses have been used to identify recurrent contamination patterns and to match these with environmental variables. In the process environmental conditions with the greatest impact on contamination are identified. Likewise, multiple regression analyses allow ranking of environmental variables based on relative influence on contamination. Understanding the impact of climate may allow development of improved management procedures, better allocation of monitoring efforts, and adjustment of agronomic practices in anticipation of global climate change.

Extensive Variation in Cadmium Tolerance and Accumulation among Populations of Chamaecrista fasciculata

PubMed Central

Henson, Tessa M.; Cory, Wendy; Rutter, Matthew T.

2013-01-01

Plant populations may vary substantially in their tolerance for and accumulation of heavy metals, and assessment of this variability is important when selecting species to use in restoration or phytoremediation projects. We examined the population variation in cadmium tolerance and accumulation in a leguminous pioneer species native to the eastern United States, the partridge pea (Chamaecrista fasciculata). We assayed growth, reproduction and patterns of cadmium accumulation in six populations of C. fasciculata grown on a range of cadmium-contaminated soils. In general, C. fasciculata exhibited tolerance in low to moderate soil cadmium concentrations. Both tolerance and accumulation patterns varied across populations. C. fasciculata exhibited many characteristics of a hyperaccumulator species, with high cadmium uptake in shoots and roots. However, cadmium was excluded from extrafloral nectar. As a legume with tolerance for moderate cadmium contamination, C. fasciculata has potential for phytoremediation. However, our findings also indicate the importance of considering the effects of genetic variation on plant performance when screening plant populations for utilization in remediation and restoration activities. Also, there is potential for cadmium contamination to affect other species through contamination of leaves, fruits, flowers, pollen and root nodules. PMID:23667586

Seasonal differences in the physiology of Carcinus maenas (Crustacea: Decapoda) from estuaries with varying levels of anthropogenic contamination

NASA Astrophysics Data System (ADS)

Dissanayake, Awantha; Galloway, Tamara S.; Jones, Malcolm B.

2011-07-01

This study reports the seasonal variability in aspects of the physiology of the shore crab Carcinus maenas from three estuaries in South-west England, each with varying anthropogenic inputs: Avon Estuary ('relatively low' impact), Yealm Estuary ('intermediate' impact) and Plym Estuary ('relatively high' impact). Crabs collected over 12 months from the Avon had a significantly 'lower' physiological condition in winter and spring compared to summer and autumn; in particular, haemocyte phagocytic capability (a general indicator of immune function) was significantly higher in winter and spring compared to summer and autumn, and total haemolymph antioxidant status (an indicator of oxidative stress) was significantly lower in winter compared to the remainder of the year. Potentially, shore crabs may be more susceptible to the effects of contaminant exposure, such as increased immunotoxicity (thus, reduction of immune function) and/or oxyradicals (or reactive oxygen species) exposure) especially in seasons of increased susceptibility i.e. summer/autumn (lower phagocytic capability) and winter (lowest antioxidant function). As the Avon was taken to represent the 'reference' site, this pattern is considered to reflect the 'normal' seasonal variability in shore crab physiology. Shore crab physiological condition from the 'relatively high' impact estuary (Plym) revealed increased cellular viability and antioxidant status in autumn and winter compared with that of the 'standard' pattern (Avon) However, crabs from the intermediate impact estuary (Yealm) only demonstrated significant physiological differences in summer as shown by a lower cellular viability. All crabs had been exposed to PAHs (confirmed by the presence of PAH metabolites in their urine) which may account for the observed differences in shore crab physiology. In conclusion, to aid understanding of the potential contaminant impacts on biota it is imperative that the 'normal' seasonal variability of physiological condition be established. Biological effects-based monitoring studies should therefore be employed seasonally to potentially highlight 'windows of sensitivity' to contaminant impact.

Reproductive success and contaminant associations in tree swallows (Tachycineta bicolor) used to assess a Beneficial Use Impairment in U.S. and Binational Great Lakes’ Areas of Concern

USGS Publications Warehouse

Custer, Christine M.; Custer, Thomas W.; Etterson, Matthew A.; Dummer, Paul; Goldberg, Diana R.; Franson, J. Christian

2018-01-01

During 2010-2014, tree swallow (Tachycineta bicolor) reproductive success was monitored at 68 sites across all 5 Great Lakes, including 58 sites located within Great Lakes Areas of Concern (AOCs) and 10 non-AOCs. Sample eggs were collected from tree swallow clutches and analyzed for contaminants including polychlorinated biphenyls (PCBs), dioxins and furans, polybrominated diphenyl ethers, and 34 other organic compounds. Contaminant data were available for 360 of the clutches monitored. Markov chain multistate modeling was used to assess the importance of 5 ecological variables and 11 of the dominant contaminants in explaining the pattern of egg and nestling failure rates. Four of 5 ecological variables (Female Age, Date within season, Year, and Site) were important explanatory variables. Of the 11 contaminants, only total dioxin and furan toxic equivalents (TEQs) explained a significant amount of the egg failure probabilities. Neither total PCBs nor PCB TEQs explained the variation in egg failure rates. In a separate analysis, polycyclic aromatic hydrocarbon exposure in nestling diet, used as a proxy for female diet during egg laying, was significantly correlated with the daily probability of egg failure. The 8 sites within AOCs which had poorer reproduction when compared to 10 non-AOC sites, the measure of impaired reproduction as defined by the Great Lakes Restoration Initiative, were associated with exposure to dioxins and furan TEQs, PAHs, or depredation. Only 2 sites had poorer reproduction than the poorest performing non-AOC. Using a classic (non-modeling) approach to estimating reproductive success, 82% of nests hatched at least 1 egg, and 75% of eggs laid, excluding those collected for contaminant analyses, hatched.

Reproductive success and contaminant associations in tree swallows (Tachycineta bicolor) used to assess a Beneficial Use Impairment in U.S. and Binational Great Lakes' Areas of Concern.

PubMed

Custer, Christine M; Custer, Thomas W; Etterson, Matthew A; Dummer, Paul M; Goldberg, Diana; Franson, J Christian

2018-05-01

During 2010-2014, tree swallow (Tachycineta bicolor) reproductive success was monitored at 68 sites across all 5 Great Lakes, including 58 sites located within Great Lakes Areas of Concern (AOCs) and 10 non-AOCs. Sample eggs were collected from tree swallow clutches and analyzed for contaminants including polychlorinated biphenyls (PCBs), dioxins and furans, polybrominated diphenyl ethers, and 34 other organic compounds. Contaminant data were available for 360 of the clutches monitored. Markov chain multistate modeling was used to assess the importance of 5 ecological variables and 11 of the dominant contaminants in explaining the pattern of egg and nestling failure rates. Four of 5 ecological variables (Female Age, Date within season, Year, and Site) were important explanatory variables. Of the 11 contaminants, only total dioxin and furan toxic equivalents (TEQs) explained a significant amount of the egg failure probabilities. Neither total PCBs nor PCB TEQs explained the variation in egg failure rates. In a separate analysis, polycyclic aromatic hydrocarbon exposure in nestling diet, used as a proxy for female diet during egg laying, was significantly correlated with the daily probability of egg failure. The 8 sites within AOCs which had poorer reproduction when compared to 10 non-AOC sites, the measure of impaired reproduction as defined by the Great Lakes Restoration Initiative, were associated with exposure to dioxins and furan TEQs, PAHs, or depredation. Only 2 sites had poorer reproduction than the poorest performing non-AOC. Using a classic (non-modeling) approach to estimating reproductive success, 82% of nests hatched at least 1 egg, and 75% of eggs laid, excluding those collected for contaminant analyses, hatched.

Effects of seasonal operation on the quality of water produced by public-supply wells

USGS Publications Warehouse

Bexfield, Laura M.; Jurgens, Bryant C.

2014-01-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.

Effects of Seasonal Operation on the Quality of Water Produced by Public-Supply Wells

PubMed Central

Bexfield, Laura M; Jurgens, Bryant C

2014-01-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin. PMID:24593780

A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Hou, Haihui Ron

1994-01-01

A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

A comparison of data-driven groundwater vulnerability assessment methods

USGS Publications Warehouse

Sorichetta, Alessandro; Ballabio, Cristiano; Masetti, Marco; Robinson, Gilpin R.; Sterlacchini, Simone

2013-01-01

Increasing availability of geo-environmental data has promoted the use of statistical methods to assess groundwater vulnerability. Nitrate is a widespread anthropogenic contaminant in groundwater and its occurrence can be used to identify aquifer settings vulnerable to contamination. In this study, multivariate Weights of Evidence (WofE) and Logistic Regression (LR) methods, where the response variable is binary, were used to evaluate the role and importance of a number of explanatory variables associated with nitrate sources and occurrence in groundwater in the Milan District (central part of the Po Plain, Italy). The results of these models have been used to map the spatial variation of groundwater vulnerability to nitrate in the region, and we compare the similarities and differences of their spatial patterns and associated explanatory variables. We modify the standard WofE method used in previous groundwater vulnerability studies to a form analogous to that used in LR; this provides a framework to compare the results of both models and reduces the effect of sampling bias on the results of the standard WofE model. In addition, a nonlinear Generalized Additive Model has been used to extend the LR analysis. Both approaches improved discrimination of the standard WofE and LR models, as measured by the c-statistic. Groundwater vulnerability probability outputs, based on rank-order classification of the respective model results, were similar in spatial patterns and identified similar strong explanatory variables associated with nitrate source (population density as a proxy for sewage systems and septic sources) and nitrate occurrence (groundwater depth).

Do contamination of and exposure to chicken meat and water drive the temporal dynamics of Campylobacter cases?

PubMed

David, J M; Pollari, F; Pintar, K D M; Nesbitt, A; Butler, A J; Ravel, A

2017-11-01

Campylobacteriosis, the most frequent bacterial enteric disease, shows a clear yet unexplained seasonality. The study purpose was to explore the influence of seasonal fluctuation in the contamination of and in the behaviour exposures to two important sources of Campylobacter on the seasonality of campylobacteriosis. Time series analyses were applied to data collected through an integrated surveillance system in Canada in 2005-2010. Data included sporadic, domestically-acquired cases of Campylobacter jejuni infection, contamination of retail chicken meat and of surface water by C. jejuni, and exposure to each source through barbequing and swimming in natural waters. Seasonal patterns were evident for all variables with a peak in summer for human cases and for both exposures, in fall for chicken meat contamination, and in late fall for water contamination. Time series analyses showed that the observed campylobacteriosis summer peak could only be significantly linked to behaviour exposures rather than sources contamination (swimming rather than water contamination and barbequing rather than chicken meat contamination). The results indicate that the observed summer increase in human cases may be more the result of amplification through more frequent risky exposures rather than the result of an increase of the Campylobacter source contamination.

Multiscale structure of Cs-137 soil contamination on the Bryansk Region (Russia) due to the accident at the Chernobyl NPP

NASA Astrophysics Data System (ADS)

Linnik, Vitaly; Sokolov, Alexander

2013-04-01

The Cs-137 contamination of the Bryansk Region occurred in the period from April 27 to May 10 into several stages. The complicated character of the soil radionuclide contamination on the Bryansk Region is caused by different nature of the radioactive fallout: dry and wet. Thus, in a number of cases Cs-137 soil pollution is directly connected with the rain intensity, which is well known, have multifractal nature. In some parts of contaminated territory the overlay of different types of fallout was observed. The radioactive contamination of the landscape is a result from nonlinear interplay of geophysical factors which intervene over a large range of scale. As a result of the fallout Cs-137 pattern can be described as a multifractal. Consequently, fields of contamination observed have an extreme spatial variability, frequently cited "hot spots" or "leopard's skin. As an estimate of background radiation levels, we relied on a dataset of air-gamma-survey of the Bryansk Region, carried out by SSC AEROGEOFIZIKA in the summer of 1993. This dataset includes geo-positioned data of Cs-137 deposition in a grid of 100x100 m with values range from 3 to 11*104 kBq/m2. Airborne gamma survey gave the smoothed values of the Cs-137 density of contamination in comparison with the data, obtained directly as a result of soil sampling. However, even in this case in the east part of the Bryansk test site we can observed the"hot spots" (by size several hundred meters) as natural phenomenon. The article presents the results of the geostatistical and multifractal analysis of the Cs-137 contamination. Scaling analysis was conducted to investigate the linkages between the spatial variability of soil Cs-137 contamination and some landscape characteristics.

Influence of estuarine processes on spatiotemporal variation in bioavailable selenium

USGS Publications Warehouse

Stewart, Robin; Luoma, Samuel N.; Elrick, Kent A.; Carter, James L.; van der Wegen, Mick

2013-01-01

Dynamic processes (physical, chemical and biological) challenge our ability to quantify and manage the ecological risk of chemical contaminants in estuarine environments. Selenium (Se) bioavailability (defined by bioaccumulation), stable isotopes and molar carbon-tonitrogen ratios in the benthic clam Potamocorbula amurensis, an important food source for predators, were determined monthly for 17 yr in northern San Francisco Bay. Se concentrations in the clams ranged from a low of 2 to a high of 22 μg g-1 over space and time. Little of that variability was stochastic, however. Statistical analyses and preliminary hydrodynamic modeling showed that a constant mid-estuarine input of Se, which was dispersed up- and down-estuary by tidal currents, explained the general spatial patterns in accumulated Se among stations. Regression of Se bioavailability against river inflows suggested that processes driven by inflows were the primary driver of seasonal variability. River inflow also appeared to explain interannual variability but within the range of Se enrichment established at each station by source inputs. Evaluation of risks from Se contamination in estuaries requires the consideration of spatial and temporal variability on multiple scales and of the processes that drive that variability.

In situ experimental assessment of lake whitefish development following a freshwater oil spill.

PubMed

Debruyn, Adrian M H; Wernick, Barbara G; Stefura, Corey; McDonald, Blair G; Rudolph, Barri-Lynn; Patterson, Luanne; Chapman, Peter M

2007-10-15

Wabamun Lake (Alberta, Canada) has been subject to ongoing contamination with polycyclic aromatic hydrocarbons (PAHs) from multiple sources for decades and in August 2005 was exposed to ca. 149 500 L of bunker C oil following a train derailment. We compared the pattern, frequency, and severity of deformity in larvae of lake whitefish (Coregonus clupeaformis) incubated in situ in areas of Wabamun Lake exposed only to "background" PAH contamination and in areas additionally exposed to PAHs from the oil. All sites in the lake (including reference areas) showed incidences of deformity higher than are typically observed in laboratory studies. A small number of oil-exposed sites showed higher incidences of some teratogenic deformities and a tendency to exhibit deformities of higher severity than sites not exposed to oil. The frequency of moderate to severe deformities in 8 of 16 classes was correlated with PAH exposure. Nonmetric multivariate ordination of deformity data revealed a general pattern of increasing incidence and severity of several skeletal (lordosis, scoliosis) and craniofacial (ocular, jaw) deformities at sites with relatively high exposure to oil-derived PAHs. A simultaneous consideration of incidence, severity, and pattern of deformity enabled us to detect a consistent (overall approximately 5% above background) response to the oil despite high variability and high background deformity rates in this historically contaminated environment.

Are red mullet efficient as bio-indicators of mercury contamination? A case study from the French Mediterranean.

PubMed

Cresson, P; Bouchoucha, M; Miralles, F; Elleboode, R; Mahé, K; Marusczak, N; Thebault, H; Cossa, D

2015-02-15

Mercury (Hg) is one of the main chemicals currently altering Mediterranean ecosystems. Red mullet (Mullus barbatus and M. surmuletus) have been widely used as quantitative bio-indicators of chemical contamination. In this study, we reassess the ability of these species to be used as efficient bio-indicators of Hg contamination by monitoring during 18 months Hg concentrations in muscle tissue of mullet sampled from 5 French Mediterranean coastal areas. Mean concentrations ranged between 0.23 and 0.78 μg g(-1) dry mass for both species. Values were consistent with expected contamination patterns of all sites except Corsica. Results confirmed that red mullets are efficient bio-indicators of Hg contamination. Nevertheless, the observed variability in Hg concentrations calls for caution regarding the period and the sample size. Attention should be paid to environmental and biologic specificities of each studied site, as they can alter the bioaccumulation of Hg, and lead to inferences about environmental Hg concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Airborne exposure patterns from a passenger source in aircraft cabins

PubMed Central

Bennett, James S.; Jones, Byron W.; Hosni, Mohammad H.; Zhang, Yuanhui; Topmiller, Jennifer L.; Dietrich, Watts L.

2015-01-01

Airflow is a critical factor that influences air quality, airborne contaminant distribution, and disease transmission in commercial airliner cabins. The general aircraft-cabin air-contaminant transport effect model seeks to build exposure-spatial relationships between contaminant sources and receptors, quantify the uncertainty, and provide a platform for incorporation of data from a variety of studies. Knowledge of infection risk to flight crews and passengers is needed to form a coherent response to an unfolding epidemic, and infection risk may have an airborne pathogen exposure component. The general aircraf-tcabin air-contaminant transport effect model was applied to datasets from the University of Illinois and Kansas State University and also to case study information from a flight with probable severe acute respiratory syndrome transmission. Data were fit to regression curves, where the dependent variable was contaminant concentration (normalized for source strength and ventilation rate), and the independent variable was distance between source and measurement locations. The data-driven model showed exposure to viable small droplets and post-evaporation nuclei at a source distance of several rows in a mock-up of a twin-aisle airliner with seven seats per row. Similar behavior was observed in tracer gas, particle experiments, and flight infection data for severe acute respiratory syndrome. The study supports the airborne pathway as part of the matrix of possible disease transmission modes in aircraft cabins. PMID:26526769

Assessing toxicant effects in a complex estuary: A case study of effects of silver on reproduction in the bivalve, Potamocorbula amurensis, in San Francisco Bay

USGS Publications Warehouse

Brown, C.L.; Parchaso, F.; Thompson, J.K.; Luoma, S.N.

2003-01-01

Contaminant exposures in natural systems can be highly variable. This variability is superimposed upon cyclic variability in biological processes. Together, these factors can confound determination of contaminant effects. Long term, multidisciplined studies with high frequency sampling can be effective in overcoming such obstacles. While studying trace metal contamination in the tissues of the clam, Potamocorbula amurensis, in the northern reach of San Francisco Bay, an episode of high Ag concentrations was identified (maximum of 5.5 ??g g-1) at two mid-estuary sites. High concentrations were not seen in clams up-estuary (maximum of 1.92 ??g g-1) from these sites and were reduced down-estuary (maximum of 2.67 ??g g-1). Silver is not common naturally in the environment, so its elevated presence is usually indicative of anthropogenic influences such as municipal and industrial discharge. Monthly sampling of reproductive status of clams characterized the reproductive cycle and differences in the patterns of reproductive activity that corresponded to changes in Ag tissue concentrations. The proportion of reproductive clams was less than 60% during periods when tissue concentrations were high (generally >2 ??g g-1). When tissue concentrations of Ag decreased (???1 ??g g-1), the proportion of reproductive clams was 80 to 100%. A comparison between the annual proportion of reproductive clams and annual Ag tissue concentrations showed a significant negative correlation. No other measured environmental variables were correlated with reproductive impairment. The weight-of-evidence approach strongly supports a cause and effect relationship between Ag contamination and reduced reproductive activity in P. amurensis.

Assessing toxicant effects in a complex estuary--A case study of effects of silver on reproduction in the bivalve, Potamocurbula amurensis, in San Francisco Bay

USGS Publications Warehouse

Brown, Cynthia L.; Parchaso, Francis; Thompson, Janet K.; Luoma, Samuel N.

2003-01-01

Contaminant exposures in natural systems can be highly variable. This variability is superimposed upon cyclic variability in biological processes. Together, these factors can confound determination of contaminant effects. Long term, multidisciplined studies with high frequency sampling can be effective in overcoming such obstacles. While studying trace metal contamination in the tissues of the clam, Potamocorbula amurensis, in the northern reach of San Francisco Bay, an episode of high Ag concentrations was identified (maximum of 5.5 µg g−1) at two mid-estuary sites. High concentrations were not seen in clams up-estuary (maximum of 1.92 µg g−1) from these sites and were reduced down-estuary (maximum of 2.67 µg g−1). Silver is not common naturally in the environment, so its elevated presence is usually indicative of anthropogenic influences such as municipal and industrial discharge. Monthly sampling of reproductive status of clams characterized the reproductive cycle and differences in the patterns of reproductive activity that corresponded to changes in Ag tissue concentrations. The proportion of reproductive clams was less than 60% during periods when tissue concentrations were high (generally >2 µg g−1). When tissue concentrations of Ag decreased (≤1 µg g−1), the proportion of reproductive clams was 80 to 100%. A comparison between the annual proportion of reproductive clams and annual Ag tissue concentrations showed a significant negative correlation. No other measured environmental variables were correlated with reproductive impairment. The weight-of-evidence approach strongly supports a cause and effect relationship between Ag contamination and reduced reproductive activity in P. amurensis.

Effects of seasonal operation on the quality of water produced by public-supply wells.

PubMed

Bexfield, Laura M; Jurgens, Bryant C

2014-09-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

Patterns of benthic bacterial diversity in coastal areas contaminated by heavy metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)

PubMed Central

Quero, Grazia Marina; Cassin, Daniele; Botter, Margherita; Perini, Laura; Luna, Gian Marco

2015-01-01

Prokaryotes in coastal sediments are fundamental players in the ecosystem functioning and regulate processes relevant in the global biogeochemical cycles. Nevertheless, knowledge on benthic microbial diversity patterns across spatial scales, or as function to anthropogenic influence, is still limited. We investigated the microbial diversity in two of the most chemically polluted sites along the coast of Italy. One site is the Po River Prodelta (Northern Adriatic Sea), which receives contaminant discharge from one of the largest rivers in Europe. The other site, the Mar Piccolo of Taranto (Ionian Sea), is a chronically polluted area due to steel production plants, oil refineries, and intense maritime traffic. We collected sediments from 30 stations along gradients of contamination, and studied prokaryotic diversity using Illumina sequencing of amplicons of a 16S rDNA gene fragment. The main sediment variables and the concentration of eleven metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured. Chemical analyses confirmed the high contamination in both sites, with concentrations of PCBs particularly high and often exceeding the sediment guidelines. The analysis of more than 3 millions 16S rDNA sequences showed that richness decreased with higher contamination levels. Multivariate analyses showed that contaminants significantly shaped community composition. Assemblages differed significantly between the two sites, but showed wide within-site variations related with spatial gradients in the chemical contamination, and the presence of a core set of OTUs shared by the two geographically distant sites. A larger importance of PCB-degrading taxa was observed in the Mar Piccolo, suggesting their potential selection in this historically polluted site. Our results indicate that sediment contamination by multiple contaminants significantly alter benthic prokaryotic diversity in coastal areas, and suggests considering the potential contribution of the resident microbes to contaminant bioremediation actions. PMID:26528247

Evaluating the Spatial Distribution of Toxic Air Contaminants in Multiple Ecosystem Indicators in the Sierra Nevada-Southern Cascades

NASA Astrophysics Data System (ADS)

Nanus, L.; Simonich, S. L.; Rocchio, J.; Flanagan, C.

2013-12-01

Toxic air contaminants originating from agricultural areas of the Central Valley in California threaten vulnerable sensitive receptors including surface water, vegetation, snow, sediments, fish, and amphibians in the Sierra Nevada-Southern Cascades region. The spatial distribution of toxic air contaminants in different ecosystem indicators depends on variation in atmospheric concentrations and deposition, and variation in air toxics accumulation in ecosystems. The spatial distribution of organic air toxics and mercury at over 330 unique sampling locations and sample types over two decades (1990-2009) in the Sierra Nevada-Southern Cascades region were compiled and maps were developed to further understand spatial patterns and linkages between air toxics deposition and ecological effects. Potential ecosystem impacts in the Sierra Nevada-Southern Cascades region include bioaccumulation of air toxics in both aquatic and terrestrial ecosystems, reproductive disruption, and immune suppression. The most sensitive ecological end points in the region that are affected by bioaccumulation of toxic air contaminants are fish. Mercury was detected in all fish and approximately 6% exceeded human consumption thresholds. Organic air toxics were also detected in fish yielding variable spatial patterns. For amphibians, which are sensitive to pesticide exposure and potential immune suppression, increasing trends in current and historic use pesticides are observed from north to south across the region. In other indicators, such as vegetation, pesticide concentrations in lichen increase with increasing elevation. Current and historic use pesticides and mercury were also observed in snowpack at high elevations in the study area. This study shows spatial patterns in toxic air contaminants, evaluates associated risks to sensitive receptors, and identifies data gaps. Future research on atmospheric modeling and information on sources is needed in order to predict which ecosystems are the most sensitive to toxic air contaminants in the Sierra Nevada-Southern Cascades region.

Concentration of arsenic in water, sediments and fish species from naturally contaminated rivers.

PubMed

Rosso, Juan José; Schenone, Nahuel F; Pérez Carrera, Alejo; Fernández Cirelli, Alicia

2013-04-01

Arsenic (As) may occur in surface freshwater ecosystems as a consequence of both natural contamination and anthropogenic activities. In this paper, As concentrations in muscle samples of 10 fish species, sediments and surface water from three naturally contaminated rivers in a central region of Argentina are reported. The study area is one of the largest regions in the world with high As concentrations in groundwater. However, information of As in freshwater ecosystems and associated biota is scarce. An extensive spatial variability of As concentrations in water and sediments of sampled ecosystems was observed. Geochemical indices indicated that sediments ranged from mostly unpolluted to strongly polluted. The concentration of As in sediments averaged 6.58 μg/g ranging from 0.23 to 59.53 μg/g. Arsenic in sediments barely followed (r = 0.361; p = 0.118) the level of contamination of water. All rivers showed high concentrations of As in surface waters, ranging from 55 to 195 μg/L. The average concentration of As in fish was 1.76 μg/g. The level of contamination with As differed significantly between species. Moreover, the level of bioaccumulation of As in fish species related to the concentration of As in water and sediments also differed between species. Whilst some fish species seemed to be able to regulate the uptake of this metalloid, the concentration of As in the large catfish Rhamdia quelen mostly followed the concentration of As in abiotic compartments. The erratic pattern of As concentrations in fish and sediments regardless of the invariable high levels in surface waters suggests the existence of complex biogeochemical processes behind the distribution patterns of As in these naturally contaminated ecosystems.

Soil invertebrate community change over fuel-contaminated sites on a subantarctic island: An ecological field-based line of evidence for site risk assessment.

PubMed

Wasley, Jane; Mooney, Thomas J; King, Catherine K

2016-04-01

A number of fuel spills, of both recent and historic origins, have occurred on World Heritage-listed subantarctic Macquarie Island. Sites contaminated by mainly diesel fuels are undergoing remediation by the Australian Antarctic Division. The risks posed by these sites are being managed using a "weight of evidence" approach, for which this study provides a preliminary line of evidence for the ecological assessment component of this site management decision framework. This knowledge is pertinent, given the absence of environmental guidelines for fuel contaminants in subantarctic ecosystems. We provide a field-based, site-specific ecological risk assessment for soil invertebrate communities across the fuel spill sites, before the commencement of in situ remediation activities. Springtails (Collembola) were the most abundant taxa. Springtail community patterns showed only limited correlations with the level of fuel contamination at the soil surface, even when elevated levels occurred in the substratum layers. Of the environmental variables measured, community patterns were most strongly correlated with vegetation cover. We identify a suite of 6 species that contribute most to the community dynamics across these sites. A subset of these we propose as useful candidates for future development of single-species toxicity tests: Folsomotoma punctata, Cryptopygus caecus, Cryptopygus antarcticus and Parisotoma insularis. Findings from this study advance our understanding of soil invertebrate community dynamics within these contaminated sites, directly contributing to the improved management and restoration of the sites. Not only does this study provide an important line of evidence for the island's ecological risk assessment for fuel contaminants, it also enhances our understanding of the potential impact of fuels at other subantarctic islands. © 2015 SETAC.

DOWN-STREAM SPATIAL DISTRIBUTION OF ANTIBIOTIC RESISTANCE TRAITS ALONG METAL CONTAMINATED STREAM REACHES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuckfield, C; J V Mcarthur

2007-04-16

Sediment bacteria samples were collected from three streams in South Carolina, two contaminated with multiple metals (Four Mile Creek and Castor Creek), one uncontaminated (Meyers Branch), and another metal contaminated stream (Lampert Creek) in northern Washington State. Growth plates inoculated with Four Mile Creek sample extracts show bacteria colony growth after incubation on plates containing either one of two aminoglycosides (kanamycin or streptomycin), tetracycline or chloramphenocol. This study analyzes the spatial pattern of antibiotic resistance in culturable sediment bacteria in all four streams that may be due to metal contamination. We summarize the two aminoglycoside resistance measures and the 10more » metals concentrations by Principal Components Analysis. Respectively, 63% and 58% of the variability was explained in the 1st principal component of each variable set. We used the respective multivariate summary metrics (i.e. 1st principal component scores) as input measures for exploring the spatial correlation between antibiotic resistance and metal concentration for each stream reach sampled. Results show a significant and negative correlation between metals scores versus aminoglycoside resistance scores and suggest that selection for metal tolerance among sediment bacteria may influence selection for antibiotic resistance differently than previously supposed.. In addition, we borrow a method from geostatistics (variography) wherein a spatial cross-correlation analysis shows that decreasing metal concentrations scores are associated with increasing aminoglycoside resistance scores as the separation distance between sediment samples decreases, but for contaminated streams only. Since these results were counter to our initial expectation and to other experimental evidence for water column bacteria, we suspect our field results are influenced by metal bioavailability in the sediments and by a contaminant promoted interaction or ''cocktail effect'' from complex combinations of pollution mediated selection agents.« less

PCDDs, PCDFs, and coplanar PCBs in albatross from the North Pacific and Southern Oceans: levels, patterns, and toxicological implications.

PubMed

Tanabe, Shinsuke; Watanabe, Mafumi; Minh, Tu Binh; Kunisue, Tatsuya; Nakanishi, Shigeyuki; Ono, Hitoshi; Tanaka, Hiroyuki

2004-01-15

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (coplanar PCBs) were determined in five albatross species collected from the North Pacific and Southern Oceans to assess the north-south differences in residue levels, accumulation patterns, and toxic potential. Black-footed and Laysan albatrosses from the North Pacific Ocean contained higher levels of PCDD/Fs and coplanar PCBs than albatrosses from the Southern Ocean, indicating that emission sources of these contaminants were predominant in the northern hemisphere. Residue levels in albatrosses from the remote North Pacific Ocean far from the point source of pollution were comparable to or higher than those in terrestrial and coastal birds from contaminated areas in developed nations, suggesting the specific exposure and accumulation of PCDD/Fs and coplanar PCBs in albatross. The long life span and ingestion of plastic resin pellets by albatrosses could be the plausible explanations for the elevated accumulation of persistent and lipophilic contaminants including PCDD/Fs and coplanar PCBs in these birds. Relative proportions of PCDFs and coplanar PCBs in albatross were higher than those observed in birds inhabiting terrestrial and coastal areas, suggesting that these toxic chemicals may have higher transportability by air and water than PCDDs. Congener patterns of PCDD/Fs in albatross showed less variability as compared to those in terrestrial species, indicating that contamination patterns of PCDD/Fs were similar within the open ocean environment. Contributions of PCDD/Fs to total TEQs in albatrosses from the open ocean were generally lower than those in terrestrial birds, suggesting different toxic potency of PCDD/Fs and coplanar PCBs on animals inhabiting open ocean and terrestrial environment. Whereas albatrosses from southern oceans retained lower TEQ concentrations, possible adverse effects of PCDD/Fs and coplanar PCBs to black-footed and Laysan albatrosses of the North Pacific Ocean may be suspected from TEQ levels.

Processes of contaminant accumulation in an Arctic beluga whale population

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hickie, B.E.; Muir, D.; Kingsley, M.

1995-12-31

As long-lived top predators in marine food chains, marine mammals accumulate high levels of persistent organic contaminants. While arctic marine mammal contaminant concentrations are lower than those from temperate regions, levels are sufficiently high to be a health concern to people who rely on marine mammals as food. Monitoring programs developed to address this problem and to define spatial and temporal trends often are difficult to interpret since tissue contaminant concentrations vary with species, age, sex, reproductive effort, and condition (ie blubber thickness). It can be difficult to relate contaminant concentrations in other environmental compartments to those in marine mammalsmore » since their residues reflect exposure over their entire life, often 20 to 30 years. Contaminant accumulation models for marine mammals enable us to better understand the importance of, and interaction between, factors affecting contaminant accumulation, and can provide a dynamic framework for interpreting contaminant monitoring data. The authors developed two models for the beluga whale (Delphinapterus leucas): one provides a detailed view of processes at the individual level, the other examines population-based processes. The models quantify uptake, release and disposition of organic contaminants over their entire lifespan by incorporating all aspects of life-history. These models are used together to examine impact of a variety of factors on patterns and variability of PCBs found in the West Greenland beluga population (sample size: 696, 729). Factors examined include: energetics, growth, birth rate, lactation, contaminant assimilation and clearance rates, and dietary contaminant concentrations. Results are discussed in relation to the use of marine mammals for monitoring contaminant trends.« less

Characterization and assessment of potential environmental risk of tailings stored in seven impoundments in the Aries river basin, Western Romania

PubMed Central

2013-01-01

Background The objective of this study was to examine the potential environmental risk of tailings resulted after precious and base metal ores processing, stored in seven impoundments located in the Aries river basin, Romania. The tailings were characterized by mineralogical and elemental composition, contamination indices, acid rock drainage generation potential and water leachability of hazardous/priority hazardous metals and ions. Multivariate statistical methods were used for data interpretation. Results Tailings were found to be highly contaminated with several hazardous/priority hazardous metals (As, Cu, Cd, Pb), and pose potential contamination risk for soil, sediments, surface and groundwater. Two out of the seven studied impoundments does not satisfy the criteria required for inert wastes, shows acid rock drainage potential and thus can contaminate the surface and groundwater. Three impoundments were found to be highly contaminated with As, Pb and Cd, two with As and other two with Cu. The tailings impoundments were grouped based on the enrichment factor, geoaccumulation index, contamination factor and contamination degree of 7 hazardous/priority hazardous metals (As, Cd, Cr, Cu, Ni, Pb, Zn) considered typical for the studied tailings. Principal component analysis showed that 47% of the elemental variability was attributable to alkaline silicate rocks, 31% to acidic S-containing minerals, 12% to carbonate minerals and 5% to biogenic elements. Leachability of metals and ions was ascribed in proportion of 61% to silicates, 11% to acidic minerals and 6% to the organic matter. A variability of 18% was attributed to leachability of biogenic elements (Na, K, Cl-, NO3-) with no potential environmental risk. Pattern recognition by agglomerative hierarchical clustering emphasized the grouping of impoundments in agreement with their contamination degree and acid rock drainage generation potential. Conclusions Tailings stored in the studied impoundments were found to be contaminated with some hazardous/ priority hazardous metals, fluoride and sulphate and thus presents different contamination risk for the environment. A long term monitoring program of these tailings impoundments and the expansion of the ecologization measures in the area is required. PMID:23311708

Origin of the Permian-Triassic komatiites, northwestern Vietnam

NASA Astrophysics Data System (ADS)

Hanski, Eero; Walker, Richard J.; Huhma, Hannu; Polyakov, Gleb V.; Balykin, Pavel A.; Tran Trong Hoa; Ngo Thi Phuong

Rare examples of Phanerozoic komatiites are found in the Song Da zone, NW Vietnam. These komatiites were erupted through continental crust and may belong to the SE extension of the Permo-Triassic Emeishan volcanic province located in SW China. They provide a good opportunity to study the source characteristics of starting plume magmas in a continental flood basalt province. Erupted on late-Permian carbonate rocks, the komatiitic rocks are interbedded with low-Ti olivine basalts. Basaltic komatiites display pyroxene spinifex textures, while more magnesian rocks (MgO up to 32 wt.%) are porphyritic, containing a single, cognate population of euhedral to elongated olivine phenocrysts with Fo up to 93.0%. This suggests a highly magnesian parental magma with 22-23 wt.% MgO. In terms of major and minor elements, the komatiites are similar to the ca. 89 Ma old Gorgona Island komatiites of Colombia. The Song Da komatiites are also strongly light-rare-earth-element- (LREE) depleted (CeN/YbN 0.30-0.62) and have unfractionated heavy rare earth element (HREE) patterns. The komatiites have high Os concentrations (up to 7.0 ppb), low but variable Re/Os ratios, and define an isochron with an age of 270+/-21 Ma, and an initial 188Os/187Os ratio of 0.12506+/- 0.00041 (γOs=+0.02+/-0.40). The Os isotopic systematics of the komatiites show no effects of crustal contamination. In contrast, their initial ɛNd values range from +3 to +8, reflecting varying but generally small degrees of contamination with Proterozoic sialic basement material. Associated low-Ti basalts have low initial ɛNd values (-0.8 to -7.5), high initial γOs values (>=15), flat or LREE-enriched REE patterns, and Nb-Ta depletion. These characteristics are also attributed to variable extents of crustal contamination.

The effect of heavy metal contamination on the bacterial community structure at Jiaozhou Bay, China.

PubMed

Yao, Xie-Feng; Zhang, Jiu-Ming; Tian, Li; Guo, Jian-Hua

In this study, determination of heavy metal parameters and microbiological characterization of marine sediments obtained from two heavily polluted sites and one low-grade contaminated reference station at Jiaozhou Bay in China were carried out. The microbial communities found in the sampled marine sediments were studied using PCR-DGGE (denaturing gradient gel electrophoresis) fingerprinting profiles in combination with multivariate analysis. Clustering analysis of DGGE and matrix of heavy metals displayed similar occurrence patterns. On this basis, 17 samples were classified into two clusters depending on the presence or absence of the high level contamination. Moreover, the cluster of highly contaminated samples was further classified into two sub-groups based on the stations of their origin. These results showed that the composition of the bacterial community is strongly influenced by heavy metal variables present in the sediments found in the Jiaozhou Bay. This study also suggested that metagenomic techniques such as PCR-DGGE fingerprinting in combination with multivariate analysis is an efficient method to examine the effect of metal contamination on the bacterial community structure. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Modeling and testing of reactive contaminant transport in drinking water pipes: chlorine response and implications for online contaminant detection.

PubMed

Jeffrey Yang, Y; Goodrich, James A; Clark, Robert M; Li, Sylvana Y

2008-03-01

A modified one-dimensional Danckwerts convection-dispersion-reaction (CDR) model is numerically simulated to explain the observed chlorine residual loss for a "slug" of reactive contaminants instantaneously introduced into a drinking water pipe of assumed no or negligible wall demand. In response to longitudinal dispersion, a contaminant propagates into the bulk phase where it reacts with disinfectants in the water. This process generates a U-shaped pattern of chlorine residual loss in a time-series concentration plot. Numerical modeling indicates that the residual loss curve geometry (i.e., slope, depth, and width) is a function of several variables such as axial Péclet number, reaction rate constants, molar fraction of the fast- and slow-reacting contaminants, and the quasi-steady-state chlorine decay inside the "slug" which serves as a boundary condition of the CDR model. Longitudinal dispersion becomes dominant for less reactive contaminants. Pilot-scale pipe flow experiments for a non-reactive sodium fluoride tracer and the fast-reacting aldicarb, a pesticide, were conducted under turbulent flow conditions (Re=9020 and 25,000). Both the experimental results and the CDR modeling are in agreement showing a close relationship among the aldicarb contaminant "slug", chlorine residual loss and its variations, and a concentration increase of chloride as the final reaction product. Based on these findings, the residual loss curve and its geometry are useful tools to identify the presence of a contaminant "slug" and infer its reactive properties in adaptive contaminant detections.

Links between contaminant hotspots in low flow estuarine systems and altered sediment biogeochemical processes

NASA Astrophysics Data System (ADS)

Sutherland, Michael D.; Dafforn, Katherine A.; Scanes, Peter; Potts, Jaimie; Simpson, Stuart L.; Sim, Vivian X. Y.; Johnston, Emma L.

2017-11-01

The urbanisation of coastal zones is a major threat to the health of global estuaries and has been linked to increased contamination (e.g. metals) and excess organic matter. Urban stormwater networks collect and funnel contaminants into waterways at point sources (e.g. stormdrains). Under dry, low flow conditions, these stormwater contaminants can accumulate in sediments over time and result in modifications to benthic sediment biogeochemical processes. To quantify these processes, this field study measured differences in benthic metabolism (CR, GPP, NEM) and sediment-water nutrient fluxes (NH3, NOx, PO4) associated with stormdrains (0 m, 200 m and 1000 m away) and increased water-retention (embayments vs channels). Significant changes to benthic metabolism were detected with distance from stormdrains, and with differences in water-retention rates, above natural spatial and temporal variation. Oxygen consumption was ∼50% higher at stormdrains (0 m) compared to 1000 m away and >70% higher at stormdrains (0 m) located in embayments compared to channels. Oxygen production also appeared to decrease with distance from stormdrains in embayments, but patterns were variable. These changes to benthic metabolism were of a magnitude expected to influence benthic nutrient cycling, but NH3, NOx and PO4 fluxes were generally low, and highly spatially and temporally variable. Overall, metal (Cu) contamination explained most of the variation in sediment biogeochemical processes between embayments and channels, while sediment grain size explained differences in fluxes with distance from stormdrains. Importantly, although there was evidence of increased productivity associated with stormdrains, we also detected evidence of early hypoxia suggesting that systems with legacy stormwater contaminants exist on a tipping point. Future work should investigate changes to sediment processes after a major rainfall event, when large and sudden inputs of potentially toxic contaminants occur. Monitoring benthic O2 fluxes could be a sensitive measure of ecological change under these conditions.

Modeling fecal contamination in the Aljezur coastal stream (Portugal)

NASA Astrophysics Data System (ADS)

Rodrigues, Marta; Oliveira, Anabela; Guerreiro, Martha; Fortunato, André Bustorff; Menaia, José; David, Luís Mesquita; Cravo, Alexandra

2011-06-01

This study aims at understanding the fecal contamination behavior in a small coastal stream (Aljezur, Portugal), which has significant economic and ecological values. Like in most small coastal systems, circulation and water renewal in the Aljezur stream exhibit a strong variability due to their dependence on tides, waves, intermittent river flows, and a highly variable morphology. Hence, the problem was approached through a combination of field surveys and the development and application of a hard-coupled three-dimensional hydrodynamic and fecal contamination model. Salinity and temperature results have shown that mixing and transport in the stream are very sensitive to the river flow and wind forcing. The model is able to represent the main patterns and trends observed in Escherichia coli and fecal enterococcus concentrations along the stream, for different environmental and contamination conditions, suggesting die-off rates on the order of 0.50-0.55 day-1. Die-off rate and the representation of the sediment-associated processes were identified as the major remaining sources of uncertainty in the model. Results show that, owing to the processes that occur along the stream, fecal bacteria reach the beaches water in numbers that comply with the European Bathing Waters Directive, even during the summer periods when the upstream concentrations are larger. In particular, results suggest a direct relation between the tidal propagation upstream and the reduction of the fecal bacteria concentrations along the stream that can be relevant for the development of a strategy for the management of the system's water safety.

Emotional and Cognitive Variables Associated with Contamination-Related Obsessive-Compulsive Symptoms.

PubMed

García-Soriano, Gemma; Rosell-Clari, Vicent; Serrano, Miguel Ángel

2016-05-23

Different variables have been associated with the development/ maintenance of contamination-related obsessive-compulsive disorder (OCD), although the relevance of these factors has not been clearly established. The present study aimed to analyze the relevance and specificity of these variables. Forty-five women with high scores on obsessive-compulsive contamination symptoms (n = 16) or checking symptoms (n = 15), or non-clinical scores (n = 14) participated in a behavioral approach/avoidance task (BAT) with a contamination-OCD stimulus. Vulnerability variables and participants' emotional, cognitive, physiological and behavioral responses to the BAT were appraised. Results show that fear of illness was a relevant vulnerability variable specific to contamination participants (p = .001; η2 p = .291). Contamination participants responded with significantly higher subjective disgust (p =.001; η2 p = .269), anxiety (p = .001; η2 p = .297), urge to wash (p < .001; η2 p = 370), threat from emotion (p < .001; η2 p = .338) and contamination severity (p = .002; η2 p = .260) appraisals, and with lower behavioral approach (p = .008; η2 p = .208) than the other two groups. Moreover, contamination participants showed lower heart rate acceleration (p = .046; η2 p = .170) and higher contamination likelihood appraisals (p < .001; η2 p = .342) than the non-clinical group. Urge to wash was predicted by state disgust (R 2 change = .346) and threat from emotion (R 2 change = .088). These responses were predicted by general anxiety sensitivity (R 2 change = .161), disgust propensity (R 2 change = .255) and fear of illness (R 2 change = .116), but not by other vulnerability variables such as dysfunctional beliefs about thoughts (Responsibility and Overestimation of threat) or disgust sensitivity. State disgust, threat from disgust, anxiety sensitivity and fear of illness were found to be the most relevant variables in contamination symptoms.

Hierarchical Bayesian models to assess between- and within-batch variability of pathogen contamination in food.

PubMed

Commeau, Natalie; Cornu, Marie; Albert, Isabelle; Denis, Jean-Baptiste; Parent, Eric

2012-03-01

Assessing within-batch and between-batch variability is of major interest for risk assessors and risk managers in the context of microbiological contamination of food. For example, the ratio between the within-batch variability and the between-batch variability has a large impact on the results of a sampling plan. Here, we designed hierarchical Bayesian models to represent such variability. Compatible priors were built mathematically to obtain sound model comparisons. A numeric criterion is proposed to assess the contamination structure comparing the ability of the models to replicate grouped data at the batch level using a posterior predictive loss approach. Models were applied to two case studies: contamination by Listeria monocytogenes of pork breast used to produce diced bacon and contamination by the same microorganism on cold smoked salmon at the end of the process. In the first case study, a contamination structure clearly exists and is located at the batch level, that is, between batches variability is relatively strong, whereas in the second a structure also exists but is less marked. © 2012 Society for Risk Analysis.

Patterns of water-quality variability in San Francisco Bay during the first six years of the regional monitoring program, 1993-1998

USGS Publications Warehouse

Cloern, J.E.; Cole, B.E.; Edmunds, J.L.; Schraga, T.S.; Arnsberg, A.

2000-01-01

Monitoring Results presents data from the Status and Trends portion of the 1998 San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP). A list of reports on Pilot and Special Studies, as well as other RMP related activities can be found at the end of this document. These reports provide perspective and insight on important contaminant issues identified by the RMP, and they describe results from projects that took advantage of RMP field operations. For a summary of the conditions of the Estuary see The Pulse . A print copy may also be ordered by contacting the San Francisco Estuary Institute (SFEI). In 1998, the San Francisco Regional Water Quality Control Board (Regional Board) and seventy-three federal, state, and local agencies and companies participated in the RMP as funders and service providers (Table 1.1). Participants also assist in directing the Program through input or participation on the Steering and Technical Review Committees. The RMP’s overall goal is to provide data and interpretation that helps to address certain information needs of the Regional Board. In general, these efforts fall under five major objectives which provide a framework for efforts to respond to more specific management questions. 1. Describe patterns and trends in contaminant concentration and distribution. 2. Describe general sources and loadings of contamination to the Estuary. 3. Measure contaminant effects on selected parts of the Estuary ecosystem. 4. Compare monitoring information to relevant water quality objectives and other guidelines. 5. Synthesize and distribute information from a range of sources to present a more complete picture of the sources, distribution, fates, and effects of contaminants in the Estuary ecosystem.

Effects of egg order on organic and inorganic element concentrations and egg characteristics in tree swallows, tachycineta bicolor

USGS Publications Warehouse

Custer, Christine M.; Gray, B.R.; Custer, T.W.

2010-01-01

The laying order of tree swallow eggs was identified from the Housatonic River, Berkshire County, Massachusetts, USA, and eggs were chemically analyzed individually to document possible effects of laying order on organic contaminant and inorganic element concentrations. Effects of laying order on other parameters such as egg weight, size, and lipid and moisture content also were assessed. Some effects of egg order on total polychlorinated biphenyls (PCBs) were detected, but the effect was not uniform across individual females or between years. In 2004, clutches with higher total PCBs tended to have concentrations decline across egg order, whereas clutches with lower concentrations of PCBs tended to increase across egg order. In contrast, in 2005, there was a tendency for concentrations to increase across egg order. Polychlorinated biphenyl concentrations were highly variable within and among clutches in both years. The directionality of egg order associations (i.e., slopes) for trace elements was element dependent, was positive for Mn and Zn, was negative for B, and had no slope for Cr. Whole egg weight increased across egg order. Percentage lipid was variable within a clutch, with no pattern common across all females. Percentage lipid was also correlated with organic contaminant concentration. In highly contaminated environments, higher lipid content could have the unanticipated corollary of having higher concentrations of lipophilic contaminants such as PCBs. To reduce the effect of high variation within a clutch when assessing contamination exposure, it is recommended that two eggs per clutch be collected and pooled for chemical analysis. We further recommend that, as long as the two eggs are randomly collected, the additional effort needed to identify and collect specific eggs is not warranted. ?? 2009 SETAC.

Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

USGS Publications Warehouse

Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

2008-01-01

Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Seasonal variability of polychlorinated biphenyls (PCBs) and polychlorinated diphenyl ethers (PBDEs) congener profiles in butter in Poland: dietary risk evaluation.

PubMed

Roszko, Marek; Szymczyk, Krystyna; Rzepkowska, Małgorzata; Jędrzejczak, Renata

2014-01-01

Various statistical methods have been employed to analyse in details seasonal diversification of polychlorinated biphenyl (PCB)/polybrominated diphenyl ether (PBDE) congener profiles found in butter fat. The variability of the PCB/PBDE congener profiles indicates the presence of various sources of the milk fat contamination. The obtained results suggest that the environmental chemical background has the highest share in the contamination sources pattern. Ion trap mass spectrometry coupled to high-resolution gas chromatography with semi-permeable membrane dialysis sample cleanup was used for determination of PCBs and PBDEs in milk fat. Determined butter fat PCB profiles were similar to the profiles characteristic for Aroclor 1254 technical mixture. Our data indicate that dietary intake of PCB/PBDE with milk and milk products may be estimated to be about 717.5 pg kg b.w.(-1) day(-1) for six-indicator PCBs, 0.329 (equivalent toxicity, TEQ) pg kg b.w.(-1) day(-1) for 12 DL PCBs and 50 pg kg b.w.(-1) day(-1) for PBDEs (sum of 14 congeners).

Occupational exposure of electrical utility linemen to pentachlorophenol.

PubMed

Thind, K S; Karmali, S; House, R A

1991-12-01

Occupational exposure to pentachlorophenol (PCP) for a crew of electrical utility linemen was monitored over a 6-month period by using total PCP in urine per gram of creatinine as a biological monitoring parameter. Urine samples were collected from three groups: A, B, and control, at a 4-week frequency during 1989. Group A was required to use new gloves after each 4-week work period; Group B changed gloves on a need basis as per normal operating procedure. The control group consisted of members of the administrative office staff who were not occupationally exposed. The used gloves returned by Group A were monitored for contamination. On the basis of analysis of the collected data the following conclusions were noted. (1) The linemen experienced a seasonal exposure pattern with exposures peaking in July and August. This seasonal effect was also observed with glove contamination data. (2) The glove contamination levels were significantly associated with urine PCP concentrations when both these variables were expressed as geometric means for the individuals in Group A. Inclusion of work experience as an additional variable enhances this association. Less experienced linemen tended to perform more activities with higher current exposure and had higher urine and glove PCP measurements and higher correlations between these variables than more experienced linemen. (3) Over the study period, the difference in long-term exposures of Group A and Group B linemen was not statistically significant. (4) The long-term individual exposures, calculated as the geometric mean of each individual's sequential sample readings, were all below the biological monitoring guideline value of 1000 micrograms PCP/g creatinine.

Fear and disgust in women: Differentiation of cardiovascular regulation patterns.

PubMed

Comtesse, Hannah; Stemmler, Gerhard

2017-02-01

Both fear and disgust facilitate avoidance of threat. From a functional view, however, cardiovascular responses to fear and disgust should differ as they prepare for appropriate behavior to protect from injury and infection, respectively. Therefore, we examined the cardiovascular responses to fear and contamination-related disgust in comparison to an emotionally neutral state induced with auditory scripts and film clips in female participants. Ten emotion and motivation self-reports and ninecardiovascular response factors derived from 23 cardiovascular variables served as dependent variables. Self-reports confirmed the specific induction of fear and disgust. In addition, fear and disgust differed in their cardiovascular response patterning. For fear, we observed specific increases in factors indicating vasoconstriction and cardiac pump function. For disgust, we found specific increases in vagal cardiac control and decreases in myocardial contractility. These findings provide support for the cardiovascular specificity of fear and disgust and are discussed in terms of a basic emotions approach. Copyright © 2016. Published by Elsevier B.V.

Impacts of the Deepwater Horizon oil spill on deep-sea coral-associated sediment communities

USGS Publications Warehouse

Demopoulos, Amanda W.J.; Bourque, Jill R.; Cordes, Erik E.; Stamler, Katherine

2016-01-01

Cold-water corals support distinct populations of infauna within surrounding sediments that provide vital ecosystem functions and services in the deep sea. Yet due to their sedentary existence, infauna are vulnerable to perturbation and contaminant exposure because they are unable to escape disturbance events. While multiple deep-sea coral habitats were injured by the 2010 Deepwater Horizon (DWH) oil spill, the extent of adverse effects on coral-associated sediment communities is unknown. In 2011, sediments were collected adjacent to several coral habitats located 6 to 183 km from the wellhead in order to quantify the extent of impact of the DWH spill on infaunal communities. Higher variance in macrofaunal abundance and diversity, and different community structure (higher multivariate dispersion) were associated with elevated hydrocarbon concentrations and contaminants at sites closest to the wellhead (MC294, MC297, and MC344), consistent with impacts from the spill. In contrast, variance in meiofaunal diversity was not significantly related to distance from the wellhead and no other community metric (e.g. density or multivariate dispersion) was correlated with contaminants or hydrocarbon concentrations. Concentrations of polycyclic aromatic hydrocarbons (PAH) provided the best statistical explanation for observed macrofaunal community structure, while depth and presence of fine-grained mud best explained meiofaunal community patterns. Impacts associated with contaminants from the DWH spill resulted in a patchwork pattern of infaunal community composition, diversity, and abundance, highlighting the role of variability as an indicator of disturbance. These data represent a useful baseline for tracking post-spill recovery of these deep-sea communities.

A novel approach to assessing environmental disturbance based on habitat selection by zebra fish as a model organism.

PubMed

Araújo, Cristiano V M; Griffith, Daniel M; Vera-Vera, Victoria; Jentzsch, Paul Vargas; Cervera, Laura; Nieto-Ariza, Beatriz; Salvatierra, David; Erazo, Santiago; Jaramillo, Rusbel; Ramos, Luis A; Moreira-Santos, Matilde; Ribeiro, Rui

2018-04-01

Aquatic ecotoxicity assays used to assess ecological risk assume that organisms living in a contaminated habitat are forcedly exposed to the contamination. This assumption neglects the ability of organisms to detect and avoid contamination by moving towards less disturbed habitats, as long as connectivity exists. In fluvial systems, many environmental parameters vary spatially and thus condition organisms' habitat selection. We assessed the preference of zebra fish (Danio rerio) when exposed to water samples from two western Ecuadorian rivers with apparently distinct disturbance levels: Pescadillo River (highly disturbed) and Oro River (moderately disturbed). Using a non-forced exposure system in which water samples from each river were arranged according to their spatial sequence in the field and connected to allow individuals to move freely among samples, we assayed habitat selection by D. rerio to assess environmental disturbance in the two rivers. Fish exposed to Pescadillo River samples preferred downstream samples near the confluence zone with the Oro River. Fish exposed to Oro River samples preferred upstream waters. When exposed to samples from both rivers simultaneously, fish exhibited the same pattern of habitat selection by preferring the Oro River samples. Given that the rivers are connected, preference for the Oro River enabled us to predict a depression in fish populations in the Pescadillo River. Although these findings indicate higher disturbance levels in the Pescadillo River, none of the physical-chemical variables measured was significantly correlated with the preference pattern towards the Oro River. Non-linear spatial patterns of habitat preference suggest that other environmental parameters like urban or agricultural contaminants play an important role in the model organism's habitat selection in these rivers. The non-forced exposure system represents a habitat selection-based approach that can serve as a valuable tool to unravel the factors that dictate organisms' spatial distribution in connected ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Biological effects of anthropogenic contaminants in the San Francisco Estuary

USGS Publications Warehouse

Thompson, B.; Adelsbach, T.; Brown, C.; Hunt, J.; Kuwabara, J.; Neale, J.; Ohlendorf, H.; Schwarzbach, S.; Spies, R.; Taberski, K.

2007-01-01

Concentrations of many anthropogenic contaminants in the San Francisco Estuary exist at levels that have been associated with biological effects elsewhere, so there is a potential for them to cause biological effects in the Estuary. The purpose of this paper is to summarize information about biological effects on the Estuary's plankton, benthos, fish, birds, and mammals, gathered since the early 1990s, focusing on key accomplishments. These studies have been conducted at all levels of biological organization (sub-cellular through communities), but have included only a small fraction of the organisms and contaminants of concern in the region. The studies summarized provide a body of evidence that some contaminants are causing biological impacts in some biological resources in the Estuary. However, no general patterns of effects were apparent in space and time, and no single contaminant was consistently related to effects among the biota considered. These conclusions reflect the difficulty in demonstrating biological effects due specifically to contamination because there is a wide range of sensitivity to contaminants among the Estuary's many organisms. Additionally, the spatial and temporal distribution of contamination in the Estuary is highly variable, and levels of contamination covary with other environmental factors, such as freshwater inflow or sediment-type. Federal and State regulatory agencies desire to develop biological criteria to protect the Estuary's biological resources. Future studies of biological effects in San Francisco Estuary should focus on the development of meaningful indicators of biological effects, and on key organism and contaminants of concern in long-term, multifaceted studies that include laboratory and field experiments to determine cause and effect to adequately inform management and regulatory decisions. ?? 2006 Elsevier Inc. All rights reserved.

Analysis of Salmonella sp bacterial contamination on Vannamei Shrimp using binary logit model approach

NASA Astrophysics Data System (ADS)

Oktaviana, P. P.; Fithriasari, K.

2018-04-01

Mostly Indonesian citizen consume vannamei shrimp as their food. Vannamei shrimp also is one of Indonesian exports comodities mainstay. Vannamei shrimp in the ponds and markets could be contaminated by Salmonella sp bacteria. This bacteria will endanger human health. Salmonella sp bacterial contamination on vannamei shrimp could be affected by many factors. This study is intended to identify what factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp. The researchers used the testing result of Salmonella sp bacterial contamination on vannamei shrimp as response variable. This response variable has two categories: 0 = if testing result indicate that there is no Salmonella sp on vannamei shrimp; 1 = if testing result indicate that there is Salmonella sp on vannamei shrimp. There are four factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp, which are the testing result of Salmonella sp bacterial contamination on farmer hand swab; the subdistrict of vannamei shrimp ponds; the fish processing unit supplied by; and the pond are in hectare. This four factors used as predictor variables. The analysis used is Binary Logit Model Approach according to the response variable that has two categories. The analysis result indicates that the factors or predictor variables which is significantly affect the Salmonella sp bacterial contamination on vannamei shrimp are the testing result of Salmonella sp bacterial contamination on farmer hand swab and the subdistrict of vannamei shrimp ponds.

Assessment of persistent brominated and chlorinated organic contaminants in the European eel (Anguilla anguilla) in Flanders, Belgium: Levels, profiles and health risk.

PubMed

Malarvannan, Govindan; Belpaire, Claude; Geeraerts, Caroline; Eulaers, Igor; Neels, Hugo; Covaci, Adrian

2014-06-01

Pooled yellow European eel (Anguilla anguilla (L.)) samples, consisting of 3-10 eels, collected between 2000 and 2009 from 60 locations in Flanders (Belgium) were investigated for persistent contaminants, such as polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and its metabolites (DDTs). The current study expands the knowledge regarding these contaminant concentrations, their patterns and distribution profiles in aquatic ecosystems. PBDEs, HBCDs, PCBs, and DDTs were detected in all eel samples and some samples had high concentrations (up to 1400, 9500, 41,600 and 7000ng/g lw, respectively). PCB levels accounted for the majority of the contamination in most samples. The high variability in PBDE, HBCD, PCB and DDT concentrations reported here is likely due to the variety in sampling locations demonstrating variable local pollution pressures, from highly industrialised areas to small rural creeks. Among PBDEs, BDE-47 (57% contribution to the sum PBDEs), -100 (19%) and -99 (15%) were the predominant congeners, similar to the composition reported in the literature in eel samples. For HBCDs, α-HBCD (74%) was predominant followed by γ-(22%) and β-HBCD (4%) isomers in almost all eel samples. CB-153 (19%) was the most dominant PCB congener, closely followed by CB-138 (11%), CB-180 (9%), CB-187 (8%) and CB-149 (7%). The contribution to the total human exposure through local wild eel consumption was also highly variable. Intake of PBDEs and HBCDs, through consumption of wild eel, was below the RfD values for the average population (consuming on average 2.9g eel/day). At 16 out 60 sites, eels exceeded largely the new EU consumption threshold for PCBs (300ng/g ww for the sum of 6 indicator PCBs). The current data shows an on-going exposure of Flemish eels to PBDEs, HBCDs, PCBs and DDTs through indirect release from contaminated sediments or direct releases from various industries. Copyright © 2014 Elsevier B.V. All rights reserved.

Understanding the Behaviour of Contamination Spread in Nagarjuna Sagar Reservoir Using Temporal Landsat Data

NASA Astrophysics Data System (ADS)

Tarun Teja, K.; Rajan, K. S.

2016-06-01

LANDSAT images are used to identify organic contaminants in water bodies, but, there is no enough evidence in present literature that LANDSAT is also good in identifying a mixture of organic and mineral contaminants such as agricultural waste. The focus of this paper is to evaluate the effectiveness of LANDSAT imagery to identify organic and mineral contamination (OMC) and to identify spread extent variations of pollution over the season/year in the Nagarjuna Sagar (NS) reservoir using only satellite images. A new band combination is proposed in order to detect OMC, because existing formulae based on band ratio proved to be inadequate in detecting the contamination in NS. Difference in reflectance values of Red and Green channel of an image helps clearly distinguish clear water from OMC water. This procedure was applied over LANDSAT data of the calendar years 2008, 2014 and 2015 to understand the contamination spread pattern through the reservoir. Results show that contamination is following a similar pattern over these calendar years. In January contamination starts at inlets and by May contamination spreads to almost 90% of the reservoir when the total area of water spread is also reduced by half. Contamination spread is low during the monsoonal period of June to September due to heavy inflow and heavy outflow of waters from NS reservoir. Post monsoon NS is contaminated again because of heavy inflow of runoffs from neighboring land use and limited water outflow. This contamination spread pattern matches the agricultural seasons and fertilizer application pattern in this region, indicating that agricultural use of fertilizers could be one of the primary causes of contamination for this waterbody.

Human health risks due to consumption of chemically contaminated fishery products.

PubMed Central

Ahmed, F E; Hattis, D; Wolke, R E; Steinman, D

1993-01-01

A small proportion of fishery products contaminated with appreciable amounts of potentially hazardous inorganic and organic contaminants from natural and environmental sources seem to pose the greatest potential for toxicity to consumers of fishery products in the United States. Health risks due to chemicals (e.g., modest changes in the overall risk of cancer, subtle deficits of neurological development in fetuses and children) are difficult to measure directly in people exposed to low levels. Immunocompetence may increase cancer risk. Inferences about the potential magnitude of these problems must be based on the levels of specific chemical present, observations of human populations and experimental animals exposed to relatively high doses, and theories about the likely mechanisms of action of specific intoxicants and the population distribution of sensitivity of human exposure. Lognormal distributions were found to provide good descriptions of the pattern of variation of contaminant concentrations among different species and geographic areas; this variability offers a solution for reduction of exposure through restricting harvest of aquatic animals from certain sites and by excluding certain species. Available information suggest that risks are not generally of high magnitude; nevertheless, their control will significantly improve public health.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8143635

Variability of mercury concentrations in domestic well water, New Jersey Coastal Plain

USGS Publications Warehouse

Szabo, Zoltan; Barringer, Julia L.; Jacobsen, Eric; Smith, Nicholas P; Gallagher, Robert A; Sites, Andrew

2010-01-01

Concentrations of total (unfiltered) mercury (Hg) exceed the Maximum Contaminant Level (2 µg/L) in the acidic water withdrawn by more than 700 domestic wells from the areally extensive unconfined Kirkwood-Cohansey aquifer system. Background concentrations of Hg generally are <0.01 µg/L. The source of the Hg contamination has been hypothesized to arise from Hg of pesticide-application, atmospheric, and geologic origin being mobilized by some component(s) of septic-system effluent or urban leachates in unsewered residential areas. Initial results at many affected wells were not reproducible upon later resampling despite rigorous quality assurance, prompting concerns that duration of well flushing could affect the Hg concentrations. A cooperative study by the U.S. Geological Survey and the New Jersey Department of Environmental Protection examined variability in Hg results during the flushing of domestic wells. Samples were collected at regular intervals (about 10 minutes) during flushing for eight domestic wells, until stabilization criteria was met for field-measured parameters; the Hg concentrations in the final samples ranged from about 0.0005 to 11 µg/L. Unfiltered Hg concentrations in samples collected during purging varied slightly, but particulate Hg concentration (unfiltered – filtered (0.45 micron capsule) concentration) typically was highly variable for each well, with no consistent pattern of increase or decrease in concentration. Surges of particulates probably were associated with pump cycling. Pre-pumping samples from the holding tanks generally had the lowest Hg concentrations among the samples collected at the well that day. Comparing the newly obtained results at each well to results from previous sampling indicated that Hg concentrations in water from the Hg-contaminated areas were generally greater among samples collected on different dates (long-term variations, months to years) than among samples collected on the same day (short-term variations, minutes to hours). The long-term variations likely are caused by changes in local pumping regimes and time-varying capture of slugs of Hg-contaminated water moving on flowpaths.

Assessing groundwater vulnerability to agrichemical contamination in the Midwest US

USGS Publications Warehouse

Burkart, M.R.; Kolpin, D.W.; James, D.E.

1999-01-01

Agrichemicals (herbicides and nitrate) are significant sources of diffuse pollution to groundwater. Indirect methods are needed to assess the potential for groundwater contamination by diffuse sources because groundwater monitoring is too costly to adequately define the geographic extent of contamination at a regional or national scale. This paper presents examples of the application of statistical, overlay and index, and process-based modeling methods for groundwater vulnerability assessments to a variety of data from the Midwest U.S. The principles for vulnerability assessment include both intrinsic (pedologic, climatologic, and hydrogeologic factors) and specific (contaminant and other anthropogenic factors) vulnerability of a location. Statistical methods use the frequency of contaminant occurrence, contaminant concentration, or contamination probability as a response variable. Statistical assessments are useful for defining the relations among explanatory and response variables whether they define intrinsic or specific vulnerability. Multivariate statistical analyses are useful for ranking variables critical to estimating water quality responses of interest. Overlay and index methods involve intersecting maps of intrinsic and specific vulnerability properties and indexing the variables by applying appropriate weights. Deterministic models use process-based equations to simulate contaminant transport and are distinguished from the other methods in their potential to predict contaminant transport in both space and time. An example of a one-dimensional leaching model linked to a geographic information system (GIS) to define a regional metamodel for contamination in the Midwest is included.

Impact of pyrene and cadmium co-contamination on prokaryotic community in coastal sediment microcosms.

PubMed

Ding, Qifang; Huang, Xiaolin; Hu, Hanjing; Hong, Man; Zhang, Demin; Wang, Kai

2017-12-01

Acute ecological impacts of co-contamination of polycyclic aromatic hydrocarbons (PAHs) and heavy metals on diversity and composition of coastal benthic prokaryotes were unclear. We took pyrene (Pyr) and cadmium (Cd) as the representatives and mimicked an eight-week exposure of moderate and high levels of Pyr, Cd and their mixtures. 16S rRNA amplicon sequencing was used to investigate interaction of the contaminants in temporal succession of prokaryotes. Generally, concentrations of Pyr and HCl-extractable Cd in the sediments were stable over time. Effects and interaction of Pyr and Cd on prokaryotic α-diversity were temporally- and dose-dependent with a decreasing trend in richness and Shannon index under various contamination regimes, particularly in the single-Cd contaminated groups at the early stage. Temporal variability and Pyr-induced pattern in prokaryotic composition were observed. However, Pyr and Cd showed a persistent interaction in prokaryotic composition after 7 days, altering successional trajectories of communities. The communities under Pyr contamination regardless of Cd could be at a developing stage for an active PAH-degrading community with appearance of a pioneer Cycloclasticus phylotype, persistently showing a strong correlation with Pyr level. The associations of phylotypes and Cd level were short-lived and weak, corresponding to the overall resistance of prokaryotic composition to Cd. In the high-throughput sequencing era, using microcosm experiment, we renewed the knowledge about how prokaryotes vary in terms of α-diversity, composition and specific taxa in response to co-contamination of model contaminants at a temporal scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems

USGS Publications Warehouse

Kraus, Johanna M.; Gibson, Polly P.; Walters, David M.; Mills, Marc A.

2017-01-01

Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems.However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI,USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r2> 0.78) and had similar mean ΣPCB concentrations when averaged acrossall years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa lesseffective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2016;9999:1–9. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

[Variability patterns of nest construction, physiological state, and morphometric traits in honey bee].

PubMed

Es'kov, E K; Es'kova, M D

2014-01-01

High variability of cells size is used selectively for reproduction of working bees and drones. A decrease in both distance between cells and cells size themselves causes similar effects to body mass and morphometric traits of developing individuals. Adaptation of honey bees to living in shelters has led to their becoming tolerant to hypoxia. Improvement of ethological and physiological mechanisms of thermal regulation is associated with limitation of ecological valence and acquiring of stenothermic features by breed. Optimal thermal conditions for breed are limited by the interval 33-34.5 degrees C. Deviations of temperature by 3-4 degrees C beyond this range have minimum lethal effect at embryonic stage of development and medium effect at the stage of pre-pupa and pupa. Developing at the low bound of the vital range leads to increasing, while developing at the upper bound--to decreasing of body mass, mandibular and hypopharyngeal glands, as well as other organs, which, later, affects the variability of these traits during the adult stage of development. Eliminative and teratogenic efficiency of ecological factors that affect a breed is most often manifested in underdevelopment of wings. However, their size (in case of wing laminas formation). is characterized by relatively low variability and size-dependent asymmetry. Asymmetry variability of wings and other pair organs is expressed through realignment of size excess from right- to left-side one with respect to their increase. Selective elimination by those traits whose emerging probability increases as developmental conditions deviate from the optimal ones promotes restrictions on individual variability. Physiological mechanisms that facilitate adaptability enhancement under conditions of increasing anthropogenic contamination of eivironment and trophic substrates consumed by honey bees, arrear to be toxicants accumulation in rectum and crops' ability to absorb contaminants from nectar in course of its processing to honey.

Applying acoustic telemetry to understand contaminant exposure and bioaccumulation patterns in mobile fishes.

PubMed

Taylor, Matthew D; van der Meulen, Dylan E; Brodie, Stephanie; Cadiou, Gwenaël; Knott, Nathan A

2018-06-01

Contamination in urbanised estuaries presents a risk to human health, and to the viability of populations of exploited species. Assessing animal movements in relation to contaminated areas may help to explain patterns in bioaccumulation, and assist in the effective management of health risks associated with consumption of exploited species. Using polychlorinated dibenzodioxin and polychlorinated dibenzofuran (PCDD/Fs) contamination in Sydney Harbour estuary as a case study, we present a study that links movement patterns resolved using acoustic telemetry to the accumulation of contaminants in mobile fish on a multi-species basis. Fifty-four individuals across six exploited species (Sea Mullet Mugil cephalus; Luderick Girella tricuspidata; Yellowfin Bream Acanthopagrus australis; Silver Trevally Pseudocaranx georgianus; Mulloway Argyrosomus japonicus; Yellowtail Kingfish Seriola lalandi) were tagged with acoustic transmitters, and their movements tracked for up to 3years. There was substantial inter-specific variation in fish distribution along the estuary. The proportion of distribution that overlapped with contaminated areas explained 84-98% of the inter-specific variation in lipid-standardised biota PCDD/F concentration. There was some seasonal variation in distribution along the estuary, but movement patterns indicated that Sea Mullet, Yellowfin Bream, Silver Trevally, and Mulloway were likely to be exposed to contaminated areas during the period of gonadal maturation. Acoustic telemetry allows examination of spatial and temporal patterns in exposure to contamination. When used alongside biota sampling and testing, this offers a powerful approach to assess exposure, bioaccumulation, and potential risks faced by different species, as well as human health risks associated with their consumption. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Sediment heavy metals and benthic diversities in Hun-Tai River, northeast of China.

PubMed

Qu, Xiaodong; Ren, Ze; Zhang, Min; Liu, Xiaobo; Peng, Wenqi

2017-04-01

In aquatic ecosystems, metal contamination in sediments has become a ubiquitous environmental problem, causing serious issues. Hun-Tai River, located in northeast of China, flows through an important heavy industry region and metropolitan area. This study examined the heavy metals (Cd, Cr, Cu, Fe, Mn, Pb, Ni, and Zn) of sediments and diversities (taxa richness, Shannon diversity, and evenness) of benthic assemblages (benthic algae and macroinvertebrate) in Hun-Tai River. The results clearly described the spatial patterns of metal contamination in terms of geo-accumulation index and contamination factor, as well as the spatial patterns of benthic diversities in terms of taxa richness, Shannon index, and evenness by kriging interpolation. The sediments were largely contaminated by Cd, followed by Cu, Fe, Zn, Mn, and Ni. Cd and Zn had similar spatial patterns and similar sources. Cu, Fe, Mn, and Ni showed similar spatial patterns and similar sources. The surface sediments were unpolluted by Cr and Pb. The metal mines and the heavy industry in the major cities were the potential pollution sources. Benthic algae and macroinvertebrate responded similarly to the heterogeneous environment and metal contamination, with high taxa richness and Shannon index in middle-upper reaches of Hun-Tai River. Evenness showed complex spatial patterns. Under low contamination, both taxa richness, Shannon diversity, and evenness had a large variation range. However, under the moderate and high contamination, the taxa richness and Shannon diversity kept to a low level but the evenness had a high level. This study provided insights into the sediment heavy metal contamination in Hun-Tai River.

Fragmentation of contaminant and endogenous DNA in ancient samples determined by shotgun sequencing; prospects for human palaeogenomics.

PubMed

García-Garcerà, Marc; Gigli, Elena; Sanchez-Quinto, Federico; Ramirez, Oscar; Calafell, Francesc; Civit, Sergi; Lalueza-Fox, Carles

2011-01-01

Despite the successful retrieval of genomes from past remains, the prospects for human palaeogenomics remain unclear because of the difficulty of distinguishing contaminant from endogenous DNA sequences. Previous sequence data generated on high-throughput sequencing platforms indicate that fragmentation of ancient DNA sequences is a characteristic trait primarily arising due to depurination processes that create abasic sites leading to DNA breaks. METHODOLOGY/PRINCIPALS FINDINGS: To investigate whether this pattern is present in ancient remains from a temperate environment, we have 454-FLX pyrosequenced different samples dated between 5,500 and 49,000 years ago: a bone from an extinct goat (Myotragus balearicus) that was treated with a depurinating agent (bleach), an Iberian lynx bone not subjected to any treatment, a human Neolithic sample from Barcelona (Spain), and a Neandertal sample from the El Sidrón site (Asturias, Spain). The efficiency of retrieval of endogenous sequences is below 1% in all cases. We have used the non-human samples to identify human sequences (0.35 and 1.4%, respectively), that we positively know are contaminants. We observed that bleach treatment appears to create a depurination-associated fragmentation pattern in resulting contaminant sequences that is indistinguishable from previously described endogenous sequences. Furthermore, the nucleotide composition pattern observed in 5' and 3' ends of contaminant sequences is much more complex than the flat pattern previously described in some Neandertal contaminants. Although much research on samples with known contaminant histories is needed, our results suggest that endogenous and contaminant sequences cannot be distinguished by the fragmentation pattern alone.

Distribution of brominated flame retardants and dechloranes between sediments and benthic fish--A comparison of a freshwater and marine habitat.

PubMed

Sühring, Roxana; Busch, Friederike; Fricke, Nicolai; Kötke, Danijela; Wolschke, Hendrik; Ebinghaus, Ralf

2016-01-15

A total of 53 halogenated flame retardants (HFRs) were analysed in sediments, European eels and dabs from both freshwater and marine sampling stations in the German Bight and the river Elbe. Classic HFRs, such as polybrominated diphenylethers (PBDEs), were the highest concentrated HFRs in eels as well as in most dabs (apart from 1,2,5,6-tetrabromocyclooctane (TBCO)). In sediments, on the other hand, alternate BFRs and especially dechloranes dominated the contamination pattern. Dabs were still found to be statistically representative for the contamination patterns and relative magnitude in sediments from their respective habitats. Contamination patterns in eels seemed to be more driven by the contamination situation in the food chain or historical contamination of their habitat. Unsuspectedly the alternate flame retardant TBCO was found in comparably high concentrations (up to 12 ng g(-1) ww) in dabs from two sampling stations as well as in sediments from these stations (up to 1.2 ng g(-1) dw). It could not be detected in any other analysed fish or sediment samples, indicating a localised contamination source in the area. This study provides information on HFR contamination patterns and behaviour in both marine and freshwater sediments and their potential role as contamination source for benthic fish. Copyright © 2015 Elsevier B.V. All rights reserved.

Distributional patterns of arsenic concentrations in contaminant plumes offer clues to the source of arsenic in groundwater at landfills

USGS Publications Warehouse

Harte, Philip T.

2015-01-01

The distributional pattern of dissolved arsenic concentrations from landfill plumes can provide clues to the source of arsenic contamination. Under simple idealized conditions, arsenic concentrations along flow paths in aquifers proximal to a landfill will decrease under anthropogenic sources but potentially increase under in situ sources. This paper presents several conceptual distributional patterns of arsenic in groundwater based on the arsenic source under idealized conditions. An example of advanced subsurface mapping of dissolved arsenic with geophysical surveys, chemical monitoring, and redox fingerprinting is presented for a landfill site in New Hampshire with a complex flow pattern. Tools to assist in the mapping of arsenic in groundwater ultimately provide information on the source of contamination. Once an understanding of the arsenic contamination is achieved, appropriate remedial strategies can then be formulated.

Temporal and spatial variation of atmospherically deposited organic contaminants at high elevation in Yosemite National Park, California, USA.

PubMed

Bradford, David F; Stanley, Kerri A; Tallent, Nita G; Sparling, Donald W; Nash, Maliha S; Knapp, Roland A; McConnell, Laura L; Massey Simonich, Staci L

2013-03-01

Contaminants used at low elevation, such as pesticides on crops, can be transported tens of kilometers and deposited in adjacent mountains in many parts of the world. Atmospherically deposited organic contaminants in the Sierra Nevada Mountains of California, USA, have exceeded some thresholds of concern, but the spatial and temporal distributions of contaminants in the mountains are not well known. The authors sampled shallow-water sediment and tadpoles (Pseudacris sierra) for pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls in four high-elevation sites in Yosemite National Park in the central Sierra Nevada twice during the summers of 2006, 2007, and 2008. Both historic- and current-use pesticides showed a striking pattern of lower concentrations in both sediment and tadpoles in Yosemite than was observed previously in Sequoia-Kings Canyon National Parks in the southern Sierra Nevada. By contrast, PAH concentrations in sediment were generally greater in Yosemite than in Sequoia-Kings Canyon. The authors suggest that pesticide concentrations tend to be greater in Sequoia-Kings Canyon because of a longer air flow path over agricultural lands for this park along with greater pesticide use near this park. Concentrations for DDT-related compounds in some sediment samples exceeded guidelines or critical thresholds in both parks. A general pattern of difference between Yosemite and Sequoia-Kings Canyon was not evident for total tadpole cholinesterase activity, an indicator of harmful exposure to organophosphorus and carbamate pesticides. Variability of chemical concentrations among sites, between sampling periods within each year, and among years, contributed significantly to total variation, although the relative contributions differed between sediment and tadpoles. Copyright © 2013 SETAC.

Biomarker responses to environmental contamination in estuaries: A comparative multi-taxa approach.

PubMed

Duarte, Irina A; Reis-Santos, Patrick; França, Susana; Cabral, Henrique; Fonseca, Vanessa F

2017-08-01

Estuaries are highly productive ecosystems subjected to numerous anthropogenic pressures with consequent environmental quality degradation. In this study, multiple biomarker responses [superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) and DNA damage (DNAd)] were determined in two fish (Dicentrarchus labrax and Pomatoschistus microps) and four macroinvertebrate species (Carcinus maenas, Crangon crangon, Hediste diversicolor and Scrobicularia plana) from the Ria de Aveiro and Tejo estuaries over distinct months. Two sites per estuarine system were selected based on anthropogenic pressures and magnitude of environmental contamination. Antioxidant enzyme activities in fish species suggested a ubiquitous response to oxidative stress, while biotransformation and effect biomarkers exhibited higher spatial and temporal variation. In invertebrate species, biotransformation enzyme activity was clearly less variable than in fish evidencing lower xenobiotic transformation capability. Overall, largest biomarker responses were found in the most contaminated sites (Tejo), yet species-specific patterns were evident. These should be factored in multi-taxa approaches, considering that the differential functional traits of species, such as habitat use, life-stage, feeding or physiology can influence exposure routes and biomarker responses. The Integrated Biomarker Response index highlighted patterns in biomarker responses which were not immediately evident when analyzing biomarkers individually. Overall, results provided insights into the complexity of species responses to contamination in naturally varying estuarine environments. Ultimately, multi-taxa and multi-biomarker approaches provide a comprehensive and complementary view of ecosystem health, encompassing diverse forms of biological integration and exposure routes, and allow the validation of results among markers and species. Copyright © 2017 Elsevier B.V. All rights reserved.

Geographical PCB and DDT patterns in shearwaters (Calonectris sp.) breeding across the NE Atlantic and the Mediterranean archipelagos.

PubMed

Roscales, Jose L; Muñoz-Arnanz, Juan; González-Solís, Jacob; Jiménez, Begoña

2010-04-01

Although seabirds have been proposed as useful biomonitors for organochlorine contaminants (OCs) in marine environments, their suitability is still unclear. To understand the geographic variability and the influence of seabird trophic ecology in OC levels, we analyzed PCBs, DDTs, delta(13)C, and delta(15)N in the blood of adult Calonectris shearwaters throughout a vast geographic range within the northeast Atlantic Ocean (from Cape Verde to Azores) and the Mediterranean Sea (from the Alboran Sea to Crete). OC concentrations were greater in birds from the Mediterranean than in those from the Atlantic colonies, showing higher and lower chlorinated PCB profiles, respectively. This large-scale pattern may reflect the influence of historical European runoffs in the Mediterranean basin and diffused sources for OCs in remote Atlantic islands. Spatial patterns also emerged within the Atlantic basin, probably associated with pollutant long-range transport and recent inputs of DDT in the food webs of shearwaters from Cape Verde and the Canary islands. Moreover, a positive association of OC concentrations with delta(15)N within each locality points out diet specialization as a major factor explaining differences in OCs at the intraspecific level. Overall, this study highlights wide range breeding seabirds, such as Calonectris shearwaters, as suitable organisms for biomonitoring large geographic trends of organochlorine contamination in the marine environment.

Enviromental influences on the {sup 137}Cs kinetics of the yellow-bellied turtle (Trachemys Scripta)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, E.L.; Brisbin, L.I. Jr.

1996-02-01

Assessments of ecological risk require accurate predictions of contaminant dynamics in natural populations. However, simple deterministic models that assume constant uptake rates and elimination fractions may compromise both their ecological realism and their general application to animals with variable metabolism or diets. In particular, the temperature-dependent model of metabolic rates characteristic of ectotherms may lead to significant differences between observed and predicted contaminant kinetics. We examined the influence of a seasonally variable thermal environment on predicting the uptake and annual cycling of contaminants by ectotherms, using a temperature-dependent model of {sup 137}Cs kinetics in free-living yellow-bellied turtles, Trachemys scripta. Wemore » compared predictions from this model with those of deterministics negative exponential and flexibly shaped Richards sigmoidal models. Concentrations of {sup 137}Cs in a population if this species in Pond B, a radionuclide-contaminated nuclear reactor cooling reservoir, and {sup 137}Cs uptake by the uncontaminated turtles held captive in Pond B for 4 yr confirmed both the pattern of uptake and the equilibrium concentrations predicted by the temperature-dependent model. Almost 90% of the variance on the predicted time-integrated {sup 137}Cs concentration was explainable by linear relationships with model paramaters. The model was also relatively insensitive to uncertainties in the estimates of ambient temperature, suggesting that adequate estimates of temperature-dependent ingestion and elimination may require relatively few measurements of ambient conditions at sites of interest. Analyses of Richards sigmoidal models of {sup 137}Cs uptake indicated significant differences from a negative exponential trajectory in the 1st yr after the turtles` release into Pond B. 76 refs., 7 figs., 5 tabs.« less

The influence of human physical activity and contaminated clothing type on particle resuspension.

PubMed

McDonagh, A; Byrne, M A

2014-01-01

A study was conducted to experimentally quantify the influence of three variables on the level of resuspension of hazardous aerosol particles from clothing. Variables investigated include physical activity level (two levels, low and high), surface type (four different clothing material types), and time i.e. the rate at which particles resuspend. A mixture of three monodisperse tracer-labelled powders, with median diameters of 3, 5, and 10 microns, was used to "contaminate" the samples, and the resuspended particles were analysed in real-time using an Aerodynamic Particle Sizer (APS), and also by Neutron Activation Analysis (NAA). The overall finding was that physical activity resulted in up to 67% of the contamination deposited on clothing being resuspended back into the air. A detailed examination of the influence of physical activity level on resuspension, from NAA, revealed that the average resuspended fraction (RF) of particles at low physical activity was 28 ± 8%, and at high physical activity was 30 ± 7%, while the APS data revealed a tenfold increase in the cumulative mass of airborne particles during high physical activity in comparison to that during low physical activity. The results also suggest that it is not the contaminated clothing's fibre type which influences particle resuspension, but the material's weave pattern (and hence the material's surface texture). Investigation of the time variation in resuspended particle concentrations indicated that the data were separable into two distinct regimes: the first (occurring within the first 1.5 min) having a high, positive rate of change of airborne particle concentration relative to the second regime. The second regime revealed a slower rate of change of particle concentration and remained relatively unchanged for the remainder of each resuspension event. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transit time distributions to assess present and future contamination risk of karst aquifers over Europe and the Mediterranean

NASA Astrophysics Data System (ADS)

Hartmann, Andreas; Gleeson, Tom; Wada, Yoshihide; Wagener, Thorsten

2016-04-01

Karst develops through the dissolution of carbonate rock. Karst groundwater in Europe is a major source of fresh water contributing up to half of the total drinking water supply in some countries. Climate model projections suggest that in the next 100 years, karst regions will experience a strong increase in temperature and a serious decrease of precipitation - especially in the Mediterranean region. Previous work showed that the karstic preferential recharge processes result in enhanced recharge rates and future climate sensitivity. But as there is fast water flow form the surface to the aquifer, there is also an enhanced risk of groundwater contamination. In this study we will assess the contamination risk of karst aquifers over Europe and the Mediterranean using simulated transit time distributions. Using a new type of semi-distributed model that considers the spatial heterogeneity of the karst system by distribution functions we simulated a range of spatially variable pathways of karstic groundwater recharge. The model is driven by the bias-corrected 5 GCMs of the ISI-MIP project (RCP8.5). Transit time distributions are calculated by virtual tracer experiments. These are repeated several times in the present (1991-2010) and the future (2080-2099). We can show that regions with larger fractions of preferential recharge show higher risks of contamination and that spatial patterns of contamination risk change towards the future.

Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dirtu, Alin C.; Department of Chemistry, “Al. I. Cuza” University of Iasi, 700506 Iasi; Malarvannan, Govindan

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs),more » hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ{sup 13}C and δ{sup 15}N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ{sup 15}N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation. - Highlights: • POPs and total Hg were measured in spinner and bottlenose dolphins from La Réunion. • Levels of PCBs, PBDEs and T-Hg were lower in spinner than in bottlenose dolphins. • Contrasted contaminant profiles were observed between the two dolphin species. • Profiles are most likely explained by dietary and foraging habitat preferences.« less

Logistic regression modeling to assess groundwater vulnerability to contamination in Hawaii, USA

NASA Astrophysics Data System (ADS)

Mair, Alan; El-Kadi, Aly I.

2013-10-01

Capture zone analysis combined with a subjective susceptibility index is currently used in Hawaii to assess vulnerability to contamination of drinking water sources derived from groundwater. In this study, we developed an alternative objective approach that combines well capture zones with multiple-variable logistic regression (LR) modeling and applied it to the highly-utilized Pearl Harbor and Honolulu aquifers on the island of Oahu, Hawaii. Input for the LR models utilized explanatory variables based on hydrogeology, land use, and well geometry/location. A suite of 11 target contaminants detected in the region, including elevated nitrate (> 1 mg/L), four chlorinated solvents, four agricultural fumigants, and two pesticides, was used to develop the models. We then tested the ability of the new approach to accurately separate groups of wells with low and high vulnerability, and the suitability of nitrate as an indicator of other types of contamination. Our results produced contaminant-specific LR models that accurately identified groups of wells with the lowest/highest reported detections and the lowest/highest nitrate concentrations. Current and former agricultural land uses were identified as significant explanatory variables for eight of the 11 target contaminants, while elevated nitrate was a significant variable for five contaminants. The utility of the combined approach is contingent on the availability of hydrologic and chemical monitoring data for calibrating groundwater and LR models. Application of the approach using a reference site with sufficient data could help identify key variables in areas with similar hydrogeology and land use but limited data. In addition, elevated nitrate may also be a suitable indicator of groundwater contamination in areas with limited data. The objective LR modeling approach developed in this study is flexible enough to address a wide range of contaminants and represents a suitable addition to the current subjective approach.

Comparison of dialysis membrane diffusion samplers and two purging methods in bedrock wells

USGS Publications Warehouse

Imbrigiotta, T.E.; Ehlke, T.A.; Lacombe, P.J.; Dale, J.M.; ,

2002-01-01

Collection of ground-water samples from bedrock wells using low-flow purging techniques is problematic because of the random spacing, variable hydraulic conductivity, and variable contamination of contributing fractures in each well's open interval. To test alternatives to this purging method, a field comparison of three ground-water-sampling techniques was conducted on wells in fractured bedrock at a site contaminated primarily with volatile organic compounds. Constituent concentrations in samples collected with a diffusion sampler constructed from dialysis membrane material were compared to those in samples collected from the same wells with a standard low-flow purging technique and a hybrid (high-flow/low-flow) purging technique. Concentrations of trichloroethene, cis-1,2-dichloroethene, vinyl chloride, calcium, chloride, and alkalinity agreed well among samples collected with all three techniques in 9 of the 10 wells tested. Iron concentrations varied more than those of the other parameters, but their pattern of variation was not consistent. Overall, the results of nonparametric analysis of variance testing on the nine wells sampled twice showed no statistically significant difference at the 95-percent confidence level among the concentrations of volatile organic compounds or inorganic constituents recovered by use of any of the three sampling techniques.

EROD activity measured in flatfish from the area of the Sea Empress oil spill.

PubMed

Kirby, M F; Neall, P; Tylor, T

1999-05-01

Dab (Limanda limanda) and plaice (Pleuronectes platessa) were collected at five stations near to the site of the Sea Empress oil spill within two weeks of the incident and a further fourteen stations three months after the spillage. Ethoxyresorufin-O-deethylase (EROD) activity was determined in the livers of the specimens to determine whether induction could be detected. Statistically significant inter-site differences in EROD levels in both species were demonstrated. Elevated levels of EROD activity in dab were found at the two stations nearest to the incident up to three months after the spill but no clear relationship to putative contaminant levels was determined. EROD levels in plaice showed a generally similar pattern of induction as in dab. Correlation of EROD levels with other variables showed that sexual maturity had the greatest influence on dab during the study period. The plaice specimens were sexually immature and, therefore, did not demonstrate a corresponding relationship. It was concluded that, for EROD monitoring purposes, fish should be sampled during their sexually inactive phase and that close attention needs to be paid to other variables (depth, temperature, GSI, length, influential contaminants etc.) when interpreting the results.

Estimation of Polychlorinated Biphenyl Sources in Industrial Port Sediments Using a Bayesian Semifactor Model Considering Unidentified Sources.

PubMed

Anezaki, Katsunori; Nakano, Takeshi; Kashiwagi, Nobuhisa

2016-01-19

Using the chemical balance method, and considering the presence of unidentified sources, we estimated the origins of PCB contamination in surface sediments of Muroran Port, Japan. It was assumed that these PCBs originated from four types of Kanechlor products (KC300, KC400, KC500, and KC600), combustion and two kinds of pigments (azo and phthalocyanine). The characteristics of these congener patterns were summarized on the basis of principal component analysis and explanatory variables determined. A Bayesian semifactor model (CMBK2) was applied to the explanatory variables to analyze the sources of PCBs in the sediments. The resulting estimates of the contribution ratio of each kind of sediment indicate that the existence of unidentified sources can be ignored and that the assumed seven sources are adequate to account for the contamination. Within the port, the contribution ratio of KC500 and KC600 (used as paints for ship hulls) was extremely high, but outside the port, the influence of azo pigments was observable to a limited degree. This indicates that environmental PCBs not derived from technical PCBs are present at levels that cannot be ignored.

Continental patterns of submarine groundwater discharge reveal coastal vulnerabilities.

PubMed

Sawyer, Audrey H; David, Cédric H; Famiglietti, James S

2016-08-12

Submarine groundwater discharge (SGD) delivers water and dissolved chemicals from continents to oceans, and its spatial distribution affects coastal water quality. Unlike rivers, SGD is broadly distributed and relatively difficult to measure, especially at continental scales. We present spatially resolved estimates of fresh (land-derived) SGD for the contiguous United States based on historical climate records and high-resolution hydrographic data. Climate controls regional patterns in fresh SGD, while coastal drainage geometry imparts strong local variability. Because the recharge zones that contribute fresh SGD are densely populated, the quality and quantity of fresh SGD are both vulnerable to anthropogenic disturbance. Our analysis unveils hot spots for contaminant discharge to marine waters and saltwater intrusion into coastal aquifers. Copyright © 2016, American Association for the Advancement of Science.

Movement patterns, habitat use and site fidelity of the white croaker (Genyonemus lineatus) in the Palos Verdes Superfund Site, Los Angeles, California.

PubMed

Wolfe, Barrett W; Lowe, Christopher G

2015-08-01

White croaker (Genyonemus lineatus family: Sciaenidae) are a schooling, benthic foraging fish historically associated with soft sediment and wastewater outfalls in southern California. While they are often used as an indicator species due to their high organochlorine contaminant loads, little is known of their movements in relation to contaminated habitats. A Vemco Positioning System acoustic telemetry array was used to collect fine-scale movement data and characterize the site fidelity, area use, and dispersal of 83 white croaker on the Palos Verdes Shelf Superfund Site, California over 27 months. White croaker generally demonstrated low residency and recurrence to the Palos Verdes Shelf, and were observed to be largely nomadic. However, individual behavior was highly variable. Although the entire monitored shelf was visited by tagged white croaker, habitats in 0-200 m proximity to wastewater outfalls and between 25 and 35 m depth were used most frequently. Approximately half of white croaker migrated into Los Angeles and Long Beach Harbors; areas where they may be targeted by subsistence fishers. A model framework for incorporating fish movement data into contaminant exposure estimates was developed to better understanding organochlorine contaminant exposure for planning future remediation and monitoring. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolutionary patterns in trace metal (cd and zn) efflux capacity in aquatic organisms.

PubMed

Poteat, Monica D; Garland, Theodore; Fisher, Nicholas S; Wang, Wen-Xiong; Buchwalter, David B

2013-07-16

The ability to eliminate (efflux) metals is a physiological trait that acts as a major driver of bioaccumulation differences among species. This species-specific trait plays a large role in determining the metal loads that species will need to detoxify to persist in chronically contaminated environments and, therefore, contributes significantly to differences in environmental sensitivity among species. To develop a better understanding of how efflux varies within and among taxonomic groupings, we compared Cd and Zn efflux rate constants (ke values) among members of two species-rich aquatic insect families, Ephemerellidae and Hydropsychidae, and discovered that ke values strongly covaried across species. This relationship allowed us to successfully predict Zn efflux from Cd data gathered from aquatic species belonging to other insect orders and families. We then performed a broader, comparative analysis of Cd and Zn ke values from existing data for arthropods, mollusks, annelids, and chordates (77 species total) and found significant phylogenetic patterns. Taxonomic groups exhibited marked variability in ke magnitudes and ranges, suggesting that some groups are more constrained than others in their abilities to eliminate metals. Understanding broader patterns of variability can lead to more rational extrapolations across species and improved protectiveness in water-quality criteria and ecological assessment.

Genetic Factors Involved in Fumonisin Accumulation in Maize Kernels and Their Implications in Maize Agronomic Management and Breeding

PubMed Central

Santiago, Rogelio; Cao, Ana; Butrón, Ana

2015-01-01

Contamination of maize with fumonisins depends on the environmental conditions; the maize resistance to contamination and the interaction between both factors. Although the effect of environmental factors is a determinant for establishing the risk of kernel contamination in a region, there is sufficient genetic variability among maize to develop resistance to fumonisin contamination and to breed varieties with contamination at safe levels. In addition, ascertaining which environmental factors are the most important in a region will allow the implementation of risk monitoring programs and suitable cultural practices to reduce the impact of such environmental variables. The current paper reviews all works done to address the influence of environmental variables on fumonisin accumulation, the genetics of maize resistance to fumonisin accumulation, and the search for the biochemical and/or structural mechanisms of the maize plant that could be involved in resistance to fumonisin contamination. We also explore the outcomes of breeding programs and risk monitoring of undertaken projects. PMID:26308050

Genetic Factors Involved in Fumonisin Accumulation in Maize Kernels and Their Implications in Maize Agronomic Management and Breeding.

PubMed

Santiago, Rogelio; Cao, Ana; Butrón, Ana

2015-08-20

Contamination of maize with fumonisins depends on the environmental conditions; the maize resistance to contamination and the interaction between both factors. Although the effect of environmental factors is a determinant for establishing the risk of kernel contamination in a region, there is sufficient genetic variability among maize to develop resistance to fumonisin contamination and to breed varieties with contamination at safe levels. In addition, ascertaining which environmental factors are the most important in a region will allow the implementation of risk monitoring programs and suitable cultural practices to reduce the impact of such environmental variables. The current paper reviews all works done to address the influence of environmental variables on fumonisin accumulation, the genetics of maize resistance to fumonisin accumulation, and the search for the biochemical and/or structural mechanisms of the maize plant that could be involved in resistance to fumonisin contamination. We also explore the outcomes of breeding programs and risk monitoring of undertaken projects.

Logistic regression modeling to assess groundwater vulnerability to contamination in Hawaii, USA.

PubMed

Mair, Alan; El-Kadi, Aly I

2013-10-01

Capture zone analysis combined with a subjective susceptibility index is currently used in Hawaii to assess vulnerability to contamination of drinking water sources derived from groundwater. In this study, we developed an alternative objective approach that combines well capture zones with multiple-variable logistic regression (LR) modeling and applied it to the highly-utilized Pearl Harbor and Honolulu aquifers on the island of Oahu, Hawaii. Input for the LR models utilized explanatory variables based on hydrogeology, land use, and well geometry/location. A suite of 11 target contaminants detected in the region, including elevated nitrate (>1 mg/L), four chlorinated solvents, four agricultural fumigants, and two pesticides, was used to develop the models. We then tested the ability of the new approach to accurately separate groups of wells with low and high vulnerability, and the suitability of nitrate as an indicator of other types of contamination. Our results produced contaminant-specific LR models that accurately identified groups of wells with the lowest/highest reported detections and the lowest/highest nitrate concentrations. Current and former agricultural land uses were identified as significant explanatory variables for eight of the 11 target contaminants, while elevated nitrate was a significant variable for five contaminants. The utility of the combined approach is contingent on the availability of hydrologic and chemical monitoring data for calibrating groundwater and LR models. Application of the approach using a reference site with sufficient data could help identify key variables in areas with similar hydrogeology and land use but limited data. In addition, elevated nitrate may also be a suitable indicator of groundwater contamination in areas with limited data. The objective LR modeling approach developed in this study is flexible enough to address a wide range of contaminants and represents a suitable addition to the current subjective approach. © 2013 Elsevier B.V. All rights reserved.

Arcobacter butzleri in sheep ricotta cheese at retail and related sources of contamination in an industrial dairy plant.

PubMed

Scarano, Christian; Giacometti, Federica; Manfreda, Gerardo; Lucchi, Alex; Pes, Emanuela; Spanu, Carlo; De Santis, Enrico Pietro Luigi; Serraino, Andrea

2014-11-01

This study aimed to evaluate Arcobacter species contamination of industrial sheep ricotta cheese purchased at retail and to establish if the dairy plant environment may represent a source of contamination. A total of 32 sheep ricotta cheeses (1.5 kg/pack) packed in a modified atmosphere were purchased at retail, and 30 samples were collected in two sampling sessions performed in the cheese factory from surfaces in contact with food and from surfaces not in contact with food. Seven out of 32 samples (21.9%) of ricotta cheese collected at retail tested positive for Arcobacter butzleri at cultural examination; all positive samples were collected during the same sampling and belonged to the same batch. Ten surface samples (33.3%) collected in the dairy plant were positive for A. butzleri. Cluster analysis identified 32 pulsed-field gel electrophoresis (PFGE) patterns. The same PFGE pattern was isolated from more than one ricotta cheese sample, indicating a common source of contamination, while more PFGE patterns could be isolated in single samples, indicating different sources of contamination. The results of the environmental sampling showed that A. butzleri may be commonly isolated from the dairy processing plant investigated and may survive over time, as confirmed by the isolation of the same PFGE pattern in different industrial plant surface samples. Floor contamination may represent a source of A. butzleri spread to different areas of the dairy plant, as demonstrated by isolation of the same PFGE pattern in different production areas. Isolation of the same PFGE pattern from surface samples in the dairy plant and from ricotta cheese purchased at retail showed that plant surfaces may represent a source of A. butzleri postprocessing contamination in cheeses produced in industrial dairy plants. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Land Use and Climate Variability Amplify Contaminant Pulses

EPA Science Inventory

Converting land to human-dominated uses has increased contaminant loads in streams and rivers and vastly transformed hydrological cycles (Vitousek et al. 1997). More recently, climate change has further altered hydrologic cycles and variability of precipitation (IPCC 2007). Toge...

Quality of nutrient data from streams and ground water sampled during water years 1992-2001

USGS Publications Warehouse

Mueller, David K.; Titus, Cindy J.

2005-01-01

Proper interpretation of water-quality data requires consideration of the effects that bias and variability might have on measured constituent concentrations. In this report, methods are described to estimate the bias due to contamination of samples in the field or laboratory and the variability due to sample collection, processing, shipment, and analysis. Contamination can adversely affect interpretation of measured concentrations in comparison to standards or criteria. Variability can affect interpretation of small differences between individual measurements or mean concentrations. Contamination and variability are determined for nutrient data from quality-control samples (field blanks and replicates) collected as part of the National Water-Quality Assessment (NAWQA) Program during water years 1992-2001. Statistical methods are used to estimate the likelihood of contamination and variability in all samples. Results are presented for five nutrient analytes from stream samples and four nutrient analytes from ground-water samples. Ammonia contamination can add at least 0.04 milligram per liter in up to 5 percent of all samples. This could account for more than 22 percent of measured concentrations at the low range of aquatic-life criteria (0.18 milligram per liter). Orthophosphate contamination, at least 0.019 milligram per liter in up to 5 percent of all samples, could account for more than 38 percent of measured concentrations at the limit to avoid eutrophication (0.05 milligram per liter). Nitrite-plus-nitrate and Kjeldahl nitrogen contamination is less than 0.4 milligram per liter in 99 percent of all samples; thus there is no significant effect on measured concentrations of environmental significance. Sampling variability has little or no effect on reported concentrations of ammonia, nitrite-plus-nitrate, orthophosphate, or total phosphorus sampled after 1998. The potential errors due to sampling variability are greater for the Kjeldahl nitrogen analytes and for total phosphorus sampled before 1999. The uncertainty in a mean of 10 concentrations caused by sampling variability is within a small range (1 to 7 percent) for all nutrients. These results can be applied to interpretation of environmental data collected during water years 1992-2001 in 52 NAWQA study units.

Molecular Analysis of Dehalococcoides 16S Ribosomal DNA from Chloroethene-Contaminated Sites throughout North America and Europe

PubMed Central

Hendrickson, Edwin R.; Payne, Jo Ann; Young, Roslyn M.; Starr, Mark G.; Perry, Michael P.; Fahnestock, Stephen; Ellis, David E.; Ebersole, Richard C.

2002-01-01

The environmental distribution of Dehalococcoides group organisms and their association with chloroethene-contaminated sites were examined. Samples from 24 chloroethene-dechlorinating sites scattered throughout North America and Europe were tested for the presence of members of the Dehalococcoides group by using a PCR assay developed to detect Dehalococcoides 16S rRNA gene (rDNA) sequences. Sequences identified by sequence analysis as sequences of members of the Dehalococcoides group were detected at 21 sites. Full dechlorination of chloroethenes to ethene occurred at these sites. Dehalococcoides sequences were not detected in samples from three sites at which partial dechlorination of chloroethenes occurred, where dechlorination appeared to stop at 1,2-cis-dichloroethene. Phylogenetic analysis of the 16S rDNA amplicons confirmed that Dehalococcoides sequences formed a unique 16S rDNA group. These 16S rDNA sequences were divided into three subgroups based on specific base substitution patterns in variable regions 2 and 6 of the Dehalococcoides 16S rDNA sequence. Analyses also demonstrated that specific base substitution patterns were signature patterns. The specific base substitutions distinguished the three sequence subgroups phylogenetically. These results demonstrated that members of the Dehalococcoides group are widely distributed in nature and can be found in a variety of geological formations and in different climatic zones. Furthermore, the association of these organisms with full dechlorination of chloroethenes suggests that they are promising candidates for engineered bioremediation and may be important contributors to natural attenuation of chloroethenes. PMID:11823182

Accumulation patterns of lipophilic organic contaminants in surface sediments and in economic important mussel and fish species from Jakarta Bay, Indonesia.

PubMed

Dwiyitno; Dsikowitzky, Larissa; Nordhaus, Inga; Andarwulan, Nuri; Irianto, Hari Eko; Lioe, Hanifah Nuryani; Ariyani, Farida; Kleinertz, Sonja; Schwarzbauer, Jan

2016-09-30

Non-target screening analyses were conducted in order to identify a wide range of organic contaminants in sediment and animal tissue samples from Jakarta Bay. High concentrations of di-iso-propylnaphthalenes (DIPNs), linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) were detected in all samples, whereas phenylmethoxynaphthalene (PMN), DDT and DDT metabolites (DDX) were detected at lower concentrations. In order to evaluate the uptake and accumulation by economic important mussel (Perna viridis) and fish species, contaminant patterns of DIPNs, LABs and PAHs in different compartments were compared. Different patterns of these contaminant groups were found in sediment and animal tissue samples, suggesting compound-specific accumulation and metabolism processes. Significantly higher concentrations of these three contaminant groups in mussel tissue as compared to fish tissue from Jakarta Bay were found. Because P. viridis is an important aquaculture species in Asia, this result is relevant for food safety. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improving surface-subsurface water budgeting using high resolution satellite imagery applied on a brownfield.

PubMed

Dujardin, J; Batelaan, O; Canters, F; Boel, S; Anibas, C; Bronders, J

2011-01-15

The estimation of surface-subsurface water interactions is complex and highly variable in space and time. It is even more complex when it has to be estimated in urban areas, because of the complex patterns of the land-cover in these areas. In this research a modeling approach with integrated remote sensing analysis has been developed for estimating water fluxes in urban environments. The methodology was developed with the aim to simulate fluxes of contaminants from polluted sites. Groundwater pollution in urban environments is linked to patterns of land use and hence it is essential to characterize the land cover in a detail. An object-oriented classification approach applied on high-resolution satellite data has been adopted. To assign the image objects to one of the land-cover classes a multiple layer perceptron approach was adopted (Kappa of 0.86). Groundwater recharge has been simulated using the spatially distributed WetSpass model and the subsurface water flow using MODFLOW in order to identify and budget water fluxes. The developed methodology is applied to a brownfield case site in Vilvoorde, Brussels (Belgium). The obtained land use map has a strong impact on the groundwater recharge, resulting in a high spatial variability. Simulated groundwater fluxes from brownfield to the receiving River Zenne were independently verified by measurements and simulation of groundwater-surface water interaction based on thermal gradients in the river bed. It is concluded that in order to better quantify total fluxes of contaminants from brownfields in the groundwater, remote sensing imagery can be operationally integrated in a modeling procedure. Copyright © 2010 Elsevier B.V. All rights reserved.

Accounting for pH heterogeneity and variability in modelling human health risks from cadmium in contaminated land.

PubMed

Gay, J Rebecca; Korre, Anna

2009-07-01

The authors have previously published a methodology which combines quantitative probabilistic human health risk assessment and spatial statistical methods (geostatistics) to produce an assessment, incorporating uncertainty, of risks to human health from exposure to contaminated land. The model assumes a constant soil to plant concentration factor (CF(veg)) when calculating intake of contaminants. This model is modified here to enhance its use in a situation where CF(veg) varies according to soil pH, as is the case for cadmium. The original methodology uses sequential indicator simulation (SIS) to map soil concentration estimates for one contaminant across a site. A real, age-stratified population is mapped across the contaminated area, and intake of soil contaminants by individuals is calculated probabilistically using an adaptation of the Contaminated Land Exposure Assessment (CLEA) model. The proposed improvement involves not only the geostatistical estimation of the contaminant concentration, but also that of soil pH, which in turn leads to a variable CF(veg) estimate which influences the human intake results. The results presented demonstrate that taking pH into account can influence the outcome of the risk assessment greatly. It is proposed that a similar adaptation could be used for other combinations of soil variables which influence CF(veg).

Multi-scale levels of Cs-137 contamination of landscapes of the Bryansk Region (with reference to results of air gamma survey)

NASA Astrophysics Data System (ADS)

Linnik, Vitaly; Sokolov, Alexander; Sokolov, Peter

2017-04-01

As a result of the Chernobyl accident on April 26, 1986, large amounts of radionuclides were released into the atmosphere, resulting in high contamination in Belarus, Ukraine, and Russia. High variability of environmental parameters and multi-scale nature of initial fallout significantly contributed to very complicated Cs-137 patterns. The first maps of radioactive contamination due to the accident at the Chernobyl nuclear power plant, built in May 1986, already identified a heterogeneous nature of the contamination zones [1]. A complex combination of factors, such as the nature of the deposition (dry, wet), various volumetric activity of radionuclides in the atmosphere during the deposition of aerosols on the earth's surface, led to the formation of multiscale fields of radionuclide contamination, where each scale correlates with "pollution spots" having their own specific nature]. Air gamma survey was conducted with a grid 100x100 m and it allowed to reveal different levels of scale "spots" of Cs-137 contamination associated with the movement of polluted air and the influence of the underlying surface - forests, river valleys. Cs-137 contamination field has an extraordinary feature - uniqueness of its spatial structure in different districts of the Bryansk region. A maximal area of "cesium" spots up to 30-50 km in size and with a contamination density of more than 1000 kBq/m2 is observed in the western part of the Bryansk Region. Their spatial structure is extremely heterogeneous, the differences in the local density of Cs-137 contamination being due to those in intensity of precipitation (wet deposition). The central part of the Bryansk Region with the density of contamination below 37 kBq/m2 (up to 3-5 kBq/m2 ) is an example of a condensing zone of "dry" deposition. With a larger scale, allowing individual elements of Cs-137 contamination to be shown in a more distinct way, it is possible to observe the relationship of contamination with a number of landscape factors. Specifically, one can find apparent relationship of Cs-137 contamination density with forests, where there is an increased deposition activity. An air gamma survey with a range of pollution 7,4-90 0 kBq/m2, conducted in the central and southern part of the Bryansk Region, revealed a complex pattern of contamination density, which is presented as a sequence of "spots" of irregular shape with a high level of radioactive contamination, as well as elongated "bands", whose orientation shows a direction of the movement of air masses, i.e., west-eastward or to the northwest- south-east. The distribution of Cs-137 contamination can be clearly related to the valley of the Sudost River, thus showing relevance of landscape factors for the formation of technogenic pollution with radionuclides. The analysis of transformation of the original Cs-137 contamination formed as a result of the deposition of radioactive aerosols in April-May 1986, due to the effect of landscape factors, has been performed. 1. Izrael Yu. A., Kvasnikova E.V., Linnik V.G. 2012 Radioactive contamination in Russia //Changing the natural environment of Russia in the 20th century (in Russian). Eds. V. M. Kotlyakov, D.I. Lyuri. Moscow: Publishing House Molnet. Pp.202-220.

Development of integrated protocols to track the deposition and impacts of metal contaminants in tidal riverine environments

NASA Astrophysics Data System (ADS)

Roe, Helen M.; Patterson, R. Timothy; Nasser, Nawaf; Edwards, Robin J.; Graham, Conor

2016-04-01

Tidally-influenced rivers are particularly vulnerable to the effects of metal contamination, yet are amongst the most complex fluvial environments in terms of their sediment deposition and transport patterns. We present the results of an interdisciplinary study that aims to elucidate the fluxes and deposition of metal contaminants in a tidally-influenced river system in Northern Ireland, with a view to developing protocols that will have wide applicability for the monitoring and assessment of metal contaminants in similar environments in other regions. We employ a novel methodology that combines ICPMS analysis of sediments, ITRAX-based core analysis and the examination a important group of shelled protozoans (foraminifera), which occur widely in tidal riverine environments, and which are highly sensitive to metal contamination. The responses shown by the group vary between species and with different levels of contaminant exposure. Some species, for example, show increased relative abundances in proximity to discharge sources, whilst others develop chamber deformities. Application of our integrated multiproxy approach to the analysis of surface sediment samples and cores provides a framework for assessing both the spatial and temporal patterns of metal deposition and the impact of contaminants on the biota. Modern sediment samples (n=90) were collected at varying distances from a point contamination source (a former industrial site) in different morpho-sedimentary settings. The impact of 25 measured variables on the modern foraminiferal faunas was considered, including 20 metals, pH, conductivity, elevation and particle size. Channel sediments in close proximity to the contamination source and with the highest levels of Fe, Cu, Zn, Mg and As, yielded the sparsest foraminiferal faunas (Shannon Diversity Index values 0-1.5), whilst the highest prevalence of foraminiferids showing chamber deformities were observed in channel edge and levée bank sites. Kernal density plots showing metal loading and foraminiferal concentrations across the site aided in determining spatial trends. The sediment core data revealed that deformed foraminiferal specimens can extend >15 cm below the contemporary floodplain surface to horizons that pre-date the historical onset of the contamination, suggesting vertical mobilisation of sediment and/or infaunal migration. Etching of the foraminiferal tests in association with reduced pH conditions was also observed for some species. Biometric analysis of tests using SEM imagery further aided in the identification of deformities and the delimitation of graded responses to contaminants. The results of this study of core and surficial samples indicate that the adoption of integrated methodologies that combine established geochemical analysis techniques (e.g. ICPMS analysis) with the observed ecophenotypic response of key indicator microfossil groups (e.g. foraminifera) can provide invaluable data on habitat responses to environmental contamination. Such long-term habitat evaluation data is invaluable to policy makers and planners when prioritising management and remediation efforts.

Landfill mining from a deposit of the chlorine/organochlorine industry as source of dioxin contamination of animal feed and assessment of the responsible processes.

PubMed

Torres, João Paulo Machado; Leite, Claudio; Krauss, Thomas; Weber, Roland

2013-04-01

In 1997, the Polychlorinated dibenzo-para-dioxin (PCDD)/Polychlorinated dibenzofuran (PCDF) concentrations in dairy products in Germany and other European countries increased. The PCDD/PCDF source was contaminated lime used in Brazilian citrus pulp pellets. The contaminated lime was mined from an industrial dump site. However, the detailed origin of the PCDD/PCDFs in the lime was not revealed. This paper investigates the contamination origin and describes the link between lime milk from the dumpsite of a chlorine/organochlorine industry and the contaminated lime. The contaminated lime stem from mining at the corporate landfill of Solvay Indupa in Sao Paulo. The landfill was used for 40 years for deposition of production residues and closed in 1996. The factory operated/operates at least two processes with potentially high PCDD/PCDFs releases namely the oxychlorination process for production of ethylene dichloride (EDC) and the chlor-alkali process. The main landfilled waste was lime milk (1.4 million tons) from the vinyl chloride monomer production (via the acetylene process) along with residues from other processes. The PCDD/PCDF fingerprint revealed that most samples from the chemical landfill showed an EDC PCDD/PCDF pattern with a characteristic octachlorodibenzofuran dominance. The PCDD/PCDF pattern of a Rio Grande sediment samples downstream the facility showed a chlor-alkali pattern with a minor impact of the EDC pattern. The case highlights that PCDD/PCDF- and persistent organic pollutants-contaminated sites need to be identified in a comprehensive manner as required by the Stockholm Convention (article 6) and controlled for their impact on the environment and human health. Landfill mining and reuse of materials from contaminated deposits should be prohibited.

TUMOR HAPLOTYPE ASSEMBLY ALGORITHMS FOR CANCER GENOMICS

PubMed Central

AGUIAR, DEREK; WONG, WENDY S.W.; ISTRAIL, SORIN

2014-01-01

The growing availability of inexpensive high-throughput sequence data is enabling researchers to sequence tumor populations within a single individual at high coverage. But, cancer genome sequence evolution and mutational phenomena like driver mutations and gene fusions are difficult to investigate without first reconstructing tumor haplotype sequences. Haplotype assembly of single individual tumor populations is an exceedingly difficult task complicated by tumor haplotype heterogeneity, tumor or normal cell sequence contamination, polyploidy, and complex patterns of variation. While computational and experimental haplotype phasing of diploid genomes has seen much progress in recent years, haplotype assembly in cancer genomes remains uncharted territory. In this work, we describe HapCompass-Tumor a computational modeling and algorithmic framework for haplotype assembly of copy number variable cancer genomes containing haplotypes at different frequencies and complex variation. We extend our polyploid haplotype assembly model and present novel algorithms for (1) complex variations, including copy number changes, as varying numbers of disjoint paths in an associated graph, (2) variable haplotype frequencies and contamination, and (3) computation of tumor haplotypes using simple cycles of the compass graph which constrain the space of haplotype assembly solutions. The model and algorithm are implemented in the software package HapCompass-Tumor which is available for download from http://www.brown.edu/Research/Istrail_Lab/. PMID:24297529

Gonadal steroidogenesis in vitro from juvenile alligators obtained from contaminated or control lakes.

PubMed Central

Guillette, L J; Gross, T S; Gross, D A; Rooney, A A; Percival, H F

1995-01-01

The ubiquitous distribution of many contaminants and the nonlethal, multigenerational effects of such contaminants on reproductive, endocrine, and immune systems have led to concerns that wildlife worldwide are affected. Although the causal agents and effects are known for some species, the underlying physiological mechanisms associated with contaminant-induced reproductive modifications are still poorly understood and require extensive research. We describe a study examining the steroidogenic activity of gonads removed from juvenile alligators (Alligator mississippiensis) obtained from contaminated or control lakes in central Florida. Synthesis of estradiol-17 beta (E2) was significantly different when ovaries from the contaminated and control lakes were compared in vitro. Additionally, testes from males obtained from the contaminated lake. Lake Apopka, synthesized significantly higher concentrations of E2 when compared to testes obtained from control males. In contrast, testosterone (T) synthesis from all testes examined in this study displayed a normal pattern and produced concentrations greater than that observed from ovaries obtained from either lake. Interestingly, the pattern of gonadal steroidogenesis differs from previously reported plasma concentrations of these hormones obtained from the same individuals. We suggest that the differences between the in vivo and in vitro patterns are due to modifications in the hepatic degradation of plasma sex steroid hormones. PMID:7556021

Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems.

PubMed

Kraus, Johanna M; Gibson, Polly P; Walters, David M; Mills, Marc A

2017-05-01

Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI, USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r 2  > 0.78) and had similar mean ΣPCB concentrations when averaged across all years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa less effective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2017;36:1278-1286. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Spatiotemporal Analysis of Microbiological Contamination in New York State Produce Fields following Extensive Flooding from Hurricane Irene, August 2011.

PubMed

Bergholz, Peter W; Strawn, Laura K; Ryan, Gina T; Warchocki, Steven; Wiedmann, Martin

2016-03-01

Although flooding introduces microbiological, chemical, and physical hazards onto croplands, few data are available on the spatial extent, patterns, and development of contamination over time postflooding. To address this paucity of information, we conducted a spatially explicit study of Escherichia coli and Salmonella contamination prevalence and genetic diversity in produce fields after the catastrophic flooding that occurred in New England during 2011. Although no significant differences were detected between the two participating farms, both random forest and logistic regression revealed changes in the spatial pattern of E. coli contamination in drag swab samples over time. Analyses also indicated that E. coli detection was associated with changes in farm management to remediate the land after flooding. In particular, E. coli was widespread in drag swab samples at 21 days postflooding, but the spatial pattern changed by 238 days postflooding such that E. coli was then most prevalent in close proximity to surface water features. The combined results of several population genetics analyses indicated that over time postflooding E. coli populations on the farms (i) changed in composition and (ii) declined overall. Salmonella was primarily detected in surface water features, but some Salmonella strains were isolated from soil and drag swab samples at 21 and 44 days postflooding. Although postflood contamination and land management responses should always be evaluated in the context of each unique farm landscape, our results provide quantitative data on the general patterns of contamination after flooding and support the practice of establishing buffer zones between flood-contaminated cropland and harvestable crops in produce fields.

Patterns of metal composition and biological condition and their association in male common carp across an environmental contaminant gradient in Lake Mead National Recreation Area, Nevada and Arizona, USA

USGS Publications Warehouse

Patino, R.; Rosen, Michael R.; Orsak, E.L.; Goodbred, S.L.; May, T.W.; Alvarez, David; Echols, K.R.; Wieser, C.M.; Ruessler, S.; Torres, L.

2012-01-01

There is a contaminant gradient in Lake Mead National Recreation Area (LMNRA) that is partly driven by municipal and industrial runoff and wastewater inputs via Las Vegas Wash (LVW). Adult male common carp (Cyprinus carpio; 10 fish/site) were collected from LVW, Las Vegas Bay (receiving LVW flow), Overton Arm (OA, upstream reference), and Willow Beach (WB, downstream) in March 2008. Discriminant function analysis was used to describe differences in metal concentrations and biological condition of fish collected from the four study sites, and canonical correlation analysis was used to evaluate the association between metal and biological traits. Metal concentrations were determined in whole-body extracts. Of 63 metals screened, those initially used in the statistical analysis were Ag, As, Ba, Cd, Co, Fe, Hg, Pb, Se, Zn. Biological variables analyzed included total length (TL), Fulton's condition factor, gonadosomatic index (GSI), hematocrit (Hct), and plasma estradiol-17?? and 11-ketotestosterone (11kt) concentrations. Analysis of metal composition and biological condition both yielded strong discrimination of fish by site (respective canonical model, p< 0.0001). Compared to OA, pairwise Mahalanobis distances between group means were WB < LVB < LVW for metal concentrations and LVB < WB < LVW for biological traits. Respective primary drivers for these separations were Ag, As, Ba, Hg, Pb, Se and Zn; and TL, GSI, 11kt, and Hct. Canonical correlation analysis using the latter variable sets showed they are significantly associated (p<0.0003); with As, Ba, Hg, and Zn, and TL, 11kt, and Hct being the primary contributors to the association. In conclusion, male carp collected along a contaminant gradient in LMNRA have distinct, collection site-dependent metal and morpho-physiological profiles that are significantly associated with each other. These associations suggest that fish health and reproductive condition (as measured by the biological variables evaluated in this study) are influenced by levels of certain metals in the Lake Mead environment. ?? 2011.

Variability of PCB burden in 5 fish and sharks species of the French Mediterranean continental slope.

PubMed

Cresson, Pierre; Fabri, Marie Claire; Miralles, Françoise Marco; Dufour, Jean-Louis; Elleboode, Romain; Sevin, Karine; Mahé, Kelig; Bouchoucha, Marc

2016-05-01

Despite being generally located far from contamination sources, deep marine ecosystems are impacted by chemicals like PCB. The PCB contamination in five fish and shark species collected in the continental slope of the Gulf of Lions (NW Mediterranean Sea) was measured, with a special focus on intra- and interspecific variability and on the driving factors. Significant differences occurred between species. Higher values were measured in Scyliorhinus canicula, Galeus melastomus and Helicolenus dactylopterus and lower values in Phycis blennoides and Lepidorhombus boscii. These differences might be explained by specific abilities to accumulate and eliminate contaminant, mostly through cytochrome P450 pathway. Interindividual variation was also high and no correlation was observed between contamination and length, age or trophic level. Despite its major importance, actual bioaccumulation of PCB in deep fish is not as documented as in other marine ecosystems, calling for a better assessment of the factors driving individual bioaccumulation mechanisms and originating high variability in PCB contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cleaning with a wet sterile gauze significantly reduces contamination of sutures, instruments, and surgical gloves in an ex-vivo pelvic flexure enterotomy model in horses.

PubMed

Giusto, Gessica; Tramuta, Clara; Caramello, Vittorio; Comino, Francesco; Nebbia, Patrizia; Robino, Patrizia; Singer, Ellen; Grego, Elena; Gandini, Marco

2017-01-01

The objective of this study was to investigate whether cleaning surgical materials used to close pelvic flexure enterotomies with a wet sterile gauze will reduce contamination and whether the use of a full thickness appositional suture pattern (F) or a partial thickness inverting (or Cushing) suture pattern (C) would make a difference in the level of contamination. Large colon specimens were assigned to group F or C and divided into subgroups N and G. In group G, a wet sterile gauze was passed over the suture material, another over the instruments, and another over the gloves. In group N, no treatment was applied. The bacterial concentration was measured by optical density (OD) at 24 h. The OD of subgroup CG was lower than that of subgroup CN ( P = 0.019). The OD of subgroup FG was lower than that of subgroup FN ( P = 0.02). The OD of subgroups CG, CN, FG, and FN was lower than that of the negative control ( P < 0.003, P < 0.001, P < 0.001, and P < 0.00). The use of a sterile wet gauze significantly reduced contamination of suture materials. A partial thickness inverting suture pattern did not produce less contamination than a full thickness appositional suture pattern.

Sedimentary record and anthropogenic pollution of a complex, multiple source fed dam reservoirs: An example from the Nové Mlýny reservoir, Czech Republic.

PubMed

Sedláček, Jan; Bábek, Ondřej; Nováková, Tereza

2017-01-01

While numerous studies of dam reservoirs contamination are reported world-wide, we present a missing link in the study of reservoirs sourced from multiple river catchments. In such reservoirs, different point sources of contaminants and variable composition of their sedimentary matrices add to extremely complex geochemical patterns. We studied a unique, step-wise filled Nové Mlýny dam reservoir, Czech Republic, which consists of three interconnected sub-basins. Their source areas are located in units with contrasting geology and different levels and sources of contamination. The aim of this study is to provide an insight into the provenance of the sediment, including lithogenic elements and anthropogenic pollutants, to investigate the sediment dispersal across the reservoir, and to assess the heavy metal pollution in each basin. The study is based on multi-proxy stratigraphic analysis and geochemistry of sediment cores. There is a considerable gradient in the sediment grain size, brightness, MS and geochemistry, which reflects changing hydrodynamic energy conditions and primary pelagic production of CaCO 3 . The thickness of sediments generally decreases from proximal to distal parts, but underwater currents can accumulate higher amounts of sediments in distal parts near the thalweg line. Average sedimentation rates vary over a wide range from 0.58cm/yr to 2.33cm/yr. In addition, the petrophysical patterns, concentrations of lithogenic elements and their ratios made it possible to identify two main provenance areas, the Dyje River catchment (upper basin) and the Svratka and Jihlava River catchments (middle and lower basin). Enrichment factors (EF) were used for distinguishing the anthropogenic element contribution from the local background levels. We found moderate Zn and Cu pollution (EF ~2 to 5) in the upper basin and Zn, Cu and Pb (EF ~2 to 4.5) in the middle basin with the peak contamination in the late 1980s, indicating that the two basins have different contamination histories. Copyright © 2016 Elsevier B.V. All rights reserved.

Contaminants in stream sediments from seven United States metropolitan areas: part I: distribution in relation to urbanization

USGS Publications Warehouse

Nowell, Lisa H.; Moran, Patrick W.; Gilliom, Robert J.; Calhoun, Daniel L.; Ingersoll, Christopher G.; Kemble, Nile E.; Kuivila, Kathryn; Phillips, Patrick J.

2013-01-01

Organic contaminants and trace elements were measured in bed sediments collected from streams in seven metropolitan study areas across the United States to assess concentrations in relation to urbanization. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, the pyrethroid insecticide bifenthrin, and several trace elements were significantly related to urbanization across study areas. Most contaminants (except bifenthrin, chromium, nickel) were significantly related to the total organic carbon (TOC) content of the sediments. Regression models explained 45–80 % of the variability in individual contaminant concentrations using degree of urbanization, sediment-TOC, and study-area indicator variables (which represent the combined influence of unknown factors, such as chemical use or release, that are not captured by available explanatory variables). The significance of one or more study-area indicator variables in all models indicates marked differences in contaminant levels among some study areas, even after accounting for the nationally modeled effects of urbanization and sediment-TOC. Mean probable effect concentration quotients (PECQs) were significantly related to urbanization. Trace elements were the major contributors to mean PECQs at undeveloped sites, whereas organic contaminants, especially bifenthrin, were the major contributors at highly urban sites. Pyrethroids, where detected, accounted for the largest share of the mean PECQ. Part 2 of this series (Kemble et al. 2012) evaluates sediment toxicity to amphipods and midge in relation to sediment chemistry.

Analysis of potential factors affecting microbiological cultures in tissue donors during procurement.

PubMed

Lannau, B; Van Geyt, C; Van Maele, G; Beele, H

2015-03-01

During the procurement of musculoskeletal grafts contamination may occur. As this might be detrimental for the acceptor, it is important to know which variables influence this occurrence and to alter procurement protocols accordingly. From 2004 to 2012 we gathered information on 6,428 allografts obtained from 291 donors. Using a multiple regression model we attempted to determine the factors that influence the contamination risk during procurement. We used the following variables: cause of death, type of hospital (i.e. university hospital vs. general hospital), previous blood vessel donation, previous organ donation, donor age, time between death and the start of the procurement, duration of the procurement, number of people attending the procurement and the number of procured grafts. The multiple regression model was only able to explain 5 % of the variability of the used outcome variable. None of the variables examined appear to have an important influence on the contamination risk.

Thruster residues on returned Mir solar panel

NASA Astrophysics Data System (ADS)

Harvey, Gale A.

2000-09-01

A solar panel with more than ten years space exposure was returned to Earth in January 1998. Several types of residues were deposited or transported onto the solar cell coverglasses during the space exposure. Self-contamination of SiOx films from the silicone potting compound was a major contamination of the coverglasses. A second type of contamination was thick, detergent-like residues of the order of a millimeter diameter on many, but not most of the coverglasses. A third, prevalent type of contamination was very thin irregular shaped films or patterns of a millimeter size which are readily visible in brilliant colors when the coverglasses are viewed with a 50x brightfield microscope. These prolific, overlapping, and almost ubiquitous patterns strongly suggest wetting on the surface. The probably cause of most of the wetted patterns on the returned Mir solar cell coverglasses is trace hydrazine nitrate in condensed water droplets produced as reaction products from Mir's and the Orbiters' hypergolic thrusters. This paper presents some of the wetted patterns, information regarding hypergolic reaction products, and type of thrusters associated with Mir operations.

Distribution and mobility of metals in contaminated sites. chemometric investigation of pollutant profiles.

PubMed

Abollino, Ornella; Aceto, Maurizio; Malandrino, Mery; Mentasti, Edoardo; Sarzanini, Corrado; Barberis, Renzo

2002-01-01

The distribution and mobility of heavy metals in the soils of two contaminated sites in Piedmont (Italy) was investigated, evaluating the horizontal and vertical profiles of 15 metals, namely Al, Cd, Cu, Cr, Fe. La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr. The concentrations in the most polluted areas of the sites were higher than the acceptable limits reported in Italian and Dutch legislations for soil reclamation. Chemometric elaboration of the results by pattern recognition techniques allowed us to identify groups of samples with similar characteristics and to find correlations among the variables. The pollutant mobility was studied by extraction with water, dilute acetic acid and EDTA and by applying Tessier's procedure. The fraction of mobile species, which potentially is the most harmful for the environment, was found to be higher than the one normally present in unpolluted soils, where heavy metals are, to a higher extent, strongly bound to the matrix.

Status of faecal pollution in ports: A basin-wide investigation in the Adriatic Sea.

PubMed

Luna, Gian Marco; Manini, Elena; Turk, Valentina; Tinta, Tinkara; D'Errico, Giuseppe; Baldrighi, Elisa; Baljak, Vanja; Buda, Donatella; Cabrini, Marina; Campanelli, Alessandra; Cenov, Arijana; Del Negro, Paola; Drakulović, Dragana; Fabbro, Cinzia; Glad, Marin; Grilec, Dolores; Grilli, Federica; Jokanović, Sandra; Jozić, Slaven; Kauzlarić, Vesna; Kraus, Romina; Marini, Mauro; Mikuš, Josip; Milandri, Stefania; Pećarević, Marijana; Perini, Laura; Quero, Grazia Marina; Šolić, Mladen; Lušić, Darija Vukić; Zoffoli, Silvia

2018-04-07

Ports are subject to a variety of anthropogenic impacts, and there is mounting evidence of faecal contamination through several routes. Yet, little is known about pollution in ports by faecal indicator bacteria (FIB). FIB spatio-temporal dynamics were assessed in 12 ports of the Adriatic Sea, a semi-enclosed basin under strong anthropogenic pressure, and their relationships with environmental variables were explored to gain insight into pollution sources. FIB were abundant in ports, often more so than in adjacent areas; their abundance patterns were related to salinity, oxygen, and nutrient levels. In addition, a molecular method, quantitative (q)PCR, was used to quantify FIB. qPCR enabled faster FIB determination and water quality monitoring that culture-based methods. These data provide robust baseline evidence of faecal contamination in ports and can be used to improve the management of routine port activities (dredging and ballast water exchange), having potential to spread pathogens in the sea. Copyright © 2018 Elsevier Ltd. All rights reserved.

Seasonal Drivers of Dissolved Metal Transport During Infiltration of Road Runoff in an Urban Roadside Environment

NASA Astrophysics Data System (ADS)

Mullins, A.; Bain, D.

2017-12-01

Infiltration-based green infrastructure (GI) is being increasingly applied in urban areas, systems characterized by substantial legacy contamination and complicated hydrology. However, it is not clear how the application of green infrastructure changes the geochemistry of urban roadside environments. Most current research on GI focuses on small sets of chemical parameters (e.g. road salt, nitrogen and phosphorous species) over relatively short time periods, limiting comprehensive understanding of geochemical function. This work measures changes in groundwater infiltration rate and dissolved metal concentrations in two infiltration trenches in Pittsburgh, PA to evaluate function and measure dissolved metal transport from the system over time. Two distinct geochemical regimes seem to be driven by seasonality: road de-icer exchange and microbial driven summer reducing conditions. Interactions between these geochemical regimes and variability in infiltration rate control the flux of different metals, varying with metal chemistry. These findings suggest the adoption of infiltration based green infrastructure will likely create complicated patterns of legacy contamination transport to downstream receptors.

Remanence of lead pollution in an urban river system: a multi-scale temporal and spatial study in the Seine River basin, France.

PubMed

Ayrault, S; Le Pape, P; Evrard, O; Priadi, C R; Quantin, C; Bonté, P; Roy-Barman, M

2014-03-01

Total lead (Pb) concentration and Pb isotopic ratio ((206)Pb/(20)7Pb) were determined in 140 samples from the Seine River basin (France), covering a period of time from 1945 to 2011 and including bed sediments (bulk and size fractionated samples), suspended particulate matter (SPM), sediment cores, and combined sewer overflow (CSO) particulate matter to constrain the spatial and temporal variability of the lead sources at the scale of the contaminated Seine River basin. A focus on the Orge River subcatchment, which exhibits a contrasted land-use pattern, allows documenting the relation between hydrodynamics, urbanization, and contamination sources. The study reveals that the Pb contamination due to leaded gasoline that peaked in the 1980s has a very limited impact in the river nowadays. In the upstream Seine River, the isotopic ratio analysis suggests a pervasive contamination which origin (coal combustion and/or gasoline lead) should be clarified. The current SPM contamination trend follows the urbanization/industrialization spatial trend. Downstream of Paris, the lead from historical use originating from the Rio Tinto mine, Spain ((206)Pb/(207)Pb=1.1634 ± 0.0001) is the major Pb source. The analysis of the bed sediments (bulk and grain size fractionated) highlights the diversity of the anthropogenic lead sources in relation with the diversity of the human activities that occurred in this basin over the years. The "urban" source, defined by waste waters including the CSO samples ((206)Pb/(207)Pb=1.157 ± 0.003), results of a thorough mixing of leaded gasoline with "historical" lead over the years. Finally, a contamination mixing scheme related to hydrodynamics is proposed.

Urban snow indicates pollution originating from road traffic.

PubMed

Kuoppamäki, Kirsi; Setälä, Heikki; Rantalainen, Anna-Lea; Kotze, D Johan

2014-12-01

Traffic is a major source of pollutants in cities. In this well-replicated study we analysed a broad array of contaminants in snowpacks along roads of different traffic intensities. The majority of pollutants showed a similar pattern with respect to traffic intensity: pH and conductivity as well as concentrations of PAHs, total suspended solids, phosphorus and most heavy metals were higher next to high intensity roads compared to low intensity roads. These pollutant levels also decreased considerably up to 5 m distance from the roads. Furthermore, apart from nitrogen, these variables increased in concentration from control sites in urban forest patches to road bank sites next to roads of low, intermediate and high traffic intensities. The deposition pattern of various traffic-derived pollutants--whether gaseous or particle-bound--was the same. Such information can be useful for the purposes of managing pollutants in urban areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

Contaminant transport in fractured rocks with significant matrix permeability, using natural fracture geometries

NASA Astrophysics Data System (ADS)

Odling, Noelle E.; Roden, Julie E.

1997-09-01

Some results from numerical models of flow and contaminant transport in fractured permeable rocks, where fractures are more conductive than rock matrix, are described. The 2D flow field in the fractured and permeable rock matrix is calculated using a finite difference, 'conductance mesh' method, and the contaminant transport is simulated by particle tracking methods using an advection-biased, random walk technique. The model is applied to simulated and naturally occurring fracture patterns. The simulated pattern is an en echelon array of unconnected fractures, as an example of a common, naturally occurring fracture geometry. Two natural fracture patterns are used: one of unconnected, sub-parallel fractures and one with oblique fracture sets which is well connected. Commonly occurring matrix permeability and fracture aperture values are chosen. The simulations show that the presence of fractures creates complex and heterogeneous flow fields and contaminant distribution in the permeable rock matrix. The modelling results have shown that some effects are non-intuitive and therefore difficult to foresee without the help of a model. With respect to contaminant transport rates and plume heterogeneity, it was found that fracture connectivity (crucial when the matrix is impermeable) can play a secondary role to fracture orientation and density. Connected fracture systems can produce smooth break-through curves of contaminants summed over, for example, a bore-hole length, whereas in detail the contaminant plume is spatially highly heterogeneous. Close to a constant-pressure boundary (e.g. an extraction bore-hole), flow and contaminants can be channelled by fractures. Thus observations at a bore-hole may suggest that contaminants are largely confined to the fracture system, when, in fact, significant contamination resides in the matrix.

[Impacts of landscape patterns on heavy metal contamination of agricultural top soils in the Pearl River Delta, South China].

PubMed

Li, Cheng; Li, Fang-bai; Wu, Zhi-feng; Cheng, Jiong

2015-04-01

Landscape patterns are known to influence many ecological processes, but the relationship between landscape patterns and soil pollution processes is not well understood. Based on 300 top soil samples, land use and cover map for the Pearl River Delta (PRD) of 2005, this study explored the characteristics and spatial pattern of heavy metal contamination of agricultural top soils and examined the impacts of landscape patterns on the heavy metal contamination in the buffers of soil samples. Research methods included geostatistical analysis, landscape pattern analysis, single-factor pollution indices, and Pearson correlation analysis. We found that: 1) out of the 235 agricultural soil samples, 3.8%, 0.4%, 17.0% and 9.4% samples exceeded the Grade II national standard for As, Pb, Cd and Ni concentrations respectively. High pollution levels were found in three cities, Guangzhou, Foshan and Zhongshan; 2) soils in the farmland were more polluted than those in the forest and orchard land, and there were no differences among different agricultural land use types in contamination level of each heavy metal (except Cd); and 3) the proportion, mean patch area as well as the degree of landscape fragmentation, landscape-level structural complexity and aggregation/connectivity of water at the buffer zone were significantly positively correlated with the contamination level of each of the four heavy metals in agricultural top soils. Part of the landscape pattern of urban land in the buffer zone also positively correlated with Pb and Cd levels (P < 0.05). On the contrary, the proportion, mean patch area and aggregation degree of forest land negatively correlated with soil Pb and Ni levels (P < 0.05); and 4) the closer to the industry land were the soil samples, the more polluted the soils were for Pb, Cd and Ni. Only landscape diversity was found to be positively correlated with soil Cd contamination. The study results provide new information and scientific basis for heavy metal pollution control and remediation, especially for agricultural soils in the PRD.

Mapping fields of 137Cs contamination in soils in the context of their stability and hierarchical spatial structure

NASA Astrophysics Data System (ADS)

Korobova, E.; Romanov, S.

2009-04-01

Technogenic radioisotopes now dispersed in the environment are involved in natural and technogenic processes forming specific geochemical fields and serving as tracers of modern mass migration and geofield transformation. Cs-137 radioisotopes having a comparatively long life time are known for a fast fixation by the top soil layer; radiocesium activity can be measured in the surface layer in field conditions. This makes 137Cs rather convenient for the study and modeling a behavior of toxic elements in soils [1-3, 5] and for the investigation of relative stability and hierarchical fractal structures of the soil contamination of the atmospheric origin [2]. The objective of the experimental study performed on the test site in Bryansk region was to find and prove polycentric regularities in the structure of 137Cs contamination field formed after the Chernobyl accident in natural conditions. Such a character of spatial variability can be seen on the maps showing different soil parameters and chemical element distribution measured in grids [3-5]. The research was undertaken to support our idea of the regular patterns in the contamination field structure that enables to apply a mathematical theory of the field to the geochemical fields modeling on the basis of a limited number of direct measurements sufficient to reproduce the configuration and main parameters of the geochemical field structure on the level of the elementary landscape geochemical system (top-slope-bottom). Cs-137 field measurements were verified by a direct soil sampling. Soil cores dissected into subsamples with increments of 2, 5 and 10 cm, were taken to the depth of 40 cm at points with various surface activity located at different elements of relief. According to laboratory measurements 137Cs inventory in soils varied from 344 to 3448 kBq/m2 (983 kBq/m2 on the average). From 95,1% to 98,0% to of the total inventory was retained in the top 20-cm soil layer. This confirmed that field gamma spectrometry could be used to investigate patterns of 137Cs spatial redistribution in the top soil layers. The portion of 137Cs conserved in top layers corresponded to the meso- and micro relief elements. The character and stability of 137Cs spatial structure was studied by measuring its activity within nested plots with different steps of 5, 2, 1 and 0,2 m (the latter was a minimum resolution step for the field NaI detector). Performed measurements showed that the contamination field of 137Cs had a regular structure of polycentric character and exhibited a decrease in spatial variability of contamination with the decrease of the measured area. Repeated measurements of soil contamination in successive years of 2005-2008 along and cross the slopes provided with topographic survey proved the stability of contamination field (r=0, 915, n=121, r=0,912, n=30) and its relation to the meso- and microrelief features. Variation 137Cs activity in lateral direction (along the slopes and thalweg of the hollow)showed a regular character also. In our opinion the regularity in 137Cs spatial structure in the soil cover may result from radionuclide redistribution with the surface and subsurface water flow highly sensitive to the changes in elevation of different scale, and to the slope length and inclination. Cs-137 lateral distribution pattern was likely to reflect alternation of lateral and vertical water mass migration along the slopes. The performed study showing regularity in 137Cs redistribution seems to open new possibilities to develop the deterministic strategy in the study of contamination fields and modeling toxic elements spatial distribution in the soil cover on different scales. The authors are much obliged to Dr. V. Samsonov and Dr. F. Moiseenko for participation in the field work and to S. Kirov for the performance of the laboratory measurement of the soil and plant samples. References 1. Khomutinin, Yu.V., Kashparov, V.A., Zhebrovskaya, E.I., 2001. Optimization of sampling and measurement of the specimen for radioecological monitoring. UkrNIISKHR, Kiev. 2. Korobova, E.M., Romanov, S.L., Samsonov, V.L., Kirov, S.S., 2006. Experimental study of spatial 137Cs redistribution in paragenetic elementary landscapes, in: Kasimov, N.S. et al (Eds.), Geochemistry of biosphere (devoted to 90-th anniversary of A.I. Perelman), MSU, IGEM, RFFI, Moscow-Smolensk, pp.157-159. 3. Linnik, V.G., Saveliev, A.A., Govorun, A.P., Ivanitsky, O.M., Sokolov, A.V., 2006. Analysis of the Cs-137 contamination field on micro-landscape scale within the virgin meadows in the western part of the Bryansk region, in: Kasimov, N.S. et al (Eds.), Geochemistry of biosphere (devoted to 90-th anniversary of A.I. Perelman), MSU, IGEM, RFFI, Moscow-Smolensk, pp. 201-204. 4. Samsonova V.P. Spatial variability of the soil parameters. On example of soddy-podozolic soils. Moscow, LKI, 2008, 156 p. 5.Shcheglov, A.I., Tsvetnova, O.B., Klyashtorin, A.I., 2001. Biogeochemical migration of technogenic radionuclides in forest ecosystems. Nauka, Moscow.

An 80-year record of sediment quality in the lower Mississippi River

USGS Publications Warehouse

Van Metre, Peter C.; Horowitz, Arthur J.

2013-01-01

In 1937, the US Army Corps of Engineers cut through the "neck" of a large meander on the lower Mississippi River (below the confluence with the Ohio River) forming the Caulk Neck cutoff and creating Lake Whittington, a 26-km long oxbow lake, in northern Mississippi. Since 1938, seasonal flooding and a boat channel connecting the lake with the Mississippi River have led to sediment accumulation in the lake, resulting in an 80-year record of sediment quality in the river. On the basis of an age-dated sediment core from the lake, trends in trace metals and hydrophobic organic compounds (except polycyclic aromatic hydrocarbons) follow well-known patterns with upward trends from the 1930s to the ca 1970s, followed by downward trends to the present. Two factors contribute to these patterns: reservoir construction and changes in emissions. The construction of seven large reservoirs on the Missouri River, in particular the closure of the Fort Randall (1953) and Gavins Point (1955) Dams, greatly reduced the load of relatively clean sediment to the Mississippi River, likely contributing to downstream increases in contaminant concentrations in the Mississippi River. Increasing anthropogenic emissions also contributed to upward trends until ca 1970 when major environmental policy actions began resulting in broad decreases in emissions and downward trends in the concentrations of most of the contaminants monitored. Polycyclic aromatic hydrocarbons and phosphorus are partial exceptions to this pattern, with increases to the 1960s and variable concentrations showing no clear trend since. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Gene transcription patterns in response to low level petroleum contaminants in Mytilus trossulus from field sites and harbors in southcentral Alaska

NASA Astrophysics Data System (ADS)

Bowen, Lizabeth; Miles, A. Keith; Ballachey, Brenda; Waters, Shannon; Bodkin, James; Lindeberg, Mandy; Esler, Daniel

2018-01-01

The 1989 Exxon Valdez oil spill damaged a wide range of natural resources, including intertidal communities, and post-spill studies demonstrated acute and chronic exposure and injury to an array of species. Standard toxicological methods to evaluate petroleum contaminants have assessed tissue burdens, with fewer assays providing indicators of health or physiology, particularly when contaminant levels are low and chronic. Marine mussels are a ubiquitous and crucial component of the nearshore environment, and new genomic technologies exist to quantify molecular responses of individual mussels to stimuli, including exposure to polycyclic aromatic hydrocarbons (PAHs). We used gene-based assays of exposure and physiological function to assess chronic oil contamination using the Pacific blue mussel, Mytilus trossulus. We developed a diagnostic gene transcription panel to investigate exposure to PAHs and other contaminants and its effects on mussel physiology and health. During 2012-2015, we analyzed mussels from five field sites in western Prince William Sound, Alaska, with varying oil histories from the 1989 Exxon Valdez oil spill, and from three boat harbors in the area. Gene transcription patterns of mussels from harbors were consistent with elevated exposure to PAHs or other contaminants, whereas transcription patterns of mussels sampled from shorelines in areas affected by the oil spill indicated no PAH exposure.

Systems Reliability Framework for Surface Water Sustainability and Risk Management

NASA Astrophysics Data System (ADS)

Myers, J. R.; Yeghiazarian, L.

2016-12-01

With microbial contamination posing a serious threat to the availability of clean water across the world, it is necessary to develop a framework that evaluates the safety and sustainability of water systems in respect to non-point source fecal microbial contamination. The concept of water safety is closely related to the concept of failure in reliability theory. In water quality problems, the event of failure can be defined as the concentration of microbial contamination exceeding a certain standard for usability of water. It is pertinent in watershed management to know the likelihood of such an event of failure occurring at a particular point in space and time. Microbial fate and transport are driven by environmental processes taking place in complex, multi-component, interdependent environmental systems that are dynamic and spatially heterogeneous, which means these processes and therefore their influences upon microbial transport must be considered stochastic and variable through space and time. A physics-based stochastic model of microbial dynamics is presented that propagates uncertainty using a unique sampling method based on artificial neural networks to produce a correlation between watershed characteristics and spatial-temporal probabilistic patterns of microbial contamination. These results are used to address the question of water safety through several sustainability metrics: reliability, vulnerability, resilience and a composite sustainability index. System reliability is described uniquely though the temporal evolution of risk along watershed points or pathways. Probabilistic resilience describes how long the system is above a certain probability of failure, and the vulnerability metric describes how the temporal evolution of risk changes throughout a hierarchy of failure levels. Additionally our approach allows for the identification of contributions in microbial contamination and uncertainty from specific pathways and sources. We expect that this framework will significantly improve the efficiency and precision of sustainable watershed management strategies through providing a better understanding of how watershed characteristics and environmental parameters affect surface water quality and sustainability. With microbial contamination posing a serious threat to the availability of clean water across the world, it is necessary to develop a framework that evaluates the safety and sustainability of water systems in respect to non-point source fecal microbial contamination. The concept of water safety is closely related to the concept of failure in reliability theory. In water quality problems, the event of failure can be defined as the concentration of microbial contamination exceeding a certain standard for usability of water. It is pertinent in watershed management to know the likelihood of such an event of failure occurring at a particular point in space and time. Microbial fate and transport are driven by environmental processes taking place in complex, multi-component, interdependent environmental systems that are dynamic and spatially heterogeneous, which means these processes and therefore their influences upon microbial transport must be considered stochastic and variable through space and time. A physics-based stochastic model of microbial dynamics is presented that propagates uncertainty using a unique sampling method based on artificial neural networks to produce a correlation between watershed characteristics and spatial-temporal probabilistic patterns of microbial contamination. These results are used to address the question of water safety through several sustainability metrics: reliability, vulnerability, resilience and a composite sustainability index. System reliability is described uniquely though the temporal evolution of risk along watershed points or pathways. Probabilistic resilience describes how long the system is above a certain probability of failure, and the vulnerability metric describes how the temporal evolution of risk changes throughout a hierarchy of failure levels. Additionally our approach allows for the identification of contributions in microbial contamination and uncertainty from specific pathways and sources. We expect that this framework will significantly improve the efficiency and precision of sustainable watershed management strategies through providing a better understanding of how watershed characteristics and environmental parameters affect surface water quality and sustainability.

Development of Tier 1 screening tool for soil and groundwater vulnerability assessment in Korea using classification algorithm in a neural network

NASA Astrophysics Data System (ADS)

Shin, K. H.; Kim, K. H.; Ki, S. J.; Lee, H. G.

2017-12-01

The vulnerability assessment tool at a Tier 1 level, although not often used for regulatory purposes, helps establish pollution prevention and management strategies in the areas of potential environmental concern such as soil and ground water. In this study, the Neural Network Pattern Recognition Tool embedded in MATLAB was used to allow the initial screening of soil and groundwater pollution based on data compiled across about 1000 previously contaminated sites in Korea. The input variables included a series of parameters which were tightly related to downward movement of water and contaminants through soil and ground water, whereas multiple classes were assigned to the sum of concentrations of major pollutants detected. Results showed that in accordance with diverse pollution indices for soil and ground water, pollution levels in both media were strongly modulated by site-specific characteristics such as intrinsic soil and other geologic properties, in addition to pollution sources and rainfall. However, classification accuracy was very sensitive to the number of classes defined as well as the types of the variables incorporated, requiring careful selection of input variables and output categories. Therefore, we believe that the proposed methodology is used not only to modify existing pollution indices so that they are more suitable for addressing local vulnerability, but also to develop a unique assessment tool to support decision making based on locally or nationally available data. This study was funded by a grant from the GAIA project(2016000560002), Korea Environmental Industry & Technology Institute, Republic of Korea.

Cleaning with a wet sterile gauze significantly reduces contamination of sutures, instruments, and surgical gloves in an ex-vivo pelvic flexure enterotomy model in horses

PubMed Central

Giusto, Gessica; Tramuta, Clara; Caramello, Vittorio; Comino, Francesco; Nebbia, Patrizia; Robino, Patrizia; Singer, Ellen; Grego, Elena; Gandini, Marco

2017-01-01

The objective of this study was to investigate whether cleaning surgical materials used to close pelvic flexure enterotomies with a wet sterile gauze will reduce contamination and whether the use of a full thickness appositional suture pattern (F) or a partial thickness inverting (or Cushing) suture pattern (C) would make a difference in the level of contamination. Large colon specimens were assigned to group F or C and divided into subgroups N and G. In group G, a wet sterile gauze was passed over the suture material, another over the instruments, and another over the gloves. In group N, no treatment was applied. The bacterial concentration was measured by optical density (OD) at 24 h. The OD of subgroup CG was lower than that of subgroup CN (P = 0.019). The OD of subgroup FG was lower than that of subgroup FN (P = 0.02). The OD of subgroups CG, CN, FG, and FN was lower than that of the negative control (P < 0.003, P < 0.001, P < 0.001, and P < 0.00). The use of a sterile wet gauze significantly reduced contamination of suture materials. A partial thickness inverting suture pattern did not produce less contamination than a full thickness appositional suture pattern. PMID:28154467

On the Evolutionary History, Population Genetics and Diversity among Isolates of Salmonella Enteritidis PFGE Pattern JEGX01.0004

PubMed Central

Allard, Marc W.; Luo, Yan; Strain, Errol; Pettengill, James; Timme, Ruth; Wang, Charles; Li, Cong; Keys, Christine E.; Zheng, Jie; Stones, Robert; Wilson, Mark R.; Musser, Steven M.; Brown, Eric W.

2013-01-01

Facile laboratory tools are needed to augment identification in contamination events to trace the contamination back to the source (traceback) of Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis). Understanding the evolution and diversity within and among outbreak strains is the first step towards this goal. To this end, we collected 106 new S. Enteriditis isolates within S. Enteriditis Pulsed-Field Gel Electrophoresis (PFGE) pattern JEGX01.0004 and close relatives, and determined their genome sequences. Sources for these isolates spanned food, clinical and environmental farm sources collected during the 2010 S. Enteritidis shell egg outbreak in the United States along with closely related serovars, S. Dublin, S. Gallinarum biovar Pullorum and S. Gallinarum. Despite the highly homogeneous structure of this population, S. Enteritidis isolates examined in this study revealed thousands of SNP differences and numerous variable genes (n = 366). Twenty-one of these genes from the lineages leading to outbreak-associated samples had nonsynonymous (causing amino acid changes) changes and five genes are putatively involved in known Salmonella virulence pathways. While chromosome synteny and genome organization appeared to be stable among these isolates, genome size differences were observed due to variation in the presence or absence of several phages and plasmids, including phage RE-2010, phage P125109, plasmid pSEEE3072_19 (similar to pSENV), plasmid pOU1114 and two newly observed mobile plasmid elements pSEEE1729_15 and pSEEE0956_35. These differences produced modifications to the assembled bases for these draft genomes in the size range of approximately 4.6 to 4.8 mbp, with S. Dublin being larger (∼4.9 mbp) and S. Gallinarum smaller (4.55 mbp) when compared to S. Enteritidis. Finally, we identified variable S. Enteritidis genes associated with virulence pathways that may be useful markers for the development of rapid surveillance and typing methods, potentially aiding in traceback efforts during future outbreaks involving S. Enteritidis PFGE pattern JEGX01.0004. PMID:23383127

Geochemical Trends and Natural Attenuation of RDX, Nitrate, and Perchlorate in the Hazardous Test Area Fractured-Granite Aquifer, White Sands Missile Range, New Mexico, 1996-2006

USGS Publications Warehouse

Langman, Jeff B.; Robertson, Andrew J.; Bynum, Jamar; Gebhardt, Fredrick E.

2008-01-01

A fractured-granite aquifer at White Sands Missile Range is contaminated with the explosive compound RDX, nitrate, and perchlorate (oxidizer associated with rocket propellant) from the previous use of the Open Burn/Open Detonation site at the Hazardous Test Area. RDX, nitrate, and perchlorate ground-water concentrations were analyzed to examine source characteristics, spatial and temporal variability, and the influence of the natural attenuation processes of dilution and degradation in the Hazardous Test Area fractured-granite aquifer. Two transects of ground-water wells from the existing monitoring-site network - one perpendicular to ground-water flow (transect A-A') and another parallel to ground-water flow (transect B-B') - were selected to examine source characteristics and the spatial and temporal variability of the contaminant concentrations. Ground-water samples collected in 2005 from a larger sampling of monitoring sites than the two transects were analyzed for various tracers including major ions, trace elements, RDX degradates, dissolved gases, water isotopes, nitrate isotopes, and sulfate isotopes to examine the natural attenuation processes of dilution and degradation. Recharge entrains contaminants at the site and transports them downgradient towards the Tularosa Basin floor through a poorly connected fracture system(s). From 1996 to 2006, RDX, nitrate, and perchlorate concentrations in ground water downgradient from the Open Burn/Open Detonation site have been relatively stable. RDX, nitrate, and perchlorate in ground water from wells near the site indicate dispersed contaminant sources in and near the Open Burn/Open Detonation pits. The sources of RDX and nitrate in the pit area have shifted with time, and the shift correlates with the regrading of the south and east berms of each pit in 2002 and 2003 following closure of the site. The largest RDX concentrations were in ground water about 0.1 mile downgradient from the pits, the largest perchlorate concentrations were in ground water about 0.15 mile downgradient from the pits, and the largest nitrate concentrations were in ground water about 0.25 mile down-gradient from the pits. Strong and moderate correlation of water level and the contaminant concentrations near the source areas and low correlation outside and downgradient from the source areas indicates a diminishing of the water level/contaminant relation with downgradient flow. Ground water was not progressively older at all locations downgradient from the Open Burn/Open Detonation site indicating multiple recharge areas. Major ion and strontium concentrations and d2H and d18O values identified similar sources of recharge waters comprising the aquifer except along the basin periphery where recharge water may be influenced by dissolution of mineral assemblages associated with ore deposits that are present along the basin margins. Ground-water ages, dissolved-solids concentrations, and calcium-strontium concentrations indicate limited or partial connectivity between fractures and contributions of uncontaminated recharge water downgradient from the site that dilutes contaminant concentrations. Changes in RDX and nitrate concentration patterns, the presence of methane, changes in carbon dioxide concentrations and d15N and d34S values, and variable reduction-oxidation conditions suggest degradation of contaminants in the downgradient direction. Estimated values of electron potential were assigned to ground water collected in October 2005 from all monitoring sites at the Hazardous Test Area. Moderate to strong reducing conditions were present upgradient from the Open Burn/Open Detonation site, at the site, and at various locations downgradient from the site, but the aquifer contained well-oxygenated water between many of the reducing areas. The spatial variability of reduction-oxidation conditions in the aquifer exemplifies the partial connectivity of the fracture system(s). Dilution of the contaminants i

Genetic variation among interconnected populations of Catostomus occidentalis: Implications for distinguishing impacts of contaminants from biogeographical structuring

USGS Publications Warehouse

Whitehead, A.; Anderson, S.L.; Kuivila, K.M.; Roach, J.L.; May, B.

2003-01-01

Exposure to contaminants can affect survivorship, recruitment, reproductive success, mutation rates and migration, and may play a significant role in the partitioning of genetic variation among exposed and nonexposed populations. However, the application of molecular population genetic data to evaluate such influences has been uncommon and often flawed. We tested whether patterns of genetic variation among native fish populations (Sacramento sucker, Catostomus occidentalis) in the Central Valley of California were consistent with long-term pesticide exposure history, or primarily with expectations based on biogeography. Field sampling was designed to rigorously test for both geographical and contamination influences. Fine-scale structure of these interconnected populations was detected with both amplified fragment length polymorphisms (AFLP) and microsatellite markers, and patterns of variation elucidated by the two marker systems were highly concordant. Analyses indicated that biogeographical hypotheses described the data set better than hypotheses relating to common historical pesticide exposure. Downstream populations had higher genetic diversity than upstream populations, regardless of exposure history, and genetic distances showed that populations from the same river system tended to cluster together. Relatedness among populations reflected primarily directions of gene flow, rather than convergence among contaminant-exposed populations. Watershed geography accounted for significant partitioning of genetic variation among populations, whereas contaminant exposure history did not. Genetic patterns indicating contaminant-induced selection, increased mutation rates or recent bottlenecks were weak or absent. We stress the importance of testing contaminant-induced genetic change hypotheses within a biogeographical context. Strategic application of molecular markers for analysis of fine-scale structure, and for evaluating contaminant impacts on gene pools, is discussed.

Impact of Temporally Variable and Uniform Pumping Regimes on Contaminant Transport in Heterogeneous Aquifers

NASA Astrophysics Data System (ADS)

Libera, A.; de Barros, F.; Guadagnini, A.

2015-12-01

We study and compare the effect of temporally variable and uniform pumping regimes on key features of contaminant transport in a randomly heterogeneous aquifer. Pumping wells are used for groundwater supply in the context of urban, agricultural, and industrial activities. Groundwater management agencies typically schedule groundwater extraction through a predefined sequence of pumping periods to balance benefits to anthropogenic activities and environmental needs. The impact of the spatial variability of aquifer hydraulic properties, such as hydraulic conductivity, on contaminant transport and associated solute residence times are widely studied. Only a limited number of studies address the way a given pumping schedule affects contaminant plume behavior in heterogeneous aquifers. In this context, the feedback between a transient pumping regime and contaminant breakthrough curves is largely unexplored. Our goal is to investigate the way diverse groundwater extraction strategies affect the history of solute concentration recovered at the well while accounting for the natural variability of the geological system, in the presence of incomplete information on hydraulic conductivity distribution. Considering the joint effects of spatially heterogeneous hydraulic conductivity and temporally varying well pumping rates, this work offers a realistic evaluation of groundwater contamination risk. The latter is here considered in the context of human health and is quantified in terms of the probability that harm will result from exposure to a contaminant found in groundwater. Two scenarios are considered: a pumping well that extracts a given amount of water operating (a) at a constant pumping rate and (b) under transient conditions. The analysis is performed within a numerical Monte Carlo framework. We probe the impact of diverse geostatistical structures to describe aquifer heterogeneity on solute breakthrough curves and the statistics of target environmental performance metrics, including, e.g., peak concentration and the time at which peak breakthrough at well occurs.

Comparison of patterns and knowledge of benefits and warnings of fish consumption between parents and children.

PubMed

Herdt-Losavio, Michele L; Lin, Shao; Chen, Ming; Luo, Ming; Tang, Jianzhong; Hwang, Syni-An

2014-07-01

We examined generational differences in fish consumption and knowledge of benefits/warnings of fish consumption among parents and children. This cross-sectional study gathered self-administered questionnaire data, including demographics, fish consumption behavior (including specific fish species) and knowledge of fish consumption warnings and benefits. Fish were later grouped into four categories by potential mercury contamination. Descriptive statistics were conducted for all variables comparing all adults and children. Benefit/risk knowledge variables were also descriptively analyzed among parent-child pairs only. Multivariate Poisson regression was conducted on pairs to assess risk factors for children eating higher mercury fish. 421 adults and 207 children (171 adult-child pairs) participated (family response rate: 71%). Slightly more adults (97.6%) ate fish in the last year than children (92.3%); however, there was no difference between consumption of fish by category of potential mercury contamination. Both adults (44%) and children (45%) ate high-mercury fish. In 71% of parent-child pairs, both the parent and the child knew of benefits of consuming fish; only 31% knew of warnings. Parental consumption of high or moderately-high-mercury fish was related to the child's consumption of fish in the same category. Parents and children need additional education to make better choices about fish consumption. Education should target the family and include specifics about benefits and risks.

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 2

EPA Science Inventory

As contaminant ground water flows downgradient from a release point, its movement is dictated by site geological conditions and hydraulics that may result in significant perpendicular contamination migration. This vertical migration pattern has been termed 'plume diving'. Under ...

Relative congener scaling of Polychlorinated dibenzo-p-dioxins and dibenzofurans to estimate building fire contributions in air, surface wipes, and dust samples.

PubMed

Pleil, Joachim D; Lorber, Matthew N

2007-11-01

The United States Environmental Protection Agency collected ambient air samples in lower Manhattan for about 9 months following the September 11, 2001 World Trade Center (WTC) attacks. Measurements were made of a host of airborne contaminants including volatile organic compounds, polycyclic aromatic hydrocarbons, asbestos, lead, and other contaminants of concern. The present study focuses on the broad class of polychlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) with specific emphasis on the 17 CDD/CDF congeners that exhibit mammalian toxicity. This work is a statistical study comparing the internal patterns of CDD/CDFs using data from an unambiguous fire event (WTC) and other data sets to help identify their sources. A subset of 29 samples all taken between September 16 and October 31, 2001 were treated as a basis set known to be heavily impacted by the WTC building fire source. A second basis set was created using data from Los Angeles and Oakland, CA as published by the California Air Resources Board (CARB) and treated as the archetypical background pattern for CDD/CDFs. The CARB data had a congener profile appearing similar to background air samples from different locations in America and around the world and in different matrices, such as background soils. Such disparate data would normally be interpreted with a qualitative pattern recognition based on congener bar graphs or other forms of factor or cluster analysis that group similar samples together graphically. The procedure developed here employs aspects of those statistical methods to develop a single continuous output variable per sample. Specifically, a form of variance structure-based cluster analysis is used to group congeners within samples to reduce collinearity in the basis sets, new variables are created based on these groups, and multivariate regression is applied to the reduced variable set to determine a predictive equation. This equation predicts a value for an output variable, OPT: the predicted value of OPT is near zero (0.00) for a background congener profile and near one (1.00) forthe profile characterized by the WTC air profile. Although this empirical method is calibrated with relatively small sets of airborne samples, it is shown to be generalizable to other WTC, fire source, and background air samples as well as other sample matrices including soils, window films and other dust wipes, and bulk dusts. However, given the limited data set examined, the method does not allow further discrimination between the WTC data and the other fire sources. This type of analysis is demonstrated to be useful for complex trace-level data sets with limited data and some below-detection entries.

Annual variability of PAH concentrations in the Potomac River watershed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maher, I.L.; Foster, G.D.

1995-12-31

Dynamics of organic contaminant transport in a large river system is influenced by annual variability in organic contaminant concentrations. Surface runoff and groundwater input control the flow of river waters. They are also the two major inputs of contaminants to river waters. The annual variability of contaminant concentrations in rivers may or may not represent similar trends to the flow changes of river waters. The purpose of the research is to define the annual variability in concentrations of polycyclic aromatic hydrocarbons (PAH) in riverine environment. To accomplish this, from March 1992 to March 1995 samples of Potomac River water weremore » collected monthly or bimonthly downstream of the Chesapeake Bay fall line (Chain Bridge) during base flow and main storm flow hydrologic conditions. Concentrations of selected PAHs were measured in the dissolved phase and the particulate phase via GC/MS. The study of the annual variability of PAH concentrations will be performed through comparisons of PAH concentrations seasonally, annually, and through study of PAH concentration river discharge dependency and rainfall dependency. For selected PAHs monthly and annual loadings will be estimated based on their measured concentrations and average daily river discharge. The monthly loadings of selected PAHs will be compared by seasons and annually.« less

Fingerprint pattern restoration by digital image processing techniques.

PubMed

Wen, Che-Yen; Yu, Chiu-Chung

2003-09-01

Fingerprint evidence plays an important role in solving criminal problems. However, defective (lacking information needed for completeness) or contaminated (undesirable information included) fingerprint patterns make identifying and recognizing processes difficult. Unfortunately. this is the usual case. In the recognizing process (enhancement of patterns, or elimination of "false alarms" so that a fingerprint pattern can be searched in the Automated Fingerprint Identification System (AFIS)), chemical and physical techniques have been proposed to improve pattern legibility. In the identifying process, a fingerprint examiner can enhance contaminated (but not defective) fingerprint patterns under guidelines provided by the Scientific Working Group on Friction Ridge Analysis, Study and Technology (SWGFAST), the Scientific Working Group on Imaging Technology (SWGIT), and an AFIS working group within the National Institute of Justice. Recently, the image processing techniques have been successfully applied in forensic science. For example, we have applied image enhancement methods to improve the legibility of digital images such as fingerprints and vehicle plate numbers. In this paper, we propose a novel digital image restoration technique based on the AM (amplitude modulation)-FM (frequency modulation) reaction-diffusion method to restore defective or contaminated fingerprint patterns. This method shows its potential application to fingerprint pattern enhancement in the recognizing process (but not for the identifying process). Synthetic and real images are used to show the capability of the proposed method. The results of enhancing fingerprint patterns by the manual process and our method are evaluated and compared.

Anthropogenic and natural variability in the composition of sedimentary organic matter of the urbanised coastal zone of Montevideo (Río de la Plata).

PubMed

Bueno, C; Brugnoli, E; Bergamino, L; Muniz, P; García-Rodríguez, F; Figueira, R

2018-01-01

This study is aimed to identify the different sources of sedimentary organic matter (SOM) within Montevideo coastal zone (MCZ). To this end δ 13 C, δ 15 N and C/N ratio were analysed in surface sediments and a sediment core. Sediment core analysis showed that until ~1950CE SOM was mainly marine, observing a shift towards lower δ 13 C in recent sediments, evidencing an estuarine composition. This trend was associated to the climatic variability, which exerted a major influence on the SOM composition, leading to an increased input of terrigenous material and associated anthropogenic contaminants. Surface sediments collected during different El Niño South Oscillation (ENSO) phases did not show inter-annual variability in SOM composition, which was mainly marine in both eastern and western region of MCZ and estuarine in Montevideo Bay. This spatial pattern provides new insights on the dynamics and factors affecting organic matter sources available for primary consumers along the study region. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of short-range spatial variability on soil sampling uncertainty.

PubMed

Van der Perk, Marcel; de Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria; Fajgelj, Ales; Sansone, Umberto; Jeran, Zvonka; Jaćimović, Radojko

2008-11-01

This paper aims to quantify the soil sampling uncertainty arising from the short-range spatial variability of elemental concentrations in the topsoils of agricultural, semi-natural, and contaminated environments. For the agricultural site, the relative standard sampling uncertainty ranges between 1% and 5.5%. For the semi-natural area, the sampling uncertainties are 2-4 times larger than in the agricultural area. The contaminated site exhibited significant short-range spatial variability in elemental composition, which resulted in sampling uncertainties of 20-30%.

Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

EPA Science Inventory

Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as adversely affecting amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at high elevation. We tested the hypothe...

Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

EPA Science Inventory

Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as a factor adversely affecting biological resources such as amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at...

Relationships between lines of evidence of pollution in estuarine areas: Linking contaminant levels with biomarker responses in mussels and with structure of macroinvertebrate benthic communities.

PubMed

De Los Ríos, A; Echavarri-Erasun, B; Lacorte, S; Sánchez-Ávila, J; De Jonge, M; Blust, R; Orbea, A; Juanes, J A; Cajaraville, M P

2016-10-01

Data obtained in a pollution survey performed in estuarine areas were integrated using multivariate statistics. The sites selected for the study were areas affected by treated and untreated urban discharges, harbours or industrial activities as well as reference sites. Mussels were transplanted to each site and after different times of exposure, samples of water, sediments and mussels were collected. Biomarkers were analysed on mussels after 3 and 21 days of transplant whereas concentrations of contaminants were measured in water, sediments and mussels after 21 days of transplant. The structure of macroinvertebrate benthic communities was studied in sediment samples. Studied variables were organised into 5 datasets, each one constituting a line of evidence (LOE): contaminants in water, contaminants in sediments, contaminants accumulated by transplanted mussels, biomarkers in transplanted mussels and changes in the structure of macroinvertebrate benthic communities of each sampling site. Principal Component Analysis (PCA) identified the variables of each LOE best explaining variability among sites. In order to know how LOEs relate to each other, Pearson's correlations were performed. Contaminants in sediments were not correlated with the rest of LOEs. Contaminants in water were significantly correlated with contaminants and biomarkers in mussels and with structure of macroinvertebrate benthic communities. Similarly, significant correlations were found between contaminants and biomarkers in mussels and between biomarkers in mussels and structure of macroinvertebrate benthic communities. In conclusion, biomarker responses give relevant information on pollution in estuarine areas and provide a link between chemical and ecological statuses of water bodies in the context of the Water Framework Directive. Copyright © 2016 Elsevier Ltd. All rights reserved.

Population genetic studies of the polar bear (Ursus maritimus): A summary of available data and interpretation of results

USGS Publications Warehouse

Scribner, Kim T.; Garner, G.W.; Amstrup, Steven C.; Cronin, M.A.; Dizon, Andrew E.; Chivers, Susan J.; Perrin, William F.

1997-01-01

A summary of existing population genetics literature is presented for polar bears (Ursus maritimus) and interpreted in the context of the species' life-history characteristics and regional heterogeneity in environmental regimes and movement patterns. Several nongenetic data sets including morphology, contaminant levels, geographic variation in reproductive characteristics, and the location and distribution of open-water foraging habitat suggest some degree of spatial structuring. Eleven populations are recognized by the IUCN Polar Bear Specialist Group. Few genetics studies exist for polar bears. Interpretation and generalizations of regional variation in intra- and interpopulation levels of genetic variability are confounded by the paucity of data from many regions and by the fact that no single informative genetic marker has been employed in multiple regions. Early allozyme studies revealed comparatively low levels of genetic variability and no compelling evidence of spatial structuring. Studies employing mitochondrial DNA (mtDNA) also found low levels of genetic variation, a lack of phylogenetic structure, and no significant evidence for spatial variation in haplotype frequency. In contrast, microsatellite variable number of tandem repeat (VNTR) loci have revealed significant heterogeneity in allele frequency among populations in the Canadian Arctic. These regions are characterized by archipelgic patterns of sea-ice movements. Further studies using highly polymorphic loci are needed in regions characterized by greater polar bear dependency on pelagic sea-ice movements and in regions for which no data currently exist (i.e., Laptev and Novaya Zemlya/Franz Josef).

High Levels of Sediment Contamination Have Little Influence on Estuarine Beach Fish Communities

PubMed Central

McKinley, Andrew C.; Dafforn, Katherine A.; Taylor, Matthew D.; Johnston, Emma L.

2011-01-01

While contaminants are predicted to have measurable impacts on fish assemblages, studies have rarely assessed this potential in the context of natural variability in physico-chemical conditions within and between estuaries. We investigated links between the distribution of sediment contamination (metals and PAHs), physico-chemical variables (pH, salinity, temperature, turbidity) and beach fish assemblages in estuarine environments. Fish communities were sampled using a beach seine within the inner and outer zones of six estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. All sampling was replicated over two years with two periods sampled each year. Shannon diversity, biomass and abundance were all significantly higher in the inner zone of estuaries while fish were larger on average in the outer zone. Strong differences in community composition were also detected between the inner and outer zones. Few differences were detected between fish assemblages in heavily modified versus relatively unmodified estuaries despite high concentrations of sediment contaminants in the inner zones of modified estuaries that exceeded recognized sediment quality guidelines. Trends in species distributions, community composition, abundance, Shannon diversity, and average fish weight were strongly correlated to physico-chemical variables and showed a weaker relationship to sediment metal contamination. Sediment PAH concentrations were not significantly related to the fish assemblage. These findings suggest that variation in some physico-chemical factors (salinity, temperature, pH) or variables that co-vary with these factors (e.g., wave activity or grain size) have a much greater influence on this fish assemblage than anthropogenic stressors such as contamination. PMID:22039470

East versus West: organic contaminant differences in brown pelican (Pelecanus occidentalis) eggs from South Carolina, USA and the Gulf of California, Mexico

USGS Publications Warehouse

Vander Pol, Stacy S.; Anderson, Daniel W.; Jodice, Patrick G.R.; Stuckey, Joyce E.

2015-01-01

Brown pelicans (Pelecanus occidentalis) were listed as endangered in the United States in 1970, largely due to reproductive failure and mortality caused by organochlorine contaminants, such as DDT. The southeast population, P.o. carolinensis, was delisted in 1985, while the west coast population, P.o. californicus, was not delisted until 2009. As fish-eating coastal seabirds, brown pelicans may serve as a biomonitors. Organic contaminants were examined in brown pelican eggs collected from the Gulf of California in 2004 and South Carolina in 2005 using gas chromatography/mass spectrometry (GC/MS). Contaminants were compared using all individual data as well as statistically pooled samples to provide similar sample sizes with little difference in results. Principal components analysis separated the Gulf of California brown pelican eggs from the South Carolina eggs based on contaminant patterns. The South Carolina population had significantly (P < 0.05) higher levels of polychlorinated biphenyls (PCBs), chlordanes, dieldrin and mirex, while the Gulf of California eggs had higher levels of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs). With the exception of dieldrin and brominated diphenyl ether (BDE) 47, this pattern was observed for mussel and oyster tissues from these regions, indicating the need for further study into the differences between east and west coast brown pelican populations and ecosystem contamination patterns.

East versus West: organic contaminant differences in brown pelican (Pelecanus occidentalis) eggs from South Carolina, USA and the Gulf of California, Mexico.

PubMed

Vander Pol, Stacy S; Anderson, Daniel W; Jodice, Patrick G R; Stuckey, Joyce E

2012-11-01

Brown pelicans (Pelecanus occidentalis) were listed as endangered in the United States in 1970, largely due to reproductive failure and mortality caused by organochlorine contaminants, such as DDT. The southeast population, P.o. carolinensis, was delisted in 1985, while the west coast population, P.o. californicus, was not delisted until 2009. As fish-eating coastal seabirds, brown pelicans may serve as a biomonitors. Organic contaminants were examined in brown pelican eggs collected from the Gulf of California in 2004 and South Carolina in 2005 using gas chromatography/mass spectrometry (GC/MS). Contaminants were compared using all individual data as well as statistically pooled samples to provide similar sample sizes with little difference in results. Principal components analysis separated the Gulf of California brown pelican eggs from the South Carolina eggs based on contaminant patterns. The South Carolina population had significantly (P<0.05) higher levels of polychlorinated biphenyls (PCBs), chlordanes, dieldrin and mirex, while the Gulf of California eggs had higher levels of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs). With the exception of dieldrin and brominated diphenyl ether (BDE) 47, this pattern was observed for mussel and oyster tissues from these regions, indicating the need for further study into the differences between east and west coast brown pelican populations and ecosystem contamination patterns. Published by Elsevier B.V.

Gene transcription patterns in response to low level petroleum contaminants in Mytilus trossulus from field sites and harbors in southcentral Alaska

USGS Publications Warehouse

Bowen, Lizabeth; Miles, A. Keith; Ballachey, Brenda E.; Waters, Shannon C.; Bodkin, James L.; Lindeberg, Mandy; Esler, Daniel N.

2017-01-01

The 1989 Exxon Valdez oil spill damaged a wide range of natural resources, including intertidal communities, and post-spill studies demonstrated acute and chronic exposure and injury to an array of species. Standard toxicological methods to evaluate petroleum contaminants have assessed tissue burdens, with fewer assays providing indicators of health or physiology, particularly when contaminant levels are low and chronic. Marine mussels are a ubiquitous and crucial component of the nearshore environment, and new genomic technologies exist to quantify molecular responses of individual mussels to stimuli, including exposure to polycyclic aromatic hydrocarbons (PAHs). We used gene-based assays of exposure and physiological function to assess chronic oil contamination using the Pacific blue mussel, Mytilus trossulus. We developed a diagnostic gene transcription panel to investigate exposure to PAHs and other contaminants and its effects on mussel physiology and health. During 2012–2015, we analyzed mussels from five field sites in western Prince William Sound, Alaska, with varying oil histories from the 1989 Exxon Valdez oil spill, and from three boat harbors in the area. Gene transcription patterns of mussels from harbors were consistent with elevated exposure to PAHs or other contaminants, whereas transcription patterns of mussels sampled from shorelines in areas affected by the oil spill indicated no PAH exposure.

The impacts of uncertainty and variability in groundwater-driven health risk assessment. (Invited)

NASA Astrophysics Data System (ADS)

Maxwell, R. M.

2010-12-01

Potential human health risk from contaminated groundwater is becoming an important, quantitative measure used in management decisions in a range of applications from Superfund to CO2 sequestration. Quantitatively assessing the potential human health risks from contaminated groundwater is challenging due to the many coupled processes, uncertainty in transport parameters and the variability in individual physiology and behavior. Perspective on human health risk assessment techniques will be presented and a framework used to predict potential, increased human health risk from contaminated groundwater will be discussed. This framework incorporates transport of contaminants through the subsurface from source to receptor and health risks to individuals via household exposure pathways. The subsurface is shown subject to both physical and chemical heterogeneity which affects downstream concentrations at receptors. Cases are presented where hydraulic conductivity can exhibit both uncertainty and spatial variability in addition to situations where hydraulic conductivity is the dominant source of uncertainty in risk assessment. Management implications, such as characterization and remediation will also be discussed.

The spatial and temporal variability of groundwater recharge in a forested basin in northern Wisconsin

USGS Publications Warehouse

Dripps, W.R.; Bradbury, K.R.

2010-01-01

Recharge varies spatially and temporally as it depends on a wide variety of factors (e.g. vegetation, precipitation, climate, topography, geology, and soil type), making it one of the most difficult, complex, and uncertain hydrologic parameters to quantify. Despite its inherent variability, groundwater modellers, planners, and policy makers often ignore recharge variability and assume a single average recharge value for an entire watershed. Relatively few attempts have been made to quantify or incorporate spatial and temporal recharge variability into water resource planning or groundwater modelling efforts. In this study, a simple, daily soil-water balance model was developed and used to estimate the spatial and temporal distribution of groundwater recharge of the Trout Lake basin of northern Wisconsin for 1996-2000 as a means to quantify recharge variability. For the 5 years of study, annual recharge varied spatially by as much as 18 cm across the basin; vegetation was the predominant control on this variability. Recharge also varied temporally with a threefold annual difference over the 5-year period. Intra-annually, recharge was limited to a few isolated events each year and exhibited a distinct seasonal pattern. The results suggest that ignoring recharge variability may not only be inappropriate, but also, depending on the application, may invalidate model results and predictions for regional and local water budget calculations, water resource management, nutrient cycling, and contaminant transport studies. Recharge is spatially and temporally variable, and should be modelled as such. Copyright ?? 2009 John Wiley & Sons, Ltd.

Accumulation of PCB congeners in nestling tree swallows (Tachycineta bicolor) on the Hudson River, New York

USGS Publications Warehouse

Echols, Kathy R.; Tillitt, Donald E.; Nichols, John W.; Secord, Anne L.; McCarty, John P.

2004-01-01

Tree swallows (Tachycineta bicolor) were used as a sentinel species to monitor the contamination and bioavailability of polychlorinated biphenyls (PCBs) in the Hudson River watershed. Several tree swallow nest box colonies around and downstream from Hudson Falls, NY, were studied. Tree swallow eggs, adults, and 5-, 10-, and 15-day-old nestlings were collected and analyzed for 103 PCB congeners. Emergent insects collected by net (primarily Odonata) or as a food bolus (primarily Diptera) taken from the mouths of adult tree swallows returning to the nest were analyzed in the same manner. Total PCB concentrations (wet weight) in eggs from two contaminated sites ranged from 9000 to 25 000 ng/g and accumulated to 32 000 and 96 000 ng/g in 15-day-old nestling at two contaminated sites. The congener patterns of PCBs in eggs, nestlings, and adults were compared to those found in emergent insects (Odonata and Diptera) using principal components analysis. The PCB patterns of the biota differed from that of Aroclor technical mixtures. PCB patterns in adult tree swallows were similar to those in eggs, while the patterns in dietary insects were similar to nestling tree swallows. Uptake rate constants were determined for tree swallow nestlings and compared between the two contaminated sites. The estimated PCB congener uptake rate constants were 0.008-0.02 d-1 based on uptake in nestlings until day 15 post-hatch. The rate constants were comparable between the two study areas and may be used to predict nestling contamination at other locations. Our studies confirm the utility of nestling tree swallows to evaluate localized PCB contamination.

A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

PubMed

Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

2017-09-15

Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

TEMPORAL VARIABILITY OF MICROBIAL INDICATORS OF FECAL CONTAMINATION OF MARINE AND FRESHWATER BEACHES

EPA Science Inventory

Monitoring methods for microbial indicators of fecal contamination are an integral component for protecting the health of swimmers exposed to potentially contaminated bathing beach waters. The design of monitoring systems which will accurately characterize the quality of water is...

The effect of impurity gasses on variable polarity plasma arc welded 2219 aluminum

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

1989-01-01

Variable polarity plasma arc (VPPA) welding has been used with considerable success by NASA for the welds on the Space Shuttle External Tank as well as by others concerned with high quality welded structures. The effects of gaseous contaminants on the appearance of VPPA welds on 2219 aluminum are examined so that a welder can recognize that such contamination is present and take corrective measures. There are many possible sources of such contamination including, contaminated gas bottles, leaks in the gas plumbing, inadequate shield gas flow, condensed moisture in the gas lines or torch body, or excessive contaminants on the workpiece. The gasses chosen for study in the program were nitrogen, oxygen, methane, and hydrogen. Welds were made in a carefully controlled environment and comparisons were made between welds with various levels of these contaminants and welds made with research purity (99.9999 percent) gasses. Photographs of the weld front and backside as well as polished and etched cross sections are presented.

Influence of seasonal and inter-annual hydro-meteorological variability on surface water fecal coliform concentration under varying land-use composition.

PubMed

St Laurent, Jacques; Mazumder, Asit

2014-01-01

Quantifying the influence of hydro-meteorological variability on surface source water fecal contamination is critical to the maintenance of safe drinking water. Historically, this has not been possible due to the scarcity of data on fecal indicator bacteria (FIB). We examined the relationship between hydro-meteorological variability and the most commonly measured FIB, fecal coliform (FC), concentration for 43 surface water sites within the hydro-climatologically complex region of British Columbia. The strength of relationship was highly variable among sites, but tended to be stronger in catchments with nival (snowmelt-dominated) hydro-meteorological regimes and greater land-use impacts. We observed positive relationships between inter-annual FC concentration and hydro-meteorological variability for around 50% of the 19 sites examined. These sites are likely to experience increased fecal contamination due to the projected intensification of the hydrological cycle. Seasonal FC concentration variability appeared to be driven by snowmelt and rainfall-induced runoff for around 30% of the 43 sites examined. Earlier snowmelt in nival catchments may advance the timing of peak contamination, and the projected decrease in annual snow-to-precipitation ratio is likely to increase fecal contamination levels during summer, fall, and winter among these sites. Safeguarding drinking water quality in the face of such impacts will require increased monitoring of FIB and waterborne pathogens, especially during periods of high hydro-meteorological variability. This data can then be used to develop predictive models, inform source water protection measures, and improve drinking water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Innovative Strategy For Long Term Monitoring Of Metal And Radionuclide Plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eddy-Dilek, Carol; Millings, Margaret R.; Looney, Brian B.

2014-01-08

Many government and private industry sites that were once contaminated with radioactive and chemical wastes cannot be cleaned up enough to permit unrestricted human access. The sites will require long term management, in some cases indefinitely, leaving site owners with the challenge of protecting human health and environmental quality at these "legacy" sites. Long-term monitoring of groundwater contamination is one of the largest projected costs in the life cycle of environmental management at the Savannah River Site, the larger DOE complex, and many large federal and private sites. There is a need to optimize the performance and manage the costmore » of long term surveillance and monitoring at their sites. Currently, SRNL is initiating a pilot field test using alternative protocols for long term monitoring of metals and radionuclides. A key component of the approach is that monitoring efforts are focused on measurement of low cost metrics related to hydrologic and chemical conditions that control contaminant migration. The strategy combines careful monitoring of hydrologic boundary conditions with measurement of master variables such as chemical surrogates along with a smaller number of standard well analyses. In plumes contaminated with metals, master variables control the chemistry of the groundwater system, and include redox variables (ORP, DO, chemicals), pH, specific conductivity, biological community (breakdown/decay products), and temperature. Significant changes in these variables will result in conditions whereby the plume may not be stable and therefore can be used to predict possible plume migration. Conversely, concentration measurements for all types of contaminants in groundwater are a lagging indicator plume movement - major changes contaminant concentrations indicate that contamination has migrated. An approach based on measurement of master variables and explicit monitoring of hydrologic boundary conditions combined with traditional metrics should lead to improved monitoring while simultaneously reducing costs. This paradigm is being tested at the SRS F-Area where an innovative passive remedial system is being monitored and evaluated over the long term prior to traditional regulatory closure. Contaminants being addressed at this site are uranium, strontium-90, iodine-129, and tritium. We believe that the proposed strategies will be more effective in early identification of potential risks; these strategies will also be cost effective because controlling variables are relatively simple to measure. These variables also directly reflect the evolution of the plume through time, so that the monitoring strategy can be modified as the plume 'ages'. This transformational long-term monitoring paradigm will generate large cost savings to DOE, other federal agencies and industry and will provide improved performance and leading indicators of environmental management performance.« less

Determining significant endpoints for ecological risk analyses. 1997 annual progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinton, T.G.; Congdon, J.; Rowe, C.

1997-11-01

'This report summarizes the first year''s progress of research funded under the Department of Energy''s Environmental Management Science Program. The research was initiated to better determine ecological risks from toxic and radioactive contaminants. More precisely, the research is designed to determine the relevancy of sublethal cellular damage to the performance of individuals and to identify characteristics of non-human populations exposed to chronic, low-level radiation, as is typically found on many DOE sites. The authors propose to establish a protocol to assess risks to non-human species at higher levels of biological organization by relating molecular damage to more relevant responses thatmore » reflect population health. They think that they can achieve this by coupling changes in metabolic rates and energy allocation patterns to meaningful population response variables, and by using novel biological dosimeters in controlled, manipulative dose/effects experiments. They believe that a scientifically defensible endpoint for measuring ecological risks can only be determined once its understood the extent to which molecular damage from contaminant exposure is detrimental at the individual and population levels of biological organization.'« less

Heavy-metal concentrations in small mammals from a diffusely polluted floodplain: importance of species- and location-specific characteristics.

PubMed

Wijnhoven, S; Leuven, R S E W; van der Velde, G; Jungheim, G; Koelemij, E I; de Vries, F T; Eijsackers, H J P; Smits, A J M

2007-05-01

The soil of several floodplain areas along large European rivers shows increased levels of heavy metals as a relict from past sedimentation of contaminants. These levels may pose risks of accumulation in food webs and toxicologic effects on flora and fauna. However, for floodplains, data on heavy-metal concentrations in vertebrates are scarce. Moreover, these environments are characterised by periodical flooding cycles influencing ecologic processes and patterns. To investigate whether the suggested differences in accumulation risks for insectivores and carnivores, omnivores, and herbivores are reflected in the actual heavy-metal concentrations in the species, we measured the current levels of Zn, Cu, Pb, and Cd in 199 specimens of 7 small mammal species (voles, mice, and shrews) and in their habitats in a diffusely polluted floodplain. The highest metal concentrations were found in the insectivorous and carnivorous shrew, Sorex araneus. Significant differences between the other shrew species, Crocidura russula, and the vole and mouse species was only found for Cd. The Cu concentration in Clethrionomys glareolus, however, was significantly higher than in several other vole and mouse species. To explain the metal concentrations found in the specimens, we related them to environmental variables at the trapping locations and to certain characteristics of the mammals. Variables taken into account were soil total and CaCl(2)-extractable metal concentrations at the trapping locations; whether locations were flooded or nonflooded; the trapping season; and the life stage; sex; and fresh weight of the specimens. Correlations between body and soil concentrations and location or specimen characteristics were weak. Therefore; we assumed that exposure of small mammals to heavy-metal contamination in floodplains is significantly influenced by exposure time, which is age related, as well as by dispersal and changes in foraging and feeding patterns under influence of periodic flooding.

Spatiotemporal changes of CVOC concentrations in karst aquifers: analysis of three decades of data from Puerto Rico

PubMed Central

Yu, Xue; Ghasemizadeh, Reza; Padilla, Ingrid; Irizarry, Celys; Kaeli, David; Alshawabkeh, Akram

2014-01-01

We studied the spatial and temporal distribution patterns of Chlorinated Volatile Organic Compounds (CVOCs) in the karst aquifers in northern Puerto Rico (1982-2013). Seventeen CVOCs were widely detected across the study area, with the most detected and persistent contaminated CVOCs including trichloroethylene (TCE), tetrachloroethylene (PCE), carbon tetrachloride (CT), chloroform (TCM), and methylene chloride (DCM). Historically, 471 (76%) and 319 (52%) of the 615 sampling sites have CVOC concentrations above the detection limit and maximum contamination level (MCL), respectively. The spatiotemporal patterns of the CVOC concentrations showed two clusters of contaminated areas, one near the Superfund site “Upjohn” and another near “Vega Alta Public Supply Wells.” Despite a decreasing trend in concentrations, there is a general northward movement and spreading of contaminants even beyond the extent of known sources of the Superfund and landfill sites. Our analyses suggest that, besides the source conditions, karst characteristics (high heterogeneity, complex hydraulic and biochemical environment) are linked to the long-term spatiotemporal patterns of CVOCs in groundwater. PMID:25522355

Assessment of restoration measures efficiency for soil contamination in Mediterranean Ecosystem. The case study of Guadiamar Green Corridor in the context of RECARE project

NASA Astrophysics Data System (ADS)

Anaya-Romero, Maria; José Blanco-Velázquez, Francisco; Muñoz-Vallés, Sara

2017-04-01

Restoration of soil ecosystems contaminated by heavy metals requires their characterization and the assessment of measures for risk reduction. Particular soil traits and history define different levels of resilience, so soil contamination assessment needs to take into account a site-by-site approach, which considers both the particular environmental characteristics of soils and the human activities. Nevertheless, current approaches for soil contamination assessment developed as academy and market solutions continue to be rather qualitative, and they do not allow as far the selection of efficient remediation measures to solve soil contamination at the long-term and extensively over larger áreas. In this context, under the framework of RECARE (Preventing and Remediating degradation of Soils in Europe through Land Care) project, we are designing a Decision Support System (DSS) which automatically assess soil contamination values by heavy metals in the topsoil and evaluate the efficiency of soil remediation measures under scenarios of climate and land-use change. The DSS works by simulating the spatio-temporal efficiency of three widely applied remediation measures (compost, sugar beet lime and iron-rich clayey materials). Input variables are divided into: (I) climate variables (mainly precipitation and temperature), (II) site variables (elevation, slope and erodibility), (III) soil (heavy metal content, pH, sand/clay content, soil organic carbon and bulk density), (IV) land use and (V) remediation measures. The predictor variables are related to soil functions expressed by % of change of heavy metal content (Currently the DSS consider cadmium dynamics due to the worldwide distribution in agricultural system and toxicity impact on health and plants), soil carbon and erosion dynamics. The pilot study area is the Guadiamar valley (SW Spain) where the main threat is soil contamination, after a mine spill occurred on April 1998. Since that time, a huge soil databse of more than 30 Gbytes, has been produced by different stakeholders (administration, scientist and private sector), which covered the spatial-temporal evolution of soil contamination by specific soil remediation measures, so the affected area has become the "virtual lab" to develop and test the DSS. Further development of the DSS tool includes its validation/calibration in other European climate zones, such as Copsa Mica in Romania, and the inclusion of new input and output variables to improve the accurancy of results.

Using generalized additive mixed models to assess spatial, temporal, and hydrologic controls on bacteria and nitrate in a vulnerable agricultural aquifer.

PubMed

Mellor, Andrea F P; Cey, Edwin E

2015-11-01

The Abbotsford-Sumas aquifer (ASA) has a history of nitrate contamination from agricultural land use and manure application to soils, yet little is known about its microbial groundwater quality. The goal of this study was to investigate the spatiotemporal distribution of pathogen indicators (Escherichia coli [E. coli] and total coliform [TC]) and nitrate in groundwater, and their potential relation to hydrologic drivers. Sampling of 46 wells over an 11-month period confirmed elevated nitrate concentrations, with more than 50% of samples exceeding 10 mg-N/L. E. coli detections in groundwater were infrequent (4 of 385 total samples) and attributed mainly to surface water-groundwater connections along Fishtrap Creek, which tested positive for E. coli in every sampling event. TC was detected frequently in groundwater (70% of samples) across the ASA. Generalized additive mixed models (GAMMs) yielded valuable insights into relationships between TC or nitrate and a range of spatial, temporal, and hydrologic explanatory variables. Increased TC values over the wetter fall and winter period were most strongly related to groundwater temperatures and levels, while precipitation and well location were weaker (but still significant) predictors. In contrast, the moderate temporal variability in nitrate concentrations was not significantly related to hydrologic forcings. TC was relatively widespread across the ASA and spatial patterns could not be attributed solely to surface water connectivity. Varying nitrate concentrations across the ASA were significantly related to both well location and depth, likely due to spatially variable nitrogen loading and localized geochemical attenuation (i.e., denitrification). Vulnerability of the ASA to bacteria was clearly linked to hydrologic conditions, and was distinct from nitrate, such that a groundwater management strategy specifically for bacterial contaminants is warranted. Copyright © 2015 Elsevier B.V. All rights reserved.

A travel mode comparison of commuters' exposures to air pollutants in Barcelona

NASA Astrophysics Data System (ADS)

de Nazelle, Audrey; Fruin, Scott; Westerdahl, Dane; Martinez, David; Ripoll, Anna; Kubesch, Nadine; Nieuwenhuijsen, Mark

2012-11-01

Daily commutes may contribute disproportionately to overall daily inhalations of urban air contaminants. Understanding factors that explain variability of exposures during travel, and especially differences across transportation modes, is essential to accurately assess health impacts of traffic emissions and to develop effective mitigating measures. We evaluated exposures and inhaled doses of air pollution and assessed factors that contributed to their variability in different travel modes in Barcelona. Black carbon (BC), ultrafine particles (UFP), carbon monoxide (CO), fine particle mass (PM2.5) and carbon dioxide (CO2) were measured and compared across walk, bike, bus, and car modes for a total of 172 trips made on two different round trip routes. On average, the car mode experienced highest concentrations for all contaminants. In pairwise t-tests between concurrent mode runs, statistically significant differences were found for cars compared to walking and biking. Car-to-walk or car-to-bike concentration ratios ranged from 1.3 for CO2 to 25 for CO and were 2-3 for PM2.5, BC, and UFP. In multivariate analyses, travel mode explained the greatest variability in travel exposures, from 8% for PM2.5 to 70% for CO. Different modal patterns emerged when estimating daily inhaled dose, with active commuters' two to three times greater total inhalation volume during travel producing about equal UFP and BC daily inhaled doses to car commuters and 33-50% higher UFP and BC doses compared to bus commuters. These findings, however, are specific to the bike and pedestrian lanes in this study being immediately adjacent to the roadways measured. Dedicated bike or pedestrian routes away from traffic would lead to lower active travel doses.

Multiscale analysis of the spatial variability of heavy metals and organic matter in soils and groundwater across Spain

NASA Astrophysics Data System (ADS)

Luque-Espinar, J. A.; Pardo-Igúzquiza, E.; Grima-Olmedo, J.; Grima-Olmedo, C.

2018-06-01

During the last years there has been an increasing interest in assessing health risks caused by exposure to contaminants found in soil, air, and water, like heavy metals or emerging contaminants. This work presents a study on the spatial patterns and interaction effects among relevant heavy metals (Sb, As and Pb) that may occur together in different minerals. Total organic carbon (TOC) have been analyzed too because it is an essential component in the regulatory mechanisms that control the amount of metal in soils. Even more, exposure to these elements is associated with a number of diseases and environmental problems. These metals can have both natural and anthropogenic origins. A key component of any exposure study is a reliable model of the spatial distribution the elements studied. A geostatistical analysis have been performed in order to show that selected metals are auto-correlated and cross-correlated and type and magnitude of such cross-correlation varies depending on the spatial scale under consideration. After identifying general trends, we analyzed the residues left after subtracting the trend from the raw variables. Three scales of variability were identified (compounds or factors) with scales of 5, 35 and 135 km. The first factor (F1) basically identifies anomalies of natural origin but, in some places, of anthropogenics origin as well. The other two are related to geology (F2 and F3) although F3 represents more clearly geochemical background related to large lithological groups. Likewise, mapping of two major structures indicates that significant faults have influence on the distribution of the studied elements. Finally, influence of soil and lithology on groundwater by means of contingency analysis was assessed.

Extreme weather events and environmental contamination are associated with case-clusters of melioidosis in the Northern Territory of Australia.

PubMed

Cheng, Allen C; Jacups, Susan P; Gal, Daniel; Mayo, Mark; Currie, Bart J

2006-04-01

Melioidosis, the infection due to the environmental organism Burkholderia pseudomallei, is endemic to northern Australia and South East Asia. It is associated with exposure to mud and pooled surface water, but environmental determinants of this disease are poorly understood. We defined case-clusters in northern Australia, determined their contribution to the observed rate of melioidosis, and explored clinical features and associated environmental factors. Using geographical information systems data, we examined clustering of melioidosis cases in time and geographical space in the Top End of the Northern Territory of Australia between 1990 and 2002 using a scan statistic. DNA macrorestriction analysis, resolved by pulsed field gel electrophoresis, was performed on isolates from patients. We defined five case-clusters involving 27 patients that occurred within 7-28 days and/or a radius of 100-300 km. Clustered cases were associated with extreme weather events or environmental contamination; no difference in the clinical pattern of disease was noted from other patients not involved in clusters. Isolates from patients linked to environmental contamination were caused by isolates with similar DNA macrorestriction patterns, but isolates from patients linked to severe weather events had more diverse DNA macrorestriction patterns. Case-clusters of melioidosis where isolates exhibit diverse DNA macrorestriction patterns in our region are linked to extreme weather events and outbreaks where isolates are predominantly of the same DNA macrorestriction pattern are linked with contamination of an environmental source.

Using structural equation modeling to investigate relationships among ecological variables

USGS Publications Warehouse

Malaeb, Z.A.; Kevin, Summers J.; Pugesek, B.H.

2000-01-01

Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1989). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables-sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude -0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0.1258. Natural variability had a positive direct effect on biodiversity of magnitude 0.5347 and a negative indirect effect mediated through growth potential of magnitude -0.1105 yielding a positive total effects of magnitude 0.4242. Sediment contamination had a negative direct effect on biodiversity of magnitude -0.1956 and a negative indirect effect on growth potential via biodiversity of magnitude -0.067. Biodiversity had a positive effect on growth potential of magnitude 0.8432, and growth potential had a positive effect on biodiversity of magnitude 0.3398. The correlation between biodiversity and growth potential was estimated at 0.7658 and that between sediment contamination and natural variability at -0.3769.

Dietary patterns in the French adult population: a study from the second French national cross-sectional dietary survey (INCA2) (2006-2007).

PubMed

Gazan, R; Béchaux, C; Crépet, A; Sirot, V; Drouillet-Pinard, P; Dubuisson, C; Havard, S

2016-07-01

Identification and characterisation of dietary patterns are needed to define public health policies to promote better food behaviours. The aim of this study was to identify the major dietary patterns in the French adult population and to determine their main demographic, socio-economic, nutritional and environmental characteristics. Dietary patterns were defined from food consumption data collected in the second French national cross-sectional dietary survey (2006-2007). Non-negative-matrix factorisation method, followed by a cluster analysis, was implemented to derive the dietary patterns. Logistic regressions were then used to determine their main demographic and socio-economic characteristics. Finally, nutritional profiles and contaminant exposure levels of dietary patterns were compared using ANOVA. Seven dietary patterns, with specific food consumption behaviours, were identified: 'Small eater', 'Health conscious', 'Mediterranean', 'Sweet and processed', 'Traditional', 'Snacker' and 'Basic consumer'. For instance, the Health-conscious pattern was characterised by a high consumption of low-fat and light products. Individuals belonging to this pattern were likely to be older and to have a better nutritional profile than the overall population, but were more exposed to many contaminants. Conversely, individuals of Snacker pattern were likely to be younger, consumed more highly processed foods, had a nutrient-poor profile but were exposed to a limited number of food contaminants. The study identified main dietary patterns in the French adult population with distinct food behaviours and specific demographic, socio-economic, nutritional and environmental features. Paradoxically, for better dietary patterns, potential health risks cannot be ruled out. Therefore, this study demonstrated the need to conduct a risk-benefit analysis to define efficient public health policies regarding diet.

Distant drivers or local signals: where do mercury trends in western Arctic belugas originate?

PubMed

Loseto, L L; Stern, G A; Macdonald, R W

2015-03-15

Temporal trends of contaminants are monitored in Arctic higher trophic level species to inform us on the fate, transport and risk of contaminants as well as advise on global emissions. However, monitoring mercury (Hg) trends in species such as belugas challenge us, as their tissue concentrations reflect complex interactions among Hg deposition and methylation, whale physiology, dietary exposure and foraging patterns. The Beaufort Sea beluga population showed significant increases in Hg during the 1990 s; since that time an additional 10 years of data have been collected. During this time of data collection, changes in the Arctic have affected many processes that underlie the Hg cycle. Here, we examine Hg in beluga tissues and investigate factors that could contribute to the observed trends after removing the effect of age and size on Hg concentrations and dietary factors. Finally, we examine available indicators of climate variability (Arctic Oscillation (AO), the Pacific Decadal Oscillation (PDO) and sea-ice minimum (SIM) concentration) to evaluate their potential to explain beluga Hg trends. Results reveal a decline in Hg concentrations from 2002 to 2012 in the liver of older whales and the muscle of large whales. The temporal increases in Hg in the 1990 s followed by recent declines do not follow trends in Hg emission, and are not easily explained by diet markers highlighting the complexity of feeding, food web dynamics and Hg uptake. Among the regional-scale climate variables the PDO exhibited the most significant relationship with beluga Hg at an eight year lag time. This distant signal points us to consider beluga winter feeding areas. Given that changes in climate will impact ecosystems; it is plausible that these climate variables are important in explaining beluga Hg trends. Such relationships require further investigation of the multiple connections between climate variables and beluga Hg. Copyright © 2014 Elsevier B.V. All rights reserved.

Bacterial Contamination of Multi-dose Eye Drops at Ophthalmology Department, University of Gondar, Northwest Ethiopia.

PubMed

Tsegaw, Asegedech; Tsegaw, Asamere; Abula, Tefera; Assefa, Yared

2017-01-01

Ophthalmic solutions used for both diagnostic and therapeutic purposes were found to be contaminated with bacteria pathogens and caused serious ocular infections such as keratitis and endophthalmitis. The objective was to assess the magnitude and pattern of bacterial contamination of multi-dose ophthalmic medications and investigate the drug susceptibility pattern of the isolates in the Department of Ophthalmology at Gondar University Teaching Hospital. A total of 100 ophthalmic medications in-use by patients and eye-care workers have been taken and cultured for potential bacterial contamination in the Microbiology Department after 1 week and >1 week of use. The dropper tip and the residual eye medications were examined for contamination. The contaminating bacteria were identified using a standard procedure and drug susceptibility testing to selected antimicrobial agents was done. Eleven ophthalmic medications were contaminated by different bacterial species with a prevalence of 11%. Multi-use and longer duration of use of eye medications were associated with higher rate of contamination. The contamination level ranges from 0% for antibiotics, 20% for local anesthetics, and 40% for povidone iodine. Among bacteria identified, Staphylococcus aureus and coagulase-negative Staphylococcus species were resistant to methicillin while others were sensitive to the antibiotics tested. The prevalence of contamination was low, but methicillin-resistant Staphylococcus was a potential risk. It is recommended that the Department of Ophthalmology should design set of rules about duration of use and safe handling of ophthalmic medications by the staff and patients.

Riparian spiders indicate the magnitude and sources of polychlorinated biphenyl (PCB) contamination at a large contaminated sediment site

USGS Publications Warehouse

Walters, David M.; Otter, Ryan R.; Kraus, Johanna M.; Mills, Marc A.

2018-01-01

We investigated PCB contamination at the Ashtabula River Area of Concern (AOC) following remedial dredging using araneid and tetragnathid spiders. PCB concentrations remain elevated in the AOC compared to reference conditions. Patterns of contamination were strikingly similar between taxa, but were higher in tetragnathids at the most contaminated sites. Spider PCB homolog distributions identified two PCB sources to the AOC. Based on these findings, we recommend situations where these taxa can be used singularly, in concert, or combined into a composite “spider” sample to assess environmental contamination. 

Contamination of the turbine air chamber: a risk of cross infection.

PubMed

Checchi, L; Montebugnoli, L; Samaritani, S

1998-08-01

In the present work, we evaluated (a) the influx of contaminating fluid into the air chamber when a high-speed turbine stops rotating, (b) the significance of a series of variables (type of handpiece and dental unit, shape of the bur, number of stops set on the turbine) which condition it, and (c) the time required to expel the contaminating fluid from the turbine head. Results showed that contamination takes place every time the turbine stops rotating with the bur in contact with an external fluid. The main variable affecting the influx of contaminating fluid into the air chamber of the turbine head was represented by the shape of the bur (F=54.9; p<0.01). Another significant variable was the type of handpiece and dental unit (F=7.3; p<0.01). The number of stops set on the turbine was irrelevant (F=0.03; p=n.s.). The expulsion of the contaminant from the turbine head showed 2 different exponential rates: a very rapid-elimination phase within 30 s and a slow-elimination phase between 60 and 300 s. In order to remove over 99% of the contaminant from the air chamber, a turbine had to run for more than 4-7 min depending on the type of the handpiece. In conclusion, data from the present study suggest that a significant cross-infection potential exists with high-speed handpieces whenever they are only externally scrubbed and disinfected so the internal cleaning and sterilization between patients is mandatory. The practice of flushing by running the turbines between patients should be discouraged.

Model assessment of additional contamination of water bodies as a result of wildfires in the Chernobyl exclusion zone.

PubMed

Bondar, Yu I; Navumau, A D; Nikitin, A N; Brown, J; Dowdall, M

2014-12-01

Forest fires and wild fires are recognized as a possible cause of resuspension and redistribution of radioactive substances when occurring on lands contaminated with such materials, and as such are a matter of concern within the regions of Belarus and the Ukraine which were contaminated by the Chernobyl accident in 1986. Modelling the effects of such fires on radioactive contaminants is a complex matter given the number of variables involved. In this paper, a probabilistic model was developed using empirical data drawn from the Polessie State Radiation-Ecological Reserve (PSRER), Belarus, and the Maximum Entropy Method. Using the model, it was possible to derive estimates of the contribution of fire events to overall variability in the levels of (137)Cs and (239,240)Pu in ground air as well as estimates of the deposition of these radionuclides to specific water bodies within the contaminated areas of Belarus. Results indicate that fire events are potentially significant redistributors of radioactive contaminants within the study area and may result in additional contamination being introduced to water bodies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Visual Inspection of Surfaces

NASA Technical Reports Server (NTRS)

Hughes, David; Perez, Xavier

2007-01-01

This presentation evaluates the parameters that affect visual inspection of cleanliness. Factors tested include surface reflectance, surface roughness, size of the largest particle, exposure time, inspector and distance from sample surface. It is concluded that distance predictions were not great, particularly because the distance at which contamination is seen may depend on more variables than those tested. Most parameters estimates had confidence of 95% or better, except for exposure and reflectance. Additionally, the distance at which surface is visibly contaminated decreases with increasing reflectance, roughness, and exposure. The distance at which the surface is visually contaminated increased with the largest particle size. These variables were only slightly affected the observer.

Semipermeable membrane devices used to estimate bioconcentration of polychlorinated biphenyls

USGS Publications Warehouse

Chambers, D.B.

1999-01-01

Aquatic organisms passively accumulate hydrophobic organic compounds, such as polychlorinated biphenyls, even when ambient water concentrations of the contaminant are below analytical detection limits. However, contaminant concentrations in tissue samples are subject to an inherently high level of variability due to differences in species, life stage, and gender bioconcentration potentials. Semipermeable membrane devices (SPMDs) were used to sample Aroclor 1254, a mixture of readily bioconcentrated polychlorinated biphenyls (PCBs), in a contaminated wetland near Flat Top, WV. The devices consisted of triolein, a lipid found in fish, enclosed in a polyethylene membrane. SPMDs were deployed in the water column and in direct contact with wetland sediments along a previously identified concentration gradient of PCBs. The devices were retrieved after a 25-day exposure period. Analytes were recovered by dialyzing the devices in nanograde hexane. Hexane dialysates were condensed and analyzed by gas chromatography. All deployed devices sequestered quantifiable amounts of Aroclor 1254. Water-column SPMDs accumulated PCBs far in excess of ambient water concentrations. The devices contacting sediments accumulated PCBs at all sites, though accumulated concentrations did not exceed concentrations in sediment. Patterns of PCB concentration in the devices corresponded to the identified gradient at the site. Results from the water-column SPMDs were used to estimate the concentration of the dissolved, bioavailable fraction of PCBs present in the water column. These concentrations ranged from 0.01 to 0.09 ??g/L of bioavailable Aroclor 1254.

Microorganisms associated with feathers of barn swallows in radioactively contaminated areas around chernobyl.

PubMed

Czirják, Gábor Arpád; Møller, Anders Pape; Mousseau, Timothy A; Heeb, Philipp

2010-08-01

The Chernobyl catastrophe provides a rare opportunity to study the ecological and evolutionary consequences of low-level, environmental radiation on living organisms. Despite some recent studies about negative effects of environmental radiation on macroorganisms, there is little knowledge about the effect of radioactive contamination on diversity and abundance of microorganisms. We examined abundance patterns of total cultivable bacteria and fungi and the abundance of feather-degrading bacterial subset present on feathers of barn swallows (Hirundo rustica), a colonial migratory passerine, around Chernobyl in relation to levels of ground level environmental radiation. After controlling for confounding variables, total cultivable bacterial loads were negatively correlated with environmental radioactivity, whereas abundance of fungi and feather-degrading bacteria was not significantly related to contamination levels. Abundance of both total and feather-degrading bacteria increased with barn swallow colony size, showing a potential cost of sociality. Males had lower abundance of feather-degrading bacteria than females. Our results show the detrimental effects of low-level environmental radiation on total cultivable bacterial assemblage on feathers, while the abundance of other microorganism groups living on barn swallow feathers, such as feather-degrading bacteria, are shaped by other factors like host sociality or host sex. These data lead us to conclude that the ecological effects of Chernobyl may be more general than previously assumed and may have long-term implications for host-microbe interactions and overall ecosystem functioning.

Integrating Monitoring and Genetic Methods To Infer Historical ...

EPA Pesticide Factsheets

Common and roseate terns are migratory piscivorous seabirds with major breeding colonies within feeding range of thepolychlorinated biphenyl (PCB)-contaminated New Bedford Harbor (NBH, MA, USA) Superfund site. Our longitudinal study shows that before PCB discharges into NBH ceased (late 1970s), tern eggs had very high but variable PCB concentrations. However, egg concentrations of PCBs as well as DDE (1,1-bis(p-chlorophenyl)-2,2-dichloroethene), the degradation product of the ubiquitous global contaminant DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane), have since declined. Rate constants for temporal decline of PCB congeners in tern eggs varied inversely with log10KOW (n-octanol−water partition coefficient), shifting egg congener patterns away from those characterizing NBH sediment. To estimate the toxic effects on tern eggs of PCB dioxin-like congener (DLC) exposures, we extrapolated published laboratory data on common terns to roseate terns by characterizing genetic and functional similarities in species aryl hydrocarbon receptors (AHRs), which mediate DLC sensitivity. Our assessment of contaminant risks suggests that terns breeding near NBH were exposed historically to toxic levels of PCBs and DDE; however, acute effects on tern egg development have become less likely since the 1970s. Our approach demonstrates how comparative genetics at target loci can effectively increase the range of inference for chemical risk assessments from tested to untested a

Water as consumed and its impact on the consumer--do we understand the variables?

PubMed

Bates, A J

2000-01-01

Water is the most important natural resource in the world, without it life cannot exist. In 1854 a cholera outbreak in London caused 10, 000 deaths and positively linked enteric disease with bacterial contamination of drinking water by sewage pollution. Since then, adequate water hygiene standards and sewage purification have played the most significant role in disease eradication and public health improvements everywhere. Standards for drinking water have become an extensive range of microbiological and chemical parametric values. Which has not increased consumer, if the media is to be believed. Customers rightly expect that the water they drink is safe and wholesome. Standard setting is perceived as a precise science and meaningful to health. Is this justified and do scientists and regulators who derive and set the standards understand the uncertainties in the system? Water is the universal solvent, therefore it will never be pure; it will contain impurities prior to and after treatment. Knowledge of its potential to become contaminated is necessary to understand the epidemiology associated with waterborne contaminants and their effects. Water use patterns vary considerably and affect assumptions based on toxicology derived from laboratory studies under tightly controlled conditions. Consideration must be given to the model systems used to assess toxicity and translate results from the laboratory to the real world, if sensible scientifically-based water quality standards are to be set and achieved cost effectively.

Congener Patterns of Persistent Organic Pollutants Establish the Extent of Contaminant Biotransport by Pacific Salmon in the Great Lakes.

PubMed

Gerig, Brandon S; Chaloner, Dominic T; Janetski, David J; Rediske, Richard R; O'Keefe, James P; Moerke, Ashley H; Lamberti, Gary A

2016-01-19

In the Great Lakes, introduced Pacific salmon (Oncorhynchus spp.) can transport persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), to new environments during their spawning migrations. To explore the nature and extent of POP biotransport by salmon, we compared 58 PCB and 6 PBDE congeners found in spawning salmon directly to those in resident stream fish. We hypothesized that stream fish exposed to salmon spawners would have congener patterns similar to those of salmon, the presumed contaminant source. Using permutational multivariate analysis of variance (PERMANOVA) and nonmetric multidimensional scaling (NMDS), we found that POP congener patterns of Pacific salmon varied among regions in the Great Lakes basin (i.e., Lake Huron, Lake Michigan, or Lake Superior), tissue type (whole fish or eggs), and contaminant type (PCB or PBDE). For stream-resident fish, POP congener pattern was influenced by the presence of salmon, location (i.e., Great Lakes Basin), and species identity (i.e., brook trout [Salvelinus fontinalis] or mottled sculpin [Cottus bairdii]). Similarity in congener patterns indicated that salmon are a source of POPs to brook trout in stream reaches receiving salmon spawners from Lake Michigan and Lake Huron but not from Lake Superior. Congener patterns of mottled sculpin differed from those of brook trout and salmon, suggesting that brook trout and mottled sculpin either use salmon tissue to differing degrees, acquire POPs from different dietary sources, or bioaccumulate or metabolize POPs differently. Overall, our analyses identified the important role of salmon in contaminant biotransport but also demonstrated that the extent of salmon-mediated POP transfer and uptake in Great Lakes tributaries is location- and species-specific.

Sediment evidence of industrial leakage-induced asynchronous changes in polycyclic aromatic hydrocarbons and trace metals from a sub-trophic lake, southwest China.

PubMed

Wang, Lei; Chen, Guangjie; Kang, Wengang; Wang, Jiaoyuan; Liu, Yuanyuan; Chen, Li

2018-05-01

It has been well established that regional patterns of atmosphere-borne polycyclic aromatic hydrocarbons (PAHs) and trace metals were predominantly associated with the trajectory of socio-economic development; however, they could be potentially modulated by anthropogenic fingerprint of local sources such as industrial spill. Here, we established historical pollution data of both PAHs and trace metals from a well-dated sediment core from Yangzong Lake of Southwest China, which experienced a severe tailing leakage accident derived from a zinc concentrate smelting plant in 2007, aiming to evaluate the heterogeneity in their temporal trajectories and their sources of contamination in the context of regional deposition patterns. Sedimentary records show that the concentrations and fluxes of both PAHs and trace metals remained a consistently low level before the 1950s. An increasing trend and the synchronous changes of both PAHs and trace metals during ~ 1950-2002 were well consistent with the temporal pattern of socio-economic development in western China, with coal combustion and smelting industries as the main sources of contamination in this region. However, arsenic (As) and PAHs exhibited a concurrent spike for the period of ~ 2007-2013, contrasting strongly to the regional pattern of these contaminants. The modern concentrations of As revealed a 5- to 14-fold increase over the pre-1950 level, with the contemporary concentrations of PAHs rising by ~ 10-14 times. The sediment records reveal that local fingerprints of smelting activities in the catchment of Yangzong Lake have overridden the temporary pattern of regional atmosphere-borne As and PAHs over the last decade. This highlights the important role of local pollution sources in modulating or even overriding the regional pattern of anthropogenic contamination in highly impacted systems.

Contamination of successive samples in portable pumping systems

Treesearch

Robert B. Thomas; Rand E. Eads

1983-01-01

Automatic discrete sample pumping systems used to monitor water quality should deliver to storage all materials pumped in a given cycle. If they do not, successive samples will be contaminated, a severe problem with highly variable suspended sediment concentrations in small streams. The cross-contamination characteristics of two small commonly used portable pumping...

Review: The distribution, flow, and quality of Grand Canyon Springs, Arizona (USA)

NASA Astrophysics Data System (ADS)

Tobin, Benjamin W.; Springer, Abraham E.; Kreamer, David K.; Schenk, Edward

2018-05-01

An understanding of the hydrogeology of Grand Canyon National Park (GRCA) in northern Arizona, USA, is critical for future resource protection. The 750 springs in GRCA provide both perennial and seasonal flow to numerous desert streams, drinking water to wildlife and visitors in an otherwise arid environment, and habitat for rare, endemic and threatened species. Spring behavior and flow patterns represent local and regional patterns in aquifer recharge, reflect the geologic structure and stratigraphy, and are indicators of the overall biotic health of the canyon. These springs, however, are subject to pressures from water supply development, changes in recharge from forest fires and other land management activities, and potential contamination. Roaring Springs is the sole water supply for residents and visitors (>6 million/year), and all springs support valuable riparian habitats with very high species diversity. Most springs flow from the karstic Redwall-Muav aquifer and show seasonal patterns in flow and water chemistry indicative of variable aquifer porosities, including conduit flow. They have Ca/Mg-HCO3 dominated chemistry and trace elements consistent with nearby deep wells drilled into the Redwall-Muav aquifer. Tracer techniques and water-age dating indicate a wide range of residence times for many springs, supporting the concept of multiple porosities. A perched aquifer produces small springs which issue from the contacts between sandstone and shale units, with variable groundwater residence times. Stable isotope data suggest both an elevational and seasonal difference in recharge between North and South Rim springs. This review highlights the complex nature of the groundwater system.

Assessment of natural attenuation of ground-water contamination at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware

USGS Publications Warehouse

Barbaro, Jeffrey R.

2002-01-01

Water-quality, aquifer-sediment, and hydro-logic data were used to assess the effectiveness of natural attenuation of ground-water contamination at Fire Training Area Three, the Rubble Area Landfill, the Liquid Waste Disposal Landfill, and the Receiver Station Landfill in the East Management Unit of Dover Air Force Base, Delaware. These sites, which are contaminated with chlorinated solvents and fuel hydrocarbons, are under-going long-term monitoring to determine if natural attenuation continues to sufficiently reduce contaminant concentrations to meet regulatory requirements. This report is the first assessment of the effectiveness of natural attenuation at these sites since long-term monitoring began in 1999, and follows a preliminary investigation done in 1995?96. This assessment was done by the U.S. Geological Survey in cooperation with the U.S. Air Force.Since 1995?96, additional information has been collected and used in the current assessment. The conclusions in this report are based primarily on ground-water samples collected from January through March 2000. Previous analytical results from selected wells, available geologic and geo-physical well logs, and newly acquired information such as sediment organic-carbon measurements, hydraulic-conductivity measurements determined from slug tests on wells in the natural attenuation study area, and water-level measurements from surficial-aquifer wells also were used in this assessment. This information was used to: (1) calculate retardation factors and estimate contaminant migration velocities, (2) improve estimates of ground-water flow directions and inferred contaminant migration pathways, (3) better define the areal extent of contamination and the proximity of contaminants to discharge areas and the Base boundary, (4) develop a better under-standing of the vertical variability of contaminant concentrations and redox conditions, (5) evaluate the effects of temporal changes on concentrations in the plumes and source areas, and (6) determine whether intrinsic biodegradation is occurring at these sites.The water-quality data indicate that intrinsic biodegradation is occurring at all three sites. The strongest indication of intrinsic biodegradation is the detection of tetrachloroethene and trichloroethene breakdown products within and down-gradient of the source areas. The patterns of electron acceptors and metabolic by-products indicate that contaminant biodegradation has changed the prevailing geochemistry of the surficial aquifer, creating the strongly reducing conditions necessary for chlorinated solvent bio-degradation. Geochemical changes include depleted dissolved oxygen and elevated ferrous iron and methane levels relative to concentrations in uncontaminated zones of the surficial aquifer. At Fire Training Area Three and the Rubble Area Landfill sites, natural attenuation appears to be adequate for controlling the migration of the contaminant plumes. At the third site, the Liquid Waste Disposal and Receiver Station Landfills, the plume is larger and the uncertainty about the effectiveness of natural attenuation in reducing contaminant concentrations and controlling plume migration is greater. Ground-water data indicate, however, that U.S. Environmental Protection Agency maximum contaminant levels were not exceeded in any point-of-compliance wells located along the Base boundary.The information presented in this report led to the development of improved conceptual models for these sites, and to the recognition of four issues that are currently unclear and may need further study. These issues include delineating the areal and vertical extent of the contaminant plumes in greater detail, determining the extent of intrinsic biodegradation downgradient of the Liquid Waste Disposal and Receiver Station Landfills, deter-mining the fate of contaminants in the ground-water discharge areas, and determining the effect of temporal variability in source concentrations and ground-water

Semianalytical solutions for contaminant transport under variable velocity field in a coastal aquifer

NASA Astrophysics Data System (ADS)

Koohbor, Behshad; Fahs, Marwan; Ataie-Ashtiani, Behzad; Simmons, Craig T.; Younes, Anis

2018-05-01

Existing closed-form solutions of contaminant transport problems are limited by the mathematically convenient assumption of uniform flow. These solutions cannot be used to investigate contaminant transport in coastal aquifers where seawater intrusion induces a variable velocity field. An adaptation of the Fourier-Galerkin method is introduced to obtain semi-analytical solutions for contaminant transport in a confined coastal aquifer in which the saltwater wedge is in equilibrium with a freshwater discharge flow. Two scenarios dealing with contaminant leakage from the aquifer top surface and contaminant migration from a source at the landward boundary are considered. Robust implementation of the Fourier-Galerkin method is developed to efficiently solve the coupled flow, salt and contaminant transport equations. Various illustrative examples are generated and the semi-analytical solutions are compared against an in-house numerical code. The Fourier series are used to evaluate relevant metrics characterizing contaminant transport such as the discharge flux to the sea, amount of contaminant persisting in the groundwater and solute flux from the source. These metrics represent quantitative data for numerical code validation and are relevant to understand the effect of seawater intrusion on contaminant transport. It is observed that, for the surface contamination scenario, seawater intrusion limits the spread of the contaminant but intensifies the contaminant discharge to the sea. For the landward contamination scenario, moderate seawater intrusion affects only the spatial distribution of the contaminant plume while extreme seawater intrusion can increase the contaminant discharge to the sea. The developed semi-analytical solution presents an efficient tool for the verification of numerical models. It provides a clear interpretation of the contaminant transport processes in coastal aquifers subject to seawater intrusion. For practical usage in further studies, the full open source semi-analytical codes are made available at the website https://lhyges.unistra.fr/FAHS-Marwan.

Bacterial contamination of ex vivo processed PBPC products under clean room conditions.

PubMed

Ritter, Markus; Schwedler, Joachim; Beyer, Jörg; Movassaghi, Kamran; Mutters, Reinier; Neubauer, Andreas; Schwella, Nimrod

2003-11-01

Patients undergoing high-dose radio- and/or chemotherapy and autologous or allogeneic PBPC transplantation are at high risk for infections owing to profound immunosuppression. In this study, the rate of microbial contamination of ex vivo processed PBPC products was analyzed, comparing preparation under clean room conditions to standard laboratory conditions. After implementation of good manufacturing practice conditions in the two participating institutions, the microbial contamination rate of 366 PBPC harvests from 198 patients was determined under certified clean room conditions (Group A) from 2000 until 2002. To investigate influence of improved environmental conditions along with other parameters, this set of samples was compared with a historical control set of 1413 PBPC products, which have been processed ex vivo under a clean bench in a regular laboratory room and were harvested from 626 patients (Group B) from 1989 until 2000. In Group B microbial contamination was found in 74 PBPC products (5.2%) from 57 patients. In Group A microbial growth was detected in 3 leukapheresis products (0.8%) from 3 patients. After exclusion of PBPC products, which were probably contaminated before manipulation, statistical analysis showed a significant difference (chi2= 10.339; p < 0.001). These data suggest an impact of clean room conditions on the bacterial contamination rate of PBPC products. To identify confounding variables, variables like technique of leukapheresis, culture methodology, and microbial colonization of central venous catheters were taken into account. Further variables might be identified in following studies.

Tracking contaminants in seabirds of Arctic Canada: temporal and spatial insights.

PubMed

Mallory, Mark L; Braune, Birgit M

2012-07-01

Levels and trends of persistent organic pollutants and trace elements in seabirds breeding in the vast Canadian Arctic have been monitored since 1975. Data from this monitoring have indicated both spatial and temporal variation across the region, attributable in part to differences in species' diets, differences in regional deposition patterns, and unidirectional trends in contaminants reaching this area from emissions in temperate and tropical areas to the south. Seabird tissues have served as effective biomonitors to examine this variation, and national and international collaboration in this monitoring effort has promoted valuable synthetic assessments of spatial and temporal patterns in Arctic contaminants. Here we review the history of the monitoring program, the critical role played by Environment Canada's National Wildlife Specimen Bank, and we summarize important spatial and temporal trends in various contaminants in Canadian Arctic seabirds. Copyright © 2012 Elsevier Ltd. All rights reserved.

Printed Circuit Board Surface Finish and Effects of Chloride Contamination, Electric Field, and Humidity on Corrosion Reliability

NASA Astrophysics Data System (ADS)

Conseil-Gudla, Hélène; Jellesen, Morten S.; Ambat, Rajan

2017-02-01

Corrosion reliability is a serious issue today for electronic devices, components, and printed circuit boards (PCBs) due to factors such as miniaturization, globalized manufacturing practices which can lead to process-related residues, and global usage effects such as bias voltage and unpredictable user environments. The investigation reported in this paper focuses on understanding the synergistic effect of such parameters, namely contamination, humidity, PCB surface finish, pitch distance, and potential bias on leakage current under different humidity levels, and electrochemical migration probability under condensing conditions. Leakage currents were measured on interdigitated comb test patterns with three different types of surface finish typically used in the electronics industry, namely gold, copper, and tin. Susceptibility to electrochemical migration was studied under droplet conditions. The level of base leakage current (BLC) was similar for the different surface finishes and NaCl contamination levels up to relative humidity (RH) of 65%. A significant increase in leakage current was found for comb patterns contaminated with NaCl above 70% to 75% RH, close to the deliquescent RH of NaCl. Droplet tests on Cu comb patterns with varying pitch size showed that the initial BLC before dendrite formation increased with increasing NaCl contamination level, whereas electrochemical migration and the frequency of dendrite formation increased with bias voltage. The effect of different surface finishes on leakage current under humid conditions was not very prominent.

A QC approach to the determination of day-to-day reproducibility and robustness of LC-MS methods for global metabolite profiling in metabonomics/metabolomics.

PubMed

Gika, Helen G; Theodoridis, Georgios A; Earll, Mark; Wilson, Ian D

2012-09-01

An approach to the determination of day-to-day analytical robustness of LC-MS-based methods for global metabolic profiling using a pooled QC sample is presented for the evaluation of metabonomic/metabolomic data. A set of 60 urine samples were repeatedly analyzed on five different days and the day-to-day reproducibility of the data obtained was determined. Multivariate statistical analysis was performed with the aim of evaluating variability and selected peaks were assessed and validated in terms of retention time stability, mass accuracy and intensity. The methodology enables the repeatability/reproducibility of extended analytical runs in large-scale studies to be determined, allowing the elimination of analytical (as opposed to biological) variability, in order to discover true patterns and correlations within the data. The day-to-day variability of the data revealed by this process suggested that, for this particular system, 3 days continuous operation was possible without the need for maintenance and cleaning. Variation was generally based on signal intensity changes over the 7-day period of the study, and was mainly a result of source contamination.

Microlensing makes lensed quasar time delays significantly time variable

NASA Astrophysics Data System (ADS)

Tie, S. S.; Kochanek, C. S.

2018-01-01

The time delays of gravitationally lensed quasars are generally believed to be unique numbers whose measurement is limited only by the quality of the light curves and the models for the contaminating contribution of gravitational microlensing to the light curves. This belief is incorrect - gravitational microlensing also produces changes in the actual time delays on the ∼day(s) light-crossing time-scale of the emission region. This is due to a combination of the inclination of the disc relative to the line of sight and the differential magnification of the temperature fluctuations producing the variability. We demonstrate this both mathematically and with direct calculations using microlensing magnification patterns. Measuring these delay fluctuations can provide a physical scale for microlensing observations, removing the need for priors on either the microlens masses or the component velocities. That time delays in lensed quasars are themselves time variable likely explains why repeated delay measurements of individual lensed quasars appear to vary by more than their estimated uncertainties. This effect is also a new important systematic problem for attempts to use time delays in lensed quasars for cosmology or to detect substructures (satellites) in lens galaxies.

Spatial prediction of water quality variables along a main river channel, in presence of pollution hotspots.

PubMed

Rizo-Decelis, L D; Pardo-Igúzquiza, E; Andreo, B

2017-12-15

In order to treat and evaluate the available data of water quality and fully exploit monitoring results (e.g. characterize regional patterns, optimize monitoring networks, infer conditions at unmonitored locations, etc.), it is crucial to develop improved and efficient methodologies. Accordingly, estimation of water quality along fluvial ecosystems is a frequent task in environment studies. In this work, a particular case of this problem is examined, namely, the estimation of water quality along a main stem of a large basin (where most anthropic activity takes place), from observational data measured along this river channel. We adapted topological kriging to this case, where each watershed contains all the watersheds of the upstream observed data ("nested support effect"). Data analysis was additionally extended by taking into account the upstream distance to the closest contamination hotspot as an external drift. We propose choosing the best estimation method by cross-validation. The methodological approach in spatial variability modeling may be used for optimizing the water quality monitoring of a given watercourse. The methodology presented is applied to 28 water quality variables measured along the Santiago River in Western Mexico. Copyright © 2017 Elsevier B.V. All rights reserved.

Aerosol climatology using a tunable spectral variability cloud screening of AERONET data

NASA Technical Reports Server (NTRS)

Kaufman, Yoram J.; Gobbi, Gian Paolo; Koren, Ilan

2005-01-01

Can cloud screening of an aerosol data set, affect the aerosol optical thickness (AOT) climatology? Aerosols, humidity and clouds are correlated. Therefore, rigorous cloud screening can systematically bias towards less cloudy conditions, underestimating the average AOT. Here, using AERONET data we show that systematic rejection of variable atmospheric optical conditions can generate such bias in the average AOT. Therefore we recommend (1) to introduce more powerful spectral variability cloud screening and (2) to change the philosophy behind present aerosol climatologies: Instead of systematically rejecting all cloud contaminations, we suggest to intentionally allow the presence of cloud contamination, estimate the statistical impact of the contamination and correct for it. The analysis, applied to 10 AERONET stations with approx. 4 years of data, shows almost no change for Rome (Italy), but up to a change in AOT of 0.12 in Beijing (PRC). Similar technique may be explored for satellite analysis, e.g. MODIS.

First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Galactic Signal Contamination from Sidelobe Pickup

NASA Astrophysics Data System (ADS)

Barnes, C.; Hill, R. S.; Hinshaw, G.; Page, L.; Bennett, C. L.; Halpern, M.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wollack, E.; Wright, E. L.

2003-09-01

Since the Galactic center is ~1000 times brighter than fluctuations in the cosmic microwave background (CMB), CMB experiments must carefully account for stray Galactic pickup. We present the level of contamination due to sidelobes for the first-year CMB maps produced by the Wilkinson Microwave Anisotropy Probe (WMAP) observatory. For each radiometer, full 4π sr antenna gain patterns are determined from a combination of numerical prediction and ground-based and space-based measurements. These patterns are convolved with the WMAP first-year sky maps and observatory scan pattern to generate the expected sidelobe signal contamination, for both intensity and polarized microwave sky maps. When the main beams are outside of the Galactic plane, we find rms values for the expected sidelobe pickup of 15, 2.1, 2.0, 0.3, and 0.5 μK for the K, Ka, Q, V, and W bands, respectively. Except for at the K band, the rms polarized contamination is <<1 μK. Angular power spectra of the Galactic pickup are presented. WMAP is the result of a partnership between Princeton University and the NASA Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

Listeria monocytogenes and Listeria spp. contamination patterns in retail delicatessen establishments in three U.S. states.

PubMed

Simmons, Courtenay; Stasiewicz, Matthew J; Wright, Emily; Warchocki, Steven; Roof, Sherry; Kause, Janell R; Bauer, Nathan; Ibrahim, Salam; Wiedmann, Martin; Oliver, Haley F

2014-11-01

Postprocessing contamination in processing plants has historically been a significant source of Listeria monocytogenes in ready-to-eat delicatessen meats, and therefore a major cause of human listeriosis cases and outbreaks. Recent risk assessments suggest that a majority of human listeriosis cases linked to consumption of contaminated deli meats may be due to L. monocytogenes contamination that occurs at the retail level. To better understand the ecology and transmission of Listeria spp. in retail delicatessens, food and nonfood contact surfaces were tested for L. monocytogenes and other Listeria spp. in a longitudinal study conducted in 30 retail delis in three U.S. states. In phase I of the study, seven sponge samples were collected monthly for 3 months in 15 delis (5 delis per state) prior to start of daily operation; in phase II, 28 food contact and nonfood contact sites were sampled in each of 30 delis during daily operation for 6 months. Among the 314 samples collected during phase I, 6.8% were positive for L. monocytogenes. Among 4,503 samples collected during phase II, 9.5% were positive for L. monocytogenes; 9 of 30 delis showed low L. monocytogenes prevalence (<1%) for all surfaces. A total of 245 Listeria spp. isolates, including 184 Listeria innocua, 48 Listeria seeligeri, and 13 Listeria welshimeri were characterized. Pulsed-field gel electrophoresis (PFGE) was used to characterize 446 L. monocytogenes isolates. PFGE showed that for 12 of 30 delis, one or more PFGE types were isolated on at least three separate occasions, providing evidence for persistence of a given L. monocytogenes subtype in the delis. For some delis, PFGE patterns for isolates from nonfood contact surfaces were distinct from patterns for occasional food contact surface isolates, suggesting limited cross-contamination between these sites in some delis. This study provides longitudinal data on L. monocytogenes contamination patterns in retail delis, which should facilitate further development of control strategies in retail delis.

Plasma cleaning of nanoparticles from EUV mask materials by electrostatics

NASA Astrophysics Data System (ADS)

Lytle, W. M.; Raju, R.; Shin, H.; Das, C.; Neumann, M. J.; Ruzic, D. N.

2008-03-01

Particle contamination on surfaces used in extreme ultraviolet (EUV) mask blank deposition, mask fabrication, and patterned mask handling must be avoided since the contamination can create significant distortions and loss of reflectivity. Particles on the order of 10nm are problematic during MLM mirror fabrication, since the introduced defects disrupt the local Bragg planes. The most serious problem is the accumulation of particles on surfaces of patterned blanks during EUV light exposure, since > 25nm particles will be printed without an out-of-focus pellicle. Particle contaminants are also a problem with direct imprint processes since defects are printed every time. Plasma Assisted Cleaning by Electrostatics (PACE) works by utilizing a helicon plasma as well as a pulsed DC substrate bias to charge particle and repel them electrostatically from the surface. Removal of this nature is a dry cleaning method and removes contamination perpendicular from the surface instead of rolling or sweeping the particles off the surface, a benefit when cleaning patterned surfaces where contamination can be rolled or trapped between features. Also, an entire mask can be cleaned at once since the plasma can cover the entire surface, thus there is no need to focus in on an area to clean. Sophisticated particle contamination detection system utilizing high power laser called DEFCON is developed to analyze the particle removal after PACE cleaning process. PACE has shown greater than 90 % particle removal efficiencies for 30 to 220 nm PSL particles on ruthenium capped quartz. Removal results for silicon surfaces and quartz surfaces show similar removal efficiencies. Results of cleaning 80 nm PSL spheres from silicon substrates will be shown.

Comparison of microbial taxonomic and functional shift pattern along contamination gradient.

PubMed

Ren, Youhua; Niu, Jiaojiao; Huang, Wenkun; Peng, Deliang; Xiao, Yunhua; Zhang, Xian; Liang, Yili; Liu, Xueduan; Yin, Huaqun

2016-06-14

The interaction mechanism between microbial communities and environment is a key issue in microbial ecology. Microbial communities usually change significantly under environmental stress, which has been studied both phylogenetically and functionally, however which method is more effective in assessing the relationship between microbial communities shift and environmental changes still remains controversial. By comparing the microbial taxonomic and functional shift pattern along heavy metal contamination gradient, we found that both sedimentary composition and function shifted significantly along contamination gradient. For example, the relative abundance of Geobacter and Fusibacter decreased along contamination gradient (from high to low), while Janthinobacterium and Arthrobacter increased their abundances. Most genes involved in heavy metal resistance (e.g., metc, aoxb and mer) showed higher intensity in sites with higher concentration of heavy metals. Comparing the two shift patterns, there were correlations between them, because functional and phylogenetic β-diversities were significantly correlated, and many heavy metal resistance genes were derived from Geobacter, explaining their high abundance in heavily contaminated sites. However, there was a stronger link between functional composition and environmental drivers, while stochasticity played an important role in formation and succession of phylogenetic composition demonstrated by null model test. Overall our research suggested that the responses of functional traits depended more on environmental changes, while stochasticity played an important role in formation and succession of phylogenetic composition for microbial communities. So profiling microbial functional composition seems more appropriate to study the relationship between microbial communities and environment, as well as explore the adaptation and remediation mechanism of microbial communities to heavy metal contamination.

EVIDENCE FOR MICROBIAL ENHANCED ELECTRICAL CONDUCTIVITY IN HYDROCARBON-CONTAMINATED SEDIMENTS

EPA Science Inventory

Electrical conductivity of sediments during microbial mineralization of diesel was investigated in a mesoscale column experiment consisting of biotic contaminated and uncontaminated columns. Microbial population numbers increased with a clear pattern of depth zonation within the ...

Radial and vertical distributions of radiocesium in tree stems of Pinus densiflora and Quercus serrata 1.5 y after the Fukushima nuclear disaster.

PubMed

Ohashi, Shinta; Okada, Naoki; Tanaka, Atsushi; Nakai, Wataru; Takano, Shigeyoshi

2014-08-01

The radial and vertical distributions of radiocesium in tree stems were investigated to understand radiocesium transfer to trees at an early stage of massive contamination from the Fukushima nuclear disaster. A conifer species (Japanese red pine) and a broad-leaved species (Japanese konara oak) were selected to determine whether the radiocesium contamination pattern differs between species. Stem disks were collected at several heights and separated into outer bark, inner bark, and wood. The radiocesium concentration was the highest in the outer bark, followed by that in the inner bark and wood. The vertical distribution of the radiocesium concentration at each stem part differed between the species. The difference between species in radiocesium concentration of the outer bark could be explained by presence or absence of leaves at the time of the disaster. However, the reasons for the differences between species in the radiocesium concentration of the inner bark and wood are unclear. The radial distribution in the wood of the studied species showed a common pattern across stem disk heights and species. However, the radiocesium concentration ratio between sapwood and inner bark was significantly different between species. Although the radial contamination pattern in the wood was similar in the studied species during the early stage of contamination, the radiocesium transport pathway and allocation would be different between the species, and the contamination pattern will likely be different between the species at later stages. Continued investigations are important for understanding the radiocesium cycle and the accumulation of radiocesium in the tree stems of each species. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lifespan mercury accumulation pattern in Liza aurata : Evidence from two southern European estuaries

NASA Astrophysics Data System (ADS)

Tavares, S.; Oliveira, H.; Coelho, J. P.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.

2011-10-01

Mercury accumulation throughout the lifespan of Liza aurata (Risso, 1810) was analysed in four tissues (muscle, gills, liver and brain) in two southern European coastal ecosystems with distinct mercury contamination. Specimens from four to five age classes were captured in two sampling sites in the Ria de Aveiro (Laranjo bay and Mira), a system historically contaminated by industrial mercury, and in one site in the Mondego estuary, assumed as a mercury-free ecosystem. Mercury concentration in all tissues was found to be significantly higher in the Ria de Aveiro (Laranjo bay) compared to the Mondego, in accordance with the environmental contamination (water, sediments and suspended particulate matter). Significant differences inside the Ria de Aveiro (between the Mira and Laranjo bay) were only detected in the liver. This tissue registered the highest levels of mercury (ranging from 0.11 to 4.2 μg g -1 ) in all sampling sites, followed by muscle, brain, and gills. In all sampling sites and tissues was denoted a mercury dilution pattern along the lifecycle (except in liver at the Mondego, the reference area where the concentrations are always very low). An exponential trend was found in the metal age variation patterns in Laranjo (the most contaminated area) and a linear trend in the Mira and the Mondego (the least contaminated areas). Organic mercury concentration in muscle generally accounted for over 95% of total mercury concentration, and followed the same accumulation pattern of total mercury. This fish species is of lesser importance in mercury transfer to adjacent coastal areas and although the consumption of fish from Laranjo may present some risk for the humans, this risk decreases with fish age/size.

Farm Management, Environment, and Weather Factors Jointly Affect the Probability of Spinach Contamination by Generic Escherichia coli at the Preharvest Stage

PubMed Central

Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Jun, Mikyoung; Han, Daikwon; Lawhon, Sara; Ivanek, Renata

2014-01-01

The National Resources Information (NRI) databases provide underutilized information on the local farm conditions that may predict microbial contamination of leafy greens at preharvest. Our objective was to identify NRI weather and landscape factors affecting spinach contamination with generic Escherichia coli individually and jointly with farm management and environmental factors. For each of the 955 georeferenced spinach samples (including 63 positive samples) collected between 2010 and 2012 on 12 farms in Colorado and Texas, we extracted variables describing the local weather (ambient temperature, precipitation, and wind speed) and landscape (soil characteristics and proximity to roads and water bodies) from NRI databases. Variables describing farm management and environment were obtained from a survey of the enrolled farms. The variables were evaluated using a mixed-effect logistic regression model with random effects for farm and date. The model identified precipitation as a single NRI predictor of spinach contamination with generic E. coli, indicating that the contamination probability increases with an increasing mean amount of rain (mm) in the past 29 days (odds ratio [OR] = 3.5). The model also identified the farm's hygiene practices as a protective factor (OR = 0.06) and manure application (OR = 52.2) and state (OR = 108.1) as risk factors. In cross-validation, the model showed a solid predictive performance, with an area under the receiver operating characteristic (ROC) curve of 81%. Overall, the findings highlighted the utility of NRI precipitation data in predicting contamination and demonstrated that farm management, environment, and weather factors should be considered jointly in development of good agricultural practices and measures to reduce produce contamination. PMID:24509926

Large-Scale Spatial Distribution Patterns of Echinoderms in Nearshore Rocky Habitats

PubMed Central

Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

2010-01-01

This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1–5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m2 quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m−2. In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m2 quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m−2. Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a network of environmental and ecological processes, and by the differing responses of various echinoderm taxa, making generalizations about the patterns of nearshore rocky habitat echinoderm assemblages difficult. PMID:21079760

Large-scale spatial distribution patterns of echinoderms in nearshore rocky habitats.

PubMed

Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

2010-11-05

This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m(2) quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m(-2). In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m(2) quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m(-2). Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a network of environmental and ecological processes, and by the differing responses of various echinoderm taxa, making generalizations about the patterns of nearshore rocky habitat echinoderm assemblages difficult.

Statistical analysis of cyprinid ethoxyresorufin-O-deethylase data in a large French watershed.

PubMed

Flammarion, P; Migeon, B; Garric, J

1998-01-01

A comparison of ethoxyresorufin-O-deethylase (EROD) data collected in 1995 in various sites in the Rhône watershed (France) was carried out to quantify the influence of factors such as contamination and biological parameters on EROD levels and within-group variabilities. Three species of cyprinids were collected and fish chemical contamination was measured. A log transformation of EROD data provided both normalization and homogeneity of variances. The influence of female sexual maturation on the variability and EROD dimorphism was quantified. A relationship with contaminant bioaccumulation was observed. A comparison with EROD data collected during previous studies by the same laboratory was made to validate the results.

Metabolic transformation shapes polychlorinated biphenyl and polybrominated diphenyl ether patterns in beluga whales (Delphinapterus leucas).

PubMed

Desforges, Jean-Pierre W; Ross, Peter S; Loseto, Lisa L

2013-04-01

While the accumulation of persistent contaminants in marine mammals can be attributed directly to their prey, the role of metabolism in shaping patterns is often overlooked. In the present study, the authors investigated the role of metabolic transformation in influencing polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) patterns in offshore and nearshore groups of beluga whales (Delphinapterus leucas) and their prey. Congener profiles and principal components analysis (PCA) revealed similar PCB and PBDE patterns in beluga whales feeding either offshore or nearshore, despite divergent contaminant patterns in the putative prey of these two feeding groups. The clustering of PCBs into metabolically derived structure-activity groups (SAGs) and the separation of metabolizable and recalcitrant groups along principal component 1 of the PCA revealed the important role of metabolic transformation in shaping PCB patterns in beluga. Lack of metabolism for congeners with high ortho-chlorine content was revealed by metabolic slopes equal to or greater than 1.0. Metabolic slopes for all other SAGs were less than 1.0 (p<0.001), suggesting metabolism of congeners with ortho-meta and meta-para vicinal hydrogens via induction of cytochrome P450 enzymes (CYP1A/2B/3A). Metabolic indices less than 1.0 for PBDEs (p<0.001) suggested that beluga metabolized these poorly understood flame retardants. The strikingly similar PCB patterns in a captive beluga and free-ranging beluga from the Beaufort Sea provide additional evidence that metabolic transformation is a dominant driver of contaminant patterns in beluga. Copyright © 2013 SETAC.

Spatial Variability in ADHD-Related Behaviors Among Children Born to Mothers Residing Near the New Bedford Harbor Superfund Site

PubMed Central

Vieira, Verónica M.; Fabian, M. Patricia; Webster, Thomas F.; Levy, Jonathan I.; Korrick, Susan A.

2017-01-01

Abstract Attention-deficit/hyperactivity disorder (ADHD) has an uncertain etiology, with potential contributions from different risk factors such as prenatal environmental exposure to organochlorines and metals, social risk factors, and genetics. The degree to which geographic variability in ADHD is independent of, or explained by, risk factors may provide etiological insight. We investigated determinants of geographic variation in ADHD-related behaviors among children living near the polychlorinated biphenyl–contaminated New Bedford Harbor (NBH) Superfund site in Massachusetts. Participants were 573 children recruited at birth (1993–1998) who were born to mothers residing near the NBH site. We assessed ADHD-related behaviors at age 8 years using Conners’ Teacher Rating Scale–Revised: Long Version. Adjusted generalized additive models were used to smooth the association of pregnancy residence with ADHD-related behaviors and assess whether prenatal organochlorine or metal exposures, sociodemographic factors, or other factors explained spatial patterns. Models that adjusted for child's age and sex displayed significantly increased ADHD-related behavior among children whose mothers resided west of the NBH site during pregnancy. These spatial patterns persisted after adjusting for prenatal exposure to organochlorines and metals but were no longer significant after controlling for sociodemographic factors. The findings underscore the value of spatial analysis in identifying high-risk subpopulations and evaluating candidate risk factors. PMID:28444119

Hydrophobic organic contaminants in surficial sediments of Baltimore Harbor: Inventories and sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashley, J.T.F.; Baker, J.E.

1999-05-01

The heavily urbanized and industrialized Baltimore Harbor/Patapsco River/Back River system is one of the most highly contaminated regions of the Chesapeake Bay. In June 1996, surficial sediments were collected at 80 sites throughout the subestuarine system, including historically undersampled creek sand embayments. The samples were analyzed for a suite of hydrophobic organic contaminants (HOCs) consisting of 32 polycyclic aromatic hydrocarbons (PAHs) and 113 polychlorinated biphenyl (PCB) congeners. Total PAH and total PCB concentrations ranged from 90 to 46,200 and 8 to 2,150 ng/g dry weight, respectively. There was enormous spatial variability in the concentrations of HOCs, which was not wellmore » correlated to grain size or organic carbon content, suggesting nonequilibrium partitioning and/or proximity to sources as important factors explaining the observed spatial variability. High concentrations of both classes of HOCs were localized around major urban stormwater runoff discharges. Elevated PAH concentrations were also centered around the Sparrow`s Point Industrial Complex, most likely a result of the pyrolysis of coal during the production of steel. All but 1 of the 80 sites exceeded the effects range-low (ERL) for total PCBs and, of those sites, 40% exceeded the effects range-medium (ERM), suggesting toxicity to marine benthic organisms would frequently occur. Using principal component analysis, differences in PAH signatures were discerned. Higher molecular weight PAHs were enriched in signatures from sediments close to suspected sources (i.e., urban stormwater runoff and steel production complexes) compared to those patterns observed at sites further from outfalls or runoff. Due to varying solubilities and affinities for organic matter of the individual PAHs, partitioning of the heavier weight PAHs may enrich settling particles with high molecular weight PAHs. Lower molecular weight PAHs, having lower affinity for particles, may travel from the source to a greater extent.« less

Nutrients versus emerging contaminants-Or a dynamic match between subsidy and stress effects on stream biofilms.

PubMed

Aristi, I; Casellas, M; Elosegi, A; Insa, S; Petrovic, M; Sabater, S; Acuña, V

2016-05-01

Freshwater ecosystems are threatened by multiple anthropogenic stressors, which might be differentiated into two types: those that reduce biological activity at all concentrations (toxic contaminants), and those that subsidize biological activity at low concentrations and reduce it at high concentrations (assimilable contaminants). When occurring in mixtures, these contaminants can have either antagonistic, neutral or synergistic effects; but little is known on their joint effects. We assessed the interaction effects of a mixture of assimilable and toxic contaminants on stream biofilms in a manipulative experiment using artificial streams, and following a factorial design with three nutrient levels (low, medium or high) and either presence or absence of a mixture of emerging contaminants (ciprofloxacin, erythromycin, diclofenac, methylparaben, and sulfamethoxazole). We measured biofilm biomass, basal fluorescence, gross primary production and community respiration. Our initial hypotheses were that biofilm biomass and activity would: increase with medium nutrient concentrations (subsidy effect), but decrease with high nutrient concentrations (stress effect) (i); decrease with emerging contaminants, with the minimum decrease at medium nutrient concentrations (antagonistic interaction between nutrients subsidy and stress by emerging contaminants) and the maximum decrease at high nutrient concentrations (synergistic interaction between nutrients and emerging contaminants stress) (ii). All the measured variables responded linearly to the available nutrients, with no toxic effect at high nutrient concentrations. Emerging contaminants only caused weak toxic effects in some of the measured variables, and only after 3-4 weeks of exposure. Therefore, only antagonistic interactions were observed between nutrients and emerging contaminants, as medium and high nutrient concentrations partly compensated the harmful effects of emerging contaminants during the first weeks of the experiment. Our results show that contaminants with a subsidy effect can alleviate the effects of toxic contaminants, and that long-term experiments are required to detect stress effects of emerging contaminants at environmentally relevant concentrations. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Carbon contamination topography analysis of EUV masks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Y.-J.; Yankulin, L.; Thomas, P.

2010-03-12

The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and potential effects on imaging performance. Current carbon contamination research primarily focuses on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on absorbing features and the printed images, as well as impacting the efficiency of cleaning process. In this work, several different techniques were used to determine possible contamination topography. Lithographic simulations were also performed and the results compared with the experimental data.

Nitrogen and phosphorus runoff losses from variable and constant intensity rainfall simulations on loamy sand under conventional and strip tillage systems.

PubMed

Franklin, D; Truman, C; Potter, T; Bosch, D; Strickland, T; Bednarz, C

2007-01-01

Further studies on the quality of runoff from tillage and cropping systems in the southeastern USA are needed to refine current risk assessment tools for nutrient contamination. Our objective was to quantify and compare effects of constant (Ic) and variable (Iv) rainfall intensity patterns on inorganic nitrogen (N) and phosphorus (P) losses from a Tifton loamy sand (Plinthic Kandiudult) cropped to cotton (Gossypium hirsutum L.) and managed under conventional (CT) or strip-till (ST) systems. We simulated rainfall at a constant intensity and a variable intensity pattern (57 mm h(-1)) and collected runoff continuously at 5-min intervals for 70 min. For cumulative runoff at 50 min, the Iv pattern lost significantly greater amounts (p < 0.05) of total Kjeldahl N (TKN) and P (TKP) (849 g N ha(-1) and 266 g P ha(-1) for Iv; 623 g N ha(-1) and 192 g P ha(-1) for Ic) than did the Ic pattern. However, at 70 min, no significant differences in total losses were evident for TKN or TKP from either rainfall intensity pattern. In contrast, total cumulative losses of dissolved reactive P (DRP) and NO3-N were greatest for ST-Ic, followed by ST-Iv, CT-Ic, and CT-Iv in diminishing order (69 g DRP ha(-1) and 361 g NO3-N ha(-1); 37 g DRP ha(-1) and 133 g NO3-N ha(-1); 3 g DRP ha(-1) and 58 g NO3-N ha(-1); 1 g DRP ha(-1) and 49 g NO3-N ha(-1)). Results indicate that constant-rate rainfall simulations may overestimate the amount of dissolved nutrients lost to the environment in overland flow from cropping systems in loamy sand soils. We also found that CT treatments lost significantly greater amounts of TKN and TKP than ST treatments and in contrast, ST treatments lost significantly greater amounts of DRP and NO3-N than CT treatments. These results indicate that ST systems may be losing more soluble fractions than CT systems, but only a fraction the total N (33%) and total P (11%) lost through overland flow from CT systems.

Environmental assessment of metal exposure to corals living in Castle Harbour, Bermuda

USGS Publications Warehouse

Prouty, N.G.; Goodkin, N.F.; Jones, R.; Lamborg, C.H.; Storlazzi, C.D.; Hughen, K.A.

2013-01-01

Environmental contamination in Castle Harbour, Bermuda, has been linked to the dissolution and leaching of contaminants from the adjacent marine landfill. This study expands the evidence for environmental impact of leachate from the landfill by quantitatively demonstrating elevated metal uptake over the last 30 years in corals growing in Castle Harbour. Coral Pb/Ca, Zn/Ca and Mn/Ca ratios and total Hg concentrations are elevated relative to an adjacent control site in John Smith's Bay. The temporal variability in the Castle Harbour coral records suggests that while the landfill has increased in size over the last 35 years, the dominant input of metals is through periodic leaching of contaminants from the municipal landfill and surrounding sediment. Elevated contaminants in the surrounding sediment suggest that resuspension is an important transport medium for transferring heavy metals to corals. Increased winds, particularly during the 1990s, were accompanied by higher coral metal composition at Castle Harbour. Coupled with wind-induced resuspension, interannual changes in sea level within the Harbour can lead to increased bioavailability of sediment-bound metals and subsequent coral metal assimilation. At John Smith's Bay, large scale convective mixing may be driving interannual metal variability in the coral record rather than impacts from land-based activities. Results from this study provide important insights into the coupling of natural variability and anthropogenic input of contaminants to the nearshore environment.

Quantitative relations between soil heavy metal contamination and landscape pattern in Wuxi, China

NASA Astrophysics Data System (ADS)

Zhu, Ming; Pu, Lijie; Xu, Yan

2017-04-01

Land use practices changed landscape pattern and meanwhile, brought forth numerous environmental problems including heavy metal contamination in soil. In this study, we investigated the quantitative relations between soil heavy metal contamination and its surrounding landscape pattern based on topsoil samples and land use map of Wuxi in 2009. The results of vector fitting with Redundancy analysis in R package vegan showed that Percent Coverage of build-up area (PCB) within 2500 m, Perimeter-Area Fractal Dimension (PAFD) within 2500 m, Edge Density (ED) within 2500 m, Patch Density (PD) within 200 m, Percent Coverage of wetland (PCW) within 2000 m and Patch Cohesion (PC) within 200 m significantly affected the contents of heavy metal elements. The results of Stepwise regression suggested that increase of build-up area and fragmentation would increase Cu and Zn, while increase of wetland would decrease the contents of As and Cu. PAFD was negative with Cd, Hg, Pb and Zn.

Current aspects of Salmonella contamination in the US poultry production chain and the potential application of risk strategies in understanding emerging hazards.

PubMed

Rajan, Kalavathy; Shi, Zhaohao; Ricke, Steven C

2017-05-01

One of the leading causes of foodborne illness in poultry products is Salmonella enterica. Salmonella hazards in poultry may be estimated and possible control methods modeled and evaluated through the use of quantitative microbiological risk assessment (QMRA) models and tools. From farm to table, there are many possible routes of Salmonella dissemination and contamination in poultry. From the time chicks are hatched through growth, transportation, processing, storage, preparation, and finally consumption, the product could be contaminated through exposure to different materials and sources. Examination of each step of the process is necessary as well as an examination of the overall picture to create effective countermeasures against contamination and prevent disease. QMRA simulation models can use either point estimates or probability distributions to examine variables such as Salmonella concentrations at retail or at any given point of processing to gain insight on the chance of illness due to Salmonella ingestion. For modeling Salmonella risk in poultry, it is important to look at variables such as Salmonella transfer and cross contamination during processing. QMRA results may be useful for the identification and control of critical sources of Salmonella contamination.

Horizontal and vertical variability of soil properties in a trace element contaminated area

NASA Astrophysics Data System (ADS)

Burgos, Pilar; Madejón, Engracia; Pérez-de-Mora, Alfredo; Cabrera, Francisco

2008-02-01

The spatial distribution of some soil chemical properties and trace element contents of a plot affected by the Aznalcóllar mine spill were investigated using statistical and geostatistical methods to assess the extent of soil contamination. Total and EDTA-extractable soil trace element concentrations and total S content showed great variability and high coefficients of variation in the three examined depths. Soil in the plot was found to be significantly contaminated by As, Cd, Cu, Pb and Zn within a wide range of pH. Total trace element concentrations at all depths (0-60 cm) were much higher than background values of non-affected soil, indicating that despite the clean-up operations, the concentration of trace elements in the experimental plot was still high. The spatial distribution of the different variables was estimated by kriging to design contour maps. These maps allowed the identification of specific zones with high metal concentrations and low pH values corresponding to spots of residual sludge. Moreover, kriged maps showed distinct spatial distribution and hence different behaviour for the elements considered. This information may be applied to optimise remediation strategies in highly and moderately contaminated areas.

Climate variability and change in the United States: potential impacts on water- and foodborne diseases caused by microbiologic agents.

PubMed Central

Rose, J B; Epstein, P R; Lipp, E K; Sherman, B H; Bernard, S M; Patz, J A

2001-01-01

Exposure to waterborne and foodborne pathogens can occur via drinking water (associated with fecal contamination), seafood (due to natural microbial hazards, toxins, or wastewater disposal) or fresh produce (irrigated or processed with contaminated water). Weather influences the transport and dissemination of these microbial agents via rainfall and runoff and the survival and/or growth through such factors as temperature. Federal and state laws and regulatory programs protect much of the U.S. population from waterborne disease; however, if climate variability increases, current and future deficiencies in areas such as watershed protection, infrastructure, and storm drainage systems will probably increase the risk of contamination events. Knowledge about transport processes and the fate of microbial pollutants associated with rainfall and snowmelt is key to predicting risks from a change in weather variability. Although recent studies identified links between climate variability and occurrence of microbial agents in water, the relationships need further quantification in the context of other stresses. In the marine environment as well, there are few studies that adequately address the potential health effects of climate variability in combination with other stresses such as overfishing, introduced species, and rise in sea level. Advances in monitoring are necessary to enhance early-warning and prevention capabilities. Application of existing technologies, such as molecular fingerprinting to track contaminant sources or satellite remote sensing to detect coastal algal blooms, could be expanded. This assessment recommends incorporating a range of future scenarios of improvement plans for current deficiencies in the public health infrastructure to achieve more realistic risk assessments. PMID:11359688

Climate variability and change in the United States: potential impacts on water- and foodborne diseases caused by microbiologic agents.

PubMed

Rose, J B; Epstein, P R; Lipp, E K; Sherman, B H; Bernard, S M; Patz, J A

2001-05-01

Exposure to waterborne and foodborne pathogens can occur via drinking water (associated with fecal contamination), seafood (due to natural microbial hazards, toxins, or wastewater disposal) or fresh produce (irrigated or processed with contaminated water). Weather influences the transport and dissemination of these microbial agents via rainfall and runoff and the survival and/or growth through such factors as temperature. Federal and state laws and regulatory programs protect much of the U.S. population from waterborne disease; however, if climate variability increases, current and future deficiencies in areas such as watershed protection, infrastructure, and storm drainage systems will probably increase the risk of contamination events. Knowledge about transport processes and the fate of microbial pollutants associated with rainfall and snowmelt is key to predicting risks from a change in weather variability. Although recent studies identified links between climate variability and occurrence of microbial agents in water, the relationships need further quantification in the context of other stresses. In the marine environment as well, there are few studies that adequately address the potential health effects of climate variability in combination with other stresses such as overfishing, introduced species, and rise in sea level. Advances in monitoring are necessary to enhance early-warning and prevention capabilities. Application of existing technologies, such as molecular fingerprinting to track contaminant sources or satellite remote sensing to detect coastal algal blooms, could be expanded. This assessment recommends incorporating a range of future scenarios of improvement plans for current deficiencies in the public health infrastructure to achieve more realistic risk assessments.

Health status of Largescale Sucker (Catostomus macrocheilus) collected along an organic contaminant gradient in the lower Columbia River, Oregon and Washington, USA

USGS Publications Warehouse

Torres, Leticia; Nilsen, Elena B.; Grove, Robert A.; Patino, Reynaldo

2014-01-01

The health of Largescale Sucker (Catostomus macrocheilus) in the lower Columbia River (USA) was evaluated using morphometric and histopathological approaches, and its association with organic contaminants accumulated in liver was evaluated in males. Fish were sampled from three sites along a contaminant gradient In 2009, body length and mass, condition factor, gonadosomatic index, and hematocrit were measured in males and females; liver and gonad tissue were collected from males for histological analyses; and organ composites were analyzed for contaminant content in males. In 2010, additional data were collected for males and females, including external fish condition assessment, histopathologies of spleen, kidney and gill and, for males, liver contaminant content. Multivariate analysis of variance indicated that biological traits in males, but not females, differed among sites in 2009 and 2010. Discriminant function analysis indicated that site-related differences among male populations were relatively small in 2009, but in 2010, when more variables were analyzed, males differed among sites in regards to kidney, spleen, and liver histopathologies and gill parasites. Kidney tubular hyperplasia, liver and spleen macrophage aggregations, and gill parasites were generally more severe in the downstream sites compared to the reference location. The contaminant content of male livers was also generally higher downstream, and the legacy pesticide hexachlorobenzene and flame retardants BDE-47 and BDE-154 were the primary drivers for site discrimination. However, bivariate correlations between biological variables and liver contaminants retained in the discriminant models failed to reveal associations between the two variable sets. In conclusion, whereas certain non-reproductive biological traits and liver contaminant contents of male Largescale Sucker differed according to an upstream-downstream gradient in the lower Columbia River, results from this study did not reveal the specific environmental factors responsible for the differences in health status among fish populations.

Modeling species richness and abundance of phytoplankton and zooplankton in radioactively contaminated water bodies.

PubMed

Shuryak, Igor

2018-06-05

Water bodies polluted by the Mayak nuclear plant in Russia provide valuable information on multi-generation effects of radioactive contamination on freshwater organisms. For example, lake Karachay was probably the most radioactive lake in the world: its water contained ∼2 × 10 7 Bq/L of radionuclides and estimated dose rates to plankton exceeded 5 Gy/h. We performed quantitative modeling of radiation effects on phytoplankton and zooplankton species richness and abundance in Mayak-contaminated water bodies. Due to collinearity between radioactive contamination, water body size and salinity, we combined these variables into one (called HabitatFactors). We employed a customized machine learning approach, where synthetic noise variables acted as benchmarks of predictor performance. HabitatFactors was the only predictor that outperformed noise variables and, therefore, we used it for parametric modeling of plankton responses. Best-fit model predictions suggested 50% species richness reduction at HabitatFactors values corresponding to dose rates of 10 4 -10 5  μGy/h for phytoplankton, and 10 3 -10 4  μGy/h for zooplankton. Under conditions similar to those in lake Karachay, best-fit models predicted 81-98% species richness reductions for various taxa (Cyanobacteria, Bacillariophyta, Chlorophyta, Rotifera, Cladocera and Copepoda), ∼20-300-fold abundance reduction for total zooplankton, but no abundance reduction for phytoplankton. Rotifera was the only taxon whose fractional abundance increased with contamination level, reaching 100% in lake Karachay, but Rotifera species richness declined with contamination level, as in other taxa. Under severe radioactive and chemical contamination, one species of Cyanobacteria (Geitlerinema amphibium) dominated phytoplankton, and rotifers from the genus Brachionus dominated zooplankton. The modeling approaches proposed here are applicable to other radioecological data sets. The results provide quantitative information and easily interpretable model parameter estimates for the shapes and magnitudes of freshwater plankton responses to a wide range of radioactive contamination levels. Copyright © 2018 Elsevier Ltd. All rights reserved.

Health status of Largescale Sucker (Catostomus macrocheilus) collected along an organic contaminant gradient in the lower Columbia River, Oregon and Washington, USA.

PubMed

Torres, Leticia; Nilsen, Elena; Grove, Robert; Patiño, Reynaldo

2014-06-15

The health of Largescale Sucker (Catostomus macrocheilus) in the lower Columbia River (USA) was evaluated using morphometric and histopathological approaches, and its association with organic contaminants accumulated in liver was evaluated in males. Fish were sampled from three sites along a contaminant gradient. In 2009, body length and mass, condition factor, gonadosomatic index, and hematocrit were measured in males and females; liver and gonad tissue were collected from males for histological analyses; and organ composites were analyzed for contaminant content in males. In 2010, additional data were collected for males and females, including external fish condition assessment, histopathologies of spleen, kidney and gill and, for males, liver contaminant content. Multivariate analysis of variance indicated that biological traits in males, but not females, differed among sites in 2009 and 2010. Discriminant function analysis indicated that site-related differences among male populations were relatively small in 2009, but in 2010, when more variables were analyzed, males differed among sites in regards to kidney, spleen, and liver histopathologies and gill parasites. Kidney tubular hyperplasia, liver and spleen macrophage aggregations, and gill parasites were generally more severe in the downstream sites compared to the reference location. The contaminant content of male livers was also generally higher downstream, and the legacy pesticide hexachlorobenzene and flame retardants BDE-47 and BDE-154 were the primary drivers for site discrimination. However, bivariate correlations between biological variables and liver contaminants retained in the discriminant models failed to reveal associations between the two variable sets. In conclusion, whereas certain non-reproductive biological traits and liver contaminant contents of male Largescale Sucker differed according to an upstream-downstream gradient in the lower Columbia River, results from this study did not reveal the specific environmental factors responsible for the differences in health status among fish populations. Published by Elsevier B.V.

Distribution and transport of sediment-bound metal contaminants in the rio grande de tarcoles, costa rica (Central America)

USGS Publications Warehouse

Fuller, C.C.; Davis, J.A.; Cain, D.J.; Lamothe, P.J.; Fries Fernandez, T.L.G.; Vargas, J.A.; Murillo, M.M.

1990-01-01

A reconnaissance survey of the extent of metal contamination in the Rio Grande de Tarcoles river system of Costa Rica indicated high levels of chromium (Cr) in the fine-grain bed sediments (83 times Cr background or 3000->5000 ??g/g). In the main channel of the river downstream of the San Jose urban area, Cr contamination in sediments was 4-6 times background and remained relatively constant over 50 km to the mouth of the river. Sediment from a mangrove swamp at the river mouth had Cr levels 2-3 times above background. Similar patterns of dilution were observed for lead (Pb) and zinc (Zn) sediment contamination, although the contamination levels were lower. The high affinity of Cr towards particulate phases, probably as Cr(III), allows the use of Cr contamination levels for delineating regions of deposition of fine-grained sediments and dilution of particle associated contaminants during transport and deposition.A reconnaissance survey of the extent of metal contamination in the Rio Grande de Tarcoles river system of Costa Rica indicated high levels of chromium (Cr) in the fine-grain bed sediments (83 times Cr background or 3000->5000 ??g/g). In the main channel of the river downstream of the San Jose urban area, Cr contamination in sediments was 4-6 times background and remained relatively constant over 50 km to the mouth of the river. Sediments from a mangrove swamp at the river mouth had Cr levels 2-3 times above background. Similar patterns of dilution were observed for lead (Pb) and zinc (Zn) sediment contamination, although the contamination levels were lower. The high affinity of Cr towards particulate phases, probably as Cr(III), allows the use of Cr contamination levels for delineating regions of deposition of fine-grained sediments and dilution of particle associated contaminants during transport and deposition.

Influence of the land use pattern on the concentrations and fluxes of priority pollutants in urban stormwater.

PubMed

Zgheib, S; Moilleron, R; Chebbo, G

2011-01-01

This paper presents the results of the concentrations (μg/L) and fluxes (g/ha) of priority substances in stormwater from three watersheds with different land use patterns (namely, residential, urban dense, high urban density). Samples were collected at the outlet of these watersheds. Thirteen chemical groups were investigated corresponding to 88 individual substances before treatment. Results showed that stormwater discharges contained 55 substances, among them some metals, organotins, PAHs, PCBs, alkylphenols, pesticides, phthalates, cholorophenols and volatile organic compounds. Therefore, stormwater was highly contaminated. However, this contamination was often comparable from site to site, since no significant difference of the pollutant load was observed between the land use patterns.

Carbon contamination analysis and its effect on extreme ultra violet mask imaging performance using coherent scattering microscopy/in-situ accelerated contamination system.

PubMed

Jeong, Chang Young; Lee, Sangsul; Doh, Jong Gul; Lee, Jae Uk; Cha, Han-sun; Nichols, William T; Lee, Dong Gun; Kim, Seong Sue; Cho, Han Ku; Rah, Seung-yu; Ahn, Jinho

2011-07-01

The coherent scattering microscopy/in-situ accelerated contamination system (CSM/ICS) is a developmental metrology tool designed to analyze the impact of carbon contamination on the imaging performance. It was installed at 11B EUVL beam-line of the Pohang Accelerator Laboratory (PAL). Monochromatized 13.5 nm wavelength beam with Mo/Si multilayer mirrors and zirconium filters was used. The CSM/ICS is composed of the CSM for measuring imaging properties and the ICS for implementing acceleration of carbon contamination. The CSM has been proposed as an actinic inspection technique that records the coherent diffraction pattern from the EUV mask and reconstructs its aerial image using a phase retrieval algorithm. To improve the CSM measurement accuracy, optical and electrical noises of main chamber were minimized. The background noise level measured by CCD camera was approximately 8.5 counts (3 sigma) when the EUV beam was off. Actinic CD measurement repeatability was <1 A (3 sigma) at 17.5 nm line and space pattern. The influence of carbon contamination on the imaging properties can be analyzed by transferring EUV mask to CSM imaging center position after executing carbon contamination without a fine alignment system. We also installed photodiode and ellipsometry for in-situ reflectivity and thickness measurement. This paper describes optical design and system performance observed during the first phase of integration, including CSM imaging performance and carbon contamination analysis results.

Fate of arsenic, phosphate and ammonium plumes in a coastal aquifer affected by saltwater intrusion.

PubMed

Colombani, N; Mastrocicco, M; Prommer, H; Sbarbati, C; Petitta, M

2015-08-01

A severe groundwater contamination with extensive plumes of arsenic, phosphate and ammonium was found in a coastal aquifer beneath a former fertilizer production plant. The implementation of an active groundwater remediation strategy, based on a comprehensive pump and treat scheme, now prevents the migration of the dissolved contaminants into the marine environment. However, due to the site's proximity to the coastline, a seawater wedge was induced by the pumping scheme. Additionally the groundwater flow and salinity patterns were also strongly affected by leakage from the site's sewer system and from a seawater-fed cooling canal. The objective of this study was to elucidate the fate of arsenic and its co-contaminants over the site's history under the complex, coupled hydrodynamic and geochemical conditions that prevail at the site. A detailed geochemical characterisation of samples from sediment cores and hydrochemical data provided valuable high-resolution information. The obtained data were used to develop various conceptual models and to constrain the development and calibration of a reactive transport model. The reactive transport simulations were performed for a sub-domain (two-dimensional transect) of an earlier developed three-dimensional flow and variable density solute transport model. The results suggest that in the upper sub-oxic zone the influx of oxygenated water promoted As attenuation via co-precipitation with Al and Fe oxides and copper hydroxides. In contrast, in the deeper aquifer zone, iron reduction, associated with the release of adsorbed As and the dissolution of As bearing phases, provided and still provides to date a persistent source for groundwater pollution. The presented monitoring and modelling approach could be broadly applied to coastal polluted sites by complex contaminant mixture containing As. Copyright © 2015 Elsevier B.V. All rights reserved.

Electron beam influence on the carbon contamination of electron irradiated hydroxyapatite thin films

NASA Astrophysics Data System (ADS)

Hristu, Radu; Stanciu, Stefan G.; Tranca, Denis E.; Stanciu, George A.

2015-08-01

Electron beam irradiation which is considered a reliable method for tailoring the surface charge of hydroxyapatite is hindered by carbon contamination. Separating the effects of the carbon contamination from those of irradiation-induced trapped charge is important for a wide range of biological applications. In this work we focus on the understanding of the electron-beam-induced carbon contamination with special emphasis on the influence of the electron irradiation parameters on this phenomenon. Phase imaging in atomic force microscopy is used to evaluate the influence of electron energy, beam current and irradiation time on the shape and size of the resulted contamination patterns. Different processes involved in the carbon contamination of hydroxyapatite are discussed.

Riparian spiders as sentinels of PCB contamination across heterogeneous aquatic ecosystems

EPA Science Inventory

Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the ...

Gas Contamination In Plasma-Arc-Welded Aluminum

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

1992-01-01

Document describes experimental investigation on visible and tactile effects of gaseous contaminants in variable-polarity plasma arc (VPPA) welding of 2219 T-87 aluminum alloy. Contaminant gases (nitrogen, methane, oxygen, and hydrogen) introduced in argon arc and in helium shield gas in various controlled concentrations. Report represents results of experiments in form of photographs of fronts, backs, polished cross sections, and etched cross sections of welds made with various contaminants at various concentrations. Provides detailed discussion of conditions under which welds made.

Element-specific behaviour and sediment properties modulate transfer and bioaccumulation of trace elements in a highly-contaminated area (Augusta Bay, Central Mediterranean Sea).

PubMed

Signa, Geraldina; Mazzola, Antonio; Di Leonardo, Rossella; Vizzini, Salvatrice

2017-11-01

High sediment contamination in the coastal area of Priolo Bay, adjacent to the highly-polluted Augusta Harbour, poses serious risks for the benthic communities inhabiting the area. Nevertheless, the transfer of trace elements and consequent bioaccumulation in the biota is an overlooked issue. This study aimed to assess the transfer and bioaccumulation patterns of As, Cd, Ni and Hg to the dominant macroalgae and benthic invertebrates of Priolo Bay. Results revealed different patterns among trace elements (TEs), not driven by sediment contamination but rather by element-specific behaviour coupled with sediment physicochemical properties. Specifically, As accumulated in macroalgae but not in invertebrates, indicating bioavailability of dissolved As only, and a lack of effective trophic transfer. Ni was confined to surface sediment and transfer to biota was not highlighted. Cd and Hg showed the highest concentrations in invertebrates and bioaccumulated especially in filter feeders and carnivores, revealing the importance of suspended particulate and diet as transfer pathways. Total organic carbon (TOC), fine-grained sediments and redox potential were the most important sediment features in shaping the sediment contamination spatial patterns as well as those of TE transfer and bioaccumulation. In particular, As and Cd transfer to macroalgae, and especially Hg bioaccumulation in benthic invertebrates was controlled by sediment properties, resulting in limited transfer and accumulation in the most contaminated stations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Local versus field scale soil heterogeneity characterization - a challenge for representative sampling in pollution studies

NASA Astrophysics Data System (ADS)

Kardanpour, Z.; Jacobsen, O. S.; Esbensen, K. H.

2015-06-01

This study is a contribution to development of a heterogeneity characterisation facility for "next generation" sampling aimed at more realistic and controllable pesticide variability in laboratory pots in experimental environmental contaminant assessment. The role of soil heterogeneity on quantification of a set of exemplar parameters, organic matter, loss on ignition (LOI), biomass, soil microbiology, MCPA sorption and mineralization is described, including a brief background on how heterogeneity affects sampling/monitoring procedures in environmental pollutant studies. The Theory of Sampling (TOS) and variographic analysis has been applied to develop a fit-for-purpose heterogeneity characterization approach. All parameters were assessed in large-scale profile (1-100 m) vs. small-scale (0.1-1 m) replication sampling pattern. Variographic profiles of experimental analytical results concludes that it is essential to sample at locations with less than a 2.5 m distance interval to benefit from spatial auto-correlation and thereby avoid unnecessary, inflated compositional variation in experimental pots; this range is an inherent characteristic of the soil heterogeneity and will differ among soils types. This study has a significant carrying-over potential for related research areas e.g. soil science, contamination studies, and environmental monitoring and environmental chemistry.

Elemental fingerprints of isotopic contamination of hebridean Palaeocene mantle-derived magmas by archaean sial

NASA Astrophysics Data System (ADS)

Thompson, R. N.; Dickin, A. P.; Gibson, I. L.; Morrison, M. A.

1982-06-01

One of the major puzzles presented by the geochemistry of the Palaeocene plateau lavas of Skye and Mull (N.W. Scotland) is that, although a very strong case can be made that the magmas are variably isotopically contaminated by Archaean Lewisian continental crust, little evidence has been gleaned to date from their major- and trace-element compositions to illuminate this hypothetical process. The combined results of published Sr-, Nd- and Pb-isotope studies of these lavas allow the basalts and hawaiites to be divided into three broad groups: essentially uncontaminated; contaminated with granulite-facies Archaean crust; contaminated with amphibolite-facies Archaean crust. Members of each group show distinctive chondrite-normalised incompatible-element patterns. The processes which gave rise to isotopic contamination of these lavas also affected the abundances and ratios of Ba, Rb, Th, K, Sr and light REE in the magmas, whilst having negligible effects on their abundances and ratios of Nb, Ta, P, Zr, Hf, Ti, Y and middle-heavy REE. Because such a wide range of elements were affected by the contamination process, it is postulated that the contaminant was a silicate melt of one or more distinctive crustal rock types, rather than an aqueous or similar fluid causing selective elemental movements from wall rocks into the magmas. As previous experimental and isotopic studies have shown that the Skye and Mull basic magmas were not constrained by cotectic equilibria at the time when they interacted with sial, the compositions of the contaminated lavas have been modelled in terms of simple magma-crust mixtures. Very close approximations to both the abundances and ratios of incompatible elements in the two groups of contaminated basalts may be obtained by adding 15% to 20% of Lewisian leucogneisses to uncontaminated Palaeocene basalt. Nevertheless, major-element constraints suggest that the maximum amount of granitic contaminant which has been added to these magmas lies between 5% and 10%. These estimates may be reconciled by postulating that the contaminants were large-fraction cotectic partial melts of Lewisian leucogneisses, leaving plagioclase residua. A corollary of this hypothesis is that it is necessary to postulate that the “magma chambers” where the sialic contamination occurred were, in fact, dykes or (more probably) sills. The very large surface-to-volume ratios of such magmas bodies would permit the systematic stripping, by partial melting, of the most-easily-fusible leucogneisses and pegmatites from the Lewisian crust, whilst failing to melt its major rock types. A present-day analogue to this situation may be the extensive sill-like magma bodies detected by geophysical methods within the continental crust beneath the Rio Grande Rift, southwestern U.S.A.

Power of tests of normality for detecting contaminated normal samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thode, H.C. Jr.; Smith, L.A.; Finch, S.J.

1981-01-01

Seventeen tests of normality or goodness of fit were evaluated for power at detecting a contaminated normal sample. This study used 1000 replications each of samples of size 12, 17, 25, 33, 50, and 100 from six different contaminated normal distributions. The kurtosis test was the most powerful over all sample sizes and contaminations. The Hogg and weighted Kolmogorov-Smirnov tests were second. The Kolmogorov-Smirnov, chi-squared, Anderson-Darling, and Cramer-von-Mises tests had very low power at detecting contaminated normal random variables. Tables of the power of the tests and the power curves of certain tests are given.

In-Situ Electrokinetic Remediation for Metal Contaminated Soils

DTIC Science & Technology

2001-03-01

Press. Riddle, M. J. 1988. Patterns in the distribution of macrofauna! communities in coral reef sediments on the central Great Barrier Reef . Mar...acidified. This acidification results in solubilization of contaminants due to desorption and dissolution of species from soil. Once contaminants are...the north and east, the Pacific Ocean on the south and west, and a Ventura County Game Reserve on the west and northwest (Figure 6). The Navy has

Albatross species demonstrate regional differences in North Pacific marine contamination

USGS Publications Warehouse

Finkelstein, M.; Keitt, B.S.; Croll, D.A.; Tershy, B.; Jarman, Walter M.; Rodriguez-Pastor, S.; Anderson, D.J.; Sievert, P.R.; Smith, D.R.

2006-01-01

Recent concern about negative effects on human health from elevated organochlorine and mercury concentrations in marine foods has highlighted the need to understand temporal and spatial patterns of marine pollution. Seabirds, long-lived pelagic predators with wide foraging ranges, can be used as indicators of regional contaminant patterns across large temporal and spatial scales. Here we evaluate contaminant levels, carbon and nitrogen stable isotope ratios, and satellite telemetry data from two sympatrically breeding North Pacific albatross species to demonstrate that (1) organochlorine and mercury contaminant levels are significantly higher in the California Current compared to levels in the high-latitude North Pacific and (2) levels of organochlorine contaminants in the North Paci.c are increasing over time. Black-footed Albatrosses (Phoebastria nigripes) had 370-460% higher organochlorine (polychlorinated biphenyls [PCBs], dichlorodiphenyltrichloroethanes [DDTs]) and mercury body burdens than a closely related species, the Laysan Albatross (P. immutabilis), primarily due to regional segregation of their North Pacific foraging areas. PCBs (the sum of the individual PCB congeners analyzed) and DDE concentrations in both albatross species were 130-360% higher than concentrations measured a decade ago. Our results demonstrate dramatically high and increasing contaminant concentrations in the eastern North Pacific Ocean, a finding relevant to other marine predators, including humans. ?? 2006 by the Ecological Society of America.

Microbial cross-contamination by airborne dispersion and contagion during defeathering of poultry.

PubMed

Allen, V M; Hinton, M H; Tinker, D B; Gibson, C; Mead, G C; Wathes, C M

2003-09-01

1. A readily identifiable strain of Escherichia coli K12 was used as a 'marker' organism to determine the sources, routes and patterns of microbial cross-contamination during mechanical defeathering of broiler chicken carcases. 2. Inoculation of scald water with the marker organism led to a relatively even pattern of carcase contamination during subsequent defeathering. Microbial cross-contamination was greater by this route of inoculation than by either surface inoculation of a 'seeder' carcase or oral inoculation of a live bird one day before slaughter. 3. Dispersal of the marker organism was strongly influenced by the mechanical action of the defeathering machines. Forward transmission of the marker occurred by aerosol or large airborne droplets and particulates such as feathers. Moving carcases through the defeathering machines when these were non-operational clearly reduced backward transmission of the marker. 4. Although microbial dispersal was unaffected by increasing the spacing between individual carcases or installing a water curtain at the entry and exit of the defeathering machines, shielding of carcases with aluminium baffles reduced counts of the marker organism from contaminated carcases by > 90%. 5. The results imply that microbial cross-contamination of broiler chicken carcases during defeathering occurs mainly via the airborne route, which could be contained by physical means.

Accumulation, metabolism, and food-chain transfer of chlorinated and brominated contaminants in subadult white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) from Svalbard, Norway.

PubMed

Wolkers, H; Lydersen, C; Kovacs, K M; Burkow, I; van Bavel, B

2006-01-01

The concentrations and patterns of polychlorinated biphenyls (PCBs), chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs) were studied in white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) from Svalbard, Norway. In addition, their main food items were included in the study. In the whales, a broad range of pollutants was found in relatively high concentrations. PCBs and pesticides were approximately 3000 and 8000 ng/g lipid, respectively, for white whales and three times higher for narwhals. PBDEs 47 were approximately 70 ng/g lipid for white whales and 170 ng/g lipid for narwhals. Compared with other marine mammals from the same area, contaminant levels are among the highest levels ever measured. These high levels are likely in part because of a decreased capacity to metabolize contaminants. Metabolic indices indicated that most compounds accumulate to the same degree in white whales and narwhals, but for some toxaphenes and chlordanes, narwhals might have a decreased metabolism and consequently a higher accumulation. The three-times-higher contaminant levels in blubber of narwhals was further explained by substantially higher contaminant levels in their more benthic diet. The high levels and broad pattern of accumulating pollutants make white whales and narwhals excellent indicators for a wide range of contaminants in the Arctic.

Food safety assessment of planting patterns of four vegetable-type crops grown in soil contaminated by electronic waste activities.

PubMed

Liu, Ling; Hu, Liangliang; Tang, Jianjun; Li, Yuefang; Zhang, Qian; Chen, Xin

2012-01-01

A field experiment was conducted to assess the effect of crop and planting pattern on levels of cadmium (Cd), lead (Pb), and copper (Cu) in crops grown in soil contaminated by electronic waste. The crops were maize (Zea mays L. var. Shentian-1), tomato (Solanum lycopersicum L. var. Zhongshu-4), cabbage (Brassica oleracea L. var. Jingfeng-1), and pakchoi (Brassica chinensis (L.) Makino. var. Youdonger-Hangzhou). The planting patterns were crop monoculture, crop co-planted with a legume, and crop co-planted with another crop. Metal concentrations in the edible parts of the crops varied with types of metals and crops. Pb concentration was higher in leafy vegetables (cabbage and pakchoi) than in maize or tomato, Cd concentration was higher in tomato and pakchoi than in maize or cabbage, and Cu concentration was higher in maize and pakchoi than in tomato or cabbage. Metal concentrations in the edible part were also influenced by planting pattern. Relative to monoculture, co-planting and especially co-planting with Japanese clover tended to decrease Pb accumulation and increase Cd accumulation. According to the maximum permissible concentration (MPC) standard of the National Standard Agency in China, only maize (under all planting patterns) could be safely consumed. Because co-planting tended to increase Cd accumulation even in maize, however, the results suggest that maize monoculture is the optimal crop and planting pattern for this kind of contaminated soil. Copyright © 2011 Elsevier Ltd. All rights reserved.

COLLOIDAL-FACILITATED TRANSPORT OF INORGANIC CONTAMINANTS IN GROUND WATER: PART I. SAMPLING CONSIDERATIONS

EPA Science Inventory

Investigations at Pinal Creek, Arizona, evaluated routine sampling procedures for determination of aqueous inorganic geochemistry and assessment of contaminant transport by colloidal mobility. Sampling variables included pump type and flow rate, collection under air or nitrogen,...

STABLE CHLORINE ISOTOPE ANALYSIS OF CHLORINATED ORGANIC CONTAMINANTS

EPA Science Inventory

The biogeochemical cycling of chlorinated organic contaminants in the environment is often difficult to understand because of the complex distributions of these compounds and variability of sources. To address these issues from an isotopic perspective, we have measured the, 37Cl...

TEMPORAL VARIABILITY OF TOXIC CONTAMINANTS IN ANIMAL DIETS

EPA Science Inventory

Uncertified commercial research animal feed (Purina Chow TM) was analyzed over forty-one months to determine essential and trace elements and toxic contaminants. Parametric statistics and graphic chronologic progressions of the results are presented for cat, monkey, rodent (rat/m...

Murre eggs (Uria aalge and Uria lomvia) as indicators of mercury contamination in the Alaskan marine environment

USGS Publications Warehouse

Day, Russel D.; Vander Pol, Stacy S.; Christopher, Steven J.; Davis, W.C.; Pugh, Rebecca S.; Simac, K.S.; Roseneau, David G.; Becker, P.R.

2006-01-01

Sixty common murre (Uria aalge) and 27 thick-billed murre (Uria lomvia) eggs collected by the Seabird Tissue Archival and Monitoring Project (STAMP) in 1999−2001 from two Gulf of Alaska and three Bering Sea nesting colonies were analyzed for total mercury (Hg) using isotope dilution cold vapor inductively coupled mass spectrometry. Hg concentrations (wet mass) ranged from 0.011 μg/g to 0.357 μg/g (relative standard deviation = 76%), while conspecifics from the same colonies and years had an average relative standard deviation of 33%. Hg levels in eggs from the Gulf of Alaska (0.166 μg/g ± 0.011 μg/g) were significantly higher (p < 0.0001) than in the Bering Sea (0.047 μg/g ± 0.004 μg/g). Within the Bering Sea, Hg was significantly higher (p = 0.0007) in eggs from Little Diomede Island near the arctic than at the two more southern colonies. Although thick-billed and common murres are ecologically similar, there were significant species differences in egg Hg concentrations within each region (p < 0.0001). In the Bering Sea, eggs from thick-billed murres had higher Hg concentrations than eggs from common murres, while in the Gulf of Alaska, common murre eggs had higher concentrations than those of thick-billed murres. A separate one-way analysis of variance on the only time−trend data currently available for a colony (St. Lazaria Island in the Gulf of Alaska) found significantly lower Hg concentrations in common murre eggs collected in 2001 compared to 1999 (p = 0.017). Results from this study indicate that murre eggs may be effective monitoring units for detecting geographic, species, and temporal patterns of Hg contamination in marine food webs. The relatively small intracolony variation in egg Hg levels and the ability to consistently obtain adequate sample sizes both within and among colonies over a large geographic range means that monitoring efforts using murre eggs will have suitable statistical power for detecting environmental patterns of Hg contamination. The potential influences of trophic effects, physical transport patterns, and biogeochemical processes on these monitoring efforts are discussed, and future plans to investigate the sources of the observed variability are presented.

Recovering the primary geochemistry of Jack Hills zircons through quantitative estimates of chemical alteration

NASA Astrophysics Data System (ADS)

Bell, Elizabeth A.; Boehnke, Patrick; Harrison, T. Mark

2016-10-01

Despite the robust nature of zircon in most crustal and surface environments, chemical alteration, especially associated with radiation damaged regions, can affect its geochemistry. This consideration is especially important when drawing inferences from the detrital record where the original rock context is missing. Typically, alteration is qualitatively diagnosed through inspection of zircon REE patterns and the style of zoning shown by cathodoluminescence imaging, since fluid-mediated alteration often causes a flat, high LREE pattern. Due to the much lower abundance of LREE in zircon relative both to other crustal materials and to the other REE, disturbance to the LREE pattern is the most likely first sign of disruption to zircon trace element contents. Using a database of 378 (148 new) trace element and 801 (201 new) oxygen isotope measurements on zircons from Jack Hills, Western Australia, we propose a quantitative framework for assessing chemical contamination and exchange with fluids in this population. The Light Rare Earth Element Index is scaled on the relative abundance of light to middle REE, or LREE-I = (Dy/Nd) + (Dy/Sm). LREE-I values vary systematically with other known contaminants (e.g., Fe, P) more faithfully than other suggested proxies for zircon alteration (Sm/La, various absolute concentrations of LREEs) and can be used to distinguish primary compositions when textural evidence for alteration is ambiguous. We find that zircon oxygen isotopes do not vary systematically with placement on or off cracks or with degree of LREE-related chemical alteration, suggesting an essentially primary signature. By omitting zircons affected by LREE-related alteration or contamination by mineral inclusions, we present the best estimate for the primary igneous geochemistry of the Jack Hills zircons. This approach increases the available dataset by allowing for discrimination of on-crack analyses (and analyses with ambiguous or no information on spot placement or zircon internal structures) that do not show evidence for chemical alteration. It distinguishes between altered and unaltered samples in ambiguous cases (e.g., relatively high Ti), identifying small groups with potentially differing provenance from the main Jack Hills population. Finally, filtering of the population using the LREE-I helps to more certainly define primary correlations among trace element variables, potentially relatable to magmatic compositional evolution.

Dilution and Mixing in transient velocity fields: a first-order analysis

NASA Astrophysics Data System (ADS)

Di Dato, Mariaines; de Barros, Felipe, P. J.; Fiori, Aldo; Bellin, Alberto

2017-04-01

An appealing remediation technique is in situ oxidation, which effectiveness is hampered by difficulties in obtaining good mixing of the injected oxidant with the contaminant, particularly when the contaminant plume is contained and therefore its deformation is physically constrained. Under such conditions (i.e. containment), mixing may be augmented by inducing temporal fluctuations of the velocity field. The temporal variability of the flow field may increase the deformation of the plume such that diffusive mass flux becomes more effective. A transient periodic velocity field can be obtained by an engineered sequence of injections and extractions from wells, which may serve also as a hydraulic barrier to confine the plume. Assessing the effectiveness of periodic flows to maximize solute mixing is a difficult task given the need to use a 3D setup and the large number of possible flow configurations that should be analyzed in order to identify the optimal one. This is the typical situation in which analytical solutions, though approximated, may assist modelers in screening possible alternative flow configurations such that solute dilution is maximized. To quantify dilution (i.e. a precondition that enables reactive mixing) we utilize the concept of the dilution index [1]. In this presentation, the periodic flow takes place in an aquifer with spatially variable hydraulic conductivity field which is modeled as a Stationary Spatial Random Function. We developed a novel first-order analytical solution of the dilution index under the hypothesis that the flow can be approximated as a sequence of steady state configurations with the mean velocity changing with time in intensity and direction. This is equivalent to assume that the characteristic time of the transient behavior is small compared to the period characterizing the change in time of the mean velocity. A few closed paths have been analyzed quantifying their effectiveness in enhancing dilution and thereby mixing between the resident contaminant and an oxidant. In particular, we considered three different flow configurations: (1) a "circular" pattern, in which the vector of the mean velocity rotates at a constant celerity; (2) a "shake" pattern, in which the velocity has a constant magnitude and changes direction alternatively leading to a "back and forth" type of movement and finally (3) a more general "shake and rotate" pattern, which combines the previous two configurations. The new analytical solution shows that dilution is affected by the configuration of the periodic mean flow. Results show that the dilution index increases when the rotation-shake configuration is adopted. In addition, the dilution index is augmented with the oscillation amplitude of the shake component. This analysis is useful to identify optimal flow configurations that may be approximately reproduced in the field and which efficiency may be checked more accurately by numerical simulations, thereby alleviating the computational burden by efficiently screening among alternative configurations. References [1] Kitanidis, P. K. (1994), The concept of the Dilution Index, Water Resour. Res., 30(7), 2011-2026, doi:10.1029/94WR00762.

Aflatoxin contamination of groundnut and maize in Zambia: observed and potential concentrations

USDA-ARS?s Scientific Manuscript database

Maize and groundnut, important staples in Zambia, are susceptible to aflatoxin-producing fungi. Aflatoxins are potent human carcinogens also associated with stunting and immunosuppression. Although health and economic burdens of aflatoxins are well known, patterns of contamination in maize and grou...

Spatial distribution of heavy metals in the surface soil of source-control stormwater infiltration devices - Inter-site comparison.

PubMed

Tedoldi, Damien; Chebbo, Ghassan; Pierlot, Daniel; Branchu, Philippe; Kovacs, Yves; Gromaire, Marie-Christine

2017-02-01

Stormwater runoff infiltration brings about some concerns regarding its potential impact on both soil and groundwater quality; besides, the fate of contaminants in source-control devices somewhat suffers from a lack of documentation. The present study was dedicated to assessing the spatial distribution of three heavy metals (copper, lead, zinc) in the surface soil of ten small-scale infiltration facilities, along with several physical parameters (soil moisture, volatile matter, variable thickness of the upper horizon). High-resolution samplings and in-situ measurements were undertaken, followed by X-ray fluorescence analyses and spatial interpolation. Highest metal accumulation was found in a relatively narrow area near the water inflow zone, from which concentrations markedly decreased with increasing distance. Maximum enrichment ratios amounted to >20 in the most contaminated sites. Heavy metal patterns give a time-integrated vision of the non-uniform infiltration fluxes, sedimentation processes and surface flow pathways within the devices. This element indicates that the lateral extent of contamination is mainly controlled by hydraulics. The evidenced spatial structure of soil concentrations restricts the area where remediation measures would be necessary in these systems, and suggests possible optimization of their hydraulic functioning towards an easier maintenance. Heterogeneous upper boundary conditions should be taken into account when studying the fate of micropollutants in infiltration facilities with either mathematical modeling or soil coring field surveys. Copyright © 2016 Elsevier B.V. All rights reserved.

Integrating Monitoring and Genetic Methods To Infer Historical Risks of PCBs and DDE to Common and Roseate Terns Nesting Near the New Bedford Harbor Superfund Site (Massachusetts, USA).

PubMed

Nacci, Diane E; Hahn, Mark E; Karchner, Sibel I; Jayaraman, Saro; Mostello, Carolyn; Miller, Kenneth M; Blackwell, Carma Gilchrist; Nisbet, Ian C T

2016-09-20

Common and roseate terns are migratory piscivorous seabirds with major breeding colonies within feeding range of the polychlorinated biphenyl (PCB)-contaminated New Bedford Harbor (NBH, MA, USA) Superfund site. Our longitudinal study shows that before PCB discharges into NBH ceased (late 1970s), tern eggs had very high but variable PCB concentrations. However, egg concentrations of PCBs as well as DDE (1,1-bis(p-chlorophenyl)-2,2-dichloroethene), the degradation product of the ubiquitous global contaminant DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane), have since declined. Rate constants for temporal decline of PCB congeners in tern eggs varied inversely with log10KOW (n-octanol-water partition coefficient), shifting egg congener patterns away from those characterizing NBH sediment. To estimate the toxic effects on tern eggs of PCB dioxin-like congener (DLC) exposures, we extrapolated published laboratory data on common terns to roseate terns by characterizing genetic and functional similarities in species aryl hydrocarbon receptors (AHRs), which mediate DLC sensitivity. Our assessment of contaminant risks suggests that terns breeding near NBH were exposed historically to toxic levels of PCBs and DDE; however, acute effects on tern egg development have become less likely since the 1970s. Our approach demonstrates how comparative genetics at target loci can effectively increase the range of inference for chemical risk assessments from tested to untested and untestable species.

Temporal assessment of microbial communities in soils of two contrasting mangroves.

PubMed

Rigonato, Janaina; Kent, Angela D; Gumiere, Thiago; Branco, Luiz Henrique Zanini; Andreote, Fernando Dini; Fiore, Marli Fátima

Variations in microbial communities promoted by alterations in environmental conditions are reflected in similarities/differences both at taxonomic and functional levels. Here we used a natural gradient within mangroves from seashore to upland, to contrast the natural variability in bacteria, cyanobacteria and diazotroph assemblages in a pristine area compared to an oil polluted area along a timespan of three years, based on ARISA (bacteria and cyanobacteria) and nifH T-RFLP (diazotrophs) fingerprinting. The data presented herein indicated that changes in all the communities evaluated were mainly driven by the temporal effect in the contaminated area, while local effects were dominant on the pristine mangrove. A positive correlation of community structure between diazotrophs and cyanobacteria was observed, suggesting the functional importance of this phylum as nitrogen fixers in mangroves soils. Different ecological patterns explained the microbial behavior in the pristine and polluted mangroves. Stochastic models in the pristine mangrove indicate that there is not a specific environmental factor that determines the bacterial distribution, while cyanobacteria and diazotrophs better fitted in deterministic model in the same area. For the contaminated mangrove site, deterministic models better represented the variations in the communities, suggesting that the presence of oil might change the microbial ecological structures over time. Mangroves represent a unique environment threatened by global change, and this study contributed to the knowledge of the microbial distribution in such areas and its response on persistent contamination historic events. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Sulphur-oxidizing and sulphate-reducing communities in Brazilian mangrove sediments.

PubMed

Varon-Lopez, Maryeimy; Dias, Armando Cavalcante Franco; Fasanella, Cristiane Cipolla; Durrer, Ademir; Melo, Itamar Soares; Kuramae, Eiko Eurya; Andreote, Fernando Dini

2014-03-01

Mangrove soils are anaerobic environments rich in sulphate and organic matter. Although the sulphur cycle is one of the major actors in this ecosystem, little is known regarding the sulphur bacteria communities in mangrove soils. We investigated the abundance, composition and diversity of sulphur-oxidizing (SOB) and sulphate-reducing (SRB) bacteria in sediments from three Brazilian mangrove communities: two contaminated, one with oil (OilMgv) and one with urban waste and sludge (AntMgv), and one pristine (PrsMgv). The community structures were assessed using quantitative real-time polymerase chain reaction (qPCR), polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and clone libraries, using genes for the enzymes adenosine-5'-phosphosulphate reductase (aprA) and sulphite reductase (Dsr) (dsrB). The abundance for qPCR showed the ratio dsrB/aprA to be variable among mangroves and higher according to the gradient observed for oil contamination in the OilMgv. The PCR-DGGE patterns analysed by Nonmetric Multidimensional Scaling revealed differences among the structures of the three mangrove communities. The clone libraries showed that Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria were the most abundant groups associated with sulphur cycling in mangrove sediments. We conclude that the microbial SOB and SRB communities in mangrove soils are different in each mangrove forest and that such microbial communities could possibly be used as a proxy for contamination in mangrove forests. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance

PubMed Central

Bokulich, Nicholas A; Bergsveinson, Jordyn; Ziola, Barry; Mills, David A

2015-01-01

Distinct microbial ecosystems have evolved to meet the challenges of indoor environments, shaping the microbial communities that interact most with modern human activities. Microbial transmission in food-processing facilities has an enormous impact on the qualities and healthfulness of foods, beneficially or detrimentally interacting with food products. To explore modes of microbial transmission and spoilage-gene frequency in a commercial food-production scenario, we profiled hop-resistance gene frequencies and bacterial and fungal communities in a brewery. We employed a Bayesian approach for predicting routes of contamination, revealing critical control points for microbial management. Physically mapping microbial populations over time illustrates patterns of dispersal and identifies potential contaminant reservoirs within this environment. Habitual exposure to beer is associated with increased abundance of spoilage genes, predicting greater contamination risk. Elucidating the genetic landscapes of indoor environments poses important practical implications for food-production systems and these concepts are translatable to other built environments. DOI: http://dx.doi.org/10.7554/eLife.04634.001 PMID:25756611

A comparison of mercury levels in feathers and eggs of osprey (Pandion haliaetus) in the North American Great Lakes.

PubMed

Hughes, K D; Ewins, P J; Clark, K E

1997-11-01

Osprey (Pandion haliaetus) eggs and chick feathers were collected for mercury analysis from nests at four Great Lakes study areas in Ontario (three "naturally formed" lakes in southern Ontario and one reservoir in northern Ontario) and two New Jersey study areas in 1991-1994. Adult osprey feathers were sampled from three Great Lakes study areas in 1991. Feathers sampled from chicks (approximately 28-35 days old) appear to be better indicators of local contaminant conditions since spatial patterns of mercury in known prey, yellow perch (Perca flavescens), also collected in these areas, were more similar to chick feathers than to eggs. Mercury levels were less variable in chick feathers than in eggs. Estimates of biomagnification factors using prey of known size at these areas were also less variable in feathers than in eggs. At naturally formed lakes, no significant correlation in mercury levels between eggs and chick feathers from the same nest was apparent, suggesting that the source of mercury contamination was not the same in these two tissues: mercury levels in eggs reflect mercury acquired on the breeding grounds, wintering grounds, and migratory route; mercury levels in chick feathers reflect local dietary conditions on the breeding grounds. Mercury levels in both osprey eggs and chick feathers were higher at the Ogoki Reservoir than at naturally formed lakes. Adult osprey feathers had higher mercury concentrations than chick feathers. Mercury levels in osprey eggs, chick feathers, and adult feathers did not approach levels associated with toxic reproductive effects.

Suspended sediment and sediment-associated contaminants in San Francisco Bay

USGS Publications Warehouse

Schoellhamer, D.H.; Mumley, T.E.; Leatherbarrow, J.E.

2007-01-01

Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by continuously measuring suspended-sediment concentration (SSC), which is an accurate, less costly, and more easily measured surrogate for several trace metals and organic contaminants. Continuous time series of SSC are collected at several sites in the Bay. Although semidiurnal and diurnal tidal fluctuations are present, most of the variability of SSC occurs at fortnightly, monthly, and semiannual tidal time scales. A seasonal cycle of sediment inflow, wind-wave resuspension, and winnowing of fine sediment also is observed. SSC and, thus, sediment-associated contaminants tend to be greater in shallower water, at the landward ends of the Bay, and in several localized estuarine turbidity maxima. Although understanding of sediment transport has improved in the first 10 years of the RMP, determining a simple mass budget of sediment or associated contaminants is confounded by uncertainties regarding sediment flux at boundaries, change in bed-sediment storage, and appropriate modeling techniques. Nevertheless, management of sediment-associated contaminants has improved greatly. Better understanding of sediment and sediment-associated contaminants in the Bay is of great interest to evaluate the value of control actions taken and the need for additional controls. ?? 2007 Elsevier Inc. All rights reserved.

Suspended sediment and sediment-associated contaminants in San Francisco Bay.

PubMed

Schoellhamer, David H; Mumley, Thomas E; Leatherbarrow, Jon E

2007-09-01

Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by continuously measuring suspended-sediment concentration (SSC), which is an accurate, less costly, and more easily measured surrogate for several trace metals and organic contaminants. Continuous time series of SSC are collected at several sites in the Bay. Although semidiurnal and diurnal tidal fluctuations are present, most of the variability of SSC occurs at fortnightly, monthly, and semiannual tidal time scales. A seasonal cycle of sediment inflow, wind-wave resuspension, and winnowing of fine sediment also is observed. SSC and, thus, sediment-associated contaminants tend to be greater in shallower water, at the landward ends of the Bay, and in several localized estuarine turbidity maxima. Although understanding of sediment transport has improved in the first 10 years of the RMP, determining a simple mass budget of sediment or associated contaminants is confounded by uncertainties regarding sediment flux at boundaries, change in bed-sediment storage, and appropriate modeling techniques. Nevertheless, management of sediment-associated contaminants has improved greatly. Better understanding of sediment and sediment-associated contaminants in the Bay is of great interest to evaluate the value of control actions taken and the need for additional controls.

Trace metals and macroelements in mussels from Chinese coastal waters: National spatial patterns and normalization.

PubMed

Lu, Guang-Yuan; Wang, Wen-Xiong

2018-06-01

Metal contamination is one of the most ubiquitous and complex problems in the Chinese coastal environment. To explore the large-scale spatial patterns of bioavailable metals, we sampled three major mussels, including 784 blue mussels (Mytilus edulis Linnaeus, 1758) of 14 sites, 224 hard-shelled mussels (Mytilus unguiculatus Valenciennes, 1858) of 4 sites, and 392 green mussels (Perna viridis (Linnaeus, 1758)) of 7 sites, ranging from temperate to tropical coastlines of China, during August and September 2015. The concentrations of macroelements (Na, K, Ca, Mg, and P) and toxic trace metals (Ag, Cd, Cr, Cu, Ni, Pb, Ti, and Zn) in the mussel's whole soft tissues were determined. Among the four Chinese coastal basins, Cd, Ti and Cr in the mussel tissues were the highest at Bohai Sea (BS) and Yellow Sea (YS), and Cu, Ni, Pb and Ag in the mussel tissues were the highest at East China Sea (ECS) and South China Sea (SCS). Zinc concentrations in mussels from YS were significantly higher than those from the other regions. Given the variability of environmental conditions such as salinity and nutrients, we further normalized the measured tissue metal concentrations with tissue Na and P levels. After Na normalization as the salinity proxy, the variability of Cd, Cu, Zn, Ag, and Ni was reduced. Trace elements accumulation in the mussel tissues was significantly related to both macroelements (Na or P) and body dry weight. The present study demonstrated that nonlinear optimization of different elements was necessary in assessing metal bioaccumulation patterns in marine mussels at a large spatial scale. Copyright © 2018 Elsevier B.V. All rights reserved.

Estimation of sport fish harvest for risk and hazard assessment of environmental contaminants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poston, T.M.; Strenge, D.L.

1989-01-01

Consumption of contaminated fish flesh can be a significant route of human exposure to hazardous chemicals. Estimation of exposure resulting from the consumption of fish requires knowledge of fish consumption and contaminant levels in the edible portion of fish. Realistic figures of sport fish harvest are needed to estimate consumption. Estimates of freshwater sport fish harvest were developed from a review of 72 articles and reports. Descriptive statistics based on fishing pressure were derived from harvest data for four distinct groups of freshwater sport fish in three water types: streams, lakes, and reservoirs. Regression equations were developed to relate harvestmore » to surface area fished where data bases were sufficiently large. Other aspects of estimating human exposure to contaminants in fish flesh that are discussed include use of bioaccumulation factors for trace metals and organic compounds. Using the bioaccumulation factor and the concentration of contaminants in water as variables in the exposure equation may also lead to less precise estimates of tissue concentration. For instance, muscle levels of contaminants may not increase proportionately with increases in water concentrations, leading to overestimation of risk. In addition, estimates of water concentration may be variable or expressed in a manner that does not truly represent biological availability of the contaminant. These factors are discussed. 45 refs., 1 fig., 7 tabs.« less

VARIABILITY OF PARAMETERS MEASURED DURING THE RESUSPENSION OF SEDIMENTS WITH A PARTICULATE ENTRAINMENT SIMULATOR

EPA Science Inventory

Contaminated sediments are a problem facing many environmental managers concerned with issues such as maintenance dredging, habitat restoration and dredged material placement. Currently, there are few methods which can be used to assess contaminant remobilization potential from ...

Quality of groundwater in the Denver Basin aquifer system, Colorado, 2003-5

USGS Publications Warehouse

Musgrove, MaryLynn; Beck, Jennifer A.; Paschke, Suzanne; Bauch, Nancy J.; Mashburn, Shana L.

2014-01-01

Water-quality data were synthesized to evaluate factors that affect spatial and depth variability in water quality and to assess aquifer vulnerability to contaminants from geologic materials and those of human origin. The quality of shallow groundwater in the alluvial aquifer and shallow bedrock aquifer system has been adversely affected by development of agricultural and urban areas. Land use has altered the pattern and composition of recharge. Increased recharge from irrigation water has mobilized dissolved constituents and increased concentrations in the shallow groundwater. Concentrations of most constituents associated with poor or degraded water quality in shallow groundwater decreased with depth; many of these constituents are not geochemically conservative and are affected by geochemical reactions such as oxidation-reduction reactions. Groundwater age tracers provide additional insight into aquifer vulnerability and help determine if young groundwater of potentially poor quality has migrated to deeper parts of the bedrock aquifers used for drinking-water supply. Age-tracer results were used to group samples into categories of young, mixed, and old groundwater. Groundwater ages transitioned from mostly young in the water-table wells to mostly mixed in the shallowest bedrock aquifer, the Dawson aquifer, to mostly old in the deeper bedrock aquifers. Although the bedrock aquifers are mostly old groundwater of good water quality, several lines of evidence indicate that young, contaminant-bearing recharge has reached shallow to moderate depths in some areas of the bedrock aquifers. The Dawson aquifer is the most vulnerable of the bedrock aquifers to contamination, but results indicate that the older (deeper) bedrock aquifers are also vulnerable to groundwater contamination and that mixing with young recharge has occurred in some areas. Heavy pumping has caused water-level declines in the bedrock aquifers in some parts of the Denver Basin, which has the potential to enhance the transport of contaminants from overlying units. Results of this study are consistent with the existing conceptual understanding of aquifer processes and groundwater issues in the Denver Basin and add new insight into the vulnerability of the bedrock aquifers to groundwater contamination.

Gene Expression Profiles in Developing Corn Kernels in Response to Drought Stress

USDA-ARS?s Scientific Manuscript database

Preharvest aflatoxin contamination of corn is aggravated by abiotic stress and the hot and humid weather patterns along with suboptimal summer rainfall favor the development. Drought stress is a major factor known to contribute to preharvest aflatoxin contamination. The gene expression studies were ...

Polybrominated diphenyl ethers (PBDEs) in fish tissue may be an indicator of plastic contamination in marine habitats.

PubMed

Rochman, Chelsea M; Lewison, Rebecca L; Eriksen, Marcus; Allen, Harry; Cook, Anna-Marie; Teh, Swee J

2014-04-01

The accumulation of plastic debris in pelagic habitats of the subtropical gyres is a global phenomenon of growing concern, particularly with regard to wildlife. When animals ingest plastic debris that is associated with chemical contaminants, they are at risk of bioaccumulating hazardous pollutants. We examined the relationship between the bioaccumulation of hazardous chemicals in myctophid fish associated with plastic debris and plastic contamination in remote and previously unmonitored pelagic habitats in the South Atlantic Ocean. Using a published model, we defined three sampling zones where accumulated densities of plastic debris were predicted to differ. Contrary to model predictions, we found variable levels of plastic debris density across all stations within the sampling zones. Mesopelagic lanternfishes, sampled from each station and analyzed for bisphenol A (BPA), alkylphenols, alkylphenol ethoxylates, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), exhibited variability in contaminant levels, but this variability was not related to plastic debris density for most of the targeted compounds with the exception of PBDEs. We found that myctophid sampled at stations with greater plastic densities did have significantly larger concentrations of BDE#s 183 -209 in their tissues suggesting that higher brominated congeners of PBDEs, added to plastics as flame-retardants, are indicative of plastic contamination in the marine environment. Our results provide data on a previously unsampled pelagic gyre and highlight the challenges associated with characterizing plastic debris accumulation and associated risks to wildlife. Copyright © 2014 Elsevier B.V. All rights reserved.

Sedimentation and contamination patterns of dike systems along the Rhône River (France)

NASA Astrophysics Data System (ADS)

Seignemartin, Gabrielle; Tena, Alvaro; Piégay, Hervé; Roux, Gwenaelle; Winiarski, Thierry

2017-04-01

Humans have historically modified the Rhône River, especially in the last centuries. In the 19th century, the river was systematically embanked for flood protection purposes, and works continued along the 20th century with dike system engineering work for navigation. The Rhône was canalised and its historical course by-passed by a series of hydroelectric dams. Besides, industrial activity polluted the river. For example, high levels of PCB's were attributed to the inputs of the heavily industrialized zone downstream from Lyon. During floods, these contaminants, associated with the suspended sediment, were trapped by the engineering works and the floodplain. Currently, a master plan to reactivate the river dynamics in the alluvial margins by removing the groyne-fields and dikes in the by-passed sections is being implemented. Within this context, this work aims to assess historical dynamics of sediment and associated contaminants in the floodplain (e.g. trace metal elements), notably in the dike system, in order to evaluate the contamination risk related to bank protection removal. With this objective, a transversal methodology has been applied coupling GIS diachronic analysis (old maps, bathymetric data, Orthophotos, LIDAR, etc.) to understand the historical floodplain evolution, sediment survey to obtain sediment thickness (metal rod and Ground Penetrating Radar), and sediment sampling (manual auger and core sampling) to obtain the metal element concentrations (X-Ray Fluorescence and Inductively Coupled Plasma Mass Spectrometry). By this way, metal element patterns were defined and used as contamination tracing indicators to apprehend the contamination history but also as geochemical background indicators to define the sediment source influence. We found that sediment temporal patterns are directly related with the by-pass construction year. Spatially, fine sediment deposition predominates in the dike systems, being lower in the floodplain already disconnected in the 20th century. Sediment thickness tends to increase in the dike systems following downstream direction. Coupling trace elements (Cu, Zn, Pb) and sediment patterns, metal pollution is mainly observed in the 1970's deposits, similarly to previous studies focused on PCB. These results constitute basic information to inform managers and improve restoration actions that are currently implemented in the Rhône River.

Effects of lead and zinc mining contamination on bacterial community diversity and enzyme activities of vicinal cropland.

PubMed

Qu, Juanjuan; Ren, Guangming; Chen, Bao; Fan, Jinghua; E, Yong

2011-11-01

In the process of mining activity, many kinds of heavy metals enter into soils with dust, causing serious contamination to the environment. In this study, six soils were sampled from cropland at different distances from a lead/zinc mine in Heilongjiang Province, China. The total contents of lead and zinc in the vicinal cropland exceeded the third level of environmental quality standard for soil in China, which indicated that soils in this area were moderately contaminated. Bacterial community diversity and population were greatly decreased when the concentrations of lead and zinc were beyond 1,500 and 995 mg kg(-1), respectively, as analyzed by plate counting and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The bands of DGGE patterns varied with the degree of contamination. The activities of soil urease, phosphatase, and dehydrogenase were negatively correlated with the concentrations of lead and zinc. The highest inhibitory effect of heavy metals on soil enzyme activities was observed in urease. It was noted that PCR-DGGE patterns combined with soil enzyme activity analysis can be indices for the soil quality assessment by heavy metal contamination.

Use of Mobile Device Data To Better Estimate Dynamic Population Size for Wastewater-Based Epidemiology.

PubMed

Thomas, Kevin V; Amador, Arturo; Baz-Lomba, Jose Antonio; Reid, Malcolm

2017-10-03

Wastewater-based epidemiology is an established approach for quantifying community drug use and has recently been applied to estimate population exposure to contaminants such as pesticides and phthalate plasticizers. A major source of uncertainty in the population weighted biomarker loads generated is related to estimating the number of people present in a sewer catchment at the time of sample collection. Here, the population quantified from mobile device-based population activity patterns was used to provide dynamic population normalized loads of illicit drugs and pharmaceuticals during a known period of high net fluctuation in the catchment population. Mobile device-based population activity patterns have for the first time quantified the high degree of intraday, week, and month variability within a specific sewer catchment. Dynamic population normalization showed that per capita pharmaceutical use remained unchanged during the period when static normalization would have indicated an average reduction of up to 31%. Per capita illicit drug use increased significantly during the monitoring period, an observation that was only possible to measure using dynamic population normalization. The study quantitatively confirms previous assessments that population estimates can account for uncertainties of up to 55% in static normalized data. Mobile device-based population activity patterns allow for dynamic normalization that yields much improved temporal and spatial trend analysis.

The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets

NASA Astrophysics Data System (ADS)

Rackham, Benjamin V.; Apai, Dániel; Giampapa, Mark S.

2018-02-01

Transmission spectra are differential measurements that utilize stellar illumination to probe transiting exoplanet atmospheres. Any spectral difference between the illuminating light source and the disk-integrated stellar spectrum due to starspots and faculae will be imprinted in the observed transmission spectrum. However, few constraints exist for the extent of photospheric heterogeneities in M dwarfs. Here we model spot and faculae covering fractions consistent with observed photometric variabilities for M dwarfs and the associated 0.3–5.5 μm stellar contamination spectra. We find that large ranges of spot and faculae covering fractions are consistent with observations and corrections assuming a linear relation between variability amplitude, and covering fractions generally underestimate the stellar contamination. Using realistic estimates for spot and faculae covering fractions, we find that stellar contamination can be more than 10× larger than the transit depth changes expected for atmospheric features in rocky exoplanets. We also find that stellar spectral contamination can lead to systematic errors in radius and therefore the derived density of small planets. In the case of the TRAPPIST-1 system, we show that TRAPPIST-1's rotational variability is consistent with spot covering fractions {f}{spot}={8}-7+18 % and faculae covering fractions {f}{fac}={54}-46+16 % . The associated stellar contamination signals alter the transit depths of the TRAPPIST-1 planets at wavelengths of interest for planetary atmospheric species by roughly 1–15× the strength of planetary features, significantly complicating JWST follow-up observations of this system. Similarly, we find that stellar contamination can lead to underestimates of the bulk densities of the TRAPPIST-1 planets of {{Δ }}(ρ )=-{8}-20+7 % , thus leading to overestimates of their volatile contents.

Metal uptake by homegrown vegetables – The relative importance in human health risk assessments at contaminated sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustsson, Anna L.M., E-mail: anna.augustsson@lnu.se; Uddh-Söderberg, Terese E.; Hogmalm, K. Johan

Risk assessments of contaminated land often involve the use of generic bioconcentration factors (BCFs), which express contaminant concentrations in edible plant parts as a function of the concentration in soil, in order to assess the risks associated with consumption of homegrown vegetables. This study aimed to quantify variability in BCFs and evaluate the implications of this variability for human exposure assessments, focusing on cadmium (Cd) and lead (Pb) in lettuce and potatoes sampled around 22 contaminated glassworks sites. In addition, risks associated with measured Cd and Pb concentrations in soil and vegetable samples were characterized and a probabilistic exposure assessmentmore » was conducted to estimate the likelihood of local residents exceeding tolerable daily intakes. The results show that concentrations in vegetables were only moderately elevated despite high concentrations in soil, and most samples complied with applicable foodstuff legislation. Still, the daily intake of Cd (but not Pb) was assessed to exceed toxicological thresholds for about a fifth of the study population. Bioconcentration factors were found to vary more than indicated by previous studies, but decreasing BCFs with increasing metal concentrations in the soil can explain why the calculated exposure is only moderately affected by the choice of BCF value when generic soil guideline values are exceeded and the risk may be unacceptable. - Highlights: • Uptake of Cd and Pb by lettuce and potatoes increased with soil contamination. • Consumption of homegrown vegetables may lead to a daily Cd intake above TDIs. • The variability in the calculated BCFs is high when compared to previous studies. • Exposure assessments are most sensitive to the choice of BCFs at low contamination.« less

Phytomonitoring of chlorinated ethenes in trees: a four-year study of seasonal chemodynamics in planta.

PubMed

Limmer, Matt A; Holmes, Amanda J; Burken, Joel G

2014-09-16

Long-term monitoring (LTM) of groundwater remedial projects is costly and time-consuming, particularly when using phytoremediation, a long-term remedial approach. The use of trees as sensors of groundwater contamination (i.e., phytoscreening) has been widely described, although the use of trees to provide long-term monitoring of such plumes (phytomonitoring) has been more limited due to unexplained variability of contaminant concentrations in trees. To assess this variability, we developed an in planta sampling method to obtain high-frequency measurements of chlorinated ethenes in oak (Quercus rubra) and baldcypress (Taxodium distichum) trees growing above a contaminated plume during a 4-year trial. The data set revealed that contaminant concentrations increased rapidly with transpiration in the spring and decreased in the fall, resulting in perchloroethene (PCE) and trichloroethene (TCE) sapwood concentrations an order of magnitude higher in late summer as compared to winter. Heartwood PCE and TCE concentrations were more buffered against seasonal effects. Rainfall events caused negligible dilution of contaminant concentrations in trees after precipitation events. Modeling evapotranspiration potential from meteorological data and comparing the modeled uptake and transport with the 4 years of high frequency data provides a foundation to advance the implementation of phytomonitoring and improved understanding of plant contaminant interactions.

A QMRA Model for Salmonella in Pork Products During Preparation and Consumption.

PubMed

Swart, A N; van Leusden, F; Nauta, M J

2016-03-01

As part of a quantitative microbiological risk assessment (QMRA) food chain model, this article describes a model for the consumer phase for Salmonella-contaminated pork products. Three pork products were chosen as a proxy for the entire pork product spectrum: pork cuts, minced meat patties, and fermented sausages. For pork cuts cross-contamination is considered the most important process and therefore it is modeled in detail. For minced meat, both cross-contamination and undercooking are the relevant processes. For those commodities bacterial growth during transport and storage is also modeled. Fermented sausages are eaten raw and the production may be defective. Variability between consumers' behavior and the impact of variability between production processes at the farm and abattoir are taken into account. Results indicate that Salmonella levels on products may increase significantly during transport and storage. Heating is very efficient at lowering concentrations, yet cross-contamination plays an important role in products that remain contaminated. For fermented sausage it is found that drying is important for Salmonella reduction. Sensitivity analysis revealed that cross- contamination factors "knife cleaning" and "preparation of a salad" are important parameters for pork cuts. For minced meat cleaning of the board, salad consumption, refrigerator temperature, and storage time were significant. © 2015 Society for Risk Analysis.

Analytical solutions to dissolved contaminant plume evolution with source depletion during carbon dioxide storage.

PubMed

Yang, Yong; Liu, Yongzhong; Yu, Bo; Ding, Tian

2016-06-01

Volatile contaminants may migrate with carbon dioxide (CO2) injection or leakage in subsurface formations, which leads to the risk of the CO2 storage and the ecological environment. This study aims to develop an analytical model that could predict the contaminant migration process induced by CO2 storage. The analytical model with two moving boundaries is obtained through the simplification of the fully coupled model for the CO2-aqueous phase -stagnant phase displacement system. The analytical solutions are confirmed and assessed through the comparison with the numerical simulations of the fully coupled model. Then, some key variables in the analytical solutions, including the critical time, the locations of the dual moving boundaries and the advance velocity, are discussed to present the characteristics of contaminant migration in the multi-phase displacement system. The results show that these key variables are determined by four dimensionless numbers, Pe, RD, Sh and RF, which represent the effects of the convection, the dispersion, the interphase mass transfer and the retention factor of contaminant, respectively. The proposed analytical solutions could be used for tracking the migration of the injected CO2 and the contaminants in subsurface formations, and also provide an analytical tool for other solute transport in multi-phase displacement system. Copyright © 2016 Elsevier B.V. All rights reserved.

Source Evaluation and Trace Metal Contamination in Benthic Sediments from Equatorial Ecosystems Using Multivariate Statistical Techniques

PubMed Central

Benson, Nsikak U.; Asuquo, Francis E.; Williams, Akan B.; Essien, Joseph P.; Ekong, Cyril I.; Akpabio, Otobong; Olajire, Abaas A.

2016-01-01

Trace metals (Cd, Cr, Cu, Ni and Pb) concentrations in benthic sediments were analyzed through multi-step fractionation scheme to assess the levels and sources of contamination in estuarine, riverine and freshwater ecosystems in Niger Delta (Nigeria). The degree of contamination was assessed using the individual contamination factors (ICF) and global contamination factor (GCF). Multivariate statistical approaches including principal component analysis (PCA), cluster analysis and correlation test were employed to evaluate the interrelationships and associated sources of contamination. The spatial distribution of metal concentrations followed the pattern Pb>Cu>Cr>Cd>Ni. Ecological risk index by ICF showed significant potential mobility and bioavailability for Cu, Cu and Ni. The ICF contamination trend in the benthic sediments at all studied sites was Cu>Cr>Ni>Cd>Pb. The principal component and agglomerative clustering analyses indicate that trace metals contamination in the ecosystems was influenced by multiple pollution sources. PMID:27257934

Relationship of parasites and pathologies to contaminant body burden in sentinel bivalves: NOAA Status and Trends 'Mussel Watch' Program.

PubMed

Kim, Yungkul; Powell, Eric N; Wade, Terry L; Presley, Bobby J

2008-03-01

The 1995-1998 database from NOAA's National Status and Trends 'Mussel Watch' Program was used to compare the distributional patterns of parasites and pathologies with contaminant body burdens. Principal components analysis (PCA) resolved five groups of contaminants in both mussels and oysters: one dominated by polycyclic aromatic hydrocarbons (PAHs), one dominated by pesticides, and three dominated by metals. Metals produced a much more complex picture of spatial trends in body burden than did either the pesticides or PAHs. Contrasted to the relative simplicity of the contaminant groupings, PCA exposed a suite of parasite/pathology groups with few similarities between the sentinel bivalve taxa. Thus, the relationship between parasites/pathologies and contaminants differs significantly between taxa despite the similarity in contaminant pattern. Moreover, the combined effects of many contaminants and parasites may be important, leading to complex biological-contaminant interactions with synergies both of biological and chemical origin. Overall, correlations between parasites/pathologies and contaminants were more frequent with metals, frequent with pesticides, and less frequent with PAHs in mussels. In oysters, correlations with pesticides and metals were about equally frequent, but correlations with PAHs were still rare. In mytilids, correlations with metals predominated. Negative and positive correlations with metals occurred with about the same frequency in both taxa. The majority of correlations with pesticides were negative in oysters; not so for mytilids. Of the many significant correlations involving parasites, few involved single-celled eukaryotes or prokaryotes. The vast majority involved multi-cellular eukaryotes and nearly all of them either cestodes, trematode sporocysts, or trematode metacercariae. The few correlations for single-celled parasites all involved proliferating protozoa or protozoa reaching high body burdens through transmission. The tendency for the larger or more numerous parasites to be involved suggests that unequal sequestration of contaminates between host and parasite tissue is a potential mediator. An alternative is that contaminants differentially affect parasites and their hosts by varying host susceptibility or parasite survival.

Multiple antibiotic resistance patterns of rhizospheric bacteria isolated from Phragmites australis growing in constructed wetland for distillery effluent treatment.

PubMed

Chaturvedi, Sonal; Chandra, Ram; Rai, Vibhuti

2008-01-01

Susceptibility patterns of 12 different antibiotics were investigated against rhizospheric bacteria isolated from Phragmites australis from three different zones i.e. upper (0-5 cm), middle (5-10 cm), lower (10-15 cm) in constructed wetland system with and without distillery effluent. The major pollutants of distillery effluent were phenols, sulphide, heavy metals, and higher levels of biological oxygen demand (BOD), chemical oxygen demand (COD) etc. The antibiotic resistance properties of bacteria were correlated with the heavy metal tolerance (one of distillery pollutant). Twenty-two species from contaminated and seventeen species from non-contaminated site were tested by agar disc-diffusion method. The results revealed that more than 63% of total isolates were resistance towards one or more antibiotics tested from all the three different zones of contaminated sites. The multiple-drug resistance property was shown by total 8 isolates from effluent contaminated region out of which 3 isolates were from upper zone, 3 isolates from middle zone and 2 isolates were from lower zone. Results indicated that isolates from contaminated rhizosphere were found more resistant to antibiotics than isolates from non-contaminated rhizosphere. Further this study produces evidence suggesting that tolerance to antibiotics was acquired by isolates for the adaptation and detoxification of all the pollutants present in the effluent at contaminated site. This consequently facilitated the phytoremediation of effluent, which emerges the tolerance and increases resistance to antibiotics.

Gull-derived trace elements trigger small-scale contamination in a remote Mediterranean nature reserve.

PubMed

Signa, Geraldina; Mazzola, Antonio; Tramati, Cecilia Doriana; Vizzini, Salvatrice

2013-09-15

The role of a yellow-legged gull (Larus michahellis) small colony in conveying trace elements (As, Cd, Cr, Cu, Ni, Pb, THg, V, Zn) was assessed in a Mediterranean nature reserve (Marinello ponds) at various spatial and temporal scales. Trace element concentrations in guano were high and seasonally variable. In contrast, contamination in the ponds was not influenced by season but showed strong spatial variability among ponds, according to the different guano input. Biogenic enrichment factor B confirmed the role of gulls in the release of trace elements through guano subsidies. In addition, comparing trace element pond concentrations to the US NOAA's SQGs, As, Cu and Ni showed contamination levels associated with possible negative biological effects. Thus, this study reflects the need to take seabirds into account as key factors influencing ecological processes and contamination levels even in remote areas, especially around the Mediterranean, where these birds are abundant but overlooked. Copyright © 2013 Elsevier Ltd. All rights reserved.

Do Contaminants Originating from State-of-the-Art Treated Wastewater Impact the Ecological Quality of Surface Waters?

PubMed Central

Stalter, Daniel; Magdeburg, Axel; Quednow, Kristin; Botzat, Alexandra; Oehlmann, Jörg

2013-01-01

Since the 1980s, advances in wastewater treatment technology have led to considerably improved surface water quality in the urban areas of many high income countries. However, trace concentrations of organic wastewater-associated contaminants may still pose a key environmental hazard impairing the ecological quality of surface waters. To identify key impact factors, we analyzed the effects of a wide range of anthropogenic and environmental variables on the aquatic macroinvertebrate community. We assessed ecological water quality at 26 sampling sites in four urban German lowland river systems with a 0–100% load of state-of-the-art biological activated sludge treated wastewater. The chemical analysis suite comprised 12 organic contaminants (five phosphor organic flame retardants, two musk fragrances, bisphenol A, nonylphenol, octylphenol, diethyltoluamide, terbutryn), 16 polycyclic aromatic hydrocarbons, and 12 heavy metals. Non-metric multidimensional scaling identified organic contaminants that are mainly wastewater-associated (i.e., phosphor organic flame retardants, musk fragrances, and diethyltoluamide) as a major impact variable on macroinvertebrate species composition. The structural degradation of streams was also identified as a significant factor. Multiple linear regression models revealed a significant impact of organic contaminants on invertebrate populations, in particular on Ephemeroptera, Plecoptera, and Trichoptera species. Spearman rank correlation analyses confirmed wastewater-associated organic contaminants as the most significant variable negatively impacting the biodiversity of sensitive macroinvertebrate species. In addition to increased aquatic pollution with organic contaminants, a greater wastewater fraction was accompanied by a slight decrease in oxygen concentration and an increase in salinity. This study highlights the importance of reducing the wastewater-associated impact on surface waters. For aquatic ecosystems in urban areas this would lead to: (i) improvement of the ecological integrity, (ii) reduction of biodiversity loss, and (iii) faster achievement of objectives of legislative requirements, e.g., the European Water Framework Directive. PMID:23593263

Do contaminants originating from state-of-the-art treated wastewater impact the ecological quality of surface waters?

PubMed

Stalter, Daniel; Magdeburg, Axel; Quednow, Kristin; Botzat, Alexandra; Oehlmann, Jörg

2013-01-01

Since the 1980s, advances in wastewater treatment technology have led to considerably improved surface water quality in the urban areas of many high income countries. However, trace concentrations of organic wastewater-associated contaminants may still pose a key environmental hazard impairing the ecological quality of surface waters. To identify key impact factors, we analyzed the effects of a wide range of anthropogenic and environmental variables on the aquatic macroinvertebrate community. We assessed ecological water quality at 26 sampling sites in four urban German lowland river systems with a 0-100% load of state-of-the-art biological activated sludge treated wastewater. The chemical analysis suite comprised 12 organic contaminants (five phosphor organic flame retardants, two musk fragrances, bisphenol A, nonylphenol, octylphenol, diethyltoluamide, terbutryn), 16 polycyclic aromatic hydrocarbons, and 12 heavy metals. Non-metric multidimensional scaling identified organic contaminants that are mainly wastewater-associated (i.e., phosphor organic flame retardants, musk fragrances, and diethyltoluamide) as a major impact variable on macroinvertebrate species composition. The structural degradation of streams was also identified as a significant factor. Multiple linear regression models revealed a significant impact of organic contaminants on invertebrate populations, in particular on Ephemeroptera, Plecoptera, and Trichoptera species. Spearman rank correlation analyses confirmed wastewater-associated organic contaminants as the most significant variable negatively impacting the biodiversity of sensitive macroinvertebrate species. In addition to increased aquatic pollution with organic contaminants, a greater wastewater fraction was accompanied by a slight decrease in oxygen concentration and an increase in salinity. This study highlights the importance of reducing the wastewater-associated impact on surface waters. For aquatic ecosystems in urban areas this would lead to: (i) improvement of the ecological integrity, (ii) reduction of biodiversity loss, and (iii) faster achievement of objectives of legislative requirements, e.g., the European Water Framework Directive.

MODIS-derived spatiotemporal water clarity patterns in optically shallow FloridaKeys waters: A new approach to remove bottom contamination

EPA Science Inventory

Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ...

Sediment microbial activity and its relation to environmental variables along the eastern Gulf of Finland coastline

NASA Astrophysics Data System (ADS)

Polyak, Yulia; Shigaeva, Tatyana; Gubelit, Yulia; Bakina, Ludmila; Kudryavtseva, Valentina; Polyak, Mark

2017-07-01

Sediment microbial activity and its relationship with the main environmental factors and pollutants were examined in the coastal area of the eastern Gulf of Finland, Baltic Sea. The activity of two common oxidoreductase enzymes: dehydrogenase (DA) and catalase (CA) varied significantly between 13 study sites. In the Neva Bay the highest microbial activities (DA: 2.64 mg TFF (10 g- 1) day- 1, CA: 6.29 mg H2O2 g- 1) were recorded, while in the outer estuary the minimum values of dehydrogenase and catalase were measured. DA, CA, and abundances of culturable heterotrophic bacteria (CHB) were positively correlated with each other, while biomass of green opportunistic algae was independent of both microbial activities and CHB. Enzymatic activity was found to be strongly positively correlated with sediment particle size and organic matter content, but unrelated to the other studied environmental parameters (temperature, pH, and salinity). Principal components analysis (PCA), controlling for environmental variables, supported direct effects of metal and oil contamination on sediment microbial activity. Also it had shown the similar patterns for algal biomass and metals. Our results suggest that copper and hydrocarbons are the main anthropogenic variables influencing enzyme distribution along the eastern Gulf of Finland coastline.

Laser pattern generator challenges in airborne molecular contamination protection

NASA Astrophysics Data System (ADS)

Ekberg, Mats; Skotte, Per-Uno; Utterback, Tomas; Paul, Swaraj; Kishkovich, Oleg P.; Hudzik, James S.

2003-08-01

The introduction of photomask laser pattern generators presents new challenges to system designers and manufacturers. One of the laser pattern generator's environmental operating challenges is Airborne Molecular Contamination (AMC), which affects both chemically amplified resists (CAResist) and laser optics. Similar challenges in CAResist protection have already been addressed in semiconductor wafer lithography with reasonable solutions and experience gained by all those involved. However, photomask and photomask equipment manufacturers have not previously had a comparable experience, and some photomask AMC issues differ from those seen in semiconductor wafer lithography. Culminating years of AMC experience, the authors discuss specific requirements of Photomask AMC. Air sampling and material of construction analysis were performed to understand these particular AMC challenges and used to develop an appropriate filtration specification for different classes of contaminates. The authors portray the importance of cooperation between tool designers and AMC experts early in the design stage to assure goal attainment to maximize both process stability and machine productivity in advanced mask making. In conclusion, the authors provide valuable recommendations to both laser tool users and other equipment manufacturers.

Bioremediation techniques applied to aqueous media contaminated with mercury.

PubMed

Velásquez-Riaño, Möritz; Benavides-Otaya, Holman D

2016-12-01

In recent years, the environmental and human health impacts of mercury contamination have driven the search for alternative, eco-efficient techniques different from the traditional physicochemical methods for treating this metal. One of these alternative processes is bioremediation. A comprehensive analysis of the different variables that can affect this process is presented. It focuses on determining the effectiveness of different techniques of bioremediation, with a specific consideration of three variables: the removal percentage, time needed for bioremediation and initial concentration of mercury to be treated in an aqueous medium.

Spatial patterns of aflatoxin levels in relation to ear-feeding insect damage in pre-harvest corn.

PubMed

Ni, Xinzhi; Wilson, Jeffrey P; Buntin, G David; Guo, Baozhu; Krakowsky, Matthew D; Lee, R Dewey; Cottrell, Ted E; Scully, Brian T; Huffaker, Alisa; Schmelz, Eric A

2011-07-01

Key impediments to increased corn yield and quality in the southeastern US coastal plain region are damage by ear-feeding insects and aflatoxin contamination caused by infection of Aspergillus flavus. Key ear-feeding insects are corn earworm, Helicoverpa zea, fall armyworm, Spodoptera frugiperda, maize weevil, Sitophilus zeamais, and brown stink bug, Euschistus servus. In 2006 and 2007, aflatoxin contamination and insect damage were sampled before harvest in three 0.4-hectare corn fields using a grid sampling method. The feeding damage by each of ear/kernel-feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs), and maize weevil population were assessed at each grid point with five ears. The spatial distribution pattern of aflatoxin contamination was also assessed using the corn samples collected at each sampling point. Aflatoxin level was correlated to the number of maize weevils and stink bug-discolored kernels, but not closely correlated to either husk coverage or corn earworm damage. Contour maps of the maize weevil populations, stink bug-damaged kernels, and aflatoxin levels exhibited an aggregated distribution pattern with a strong edge effect on all three parameters. The separation of silk- and cob-feeding insects from kernel-feeding insects, as well as chewing (i.e., the corn earworm and maize weevil) and piercing-sucking insects (i.e., the stink bugs) and their damage in relation to aflatoxin accumulation is economically important. Both theoretic and applied ramifications of this study were discussed by proposing a hypothesis on the underlying mechanisms of the aggregated distribution patterns and strong edge effect of insect damage and aflatoxin contamination, and by discussing possible management tactics for aflatoxin reduction by proper management of kernel-feeding insects. Future directions on basic and applied research related to aflatoxin contamination are also discussed.

Spatial Patterns of Aflatoxin Levels in Relation to Ear-Feeding Insect Damage in Pre-Harvest Corn

PubMed Central

Ni, Xinzhi; Wilson, Jeffrey P.; Buntin, G. David; Guo, Baozhu; Krakowsky, Matthew D.; Lee, R. Dewey; Cottrell, Ted E.; Scully, Brian T.; Huffaker, Alisa; Schmelz, Eric A.

2011-01-01

Key impediments to increased corn yield and quality in the southeastern US coastal plain region are damage by ear-feeding insects and aflatoxin contamination caused by infection of Aspergillus flavus. Key ear-feeding insects are corn earworm, Helicoverpa zea, fall armyworm, Spodoptera frugiperda, maize weevil, Sitophilus zeamais, and brown stink bug, Euschistus servus. In 2006 and 2007, aflatoxin contamination and insect damage were sampled before harvest in three 0.4-hectare corn fields using a grid sampling method. The feeding damage by each of ear/kernel-feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs), and maize weevil population were assessed at each grid point with five ears. The spatial distribution pattern of aflatoxin contamination was also assessed using the corn samples collected at each sampling point. Aflatoxin level was correlated to the number of maize weevils and stink bug-discolored kernels, but not closely correlated to either husk coverage or corn earworm damage. Contour maps of the maize weevil populations, stink bug-damaged kernels, and aflatoxin levels exhibited an aggregated distribution pattern with a strong edge effect on all three parameters. The separation of silk- and cob-feeding insects from kernel-feeding insects, as well as chewing (i.e., the corn earworm and maize weevil) and piercing-sucking insects (i.e., the stink bugs) and their damage in relation to aflatoxin accumulation is economically important. Both theoretic and applied ramifications of this study were discussed by proposing a hypothesis on the underlying mechanisms of the aggregated distribution patterns and strong edge effect of insect damage and aflatoxin contamination, and by discussing possible management tactics for aflatoxin reduction by proper management of kernel-feeding insects. Future directions on basic and applied research related to aflatoxin contamination are also discussed. PMID:22069748

Modelling the migration of contaminants through variably saturated dual-porosity, dual-permeability chalk.

PubMed

Brouyère, Serge

2006-01-10

In the Hesbaye region in Belgium, tracer tests performed in variably saturated fissured chalk rocks presented very contrasting results in terms of transit times, according to artificially controlled water recharge conditions prevailing during the experiments. Under intense recharge conditions, tracers migrated across the partially or fully saturated fissure network, at high velocity in accordance with the high hydraulic conductivity and low effective porosity (fracture porosity). At the same time, a portion of the tracer was temporarily retarded in the almost immobile water located in the matrix. Under natural infiltration conditions, the fissure network remained inactive. Tracers migrated downward through the matrix, at low velocity in relation with the low hydraulic conductivity and the large porosity of the matrix. Based on these observations, Brouyère et al. (2004a) [Brouyère, S., Dassargues, A., Hallet, V., 2004a. Migration of contaminants through the unsaturated zone overlying the Hesbaye chalky aquifer in Belgium: a field investigation, J. Contam. Hydrol., 72 (1-4), 135-164, doi: 10.1016/j.conhyd.2003.10.009] proposed a conceptual model in order to explain the migration of solutes in variably saturated, dual-porosity, dual-permeability chalk. Here, mathematical and numerical modelling of tracer and contaminant migration in variably saturated fissured chalk is presented, considering the aforementioned conceptual model. A new mathematical formulation is proposed to represent the unsaturated properties of the fissured chalk in a more dynamic and appropriate way. At the same time, the rock water content is partitioned between mobile and immobile water phases, as a function of the water saturation of the chalk rock. The groundwater flow and contaminant transport in the variably saturated chalk is solved using the control volume finite element method. Modelling the field tracer experiments performed in the variably saturated chalk shows the adequacy and usefulness of the new conceptual, mathematical and numerical model.

Temporal dynamics of urbanization-driven environmental changes explored by metal contamination in surface sediments in a restoring urban wetland park.

PubMed

Ma, Jun; Liu, Yi; Yu, Guangbin; Li, Hongbo; Yu, Shen; Jiang, Yueping; Li, Guilin; Lin, Jinchang

2016-05-15

Spatial patterns of metal distribution along urban-rural or multi-city gradients indicate that the urbanization process directly lead to metal enrichment and contamination in the environments. However, it has not yet looked at homogenization dynamics of an urban-rural gradient pattern over time with urbanization process in an area. This study monitored anthropogenic metals (Cr, Cu, Pb, and Zn) in surface sediments from channels of a newly-opened National Wetland Park to elucidate the urbanization-driven dissolution of urban-rural gradient pattern between 2008 and 2011. Sixty-eight surface sediment samples were taken from these channels in July of both 2008 and 2011. Results showed that a spatial distribution pattern of total metal contents along the gradient of urbanization influence, evident in 2008, was homogenized in 2011 with the area development. The lead stable isotope ratio analysis identified anthropogenic Pb origins from vehicular exhausts, cements, and coal flying ashes, which elevated metal contents in the inner channels via atmospheric deposition. Specific hazard quotients of the metal contamination in surface sediment were also assessed and enhanced over time in the study wetland park. These findings suggest that emissions from traffic, construction, and energy generation contribute metal loadings in the urbanizing environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Combining particle-tracking and geochemical data to assess public supply well vulnerability to arsenic and uranium

USGS Publications Warehouse

Hinkle, S.R.; Kauffman, L.J.; Thomas, M.A.; Brown, C.J.; McCarthy, K.A.; Eberts, S.M.; Rosen, Michael R.; Katz, B.G.

2009-01-01

Flow-model particle-tracking results and geochemical data from seven study areas across the United States were analyzed using three statistical methods to test the hypothesis that these variables can successfully be used to assess public supply well vulnerability to arsenic and uranium. Principal components analysis indicated that arsenic and uranium concentrations were associated with particle-tracking variables that simulate time of travel and water fluxes through aquifer systems and also through specific redox and pH zones within aquifers. Time-of-travel variables are important because many geochemical reactions are kinetically limited, and geochemical zonation can account for different modes of mobilization and fate. Spearman correlation analysis established statistical significance for correlations of arsenic and uranium concentrations with variables derived using the particle-tracking routines. Correlations between uranium concentrations and particle-tracking variables were generally strongest for variables computed for distinct redox zones. Classification tree analysis on arsenic concentrations yielded a quantitative categorical model using time-of-travel variables and solid-phase-arsenic concentrations. The classification tree model accuracy on the learning data subset was 70%, and on the testing data subset, 79%, demonstrating one application in which particle-tracking variables can be used predictively in a quantitative screening-level assessment of public supply well vulnerability. Ground-water management actions that are based on avoidance of young ground water, reflecting the premise that young ground water is more vulnerable to anthropogenic contaminants than is old ground water, may inadvertently lead to increased vulnerability to natural contaminants due to the tendency for concentrations of many natural contaminants to increase with increasing ground-water residence time.

How Will Climate Change Impact Cholera Outbreaks?

NASA Astrophysics Data System (ADS)

Nasr Azadani, F.; Jutla, A.; Rahimikolu, J.; Akanda, A. S.; Huq, A.; Colwell, R. R.

2014-12-01

Environmental parameters associated with cholera are well documented. However, cholera continues to be a global public health threat. Uncertainty in defining environmental processes affecting growth and multiplication of the cholera bacteria can be affected significantly by changing climate at different temporal and spatial scales, either through amplification of the hydroclimatic cycle or by enhanced variability of large scale geophysical processes. Endemic cholera in the Bengal Delta region of South Asia has a unique pattern of two seasonal peaks and there are associated with asymmetric and episodic variability in river discharge. The first cholera outbreak in spring is related with intrusion of bacteria laden coastal seawater during low river discharge. Cholera occurring during the fall season is hypothesized to be associated with high river discharge related to a cross-contamination of water resources and, therefore, a second wave of disease, a phenomenon characteristic primarily in the inland regions. Because of difficulties in establishing linkage between coarse resolutions of the Global Climate Model (GCM) output and localized disease outbreaks, the impact of climate change on diarrheal disease has not been explored. Here using the downscaling method of Support Vector Machines from HADCM3 and ECHAM models, we show how cholera outbreak patterns are changing in the Bengal Delta. Our preliminary results indicate statistically significant changes in both seasonality and magnitude in the occurrence of cholera over the next century. Endemic cholera is likely to transform into epidemic forms and new geographical areas will be at risk for cholera outbreaks.

Spatial Variability in ADHD-Related Behaviors Among Children Born to Mothers Residing Near the New Bedford Harbor Superfund Site.

PubMed

Vieira, Verónica M; Fabian, M Patricia; Webster, Thomas F; Levy, Jonathan I; Korrick, Susan A

2017-05-15

Attention-deficit/hyperactivity disorder (ADHD) has an uncertain etiology, with potential contributions from different risk factors such as prenatal environmental exposure to organochlorines and metals, social risk factors, and genetics. The degree to which geographic variability in ADHD is independent of, or explained by, risk factors may provide etiological insight. We investigated determinants of geographic variation in ADHD-related behaviors among children living near the polychlorinated biphenyl-contaminated New Bedford Harbor (NBH) Superfund site in Massachusetts. Participants were 573 children recruited at birth (1993-1998) who were born to mothers residing near the NBH site. We assessed ADHD-related behaviors at age 8 years using Conners' Teacher Rating Scale-Revised: Long Version. Adjusted generalized additive models were used to smooth the association of pregnancy residence with ADHD-related behaviors and assess whether prenatal organochlorine or metal exposures, sociodemographic factors, or other factors explained spatial patterns. Models that adjusted for child's age and sex displayed significantly increased ADHD-related behavior among children whose mothers resided west of the NBH site during pregnancy. These spatial patterns persisted after adjusting for prenatal exposure to organochlorines and metals but were no longer significant after controlling for sociodemographic factors. The findings underscore the value of spatial analysis in identifying high-risk subpopulations and evaluating candidate risk factors. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.

Public health significance of major genotypes of Salmonella enterica serovar Enteritidis present in both human and chicken isolates in Korea.

PubMed

Kang, Min-Su; Oh, Jae-Young; Kwon, Yong-Kuk; Lee, Deog-Yong; Jeong, Ok-Mi; Choi, Byung-Kook; Youn, So-Youn; Jeon, Byung-Woo; Lee, Hye-Jin; Lee, Hee-Soo

2017-06-01

Salmonella enterica serovar Enteritidis is one of the most common serotypes implicated in Salmonella infections in both humans and poultry worldwide. It has been reported that human salmonellosis is mainly associated with the consumption of poultry products contaminated with serovar Enteritidis. The present study was to extensively analyze the public health risk of serovar Enteritidis isolates from chickens in Korea. A total of 127 chicken isolates were collected from clinical cases, on-farm feces, and chicken meat between 1998 and 2012 and 20 human clinical isolates were obtained from patients with diarrhea between 2000 and 2006 in Korea. To characterize the isolates from chickens and humans, we compared the pulsed-field gel electrophoresis (PFGE) patterns and multilocus variable-number tandem-repeat analysis (MLVA) profiles of the isolates. We further characterized representative isolates of different genotypes using a DNA microarray. PFGE revealed 28 patterns and MLVA identified 16 allelic profiles. The DNA microarray showed high genetic variability in plasmid regions and other fimbrial subunits of the isolates although the virulence gene contents of isolates from the same source and/or of the same genotype were unrelated. PFGE and MLVA showed that major genotypes were present in both human and chicken isolates. This result suggests that chickens in Korea pose a significant risk to public health as a source of serovar Enteritidis as has been noted in other countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temporal trends in mercury concentrations in raptor flight feathers stored in an environmental specimen bank in Galicia (NW Spain) between 2000 and 2013.

PubMed

García-Seoane, Rita; Varela, Zulema; Carballeira, Alejo; Aboal, Jesús R; Fernández, J Ángel

2017-03-01

Temporal trends in Hg concentrations were investigated in primary flight feathers from 319 specimens of three birds of prey: P7 in the northern goshawk (Accipiter gentilis), P6 in the common buzzard (Buteo buteo) and P5 in the tawny owl (Strix aluco). The samples were stored in a regional environmental specimen bank and belonged to specimens which died between 2000 and 2013 in Galicia (NW Spain). We would expect to see a decline in Hg concentrations across the study period, as data of atmospheric emissions show a gradual reduction of this pollutant in Europe in the last two decades. The study did not reveal any temporal pattern in Hg concentrations of feathers in any of the three species for the study period, may be due to the persistence of Hg in the environment, but showed a low level of contamination by this metal in the study area. In addition, the results show high intra-specific, as well as, inter-annual and inter-specific variability in data, mainly attributed to the level of exposure of the raptors to this pollutant and to the biomagnification process of Hg through food chains. These findings indicate that the high variability can be a limiting factor in the use of raptors for biomonitoring temporal patterns of Hg, but nevertheless, the technique provides qualitative information about the amount of Hg that reach the top of the terrestrial food chains.

Development of Chemical Indicators of Groundwater Contamination Near the Carcass Burial Site

NASA Astrophysics Data System (ADS)

Kim, H.; Choi, J.; Kim, M.; Choi, J.; Lee, M.; Lee, H.; Jeon, S.; Bang, S.; Noh, H.; Yoo, J.; Park, S.; Kim, H.; Kim, D.; Lee, Y.; Han, J.

2011-12-01

A serious outbreak of foot and mouth disease (FMD) and avian influenza (AI) led to the culling of millions of livestock in South Korea from late 2010 to earlier 2011. Because of the scale of FMD and AI epidemic in Korea and rapid spread of the diseases, mass burial for the disposal of carcass was conducted to halt the outbreak. The improper construction of the burial site or inappropriate management of the carcass burial facility can cause the contamination of groundwater mainly due to the discharges of leachate through the base of disposal pit. The leachate from carcass burial contains by products of carcass decay such as amino acids, nitrate, ammonia and chloride. The presence of these chemical components in groundwater can be used as indicators demonstrating contamination of groundwater with leachate from carcass. The major concern about using these chemical indicators is that other sources including manures, fertilizers and waste waters from human or animal activities already exist in farming area. However, we lack the understanding of how groundwater contamination due to mass burial of carcass can be differentiated from the contamination due to livestock manures which shows similar chemical characteristics. The chemical compositions of the leachate from carcass burial site and the wastewater from livestock manure treatment facilities were compared. The chemical compositions considered include total organic carbon (TOC), total nitrogen (TN), nitrate, organic nitrogen (Organic nitrogen =TN-Ammonium Nitrogen- Nitrate nitrogen), ammonia, chloride, sodium, potassium and amino acids (20 analytes). The ratios of concentrations of the chemical compositions as indicators of contamination were determined to distinguish the sources of contamination in groundwater. Indicators which showed a linear relationship between two factors and revealed a distinct difference between the carcass leachate and livestock manure were chosen. In addition, the background level of the indicators in groundwater which was presumed not to be contaminated with the leachate was also considered. The indicators selected from these step were TN/nitrate nitrogen, organic nitrogen/TN, organic nitrogen/Cl and organic nitrogen/Na. In a similar manner, concentrations and peak pattern of amino acids with LC-MSMS as indicators were also selected. One more step added to identify the source of a contaminant release was the consideration of the transport of 20 amino acids in the subsurface which could significantly change the peak pattern among different amino acids. Six group of amino acid as indicators were chosen and they were Isoleucine/Valine, Leucine/Tryptophane, Valine/Tryptophane, Lysine/Leucine, Lysine/Isoleucine and Methionine/Lysine. The use of chemical indicators was attempted in this study to distinguish the sources of contamination by considering both the concentration of contaminants and the unique patterns of contamination.

Removal of Dissolved Salts and Particulate Contaminants from Seawater: Village Marine Tec., Expeditionary Unit Water Purifier, Generation 1

EPA Science Inventory

The EUWP was developed to treat challenging water sources with variable turbidity, chemical contamination, and very high total dissolved solids (TDS), including seawater, during emergency situations when other water treatment facilities are incapacitated. The EUWP components incl...

Modeling: The Right Tool for the Job.

ERIC Educational Resources Information Center

Gavanasen, Varut; Hussain, S. Tariq

1993-01-01

Reviews the different types of models that can be used in groundwater modeling. Discusses the flow and contaminant transport models in the saturated zone, flow and contaminant transport in variably saturated flow regime, vapor transport, biotransformation models, multiphase models, optimization algorithms, and potentials pitfalls of using these…

Effects of Contaminated Site Age on Dissolution Dynamics

NASA Astrophysics Data System (ADS)

Jawitz, J. W.

2004-12-01

This work presents a streamtube-based analytical approach to evaluate reduction in groundwater contaminant flux resulting from partial mass reduction in a nonaqueous phase liquid (NAPL) source zone. The reduction in contaminant flux, Rj, discharged from the source zone is a remediation performance metric that has a direct effect on the fundamental drivers of remediation: protection of human health risks and the environment. Spatial variability is described within a Lagrangian framework where aquifer hydrodynamic heterogeneities are characterized using nonreactive travel time distributions, while NAPL spatial distribution heterogeneity can be similarly described using reactive travel time distributions. The combined statistics of these distributions are used to evaluate the relationship between reduction in contaminant mass, Rm, and Rj. A portion of the contaminant mass in the source zone is assumed to be removed via in-situ flushing remediation, with the initial and final conditions defined as steady-state natural-gradient groundwater flow through the contaminant source zone. The combined effect of aquifer and NAPL heterogeneities are shown to be captured in a single parameter, reactive travel time variability, that was determined to be the most important factor controlling the relationship between Rm and Rj. Increased values of the following parameters are shown to result in more favorable contaminant elution dynamics (i.e., greater flux reduction for a given reduction in mass): aquifer hydrodynamic heterogeneity, NAPL source zone heterogeneity, positive correlation between travel time and NAPL content, and time since the contamination event. Less favorable elution behavior is shown to result from negative correlations between travel time and NAPL content and rate-limited dissolution. The specific emphasis of this presentation is on the effects of the length of time that has elapsed since the contamination event (site age) on the dissolution dynamics.

A multilevel analysis of long-term psychological distress among Belarusians affected by the Chernobyl disaster.

PubMed

Beehler, G P; Baker, J A; Falkner, K; Chegerova, T; Pryshchepava, A; Chegerov, V; Zevon, M; Bromet, E; Havenaar, J; Valdismarsdottir, H; Moysich, K B

2008-11-01

Radiation contamination and sociopolitical instability following the Chernobyl nuclear power plant disaster have had a profound impact on Belarus. To investigate the factors that impact long-term mental health outcomes of this population almost 20 years after the disaster. Cross-sectional study. In-person interviews were conducted with 381 men and women from two geographic areas of differing radiation contamination within Belarus. Participants completed surveys of demographics, psychosocial factors and psychological distress. Individual-level characteristics were combined with household-level measures of radiation contamination exposure and family characteristics to create multilevel predictive models of psychological distress. Between-household effects accounted for 20% of variability in depression and anxiety scores, but only 8% of variability in somatization scores. Degree of chronic daily stressors showed a significant positive relationship with psychological distress, whereas mastery/controllability showed a significant inverse relationship with distress. At household level, perceived family problems, but not level of residential radiation contamination, was the best predictor of distress. Multilevel modelling indicates that long-term psychological distress among Belarusians affected by the Chernobyl disaster is better predicted by stress-moderating psychosocial factors present in one's daily life than by level of residential radiation contamination.

Simulating Heterogeneous Infiltration and Contaminant leaching Processes at Chalk River, Ontario

NASA Astrophysics Data System (ADS)

Ali, M. A.; Ireson, A. M.; Keim, D.

2015-12-01

A study is conducted at a waste management area in Chalk River, Ontario to characterize flow and contaminant transport with the aim of contributing to improved hydrogeological risk assessment in the context of waste management. Field monitoring has been performed to gain insights into the unsaturated zone characteristics, moisture dynamics, and contaminant transport rates. The objective is to provide quantitative estimates of surface fluxes (quantification of infiltration and evaporation) and investigations of unsaturated zone processes controlling water infiltration and spatial variability in head distributions and flow rates. One particular issue is to examine the effectiveness of the clayey soil cap installed to prevent infiltration of water into the waste repository and the top sand soil cover above the clayey layer to divert the infiltrated water laterally. The spatial variability in the unsaturated zone properties and associated effects on water flow and contaminant transport observed at the site, have led to a concerted effort to develop improved model of flow and transport based on stochastic concepts. Results obtained through the unsaturated zone model investigations are combined with the hydrogeological and geochemical components and develop predictive tools to assess the long term fate of the contaminants at the waste management site.

Estimating aquatic toxicity as determined through laboratory tests of great lakes sediments containing complex mixtures of environmental contaminants

USGS Publications Warehouse

1996-01-01

We developed and evaluated a total toxic units modeling approach for predicting mean toxicity as measured in laboratory tests for Great Lakes sediments containing complex mixtures of environmental contaminants (e.g., polychlorinated biphenyls, polycyclic aromatic hydrocarbons, pesticides, chlorinated dioxins, and metals). The approach incorporates equilibrium partitioning and organic carbon control of bioavailability for organic contaminants and acid volatile sulfide (AVS) control for metals, and includes toxic equivalency for planar organic chemicals. A toxic unit is defined as the ratio of the estimated pore-water concentration of a contaminant to the chronic toxicity of that contaminant, as estimated by U.S. Environmental Protection Agency Ambient Water Quality Criteria (AWQC). The toxic unit models we developed assume complete additivity of contaminant effects, are completely mechanistic in form, and were evaluated without any a posteriori modification of either the models or the data from which the models were developed and against which they were tested. A linear relationship between total toxic units, which included toxicity attributable to both iron and un-ionized ammonia, accounted for about 88% of observed variability in mean toxicity; a quadratic relationship accounted for almost 94%. Exclusion of either bioavailability components (i.e., equilibrium partitioning control of organic contaminants and AVS control of metals) or iron from the model substantially decreased its ability to predict mean toxicity. A model based solely on un-ionized ammonia accounted for about 47% of the variability in mean toxicity. We found the toxic unit approach to be a viable method for assessing and ranking the relative potential toxicity of contaminated sediments.

Contamination of the Arctic reflected in microbial metagenomes from the Greenland ice sheet

NASA Astrophysics Data System (ADS)

Hauptmann, Aviaja L.; Sicheritz-Pontén, Thomas; Cameron, Karen A.; Bælum, Jacob; Plichta, Damian R.; Dalgaard, Marlene; Stibal, Marek

2017-07-01

Globally emitted contaminants accumulate in the Arctic and are stored in the frozen environments of the cryosphere. Climate change influences the release of these contaminants through elevated melt rates, resulting in increased contamination locally. Our understanding of how biological processes interact with contamination in the Arctic is limited. Through shotgun metagenomic data and binned genomes from metagenomes we show that microbial communities, sampled from multiple surface ice locations on the Greenland ice sheet, have the potential for resistance to and degradation of contaminants. The microbial potential to degrade anthropogenic contaminants, such as toxic and persistent polychlorinated biphenyls, was found to be spatially variable and not limited to regions close to human activities. Binned genomes showed close resemblance to microorganisms isolated from contaminated habitats. These results indicate that, from a microbiological perspective, the Greenland ice sheet cannot be seen as a pristine environment.

Reticle haze: an industrial approach

NASA Astrophysics Data System (ADS)

Gough, Stuart; Gérard, Xavier; Bichebois, Pascal; Roche, Agnès; Sundermann, Frank; Guyader, Véronique; Bièron, Yann; Galvier, Jean; Nicoleau, Serge

2007-02-01

Crystal growth on advanced reticles is currently a world wide industrial problem in high end semiconductor production environment, crystals are mainly found on reticles that use high energy photons at 193nm wavelength. The most common crystals to be found on masks are ammonium sulphate, a combination of sulphate, from maskshop residues after clean, pellicle materials and storage conditions and amines from clean room, tool and storage environments. High energy photons act as a catalyst to form crystals on both the pattern side as well as the backglass surface. After a number of exposures crystals can grow in size and eventually become printable. In order to detect HAZE before critical dimensions have been reached suitable detection methods need to be implemented to ensure image integrity. These detection methods are different and complementary depending on the surface to be inspected. Once crystals have started growing, the only method to regain mask quality is to clean the mask at the manufacturers site. This brings with it several undesirable situations, not only is the mask unavailable for production but the cleaning of a mask leads to a potential risk of damaging the mask especially for sub resolution patterns such as scatter bars and phase and transmission changes for eaPSM (Embedded Attenuated Phase Shift Mask) masks. This paper will discuss the initial haze issues seen in a 300mm wafer fab and actions put in place to address the problem. An explanation of results gained from haze reduction actions implemented in a wafer fab will be given. Haze seen by reticle inspection and surface analysis tools can be characterised by typical contamination patterns. These signatures appear after a certain number of wafers exposed depending on several reticle variables such as transmission, Binary, eaPSM, Pellicle. Details will be given of how reticles are managed to ensure minimum impact to a production environment with an appropriate reticle control plan. AMC (Airborne Molecular Contamination) in wafer fab and equipment environment is a key factor for crystal growth. The type of filtration installed to reduce AMC and method of atmospheric monitoring for critical areas will be explained. Choice of reticle storage conditions and materials used for transport during the life of the reticle will be included. Improvements in maskshop cleaning processes, reticle materials and environmental control have lead to extended mask lifetime in the wafer fab of more than 20 times. The fundamental differences and relative monitoring will be described and gain from implemented actions will be presented Once crystals have started growing, the only method to regain mask quality is to clean the mask at the manufacturers site. This brings with it several undesirable situations, not only is the mask unavailable for production but the cleaning of a mask leads to a potential risk of damaging the mask especially for sub resolution patterns such as scatter bars and phase and transmission changes for eaPSM (Embedded Attenuated Phase Shift Mask) masks. This paper will discuss the initial haze issues seen in a 300mm wafer fab and actions put in place to address the problem. An explanation of results gained from haze reduction actions implemented in a wafer fab will be given. Haze seen by reticle inspection and surface analysis tools can be characterised by typical contamination patterns. These signatures appear after a certain number of wafers exposed depending on several reticle variables such as transmission, Binary, eaPSM, Pellicle. Details will be given of how reticles are managed to ensure minimum impact to a production environment with an appropriate reticle control plan. AMC (Airborne Molecular Contamination) in wafer fab and equipment environment is a key factor for crystal growth. The type of filtration installed to reduce AMC and method of atmospheric monitoring for critical areas will be explained. Choice of reticle storage conditions and materials used for transport during the life of the reticle will be included. Improvements in maskshop cleaning processes, reticle materials and environmental control have lead to extended mask lifetime in the wafer fab of more than 20 times. The fundamental differences and relative monitoring will be described and gain from implemented actions will be presented

Interindividual variability of electromyographic patterns and pedal force profiles in trained cyclists.

PubMed

Hug, François; Drouet, Jean Marc; Champoux, Yvan; Couturier, Antoine; Dorel, Sylvain

2008-11-01

The aim of this study was to determine whether high inter-individual variability of the electromyographic (EMG) patterns during pedaling is accompanied by variability in the pedal force application patterns. Eleven male experienced cyclists were tested at two submaximal power outputs (150 and 250 W). Pedal force components (effective and total forces) and index of mechanical effectiveness were measured continuously using instrumented pedals and were synchronized with surface electromyography signals measured in ten lower limb muscles. The intersubject variability of EMG and mechanical patterns was assessed using standard deviation, mean deviation, variance ratio and coefficient of cross-correlation (_R(0), with lag time = 0). The results demonstrated a high intersubject variability of EMG patterns at both exercise intensities for biarticular muscles as a whole (and especially for Gastrocnemius lateralis and Rectus femoris) and for one monoarticular muscle (Tibialis anterior). However, this heterogeneity of EMG patterns is not accompanied by a so high intersubject variability in pedal force application patterns. A very low variability in the three mechanical profiles (effective force, total force and index of mechanical effectiveness) was obtained in the propulsive downstroke phase, although a greater variability in these mechanical patterns was found during upstroke and around the top dead center, and at 250 W when compared to 150 W. Overall, these results provide additional evidence for redundancy in the neuromuscular system.

Viral and bacterial contamination in a sedimentary aquifer in Uruguay: evaluation of coliforms as regional indicators of viral contamination.

NASA Astrophysics Data System (ADS)

Gamazo, Pablo; Colina, Rodney; Victoria, Matias; Alvareda, Elena; Burutatran, Luciana; Ramos, Julian; Olivera, María; Soler, Joan

2015-04-01

In many areas of Uruguay groundwater is the only source of water for human consumption and for industrial-agricultural economic activities. Traditionally considered as a safe source, groundwater is commonly used without any treatment. The Uruguayan law requires bacteriological (fecal) analysis for most water uses, but virological analyses are not mentioned in the legislation. In the Salto district, where groundwater is used for human consumption and for agricultural activities, bacterial contamination has been detected in several wells but no viruses analysis have been performed. The Republic University (UDELAR), with the support of the National Agency for Research and Innovation (ANII), is studying the incidence of virus and fecal bacteria in groundwater on an intensive agriculture area of the Salto district. An initial screening campaign of 44 wells was performed in which, besides total and fecal coliforms, rotavirus and adenovirus were detected. A subgroup of the screening wells (15) where selected for bimonthly sampling during a year. In accordance with literature results, single well data analysis shows that coliform and viral contamination can be considered as independent variables. However, when spatial data is integrated, coliform and viral contamination show linear correlation. In this work we present the survey results, we analyse the temporal incidence of variables like precipitation, temperature and chemical composition in well contamination and we discuss the value of coliforms as global indicator of viral contamination for the Salto aquifer.

Assessing Aircraft Supply Air to Recommend Compounds for Timely Warning of Contamination

NASA Astrophysics Data System (ADS)

Fox, Richard B.

Taking aircraft out of service for even one day to correct fume-in-cabin events can cost the industry roughly $630 million per year in lost revenue. The quantitative correlation study investigated quantitative relationships between measured concentrations of contaminants in bleed air and probability of odor detectability. Data were collected from 94 aircraft engine and auxiliary power unit (APU) bleed air tests from an archival data set between 1997 and 2011, and no relationships were found. Pearson correlation was followed by regression analysis for individual contaminants. Significant relationships of concentrations of compounds in bleed air to probability of odor detectability were found (p<0.05), as well as between compound concentration and probability of sensory irritancy detectability. Study results may be useful to establish early warning levels. Predictive trend monitoring, a method to identify potential pending failure modes within a mechanical system, may influence scheduled down-time for maintenance as a planned event, rather than repair after a mechanical failure and thereby reduce operational costs associated with odor-in-cabin events. Twenty compounds (independent variables) were found statistically significant as related to probability of odor detectability (dependent variable 1). Seventeen compounds (independent variables) were found statistically significant as related to probability of sensory irritancy detectability (dependent variable 2). Additional research was recommended to further investigate relationships between concentrations of contaminants and probability of odor detectability or probability of sensory irritancy detectability for all turbine oil brands. Further research on implementation of predictive trend monitoring may be warranted to demonstrate how the monitoring process might be applied to in-flight application.

Contaminants of emerging concern: Mass balance and comparison of wastewater effluent and upstream sources in a mixed-use watershed

USDA-ARS?s Scientific Manuscript database

Understanding the sources, transport, and spatiotemporal variability of contaminants of emerging concern (CECs) is important for understanding risks and developing monitoring and mitigation strategies. This study compared CEC loading and transport from a wastewater treatment plant and upstream areas...

GOLF COURSES AS A SOURCE OF COASTAL CONTAMINATION AND TOXICITY: A FLORIDA EXPERIENCE

EPA Science Inventory

The chemical and biological impacts of two coastal golf courses that receive wastewater spray irrigation were determined during a two-year period. A variety of techniques were used to assess the spatial and temporal variability of contaminant levels and their bioavailability in t...

Distribution of Gull Specific Molecular Marker in Coastal Areas of Lake Ontario

EPA Science Inventory

Gulls have been implicated as primary sources of fecal contamination in the Great Lakes, a fact that may have health implications due to the potential spread of microbial pathogens by waterfowl. To better understand the spatial variability of gull fecal contamination, a gull-spe...

PILOT IN SITU CAPPING PROJECT FOR PALOS VERDES SHELF CONTAMINATED SEDIMENTS

EPA Science Inventory

The Palos Verdes Shelf Pilot Capping Project will evaluate the short-term results of capping the DDT- and PCB-contaminated sediment with clean sediment. It will also determine how these results are affected by variables such as cap material, placement method and water depth. The ...

CREATION OF A GEOGRAPHIC INFORMATION SYSTEM TO IDENTIFY AT-RISK POPULATIONS IN NEW JERSEY AND NEW YORK FOR CONSUMPTION OF CONTAMINATED FISH AND SEAFOOD

EPA Science Inventory

Project Objective: To identify at-risk populations, particularly women of child bearing years and young children, for consumption of contaminated fish and seafood via the use of geographically and demographically defined seafood consumption patterns and fish/seafood contaminatio...

Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region, Jordan

NASA Astrophysics Data System (ADS)

Xanke, Julian; Liesch, Tanja; Goeppert, Nadine; Klinger, Jochen; Gassen, Niklas; Goldscheider, Nico

2017-09-01

Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.

Semi-quantitative evaluation of fecal contamination potential by human and ruminant sources using multiple lines of evidence

USGS Publications Warehouse

Stoeckel, D.M.; Stelzer, E.A.; Stogner, R.W.; Mau, D.P.

2011-01-01

Protocols for microbial source tracking of fecal contamination generally are able to identify when a source of contamination is present, but thus far have been unable to evaluate what portion of fecal-indicator bacteria (FIB) came from various sources. A mathematical approach to estimate relative amounts of FIB, such as Escherichia coli, from various sources based on the concentration and distribution of microbial source tracking markers in feces was developed. The approach was tested using dilute fecal suspensions, then applied as part of an analytical suite to a contaminated headwater stream in the Rocky Mountains (Upper Fountain Creek, Colorado). In one single-source fecal suspension, a source that was not present could not be excluded because of incomplete marker specificity; however, human and ruminant sources were detected whenever they were present. In the mixed-feces suspension (pet and human), the minority contributor (human) was detected at a concentration low enough to preclude human contamination as the dominant source of E. coli to the sample. Without the semi-quantitative approach described, simple detects of human-associated marker in stream samples would have provided inaccurate evidence that human contamination was a major source of E. coli to the stream. In samples from Upper Fountain Creek the pattern of E. coli, general and host-associated microbial source tracking markers, nutrients, and wastewater-associated chemical detections-augmented with local observations and land-use patterns-indicated that, contrary to expectations, birds rather than humans or ruminants were the predominant source of fecal contamination to Upper Fountain Creek. This new approach to E. coli allocation, validated by a controlled study and tested by application in a relatively simple setting, represents a widely applicable step forward in the field of microbial source tracking of fecal contamination. ?? 2011 Elsevier Ltd.

Assessment of the environmental microbiological cross contamination following hand drying with paper hand towels or an air blade dryer.

PubMed

Margas, E; Maguire, E; Berland, C R; Welander, F; Holah, J T

2013-08-01

This study compared the potential for cross contamination of the surrounding environment resulting from two different hand-drying methods: paper towels and the use of an air blade dryer. One hundred volunteers for each method washed their hands and dried them using one of the two methods. Bacterial contamination of the surrounding environment was measured using settle plates placed on the floor in a grid pattern, air sampling and surface swabs. Both drying methods produced ballistic droplets in the immediate vicinity of the hand-drying process. The air blade dryer produced a larger number of droplets which were dispersed over a larger area. Settle plates showed increased microbial contamination in the grid squares which were affected by ballistic droplets. Using the settle plates counts, it was estimated that approx. 1.7 × 10(5) cfu more micro-organisms were left on the laboratory floor (total area approx. 17.15 m(2)) after 100 volunteers used an air blade dryer compared to when paper towels were used. The two drying methods led to different patterns of ballistic droplets and levels of microbial contamination under heavy use conditions. Whilst the increase in microbial levels in the environment is not significant if only nonpathogenic micro-organisms are spread, it may increase the risk of pathogen contamination of the environment when pathogens are occasionally present on people's hands. The study suggests that the risk of cross contamination from the washroom users to the environment and subsequent users should be considered when choosing a hand-drying method. The data could potentially give guidance following the selection of drying methods on implementing measures to minimise the risk of cross contamination. © 2013 The Society for Applied Microbiology.

Biogeochemistry of heavy metals in contaminated excessively moistened soils (Analytical review)

NASA Astrophysics Data System (ADS)

Vodyanitskii, Yu. N.; Plekhanova, I. O.

2014-03-01

The biogeochemical behavior of heavy metals in contaminated excessively moistened soils depends on the development of reducing conditions (either moderate or strong). Upon the moderate biogenic reduction, Cr as the metal with variable valence forms low-soluble compounds, which decreases its availability to plants and prevents its penetration into surface- and groundwater. Creation of artificial barriers for Cr fixation on contaminated sites is based on the stimulation of natural metal-reducing bacteria. Arsenic, being a metalloid with a variable valence, is mobilized upon the moderate biogenic reduction. The mobility of siderophilic heavy metals with a constant valence grows under the moderate reducing conditions at the expense of dissolution of iron (hydr)oxides as carriers of these metals. Zinc, which can enter the newly formed goethite lattice, is an exception. Strong reduction processes in organic excessively moist and flooded soils (usually enriched in S) lead to the formation of low-soluble sulfides of heavy elements with both variable (As) and constant (Cu, Ni, Zn, and Pb) valence. On changing aquatic regime in overmoistened soils and their drying, sulfides of heavy metals are oxidized, and previously fixed metals are mobilized.

Geochemical patterns in soils of the karst region, Croatia

USGS Publications Warehouse

Prohic, E.; Hausberger, G.; Davis, J.C.

1997-01-01

Soil samples were collected at 420 locations in a 5-km grid pattern in the Istria and Gorski Kotar areas of Croatia, and on the Croatian islands of Cres, Rab and Krk, in order to relate geochemical variation in the soils to underlying differences in geology, bedrock lithology, soil type, environment and natural versus anthropogenic influences. Specific objectives included assessment of possible agricultural and industrial sources of contamination, especially from airborne effluent emitted by a local power plant. The study also tested the adequacy of a fixed-depth soil sampling procedure developed for meager karstic soils. Although 40 geochemical variables were analyzed, only 15 elements and 5 radionuclides are common to all the sample locations. These elements can be divided into three groups: (1) those of mostly anthropogenic origin -Pb, V, Cu and Cr; (2) those of mixed origin - radionuclides and Zn; and (3) those of mostly geogene origin -Ba, Sr, Ti, Al, Na, Ca, Mg, Fe, Mn, Ni and Co. Variation in Pb shows a strong correlation with the pattern of road traffic in Istria. The distributions of Ca, Na and Mg in the flysch basins of southern Istria and Slovenia are clearly distinguishable from the distributions of these elements in the surrounding carbonate terrains, a consequence of differences in bedrock permeability, type of drainage and pH. The spatial pattern of Cs from the Chernobyl nuclear power plant accident reflects almost exclusively the precipitation in Istria during the days immediately after the explosion. ?? 1997 Elsevier Science B.V.

Analysis of Nonvolatile Residue (NVR) from Spacecraft Systems

NASA Technical Reports Server (NTRS)

Colony, J. A.

1985-01-01

Organic contamination on critical spacecraft surfaces can cause electronic problems, serious attenuation of various optical signals, thermal control changes, and adhesion problems. Such contaminants can be detected early by the controlled use of witness mirrors, witness plates, wipe sampling, or direct solvent extraction. Each method requires careful control of variables of technique and materials to attain the ultimate sensitivities inherent to that procedure. Subsequent chemical analysis of the contaminant sample by infrared and mass spectrometry identifies the components, gives semiquantitative estimates of contaminant thickness, indicates possible sources of the nonvolatile residue (NVR), and provides guidance for effective cleanup procedures.

A true real-time, on-line security system for waterborne pathogen surveillance

NASA Astrophysics Data System (ADS)

Adams, John A.; McCarty, David L.

2008-04-01

Over the past several years many advances have been made to monitor potable water systems for toxic threats. However, the need for real-time, on-line systems to detect the malicious introduction of deadly pathogens still exists. Municipal water distribution systems, government facilities and buildings, and high profile public events remain vulnerable to terrorist-related biological contamination. After years of research and development, an instrument using multi-angle light scattering (MALS) technology has been introduced to achieve on-line, real-time detection and classification of a waterborne pathogen event. The MALS system utilizes a continuous slip stream of water passing through a flow cell in the instrument. A laser beam, focused perpendicular to the water flow, strikes particles as they pass through the beam generating unique light scattering patterns that are captured by photodetectors. Microorganisms produce patterns termed 'bio-optical signatures' which are comparable to fingerprints. By comparing these bio-optical signatures to an on-board database of microorganism patterns, detection and classification occurs within minutes. If a pattern is not recognized, it is classified as an 'unknown' and the unidentified contaminant is registered as a potential threat. In either case, if the contaminant exceeds a customer's threshold, the system will immediately alert personnel to the contamination event while extracting a sample for confirmation. The system, BioSentry TM, developed by JMAR Technologies is now field-tested and commercially available. BioSentry is cost effective, uses no reagents, operates remotely, and can be used for continuous microbial surveillance in many water treatment environments. Examples of HLS installations will be presented along with data from the US EPA NHSRC Testing and Evaluation Facility.

Organochlorine contaminant and stable isotope profiles in Arctic fox (Alopex lagopus) from the Alaskan and Canadian Arctic.

PubMed

Hoekstra, P F; Braune, B M; O'Hara, T M; Elkin, B; Solomon, K R; Muir, D C G

2003-01-01

Arctic fox (Alopex lagopus) is a circumpolar species distributed across northern Canada and Alaska. Arctic fox muscle and liver were collected at Barrow, AK, USA (n=18), Holman, NT, Canada (n=20), and Arviat, NU, Canada (n=20) to elucidate the feeding ecology of this species and relate these findings to body residue patterns of organochlorine contaminants (OCs). Stable carbon (delta 13C) and nitrogen (delta 15N) isotope analyses of Arctic fox muscle indicated that trophic position (estimated by delta 15N) is positively correlated with increasing delta 13C values, suggesting that Arctic fox with a predominantly marine-based foraging strategy occupy a higher trophic level than individuals mostly feeding from a terrestrial-based carbon source. At all sites, the rank order for OC groups in muscle was polychlorinated biphenyls (Sigma PCB) > chlordane-related compounds (Sigma CHLOR) > hexachlorocyclohexane (Sigma HCH) > total toxaphene (TOX) > or = chlorobenzenes (Sigma ClBz) > DDT-related isomers (Sigma DDT). In liver, Sigma CHLOR was the most abundant OC group, followed by Sigma PCB > TOX > Sigma HCH > Sigma ClBz > Sigma DDT. The most abundant OC analytes detected from Arctic fox muscle and liver were oxychlordane, PCB-153, and PCB-180. The comparison of delta 15N with OC concentrations indicated that relative trophic position might not accurately predict OC bioaccumulation in Arctic fox. The bioaccumulation pattern of OCs in the Arctic fox is similar to the polar bear. While Sigma PCB concentrations were highly variable, concentrations in the Arctic fox were generally below those associated with the toxicological endpoints for adverse effects on mammalian reproduction. Further research is required to properly elucidate the potential health impacts to this species from exposure to OCs.

Contamination by Microcystis and microcystins of blue-green algae food supplements (BGAS) on the Italian market and possible risk for the exposed population.

PubMed

Vichi, Susanna; Lavorini, Paolo; Funari, Enzo; Scardala, Simona; Testai, Emanuela

2012-12-01

Blue green algae supplements (BGAS) are generally proposed as health-promoting natural products for their purported beneficial effects. Spirulina spp. and Aphanizomenon flos aquae are mainly used in BGAS production. They are usually collected from the natural environment, where other potentially toxic cyanobacteria can be present, making possible BGAS contamination by cyanotoxins, with potential risk for human health. In this work we apply a combined approach, by using chemical and molecular techniques, on BGAS of 17 brands available in Italy. Samples containing Spirulina-only were free of contamination. The Aphanizomenon flos aquae-based samples were contaminated by highly variable levels of microcystins (MC-LR and MC-LA congeners), up to 5.2 μg MC-LR equivalents per gram product. The highest variability (up to 50 fold) was among batches of the same brand, although intra-batch differences were also evidenced. PCR analyses were positive only for the presence of Microcystis sp., identified as the toxin-producing species responsible for contamination. At the maximum contamination levels found, a risk for consumers can be expected following chronic or sub-chronic exposure to a reasonable daily BGAS consumption of 4 g. The need for a strict monitoring by producers and Health Authority to assure an adequate protection for consumers is underscored. Copyright © 2012 Elsevier Ltd. All rights reserved.

Children's Exposure to Environmental Contaminants: An Editorial Reflection of Articles in the IJERPH Special Issue Entitled, "Children's Exposure to Environmental Contaminants".

PubMed

Ferguson, Alesia; Solo-Gabriele, Helena

2016-11-09

Children are at increased vulnerability to many environmental contaminants compared to adults due to their unique behavior patterns, increased contaminant intake per body weight, and developing biological systems. Depending upon their age, young children may crawl on the floor and may practice increased hand to mouth activity that may increase their dose-intake of specific contaminants that accumulate in dust and other matrices. Children are also smaller in size than adults, resulting in a greater body burden for a given contaminant dose. Because children undergo rapid transitions through particular developmental stages they are also especially vulnerable during certain growth-related time windows. A Special Issue was organized focused on the latest findings in the field of children's environmental exposure for these reasons. This editorial introduces articles in this Special Issue and emphasizes their main findings in advancing the field. From the many articles submitted to this Special Issue from around the world, 23 were accepted and published. They focus on a variety of research areas such as children's activity patterns, improved risk assessment methods to estimate exposures, and exposures in various contexts and to various contaminants. The future health of a nation relies on protecting the children from adverse exposures and understanding the etiology of childhood diseases. The field of children's environmental exposures must consider improved and comprehensive research methods aimed at introducing mitigation strategies locally, nationally, and globally. We are happy to introduce a Special Issue focused on children's environmental exposure and children's health and hope that it contributes towards improved health of children.

Combining Individual-Based Modeling and Food Microenvironment Descriptions To Predict the Growth of Listeria monocytogenes on Smear Soft Cheese

PubMed Central

Ferrier, Rachel; Hezard, Bernard; Lintz, Adrienne; Stahl, Valérie

2013-01-01

An individual-based modeling (IBM) approach was developed to describe the behavior of a few Listeria monocytogenes cells contaminating smear soft cheese surface. The IBM approach consisted of assessing the stochastic individual behaviors of cells on cheese surfaces and knowing the characteristics of their surrounding microenvironments. We used a microelectrode for pH measurements and micro-osmolality to assess the water activity of cheese microsamples. These measurements revealed a high variability of microscale pH compared to that of macroscale pH. A model describing the increase in pH from approximately 5.0 to more than 7.0 during ripening was developed. The spatial variability of the cheese surface characterized by an increasing pH with radius and higher pH on crests compared to that of hollows on cheese rind was also modeled. The microscale water activity ranged from approximately 0.96 to 0.98 and was stable during ripening. The spatial variability on cheese surfaces was low compared to between-cheese variability. Models describing the microscale variability of cheese characteristics were combined with the IBM approach to simulate the stochastic growth of L. monocytogenes on cheese, and these simulations were compared to bacterial counts obtained from irradiated cheeses artificially contaminated at different ripening stages. The simulated variability of L. monocytogenes counts with the IBM/microenvironmental approach was consistent with the observed one. Contrasting situations corresponding to no growth or highly contaminated foods could be deduced from these models. Moreover, the IBM approach was more effective than the traditional population/macroenvironmental approach to describe the actual bacterial behavior variability. PMID:23872572

Escherichia coli O157:H7 infections associated with consumption of locally grown strawberries contaminated by deer.

PubMed

Laidler, Matthew R; Tourdjman, Mathieu; Buser, Genevieve L; Hostetler, Trevor; Repp, Kimberly K; Leman, Richard; Samadpour, Mansour; Keene, William E

2013-10-01

An outbreak of Escherichia coli O157:H7 was identified in Oregon through an increase in Shiga toxin-producing E. coli cases with an indistinguishable, novel pulsed-field gel electrophoresis (PFGE) subtyping pattern. We defined confirmed cases as persons from whom E. coli O157:H7 with the outbreak PFGE pattern was cultured during July-August 2011, and presumptive cases as persons having a household relationship with a case testing positive for E. coli O157:H7 and coincident diarrheal illness. We conducted an investigation that included structured hypothesis-generating interviews, a matched case-control study, and environmental and traceback investigations. We identified 15 cases. Six cases were hospitalized, including 4 with hemolytic uremic syndrome (HUS). Two cases with HUS died. Illness was significantly associated with strawberry consumption from roadside stands or farmers' markets (matched odds ratio, 19.6; 95% confidence interval, 2.9-∞). A single farm was identified as the source of contaminated strawberries. Ten of 111 (9%) initial environmental samples from farm A were positive for E. coli O157:H7. All samples testing positive for E. coli O157:H7 contained deer feces, and 5 tested farm fields had ≥ 1 sample positive with the outbreak PFGE pattern. The investigation identified fresh strawberries as a novel vehicle for E. coli O157:H7 infection, implicated deer feces as the source of contamination, and highlights problems concerning produce contamination by wildlife and regulatory exemptions for locally grown produce. A comprehensive hypothesis-generating questionnaire enabled rapid identification of the implicated product. Good agricultural practices are key barriers to wildlife fecal contamination of produce.

Patterns of organochlorine contamination in lake trout from Wisconsin waters of the Great Lakes

USGS Publications Warehouse

Miller, Michael A.; Madenjian, Charles P.; Masnado, Robert G.

1992-01-01

To investigate spatial and temporal patterns of organochlorine contamination in lake trout from Wisconsin waters of the Great Lakes, we examined laboratory contaminant analysis data of muscle tissue samples from Lake Michigan (n=317) and Lake Superior (n=53) fish. Concentrations of polychlorinated biphenyls (PCBs), chlordane, and dieldrin, reported as mg/kg wet weight in 620 mm to 640 mm mean length Lake Michigan lake trout, decreased over time. Mean total PCB concentration declined exponentially from 9.7 in 1975 to 1.9 in 1990. Total chlordane concentration declined 63 percent from 0.48 in 1983 to 0.18 in 1990, and dieldrin declined 52 percent during this same period, from 0.21 to 0.10. The bioaccumulation rate of PCBs is significantly lower for lake trout inhabiting Lake Michigan's midlake reef complex, compared to lake trout from the nearshore waters of western Lake Michigan. Organochlorine compound concentrations were greater in Lake Michigan lake trout than Lake Superior fish. Lake Superior lean lake trout and siscowet exhibited similar rates of PCB bioaccumulation despite major differneces in muscle tissue lipid content between the two subspecies. The lack of a significant difference in the PCB bioaccumulation rates of lean trout and siscowet suggests that lipid content may not be an important factor influencing PCB bioaccumulation in lake trout, within the range of lipid concentrations observed. Relative concentrations of the various organochlorine contaminants found in lake trout were highly correlated, suggesting similar mass balance processes for these compounds. Evidence presented revealing spatial and temporal patterns of organochlorine contamination may be of value in reestablishing self-sustaining populations of lake trout in Lake Michigan.

Processing-Dependent and Clonal Contamination Patterns of Listeria monocytogenes in the Cured Ham Food Chain Revealed by Genetic Analysis

PubMed Central

Morganti, Marina; Scaltriti, Erika; Cozzolino, Paolo; Bolzoni, Luca; Casadei, Gabriele; Pierantoni, Marco; Foni, Emanuela

2015-01-01

The quantitative and qualitative patterns of environmental contamination by Listeria monocytogenes were investigated in the production chain of dry-cured Parma ham. Standard arrays of surfaces were sampled in processing facilities during a single visit per plant in the three compartments of the food chain, i.e., ham production (19 plants) and postproduction, which was divided into deboning (43 plants) and slicing (25 plants) steps. The numbers of sampled surfaces were 384 in ham production, with 25 positive for L. monocytogenes, and 1,084 in postproduction, with 83 positives. Statistical analysis of the prevalence of contaminated surfaces showed that in ham production, contamination was higher at the beginning of processing and declined significantly toward the end, while in postproduction, prevalence rose toward the end of processing. Prevalence was higher in the deboning facilities than in slicing facilities and was dependent on the type of surface (floor/drainage > clothing > equipment). The qualitative pattern of contamination was investigated through an analysis of the survey isolates and a set of isolates derived from routine monitoring, including longitudinal isolations. Pulsed-field gel electrophoresis (PFGE) and whole-genome single-nucleotide polymorphism (SNP) analysis revealed a remarkable clonality of L. monocytogenes within plants, with the detection of 16 plant-specific clones out of 17 establishments with multiple isolates. Repeated detections of clonal isolates >6 months apart were also observed. Six was the maximum number of between-isolate differences in core SNPs observed within these clones. Based on the same six-SNP threshold, three clusters of clonal isolates, shared by six establishments, were also identified. The spread of L. monocytogenes within and between plants, as indicated by its clonal behavior, is a matter of concern for the hygienic management of establishments. PMID:26590278

Human health risk assessment in restoring safe and productive use of abandoned contaminated sites.

PubMed

Wcisło, Eleonora; Bronder, Joachim; Bubak, Anicenta; Rodríguez-Valdés, Eduardo; Gallego, José Luis R

2016-09-01

In Europe soil contamination has been recognized as a serious problem. The needs to remediate contaminated sites are not questionable, although the remediation actions are often hindered by their very high financial costs. On the other hand, the abandoned contaminated sites may have the potential for redevelopment and creating conditions appropriate for their productive reuse bringing social, economic and environmental benefits. The main concern associated with the contaminated sites is their potential adverse health impact. Therefore, in the process of contaminated site redevelopment the risk assessment and the subsequent risk management decisions will play a crucial role. The main objective of this study was to illustrate the role of the human health risk assessment (HRA) in supporting site remediation and reuse decisions. To exemplify the significance of the HRA process in this field the Nitrastur site, located in Asturias, Spain was used. Risks resulting from soil contamination with arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), mercury (Hg), zinc (Zn) and lead (Pb) were assessed under three potential future land use patterns: industrial, residential and recreational. The results of the study indicated that soil at the Nitrastur site might pose non-cancer and cancer risks to potential future receptors - industrial workers, residents and recreational users. Arsenic and lead are the main substances responsible for the health risk and the primary drivers of remedial decisions at the site. The highest total cancer risks were observed under the residential scenario, followed in descending order by the recreational and industrial ones. The remedial maps illustrate in which areas remediation activities are required, depending on a given land use pattern. The obtained results may be used to develop, analyse, compare and select the remedial options within the intended land use pattern. They may also be used to support the decisions concerning the reuse of the site or to create different redevelopment plans for different parts of the site. The study may help improve understanding and interaction between risk assessors and risk managers which are necessary to make proper, fully informed decisions enhancing public trust and credibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determining significant endpoints for ecological risk analyses. 1998 annual progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinton, T.G.; Congdon, J.; Scott, D.

1998-06-01

'The goal of this report is to establish a protocol for assessing risks to non-human populations exposed to environmental stresses typically found on many DOE sites. The authors think that they can achieve this by using novel biological dosimeters in controlled, manipulative dose/effects experiments, and by coupling changes in metabolic rates and energy allocation patterns to meaningful population response variables (such as age-specific survivorship, reproductive output, age at maturity and longevity). This research is needed to determine the relevancy of sublethal cellular damage to the performance of individuals and populations exposed to chronic, low-level radiation, and radiation with concomitant exposuremore » to chemicals. They believe that a scientifically defensible endpoint for measuring ecological risks can only be determined once its understood the extent to which molecular damage from contaminant exposure is detrimental at the individual and population levels of biological organization. The experimental facility will allow them to develop a credible assessment tool for appraising ecological risks, and to evaluate the effects of radionuclide/chemical synergisms on non-human species. This report summarizes work completed midway of a 3-year project that began in November 1996. Emphasis to date has centered on three areas: (1) developing a molecular probe to measure stable chromosomal aberrations known as reciprocal translocations, (2) constructing an irradiation facility where the statistical power inherent in replicated mesocosms can be used to address the response of non-human organisms to exposures from low levels of radiation and metal contaminants, and (3) quantifying responses of organisms living in contaminated mesocosms and field sites.'« less

Evaluating the temporal variability of concentrations of POPs in a glacier-fed stream food chain using a combined modeling approach.

PubMed

Morselli, Melissa; Semplice, Matteo; Villa, Sara; Di Guardo, Antonio

2014-09-15

Falling snow acts as an efficient scavenger of contaminants from the atmosphere and, accumulating on the ground surface, behaves as a temporary storage reservoir; during snow aging and metamorphosis, contaminants may concentrate and be subject to pulsed release during intense snow melt events. In high-mountain areas, firn and ice play a similar role. The consequent concentration peaks in surface waters can pose a risk to high-altitude ecosystems, since snow and ice melt often coincide with periods of intense biological activity. In such situations, the role of dynamic models can be crucial when assessing environmental behavior of contaminants and their accumulation patterns in aquatic organisms. In the present work, a dynamic fate modeling approach was combined to a hydrological module capable of estimating water discharge and snow/ice melt contributions on an hourly basis, starting from hourly air temperatures. The model was applied to the case study of the Frodolfo glacier-fed stream (Italian Alps), for which concentrations of a number of persistent organic pollutants (POPs), such as polychlorinated biphenyl (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) in stream water and four macroinvertebrate groups were available. Considering the uncertainties in input data, results showed a satisfying agreement for both water and organism concentrations. This study showed the model adequacy for the estimation of pollutant concentrations in surface waters and bioaccumulation in aquatic organisms, as well as its possible role in assessing the consequences of climate change on the cycle of POPs. Copyright © 2014 Elsevier B.V. All rights reserved.

Spike Pattern Structure Influences Synaptic Efficacy Variability under STDP and Synaptic Homeostasis. II: Spike Shuffling Methods on LIF Networks

PubMed Central

Bi, Zedong; Zhou, Changsong

2016-01-01

Synapses may undergo variable changes during plasticity because of the variability of spike patterns such as temporal stochasticity and spatial randomness. Here, we call the variability of synaptic weight changes during plasticity to be efficacy variability. In this paper, we investigate how four aspects of spike pattern statistics (i.e., synchronous firing, burstiness/regularity, heterogeneity of rates and heterogeneity of cross-correlations) influence the efficacy variability under pair-wise additive spike-timing dependent plasticity (STDP) and synaptic homeostasis (the mean strength of plastic synapses into a neuron is bounded), by implementing spike shuffling methods onto spike patterns self-organized by a network of excitatory and inhibitory leaky integrate-and-fire (LIF) neurons. With the increase of the decay time scale of the inhibitory synaptic currents, the LIF network undergoes a transition from asynchronous state to weak synchronous state and then to synchronous bursting state. We first shuffle these spike patterns using a variety of methods, each designed to evidently change a specific pattern statistics; and then investigate the change of efficacy variability of the synapses under STDP and synaptic homeostasis, when the neurons in the network fire according to the spike patterns before and after being treated by a shuffling method. In this way, we can understand how the change of pattern statistics may cause the change of efficacy variability. Our results are consistent with those of our previous study which implements spike-generating models on converging motifs. We also find that burstiness/regularity is important to determine the efficacy variability under asynchronous states, while heterogeneity of cross-correlations is the main factor to cause efficacy variability when the network moves into synchronous bursting states (the states observed in epilepsy). PMID:27555816

Effective application of multiple locus variable number of tandem repeats analysis to tracing Staphylococcus aureus in food-processing environment.

PubMed

Rešková, Z; Koreňová, J; Kuchta, T

2014-04-01

A total of 256 isolates of Staphylococcus aureus were isolated from 98 samples (34 swabs and 64 food samples) obtained from small or medium meat- and cheese-processing plants in Slovakia. The strains were genotypically characterized by multiple locus variable number of tandem repeats analysis (MLVA), involving multiplex polymerase chain reaction (PCR) with subsequent separation of the amplified DNA fragments by an automated flow-through gel electrophoresis. With the panel of isolates, MLVA produced 31 profile types, which was a sufficient discrimination to facilitate the description of spatial and temporal aspects of contamination. Further data on MLVA discrimination were obtained by typing a subpanel of strains by multiple locus sequence typing (MLST). MLVA coupled to automated electrophoresis proved to be an effective, comparatively fast and inexpensive method for tracing S. aureus contamination of food-processing factories. Subspecies genotyping of microbial contaminants in food-processing factories may facilitate identification of spatial and temporal aspects of the contamination. This may help to properly manage the process hygiene. With S. aureus, multiple locus variable number of tandem repeats analysis (MLVA) proved to be an effective method for the purpose, being sufficiently discriminative, yet comparatively fast and inexpensive. The application of automated flow-through gel electrophoresis to separation of DNA fragments produced by multiplex PCR helped to improve the accuracy and speed of the method. © 2013 The Society for Applied Microbiology.

Spatial and temporal migration of a landfill leachate plume in alluvium

USGS Publications Warehouse

Masoner, Jason R.; Cozzarelli, Isabelle M.

2015-01-01

Leachate from unlined or leaky landfills can create groundwater contaminant plumes that last decades to centuries. Understanding the dynamics of leachate movement in space and time is essential for monitoring, planning and management, and assessment of risk to groundwater and surface-water resources. Over a 23.4-year period (1986–2010), the spatial extent of the Norman Landfill leachate plume increased at a rate of 7800 m2/year and expanded by 878 %, from an area of 20,800 m2 in 1986 to 203,400 m2 in 2010. A linear plume velocity of 40.2 m/year was calculated that compared favorably to a groundwater-seepage velocity of 55.2 m/year. Plume-scale hydraulic conductivity values representative of actual hydrogeological conditions in the alluvium ranged from 7.0 × 10−5 to 7.5 × 10−4 m/s, with a median of 2.0 × 10−4 m/s. Analyses of field-measured and calculated plume-scale hydraulic conductivity distributions indicate that the upper percentiles of field-measured values should be considered to assess rates of plume-scale migration, spreading, and biodegradation. A pattern of increasing Cl− concentrations during dry periods and decreasing Cl− concentrations during wet periods was observed in groundwater beneath the landfill. The opposite occurred in groundwater downgradient from the landfill; that is, Cl− concentrations in groundwater downgradient from the landfill decreased during dry periods and increased during wet periods. This pattern of changing Cl−concentrations in response to wet and dry periods indicates that the landfill retains or absorbs leachate during dry periods and produces lower concentrated leachate downgradient. During wet periods, the landfill receives more recharge which dilutes leachate in the landfill but increases leachate migration from the landfill and produces a more concentrated contaminant plume. This approach of quantifying plume expansion, migration, and concentration during variable hydrologic conditions provides increased understanding of plume behavior and migration potential and may be applied at less monitored landfill sites to evaluate potential risks of contamination to downgradient receptors.

Bacterial biogeographical patterns in a cooking center for hospital foodservice.

PubMed

Stellato, Giuseppina; La Storia, Antonietta; Cirillo, Teresa; Ercolini, Danilo

2015-01-16

Microbial contamination in foodservice environments plays a fundamental role in food quality and safety. In such environments the composition of the microbiota is influenced by the characteristics of the specific surfaces and by food handling and processing and a resident microbiota may be present in each site. In this study, the bacterial biogeographical patterns in a hospital cooking center was studied by 16S rRNA-based culture-independent high-throughput amplicon sequencing in order to provide a comprehensive mapping of the surfaces and tools that come in contact with foods during preparation. Across all area, surface swab-samples from work surfaces of different zones were taken: food pre-processing rooms (dedicated to fish, vegetables, and red and white meat), storage room and kitchen. The microbiota of environmental swabs was very complex, including more than 500 operational taxonomic units (OTUs) with extremely variable relative abundances (0.02-99%) depending on the species. A core microbiota was found that was common to more than 70% of the samples analyzed and that included microbial species that were common across all areas such as Acinetobacter, Chryseobacterium, Moraxellaceae, and Alicyclobacillus, although their abundances were below 10% of the microbiota. Some surfaces were contaminated by high levels of either Pseudomonas, Psychrobacter, Paracoccus, or Kocuria. However, beta diversity analysis showed that, based on the composition of the microbiota, the environmental samples grouped according to the sampling time but not according to the specific area of sampling except for the case of samples from the vegetable pre-processing room that showed a higher level of similarity. The cleaning procedures can have a very strong impact on the spatial distribution of the microbial communities, as the use of the same cleaning tools can be even a possible vector of bacterial diffusion. Most of the microbial taxa found are not those commonly found in food as spoilers or hazardous bacteria, which indicates that food and storage conditions can be very selective in the growth of possible contaminants. Copyright © 2014 Elsevier B.V. All rights reserved.

Relationship Between Chronic Obstructive Pulmonary Disease and Air Pollutants Depending on the Origin and Trajectory of Air Masses in the North of Spain.

PubMed

Santurtún, Ana; Rasilla, Domingo F; Riancho, Leyre; Zarrabeitia, María T

2017-11-01

Chronic obstructive pulmonary disease (COPD) is a common respiratory condition and one of the leading causes of death. Our aim was to analyze the association between emergency room visits due to this disease and meteorological variables and atmospheric contaminant levels in Santander, depending on the origin and trajectory of air masses. Data from emergency room visits at Hospital Marqués de Valdecilla were collected on a daily basis during an 8-year period. Data on concentrations of the main atmospheric pollutants and meteorological variables were also recorded.Retrotrajectories leading to Santander at a height of1,500 meters above sea level were then calculated. Finally, a correlation model was produced to evaluate the effect of the contaminants on emergency visitsdue to COPD. There is a direct association between PM 10 levels and the number of visits to the emergency room due to COPD. For every 10μg/m3 increase in pollutantlevels, emergency visitsincrease by3.34% (p=0.00005), and thiseffect is enhanced in individualsover 74 years of age. This effect is heightened when PM10 levels depend on air masses from the South and when air recirculation occurs. There is no association betweenother pollutants and the number of visits to the emergency room. Exposure to high levels of PM10 causes exacerbations in COPD patients. By studying the atmospheric circulation pattern, we can predict whether PM10 levels will be inappropriately high, and we can also obtain information about the particle components. Copyright © 2017 SEPAR. Publicado por Elsevier España, S.L.U. All rights reserved.

Prognostics Health Management Model for LED Package Failure Under Contaminated Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lall, Pradeep; Zhang, Hao; Davis, J Lynn

2015-06-06

The reliability consideration of LED products includes both luminous flux drop and color shift. Previous research either talks about luminous maintenance or color shift, because luminous flux degradation usually takes very long time to observe. In this paper, the impact of a VOC (volatile organic compound) contaminated luminous flux and color stability are examined. As a result, both luminous degradation and color shift had been recorded in a short time. Test samples are white, phosphor-converted, high-power LED packages. Absolute radiant flux is measured with integrating sphere system to calculate the luminous flux. Luminous flux degradation and color shift distance weremore » plotted versus aging time to show the degradation pattern. A prognostic health management (PHM) method based on the state variables and state estimator have been proposed in this paper. In this PHM framework, unscented kalman filter (UKF) was deployed as the carrier of all states. During the estimation process, third order dynamic transfer function was used to implement the PHM framework. Both of the luminous flux and color shift distance have been used as the state variable with the same PHM framework to exam the robustness of the method. Predicted remaining useful life is calculated at every measurement point to compare with the tested remaining useful life. The result shows that state estimator can be used as the method for the PHM of LED degradation with respect to both luminous flux and color shift distance. The prediction of remaining useful life of LED package, made by the states estimator and data driven approach, falls in the acceptable error-bounds (20%) after a short training of the estimator.« less

Microbial community functional structures in wastewater treatment plants as characterized by GeoChip.

PubMed

Wang, Xiaohui; Xia, Yu; Wen, Xianghua; Yang, Yunfeng; Zhou, Jizhong

2014-01-01

Biological WWTPs must be functionally stable to continuously and steadily remove contaminants which rely upon the activity of complex microbial communities. However, knowledge is still lacking in regard to microbial community functional structures and their linkages to environmental variables. To investigate microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and to understand the effects of environmental factors on their structure. 12 activated sludge samples were collected from four WWTPs in Beijing. A comprehensive functional gene array named GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes such as carbon, nitrogen, phosphorous and sulfur cycles, metal resistance, antibiotic resistance and organic contaminant degradation. High similarities of the microbial community functional structures were found among activated sludge samples from the four WWTPs, as shown by both diversity indices and the overlapped genes. For individual gene category, such as egl, amyA, lip, nirS, nirK, nosZ, ureC, ppx, ppk, aprA, dsrA, sox and benAB, there were a number of microorganisms shared by all 12 samples. Canonical correspondence analysis (CCA) showed that the microbial functional patterns were highly correlated with water temperature, dissolved oxygen (DO), ammonia concentrations and loading rate of chemical oxygen demand (COD). Based on the variance partitioning analyses (VPA), a total of 53% of microbial community variation from GeoChip data can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively. This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs.

Isolation and characterization of Escherichia coli pathotypes and factors associated with well and boreholes water contamination in Mombasa County

PubMed Central

Thani, Thani Suleiman; Symekher, Samwel Morris Lifumo; Boga, Hamadi; Oundo, Joseph

2016-01-01

Introduction Safe water for human consumption is important, but there is a limited supply. Mombasa County has water shortages making residences rely on other sources of water including boreholes and wells. Microbiological evaluation of drinking water is important to reduce exposure to water borne enteric diseases. This cross sectional study aimed at determining the frequency and characterization of Escherichia coli (E. coli) pathotypes from water samples collected from wells and boreholes in Mombasa County. Methods One hundred and fifty seven (157) water samples were collected from four divisions of the county and a questionnaire administered. The samples were inoculated to double strength MacConkey broth and incubated at 370C for up to 48 hours. Positive results were compared to the 3 tube McCrady MPN table. The E. coli were confirmed by Eijkman's test and antibiotic susceptibility carried out. Using polymerase chain reaction (PCR), the E. coli were characterized to establish pathotypes. Results One hundred and thirty one (n = 131; 83.4%) samples had coliform bacteria with only 79 (60.3%) samples having E. coli. Significant values (<0.05) were noted when coliforms were compared to variables with E. Coli showing no significance when compared to similar variables. E. coli (n = 77; 100%) tested were sensitive to Gentamicin, while all (n = 77; 100%) isolates were resistant to Ampicillin. PCR typed isolates as enteroinvasive E. Coli (EIEC). Conclusion Findings suggest that coliforms and E. coli are major contaminants of wells and boreholes in Mombasa County. The isolates have a variety of resistant and sensitivity patterns to commonly used antibiotics. PMID:27200121

The Use of Field and Mesocosm Experiments to Quantify Effects of Physical and Chemical Stressors in Mining-Contaminated Streams.

PubMed

Cadmus, Pete; Clements, William H; Williamson, Jacob L; Ranville, James F; Meyer, Joseph S; Gutiérrez Ginés, María Jesús

2016-07-19

Identifying causal relationships between acid mine drainage (AMD) and ecological responses in the field is challenging. In addition to the direct toxicological effects of elevated metals and reduced pH, mining activities influence aquatic organisms indirectly through physical alterations of habitat. The primary goal of this research was to quantify the relative importance of physical (metal-oxide deposition) and chemical (elevated metal concentrations) stressors on benthic macroinvertebrate communities. Mesocosm experiments conducted with natural assemblages of benthic macroinvertebrates established concentration-response relationships between metals and community structure. Field experiments quantified effects of metal-oxide contaminated substrate and showed significant differences in sensitivity among taxa. To predict the recovery of dominant taxa in the field, we integrated our measures of metal tolerance and substrate tolerance with estimates of drift propensity obtained from the literature. Our estimates of recovery were consistent with patterns observed at downstream recovery sites in the NFCC, which were dominated by caddisflies and baetid mayflies. We conclude that mesocosm and small-scale field experiments, particularly those conducted with natural communities, provide an ecologically realistic complement to laboratory toxicity tests. These experiments also control for the confounding variables associated with field-based approaches, thereby supporting causal relationships between AMD stressors and responses.

Occurrence and diversity of naphthalene dioxygenase genes in soil microbial communities from the Maritime Antarctic.

PubMed

Flocco, Cecilia G; Gomes, Newton C M; Mac Cormack, Walter; Smalla, Kornelia

2009-03-01

The diversity of naphthalene dioxygenase genes (ndo) in soil environments from the Maritime Antarctic was assessed, dissecting as well the influence of the two vascular plants that grow in the Antarctic: Deschampsia antarctica and Colobanthus quitensis. Total community DNA was extracted from bulk and rhizosphere soil samples from Jubany station and Potter Peninsula, South Shetland Islands. ndo genes were amplified by a nested PCR and analysed by denaturant gradient gel electrophoresis approach (PCR-DGGE) and cloning and sequencing. The ndo-DGGE fingerprints of oil-contaminated soil samples showed even and reproducible patterns, composed of four dominant bands. The presence of vascular plants did not change the relative abundance of ndo genotypes compared with bulk soil. For non-contaminated sites, amplicons were not obtained for all replicates and the variability among the fingerprints was comparatively higher, likely reflecting a lower abundance of ndo genes. The phylogenetic analyses showed that all sequences were affiliated to the nahAc genes closely related to those described for Pseudomonas species and related mobile genetic elements. This study revealed that a microdiversity of nahAc-like genes exists in microbial communities of Antarctic soils and quantitative PCR indicated that their relative abundance was increased in response to anthropogenic sources of pollution.

Sensitivity analyses of a colloid-facilitated contaminant transport model for unsaturated heterogeneous soil conditions.

NASA Astrophysics Data System (ADS)

Périard, Yann; José Gumiere, Silvio; Rousseau, Alain N.; Caron, Jean

2013-04-01

Certain contaminants may travel faster through soils when they are sorbed to subsurface colloidal particles. Indeed, subsurface colloids may act as carriers of some contaminants accelerating their translocation through the soil into the water table. This phenomenon is known as colloid-facilitated contaminant transport. It plays a significant role in contaminant transport in soils and has been recognized as a source of groundwater contamination. From a mechanistic point of view, the attachment/detachment of the colloidal particles from the soil matrix or from the air-water interface and the straining process may modify the hydraulic properties of the porous media. Šimůnek et al. (2006) developed a model that can simulate the colloid-facilitated contaminant transport in variably saturated porous media. The model is based on the solution of a modified advection-dispersion equation that accounts for several processes, namely: straining, exclusion and attachement/detachement kinetics of colloids through the soil matrix. The solutions of these governing, partial differential equations are obtained using a standard Galerkin-type, linear finite element scheme, implemented in the HYDRUS-2D/3D software (Šimůnek et al., 2012). Modeling colloid transport through the soil and the interaction of colloids with the soil matrix and other contaminants is complex and requires the characterization of many model parameters. In practice, it is very difficult to assess actual transport parameter values, so they are often calibrated. However, before calibration, one needs to know which parameters have the greatest impact on output variables. This kind of information can be obtained through a sensitivity analysis of the model. The main objective of this work is to perform local and global sensitivity analyses of the colloid-facilitated contaminant transport module of HYDRUS. Sensitivity analysis was performed in two steps: (i) we applied a screening method based on Morris' elementary effects and the one-at-a-time approach (O.A.T); and (ii), we applied Sobol's global sensitivity analysis method which is based on variance decompositions. Results illustrate that ψm (maximum sorption rate of mobile colloids), kdmc (solute desorption rate from mobile colloids), and Ks (saturated hydraulic conductivity) are the most sensitive parameters with respect to the contaminant travel time. The analyses indicate that this new module is able to simulate the colloid-facilitated contaminant transport. However, validations under laboratory conditions are needed to confirm the occurrence of the colloid transport phenomenon and to understand model prediction under non-saturated soil conditions. Future work will involve monitoring of the colloidal transport phenomenon through soil column experiments. The anticipated outcome will provide valuable information on the understanding of the dominant mechanisms responsible for colloidal transports, colloid-facilitated contaminant transport and, also, the colloid detachment/deposition processes impacts on soil hydraulic properties. References: Šimůnek, J., C. He, L. Pang, & S. A. Bradford, Colloid-Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification, Vadose Zone Journal, 2006, 5, 1035-1047 Šimůnek, J., M. Šejna, & M. Th. van Genuchten, The C-Ride Module for HYDRUS (2D/3D) Simulating Two-Dimensional Colloid-Facilitated Solute Transport in Variably-Saturated Porous Media, Version 1.0, PC Progress, Prague, Czech Republic, 45 pp., 2012.

Lumbar kinematic variability during gait in chronic low back pain and associations with pain, disability and isolated lumbar extension strength.

PubMed

Steele, James; Bruce-Low, Stewart; Smith, Dave; Jessop, David; Osborne, Neil

2014-12-01

Chronic low back pain is a multifactorial condition with many dysfunctions including gait variability. The lumbar spine and its musculature are involved during gait and in chronic low back pain the lumbar extensors are often deconditioned. It was therefore of interest to examine relationships between lumbar kinematic variability during gait, with pain, disability and isolated lumbar extension strength in participants with chronic low back pain. Twenty four participants with chronic low back pain were assessed for lumbar kinematics during gait, isolated lumbar extension strength, pain, and disability. Angular displacement and kinematic waveform pattern and offset variability were examined. Angular displacement and kinematic waveform pattern and offset variability differed across movement planes; displacement was highest and similar in frontal and transverse planes, and pattern variability and offset variability higher in the sagittal plane compared to frontal and transverse planes which were similar. Spearman's correlations showed significant correlations between transverse plane pattern variability and isolated lumbar extension strength (r=-.411) and disability (r=.401). However, pain was not correlated with pattern variability in any plane. The r(2) values suggested 80.5% to 86.3% of variance was accounted for by other variables. Considering the lumbar extensors role in gait, the relationship between both isolated lumbar extension strength and disability with transverse plane pattern variability suggests that gait variability may result in consequence of lumbar extensor deconditioning or disability accompanying chronic low back pain. However, further study should examine the temporality of these relationships and other variables might account for the unexplained variance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plant species affect colonization patterns and metabolic activity of associated endophytes during phytoremediation of crude oil-contaminated soil.

PubMed

Fatima, K; Imran, A; Amin, I; Khan, Q M; Afzal, M

2016-04-01

Plants coupled with endophytic bacteria hold great potential for the remediation of polluted environment. The colonization patterns and activity of inoculated endophytes in rhizosphere and endosphere of host plant are among the primary factors that may influence the phytoremediation process. However, these colonization patterns and metabolic activity of the inoculated endophytes are in turn controlled by none other than the host plant itself. The present study aims to determine such an interaction specifically for plant-endophyte systems remediating crude oil-contaminated soil. A consortium (AP) of two oil-degrading endophytic bacteria (Acinetobacter sp. strain BRSI56 and Pseudomonas aeruginosa strain BRRI54) was inoculated to two grasses, Brachiaria mutica and Leptochloa fusca, vegetated in crude oil-contaminated soil. Colonization patterns and metabolic activity of the endophytes were monitored in the rhizosphere and endosphere of the plants. Bacterial augmentation enhanced plant growth and crude oil degradation. Maximum crude oil degradation (78%) was achieved with B. mutica plants inoculated with AP consortium. This degradation was significantly higher than those treatments, where plants and bacteria were used individually or L. fusca and endophytes were used in combination. Moreover, colonization and metabolic activity of the endophytes were higher in the rhizosphere and endosphere of B. mutica than L. fusca. The plant species affected not only colonization pattern and biofilm formation of the inoculated bacteria in the rhizosphere and endosphere of the host plant but also affected the expression of alkane hydroxylase gene, alkB. Hence, the investigation revealed that plant species can affect colonization patterns and metabolic activity of inoculated endophytic bacteria and ultimately the phytoremediation process.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on small intestinal morphology of turkeys.

PubMed

Girish, C K; Smith, T K

2008-06-01

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on morphometric indices of duodenum, jejunum, and ileum in turkeys. The possible preventative effect of a polymeric glucomannan mycotoxin adsorbent (GMA) was also determined. Three hundred 1-d-old male turkey poults were fed wheat, corn, and soybean meal-based starter (0 to 3 wk), grower (4 to 6 wk), developer (7 to 9 wk), and finisher (10 to 12 wk) diets formulated with control grains, contaminated grains, and contaminated grains + 0.2% GMA. Morphometric indices were measured at the end of each growth phase and included villus height (VH), crypt depth, villus width, thicknesses of submucosa and muscularis, villus-to-crypt ratio, and apparent villus surface area (AVSA). At the end of the starter phase, feedborne mycotoxins significantly decreased the VH in the duodenum, and supplementation of the contaminated diet with GMA prevented this effect. The feeding of contaminated grains also reduced (P < 0.05) VH and AVSA in jejunum, whereas none of the variables were affected in the ileum. Villus width and AVSA of duodenum, VH, and AVSA of jejunum and submucosa thickness of ileum were significantly reduced when birds were fed contaminated grains at the end of the grower phase, and supplementation with GMA prevented these effects in jejunum and ileum. No effects of diets were seen on morphometric variables at the end of the developer and finisher phases. It was concluded that consumption of grains naturally contaminated with Fusarium mycotoxins results in adverse effects on intestinal morphology during early growth phases of turkeys, and GMA can prevent many of these effects.

Removal of Inorganic, Microbial, and Particulate Contaminants from Secondary Treated Wastewater - Village Marine Tec. Expeditionary Unit Water Purifier, Generation 1 at Gallup, NM

EPA Science Inventory

The EUWP was developed to treat challenging water sources with variable turbidity, chemical contamination, and very high total dissolved solids (TDS) including seawater, during emergency situations when other water treatment facilities are incapacitated. The EUWP components are ...

COMPARISON OF THE TEMPORAL VARIABILITY OF ENTEROCOCCAL CLUSTERS IN IMPACTED STREAMS USING A MULTIPLEX POLYMERASE CHAIN REACTION PROCEDURE

EPA Science Inventory

Understanding how fecal indicator bacteria and/or fecal indicator genotypes vary over time is important to determine the sources of fecal contamination. Enterococcus is one of the two indicators recommended by the EPA to monitor freshwaters for fecal contamination. Along with E...

H51E-1535: Biogeochemical factors influencing the transport and fate of colloids and colloid-associated contaminants in the vadose zone

USDA-ARS?s Scientific Manuscript database

The vadose zone exhibits large spatial and temporal variability in many physical, chemical, and biological factors that strongly influence the transport and fate of colloids (e.g., microbes, nanoparticles, clays, and dissolved organic matter) and colloid-associated contaminants (e.g., heavy metals, ...

Quality of major ion and total dissolved solids data from groundwater sampled by the National Water-Quality Assessment Program, 1992–2010

USGS Publications Warehouse

Gross, Eliza L.; Lindsey, Bruce D.; Rupert, Michael G.

2012-01-01

Field blank samples help determine the frequency and magnitude of contamination bias, and replicate samples help determine the sampling variability (error) of measured analyte concentrations. Quality control data were evaluated for calcium, magnesium, sodium, potassium, chloride, sulfate, fluoride, silica, and total dissolved solids. A 99-percent upper confidence limit is calculated from field blanks to assess the potential for contamination bias. For magnesium, potassium, chloride, sulfate, and fluoride, potential contamination in more than 95 percent of environmental samples is less than or equal to the common maximum reporting level. Contamination bias has little effect on measured concentrations greater than 4.74 mg/L (milligrams per liter) for calcium, 14.98 mg/L for silica, 4.9 mg/L for sodium, and 120 mg/L for total dissolved solids. Estimates of sampling variability are calculated for high and low ranges of concentration for major ions and total dissolved solids. Examples showing the calculation of confidence intervals and how to determine whether measured differences between two water samples are significant are presented.

Computational ghost imaging using deep learning

NASA Astrophysics Data System (ADS)

Shimobaba, Tomoyoshi; Endo, Yutaka; Nishitsuji, Takashi; Takahashi, Takayuki; Nagahama, Yuki; Hasegawa, Satoki; Sano, Marie; Hirayama, Ryuji; Kakue, Takashi; Shiraki, Atsushi; Ito, Tomoyoshi

2018-04-01

Computational ghost imaging (CGI) is a single-pixel imaging technique that exploits the correlation between known random patterns and the measured intensity of light transmitted (or reflected) by an object. Although CGI can obtain two- or three-dimensional images with a single or a few bucket detectors, the quality of the reconstructed images is reduced by noise due to the reconstruction of images from random patterns. In this study, we improve the quality of CGI images using deep learning. A deep neural network is used to automatically learn the features of noise-contaminated CGI images. After training, the network is able to predict low-noise images from new noise-contaminated CGI images.

Combination of bioaugmentation and biostimulation for remediation of paddy soil contaminated with 2,4-dichlorophenoxyacetic acid.

PubMed

Yang, Zhiman; Xu, Xiaohui; Dai, Meng; Wang, Lin; Shi, Xiaoshuang; Guo, Rongbo

2018-04-22

The batch and fed-batch tests were performed to evaluate the efficiency of bioaugmentation in combination with biostimulation for remediation of paddy soil contaminated with 2,4-dichlorophenoxyacetic acid (2,4-D). 2,4-D degrading enrichments were used for bioaugmentation, and effluents prepared through biological hydrogen production process were used as substrate for biostimulation. The batch tests indicated that 2,4-D degradation depended on the enrichment/substrate ratio (E/S), where E/S of 0.03 showed an excellent performance. The fed-batch tests showed that biostimulation only led to an improvement in 2,4-D degradation, while the pattern of repeated augmentation of enrichments (FRA) together with biostimulation obviously improved degradation of 2,4-D, 2-chlorophenol (2-CP) and phenol. DNA-sequencing approach showed that the FRA pattern altered the bacterial community composition, and high removal of 2,4-D, 2-CP and phenol may be attributed to the acclimation and persistence of Thauera. The findings demonstrated the importance of the FRA pattern on remediation of paddy soil contaminated with 2,4-D. Copyright © 2018 Elsevier B.V. All rights reserved.

Output variability across animals and levels in a motor system

PubMed Central

Norris, Brian J; Günay, Cengiz; Kueh, Daniel

2018-01-01

Rhythmic behaviors vary across individuals. We investigated the sources of this output variability across a motor system, from the central pattern generator (CPG) to the motor plant. In the bilaterally symmetric leech heartbeat system, the CPG orchestrates two coordinations in the bilateral hearts with different intersegmental phase relations (Δϕ) and periodic side-to-side switches. Population variability is large. We show that the system is precise within a coordination, that differences in repetitions of a coordination contribute little to population output variability, but that differences between bilaterally homologous cells may contribute to some of this variability. Nevertheless, much output variability is likely associated with genetic and life history differences among individuals. Variability of Δϕ were coordination-specific: similar at all levels in one, but significantly lower for the motor pattern than the CPG pattern in the other. Mechanisms that transform CPG output to motor neurons may limit output variability in the motor pattern. PMID:29345614

PATTERN PREDICTION OF ACADEMIC SUCCESS.

ERIC Educational Resources Information Center

LUNNEBORG, CLIFFORD E.; LUNNEBORG, PATRICIA W.

A TECHNIQUE OF PATTERN ANALYSIS WHICH EMPHASIZES THE DEVELOPMENT OF MORE EFFECTIVE WAYS OF SCORING A GIVEN SET OF VARIABLES WAS FORMULATED. TO THE ORIGINAL VARIABLES WERE SUCCESSIVELY ADDED TWO, THREE, AND FOUR VARIABLE PATTERNS AND THE INCREASE IN PREDICTIVE EFFICIENCY ASSESSED. RANDOMLY SELECTED HIGH SCHOOL SENIORS WHO HAD PARTICIPATED IN THE…

Soil contamination by heavy metals in the city: a case study of Petach-Tikva, Israel

NASA Astrophysics Data System (ADS)

Sarah, Pariente; Zhevelev, Helena; Ido-Lichtman, Orna

2017-04-01

Heavy metals are among the most important pollutants which are affected by human activities. These pollutants impact both the natural and urban ecosystems. In the latter they are associated with the human health of the residents. The general aim of the study is to investigate the spatial variability of soil heavy metals in the city of Petach-Tikva. We asked if and to what extent the urban structure determines the spatial pattern of soil contamination. Urban structure in this study refers to the morphology of neighborhoods (density and height of buildings), the industrial area location and the roads system. It includes three main and industrial areas in the margins of the city. The city is also subjected to heavy traffic and contains different types of neighborhood morphology. To promote the above aim a preliminary study was conducted in 2016. Soil sampling was carried out along a strip, running from the Northwest industrial region of the city to the residential region in the center. Soil samples were randomly taken, from 0-5 cm, from industrial, near high traffic roads and between buildings areas. Each was analyzed for three heavy metals (Pb, Zn, Cu) commonly associated with industry and traffic emissions. Primary results show that for all the city studied areas the range values of Cu Zn and Pb concentrations were 1800, 1270 and 150 ppm, respectively, meaning high spatial variability of the heavy metals. In the soil of the industrial area the averages and the maximum values of Pb, Zn, and Cu concentrations were 76, 353 and 500 ppm and 153, 1286 and 1847 ppm, respectively. In the soil between buildings the averages were 20, 78 and 13 ppm and the maximum values reached 38, 165 and 37 ppm for Pb, Zn, and Cu, respectively. In the soil near roads the averages were 39, 120 and 214 ppm, and the maximum values were 153, 477 and 74 ppm for Pb, Zn, and Cu, respectively. These results indicate that the city industry has the greatest effect on soil pollution. Within the city neighborhoods the traffic effect on soil contamination was more pronounced in areas close to the roads with respect to the areas far from them. Some of soil sampling points showed heavy metals contents, which were higher than the values permitted by the guidelines of the Israeli EPM. These hot spots can be attributed to combined contamination factors or to high intensity of a single human activity or to low soil sheltering. The preliminary study leads to the conclusion that under the industry and traffic that prevailed in the city soil contamination increases in the vicinity of the residential area. The effect of neighborhood morphology is still under analysis.

Trends in blood culture contamination: a College of American Pathologists Q-Tracks study of 356 institutions.

PubMed

Bekeris, Leonas G; Tworek, Joseph A; Walsh, Molly K; Valenstein, Paul N

2005-10-01

Blood culture contamination extends hospital stays and increases the cost of care. To measure blood culture contamination rates in a large number of institutions over time and to elucidate practice patterns and demographic factors associated with sustained reduction in contamination rates. Longitudinal cohort study of 356 clinical laboratories that provided quarterly data about blood culture results, using a uniform definition of contamination. Mixed linear model analysis of the 1999 through 2003 data set. Blood culture contamination was significantly higher in institutions that used nonlaboratory personnel to collect blood (P = .03) and significantly lower in facilities that used a dedicated phlebotomy team (P < .001). Higher volume of blood collection was significantly associated with lower contamination rates (P < .001). Continued participation in the Q-Tracks monitoring program was associated with significant and progressive reduction in contamination rates. By the fifth year of participation, the median institution had reduced its blood culture contamination rate by 0.67% (P < .001). Institutions that use decentralized patient-centered personnel rather than dedicated phlebotomy teams to collect blood cultures experience significantly higher contamination rates. Long-term monitoring of contamination is associated with sustained improvement in performance.

Two-Piece Screens for Decontaminating Granular Material

NASA Technical Reports Server (NTRS)

Backes, Douglas; Poulter, Clay; Godfrey, Max; Dutton, Melinda; Tolman, Dennis

2009-01-01

Two-piece screens have been designed specifically for use in filtering a granular material to remove contaminant particles that are significantly wider or longer than are the desired granules. In the original application for which the twopiece screens were conceived, the granular material is ammonium perchlorate and the contaminant particles tend to be wires and other relatively long, rigid strands. The basic design of the twopiece screens can be adapted to other granular materials and contaminants by modifying critical dimensions to accommodate different grain and contaminant- particle sizes. A two-piece screen of this type consists mainly of (1) a top flat plate perforated with circular holes arranged in a hexagonal pattern and (2) a bottom plate that is also perforated with circular holes (but not in a pure hexagonal pattern) and is folded into an accordion structure. Fabrication of the bottom plate begins with drilling circular holes into a flat plate in a hexagonal pattern that is interrupted, at regular intervals, by parallel gaps. The plate is then folded into the accordion structure along the gaps. Because the folds are along the gaps, there are no holes at the peaks and valleys of the accordion screen. The top flat plate and the bottom accordion plate are secured within a metal frame. The resulting two-piece screen is placed at the bottom opening of a feed hopper containing the granular material to be filtered. Tests have shown that such long, rigid contaminant strands as wires readily can pass through a filter consisting of the flat screen alone and that the addition of the accordion screen below the flat screen greatly increases the effectiveness of removal of wires and other contaminant strands. Part of the reason for increased effectiveness is in the presentation of the contaminant to the filter surface. Testing has shown that wire type contamination will readily align itself parallel to the material direction flow. Since this direction of flow is nearly always perpendicular to the filter surface holes, the contamination is automatically aligned to pass through. The two-filter configuration reduces the likelihood that a given contaminant strand will be aligned with the flow of material by eliminating the perpendicular presentation angle. Thus, for wires of a certain diameter, a two-piece screen is 20 percent more effective than is the corresponding flat perforated plate alone, even if the holes in the flat plate are narrower. An accordion screen alone is similarly effective in catching contaminants, but lumps of agglomerated granules of the desired material often collect in the valleys and clog the screen. The addition of a flat screen above the accordion screen prevents clogging of the accordion screen. Flat wire screens have often been used to remove contaminants from granular materials, and are about as effective as are the corresponding perforated flat plates used alone.

Copper in indigenous and transplanted zebra mussels in relation to changing water concentrations and body weight

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mersch, J.; Wagner, P.; Pihan, J.C.

Zebra mussels, Dreissena polymorpha, were collected monthly from a copper-contaminated reservoir over a period of nearly 3 years. Copper concentrations in the organisms showed marked fluctuations reflecting changes in the water contamination. Bioconcentration patterns were influenced by the specific capacity of this sentinel organism to biologically integrate the continuously evolving water pollution; the sampling pattern, which inevitably introduced a certain subjectivity into monitoring results; and weight changes in the animals within the yearly cycle. Consequently, the successive monthly indications obtained with the zebra mussels provided a current biological assessment of a complex dynamic contamination situation. In a second experiment, cagedmore » mussels from three different populations were transferred for 3 months into the reservoir and sampled on six occasions. Mortality rates, attachment capacity, and a condition index revealed no substantial fitness disturbances in the transplanted organisms. Differences in dry weight throughout the experiment were attributable to the initial characteristics of each population. The influence of body mass on monitoring results was eliminated by replacing copper concentrations ({micro}g/g dry weight) with copper burdens ({micro}g/specimen). In terms of copper burdens, the three transplanted populations exhibited very similar metal patterns. Moderate quantitative differences between introduced and indigenous populations were interpreted as the result of physiological adaptation of the indigenous mussels to their contaminated environment. This study showed that the transfer technique with D. polymorpha is a useful tool for active biomonitoring programs.« less

Bacterial interactions and implications for oil biodegradation process in mangrove sediments.

PubMed

Grativol, Adriana Daudt; Marchetti, Albany A; Wetler-Tonini, Rita M; Venancio, Thiago M; Gatts, Carlos En; Thompson, Fabiano L; Rezende, Carlos E

2017-05-15

Mangrove sediment harbors a unique microbiome and is a hospitable environment for a diverse group of bacteria capable of oil biodegradation. Our goal was to understand bacterial community dynamics from mangrove sediments contaminated with heavy-oil and to evaluate patterns potentially associated with oil biodegradation is such environments. We tested the previously proposed hypothesis of a two-phase pattern of petroleum biodegradation, under which key events in the degradation process take place in the first three weeks after contamination. Two sample sites with different oil pollution histories were compared through T-RFLP analyses and using a pragmatic approach based on the Microbial Resource Management Framework. Our data corroborated the already reported two-phase pattern of oil biodegradation, although the original proposed explanation related to the biophysical properties of the soil is questioned, opening the possibility to consider other plausible hypotheses of microbial interactions as the main drivers of this pattern. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pit Latrines and Their Impacts on Groundwater Quality: A Systematic Review

PubMed Central

Polizzotto, Matthew L.

2013-01-01

Background: Pit latrines are one of the most common human excreta disposal systems in low-income countries, and their use is on the rise as countries aim to meet the sanitation-related target of the Millennium Development Goals. There is concern, however, that discharges of chemical and microbial contaminants from pit latrines to groundwater may negatively affect human health. Objectives: Our goals were to a) calculate global pit latrine coverage, b) systematically review empirical studies of the impacts of pit latrines on groundwater quality, c) evaluate latrine siting standards, and d) identify knowledge gaps regarding the potential for and consequences of groundwater contamination by latrines. Methods: We used existing survey and population data to calculate global pit latrine coverage. We reviewed the scientific literature on the occurrence of contaminants originating from pit latrines and considered the factors affecting transport of these contaminants. Data were extracted from peer-reviewed articles, books, and reports identified using Web of ScienceSM, PubMed, Google, and document reference lists. Discussion: We estimated that approximately 1.77 billion people use pit latrines as their primary means of sanitation. Studies of pit latrines and groundwater are limited and have generally focused on only a few indicator contaminants. Although groundwater contamination is frequently observed downstream of latrines, contaminant transport distances, recommendations based on empirical studies, and siting guidelines are variable and not well aligned with one another. Conclusions: In order to improve environmental and human health, future research should examine a larger set of contextual variables, improve measurement approaches, and develop better criteria for siting pit latrines. PMID:23518813

A Random Forest Approach to Predict the Spatial Distribution ...

EPA Pesticide Factsheets

Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF) model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) (TCS), in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies) and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high) for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC) (transport and fate proxy) was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry) and sand (transport and fate proxy) were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary), which was validated wi

DETERMINANTS OF TEMPORAL VARIABILITY IN NHEXAS-MARYLAND ENVIRONMENTAL CONCENTRATIONS, EXPOSURES, AND BIOMARKERS

EPA Science Inventory

The longitudinal NHEXAS-Maryland study measured metals, PAHs, and pesticides in several media to capture temporal variability. Questionnaires were concurrently administered to identify factors that influenced changes in contaminant levels over time. We constructed mixed-effects...

Use of limestone filler as a sorbent for the removal of As(V), Pb(II), Cu(II), Zn(II) and Cd(II) in contaminated sites

NASA Astrophysics Data System (ADS)

Martinez Sanchez, Maria Jose; Veiga, Jose Manuel; Garcia-Lorenzo, Maria Luz; Hernandez Cordoba, Manuel; Martinez-Lopez, Salvadora; Perez-Sirvent, Carmen

2017-04-01

Many of the approaches used to treat soils contaminated by heavy metals are invasive, and do not restore the natural equilibrium of the environment [1]. For this reason, one of procedures used to stabilise heavy metal-contaminated soils in situ is to directly add amendments, which, while they may not totally eliminate toxic elements, help natural retention mechanisms, induce sorption and reduce mobility and bioavailability. In this respect, the use of calcareous materials may be an excellent, eco-friendly way for recovering this type of soils [2], and this communication reports studies made in our laboratory for such a purpose. The influence of different variables in the preparation of mixtures used to stabilize contaminated soils (soil pH, temperature and composition of the contaminated soil / limestone filler) was studied by means of a factorial experimental design. The main interaction effects of the factors obtained on different contaminated soils were used along with the results of the physicochemical and mineralogical characterization in the same data matrix to be analyzed by principal components analysis (PCA). To evaluate the optimal values of the variables, spectroscopic techniques were used to measure the level of leached metals (Pb, Cd, Cu, As, Zn and Fe). The environmental conditions were simulated and controlled by means of a climatic chamber to evaluate simultaneously the processes of geochemical alteration and passivation of the mixture. The results obtained showed that the corresponding factors of the experimental design may be an important source of information to show correlations on some of the most significant variables such as the concentration of metals and, in this way, optimize the use of the in situ stabilizer. [1] H. Genç-Fuhrman, P.S. Mikkelsen, A. Ledin. Water Res 41 (2007) 591-602. [2] C. A. Cravotta, M.K. Trahan. Appl. Geochem 5 (1999) 581-606.

Estimating the Risk of Domestic Water Source Contamination following Precipitation Events

PubMed Central

Eisenhauer, Ian F.; Hoover, Christopher M.; Remais, Justin V.; Monaghan, Andrew; Celada, Marco; Carlton, Elizabeth J.

2016-01-01

Climate change is expected to increase precipitation extremes, threatening water quality. In low resource settings, it is unclear which water sources are most vulnerable to contamination following rainfall events. We evaluated the relationship between rainfall and drinking water quality in southwest Guatemala where heavy rainfall is frequent and access to safe water is limited. We surveyed 59 shallow household wells, measured precipitation, and calculated simple hydrological variables. We compared Escherichia coli concentration at wells where recent rainfall had occurred versus had not occurred, and evaluated variability in the association between rainfall and E. coli concentration under different conditions using interaction models. Rainfall in the past 24 hours was associated with greater E. coli concentrations, with the strongest association between rainfall and fecal contamination at wells where pigs were nearby. Because of the small sample size, these findings should be considered preliminary, but provide a model to evaluate vulnerability to climate change. PMID:27114298

Predictive Validity of Explicit and Implicit Threat Overestimation in Contamination Fear

PubMed Central

Green, Jennifer S.; Teachman, Bethany A.

2012-01-01

We examined the predictive validity of explicit and implicit measures of threat overestimation in relation to contamination-fear outcomes using structural equation modeling. Undergraduate students high in contamination fear (N = 56) completed explicit measures of contamination threat likelihood and severity, as well as looming vulnerability cognitions, in addition to an implicit measure of danger associations with potential contaminants. Participants also completed measures of contamination-fear symptoms, as well as subjective distress and avoidance during a behavioral avoidance task, and state looming vulnerability cognitions during an exposure task. The latent explicit (but not implicit) threat overestimation variable was a significant and unique predictor of contamination fear symptoms and self-reported affective and cognitive facets of contamination fear. On the contrary, the implicit (but not explicit) latent measure predicted behavioral avoidance (at the level of a trend). Results are discussed in terms of differential predictive validity of implicit versus explicit markers of threat processing and multiple fear response systems. PMID:24073390

Extremely Low Frequency (ELF) Communications System Ecological Monitoring Program: Summary of 1986 Progress.

DTIC Science & Technology

1987-12-01

assessment of data collection techniques *quantification of temporal and spatial patterns of variables *assessment of end point variability...nutrient variables are also being examined as covarlates. Development of a model to test for differences in growth patterns is continuing. At each of...condition. These variables are recorded at the end of each growing season. For evaluation of height growth patterns , a subsample of 100 seedlings per

Coastal recirculation potential affecting air pollutants in Portugal: The role of circulation weather types

NASA Astrophysics Data System (ADS)

Russo, Ana; Gouveia, Célia; Levy, Ilan; Dayan, Uri; Jerez, Sonia; Mendes, Manuel; Trigo, Ricardo

2016-06-01

Coastal zones are under increasing development and experience air pollution episodes regularly. These episodes are often related to peaks in local emissions from industry or transportation, but can also be associated with regional transport from neighbour urban areas influenced by land-sea breeze recirculation. This study intends to analyze the relation between circulation weather patterns, air mass recirculation and pollution levels in three coastal airsheds of Portugal (Lisbon, Porto and Sines) based on the application of an objective quantitative measure of potential recirculation. Although ventilation events have a dominant presence throughout the studied 9-yrs period on all the three airsheds, recirculation and stagnation conditions occur frequently. The association between NO2, SO2 and O3 levels and recirculation potential is evident during summer months. Under high average recirculation potential and high variability, NO2 and SO2 levels are higher for the three airsheds, whilst for O3 each airshed responds differently. This indicates a high heterogeneity among the three airsheds in (1) the type of emission - traffic or industry - prevailing for each contaminant, and (2) the response to the various circulation weather patterns and recirculation situations. Irrespectively of that, the proposed methodology, based on iterative K-means clustering, allows to identify which prevailing patterns are associated with high recirculation potential, having the advantage of being applicable to any geographical location.

Probability-based nitrate contamination map of groundwater in Kinmen.

PubMed

Liu, Chen-Wuing; Wang, Yeuh-Bin; Jang, Cheng-Shin

2013-12-01

Groundwater supplies over 50% of drinking water in Kinmen. Approximately 16.8% of groundwater samples in Kinmen exceed the drinking water quality standard (DWQS) of NO3 (-)-N (10 mg/L). The residents drinking high nitrate-polluted groundwater pose a potential risk to health. To formulate effective water quality management plan and assure a safe drinking water in Kinmen, the detailed spatial distribution of nitrate-N in groundwater is a prerequisite. The aim of this study is to develop an efficient scheme for evaluating spatial distribution of nitrate-N in residential well water using logistic regression (LR) model. A probability-based nitrate-N contamination map in Kinmen is constructed. The LR model predicted the binary occurrence probability of groundwater nitrate-N concentrations exceeding DWQS by simple measurement variables as independent variables, including sampling season, soil type, water table depth, pH, EC, DO, and Eh. The analyzed results reveal that three statistically significant explanatory variables, soil type, pH, and EC, are selected for the forward stepwise LR analysis. The total ratio of correct classification reaches 92.7%. The highest probability of nitrate-N contamination map presents in the central zone, indicating that groundwater in the central zone should not be used for drinking purposes. Furthermore, a handy EC-pH-probability curve of nitrate-N exceeding the threshold of DWQS was developed. This curve can be used for preliminary screening of nitrate-N contamination in Kinmen groundwater. This study recommended that the local agency should implement the best management practice strategies to control nonpoint nitrogen sources and carry out a systematic monitoring of groundwater quality in residential wells of the high nitrate-N contamination zones.

Fluorescent aromatic hydrocarbons in bile as a biomarker of exposure of brown bullheads (Ameiurus nebulosus) to contaminated sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leadly, T.A.; Haffner, G.D.; Arcand-Hoy, L.D.

1999-04-01

Analysis of fluorescent aromatic compounds (FACs) in the bile of fish has been widely used as a biomarker of exposure to polynuclear aromatic hydrocarbon (PAH) contamination. However, bile FAC data for feral fish populations are typically highly variable, and in a few cases, elevation of FACs has not been observed in fish from contaminated areas. In this study, the bile FACs and hepatic ethoxyresorufin-O-deethylase activity in brown bullheads (Ameiurus nebulosus) exposed in the laboratory to contaminated sediments from Hamilton Harbour, Ontario, Canada, increased by 173-fold within 72 h of initial exposure and rapidly declined thereafter. In bullheads caged in themore » contaminated Trenton Channel area of the Detroit River, bile FACs also increased rapidly within 4 d of initial exposure to mean levels >3,000 ng of benzo[a]pyrene equivalents per milliliter of bile. Surprisingly, there was no difference in the mean-levels of bile FACs in fish caged above the sediment versus fish caged in direct contact with the sediment, indicating that water may be the major vector for uptake of PAHs. The lower bile FACs in bullheads caged in other regions of the Detroit River were consistent with the lower concentrations of PAHs in the sediments from these areas. These data indicate that bile FAC levels are a biomarker of recent exposure to aromatic hydrocarbons in sediments. However, FAC data were highly variable even in these studies, in which fish were relatively homogenous in size, feeding status, and exposure history. Therefore, Even higher variability in bile FAC data are expected in biomarker studies as a result of differences in reproductive status, size, diet, and mobility of the fish.« less

Examination of the uncertainty in contaminant fate and transport modeling: a case study in the Venice Lagoon.

PubMed

Sommerfreund, J; Arhonditsis, G B; Diamond, M L; Frignani, M; Capodaglio, G; Gerino, M; Bellucci, L; Giuliani, S; Mugnai, C

2010-03-01

A Monte Carlo analysis is used to quantify environmental parametric uncertainty in a multi-segment, multi-chemical model of the Venice Lagoon. Scientific knowledge, expert judgment and observational data are used to formulate prior probability distributions that characterize the uncertainty pertaining to 43 environmental system parameters. The propagation of this uncertainty through the model is then assessed by a comparative analysis of the moments (central tendency, dispersion) of the model output distributions. We also apply principal component analysis in combination with correlation analysis to identify the most influential parameters, thereby gaining mechanistic insights into the ecosystem functioning. We found that modeled concentrations of Cu, Pb, OCDD/F and PCB-180 varied by up to an order of magnitude, exhibiting both contaminant- and site-specific variability. These distributions generally overlapped with the measured concentration ranges. We also found that the uncertainty of the contaminant concentrations in the Venice Lagoon was characterized by two modes of spatial variability, mainly driven by the local hydrodynamic regime, which separate the northern and central parts of the lagoon and the more isolated southern basin. While spatial contaminant gradients in the lagoon were primarily shaped by hydrology, our analysis also shows that the interplay amongst the in-place historical pollution in the central lagoon, the local suspended sediment concentrations and the sediment burial rates exerts significant control on the variability of the contaminant concentrations. We conclude that the probabilistic analysis presented herein is valuable for quantifying uncertainty and probing its cause in over-parameterized models, while some of our results can be used to dictate where additional data collection efforts should focus on and the directions that future model refinement should follow. (c) 2009 Elsevier Inc. All rights reserved.

Legacies of Lead in Charm City’s Soil: Lessons from the Baltimore Ecosystem Study

PubMed Central

Schwarz, Kirsten; Pouyat, Richard V.; Yesilonis, Ian

2016-01-01

Understanding the spatial distribution of soil lead has been a focus of the Baltimore Ecosystem Study since its inception in 1997. Through multiple research projects that span spatial scales and use different methodologies, three overarching patterns have been identified: (1) soil lead concentrations often exceed state and federal regulatory limits; (2) the variability of soil lead concentrations is high; and (3) despite multiple sources and the highly heterogeneous and patchy nature of soil lead, discernable patterns do exist. Specifically, housing age, the distance to built structures, and the distance to a major roadway are strong predictors of soil lead concentrations. Understanding what drives the spatial distribution of soil lead can inform the transition of underutilized urban space into gardens and other desirable land uses while protecting human health. A framework for management is proposed that considers three factors: (1) the level of contamination; (2) the desired land use; and (3) the community’s preference in implementing the desired land use. The goal of the framework is to promote dialogue and resultant policy changes that support consistent and clear regulatory guidelines for soil lead, without which urban communities will continue to be subject to the potential for lead exposure. PMID:26861371

Patterns of neural response to emotive stimuli distinguish the different symptom dimensions of obsessive-compulsive disorder.

PubMed

Phillips, Mary L; Mataix-Cols, David

2004-04-01

Despite its heterogeneous symptomatology, obsessive-compulsive disorder (OCD) is currently conceptualized as a unitary diagnostic entity. Recent factor-analytic studies have identified several OCD symptom dimensions that are associated with different demographic variables, comorbidity, patterns of genetic transmission, and treatment response. Functional abnormalities in neural systems important for emotion perception, including the orbitofrontal cortex, lateral prefrontal cortex, anterior cingulate gyrus, and limbic regions, have been reported in OCD. In this review, we discuss the extent to which neurobiological markers may distinguish these different symptom dimensions and whether specific symptom dimensions, such as contamination/washing, are associated with abnormalities in emotion and, in particular, disgust, perception in OCD. Also discussed are findings that indicate that anxiety can be induced in healthy volunteers in response to OCD symptom-related material, and that associated increases in activity within neural systems important for emotion perception occur to washing- and hoarding-related material in particular in these subjects. Further examination of neural responses during provocation of different symptom dimensions in OCD patients will help determine the extent to which specific abnormalities in neural systems underlying emotion perception are associated with different symptom dimensions and predict treatment response in OCD.

Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, Scott C.; Lowe, Kenneth Alan

We conducted a diel sampling campaign at three locations along the Hg contaminated East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee to (i) quantify diel patterns of particulate and dissolved mercury (Hg) and monomethylmercury (MMHg) (HgD, HgP, MMHgD, and MMHgP, respectively) and associated water quality parameters along a longitudinal gradient of EFPC during the summer season, (ii) determine if diel patterns in Hg and/or MMHg are related to the daily photocycle or any other short term cycle, such as wastewater treatment plant discharge, (iii) determine if diel variability in turbidity and dissolved organic matter (DOM) composition correspond to particulatemore » HgP or MMHgP and dissolved organic carbon (DOC) or dissolved HgD or MMHgD. Samples were collected every two hours for a 30 hour period. The farthest upstream site was located at the boundary of Y-12 and the City of Oak Ridge (EFK 23.4) while two additional sites were located 7.2 kilometers (Wiltshire Drive, EFK 16.2) and 18 kilometers (Horizon Center, EFK 5.4) downstream of EFK 23.4).HgP and MMHgP concentrations increased overnight at EFK 16.2 and EFK 5.4 coincident with increases in turbidity and total suspended solids (TSS). These overnight increases were likely due to diel changes in the activity of macrobiota (re)suspending contaminated sediments in the creek. Both HgD and MMHgD were higher during the day at EFK 23.4 and EFK 5.4. The underlying causes for the patterns in HgD and MMHgD are less clear but correspond with similar patterns in DOC concentration and DOM composition. Photochemical reactions may also play a role in these HgD, MMHgD, DOC, and DOM patterns. Both Hg and MMHg loading increased with downstream distance. The greatest increase in loading occurred in the reach from EFK 23.4 to EFK 16.2 which encompasses areas where the Historic Release Deposits (HRD) have been identified. These results suggest that diffuse legacy sources of Hg, outside of Y-12, contribute Hg load to EFPC whereas MMHg is generated from instream processes.Intraday patterns in Hg and MMHg concentration and speciation have implications with respect to biotic exposure. Greater biotic activity and feeding during times of higher concentration would correspond to greater exposure than estimated from daily or longer term averages. Both Hg and MMHg responded rapidly to processes governing their concentration. This latter point is encouraging from the perspective of site remediation as it suggests that MMHg concentrations and flux in EFPC would respond rapidly to appropriate remedial actions.« less

[The status of soil contamination in areas of northern and northwestern Bohemia affected by pollution].

PubMed

Podlesáková, E; Nĕmecek, J; Vácha, R

1999-10-20

A regional study of soil contamination in North and Northwest immission-impacted Bohemian regions present the results of the assessment of soil loads of agricultural soils by hazardous trace elements and organic xenobiotic substances. The evaluation is based on the exceeding of background values of contaminants (upper limit of their variability). Two forms of soil loads by trace elements are differentiated, the anthropogenic and geogenic one. They occur simultaneously on the territory under study. Geogenic "loads" prevail (basalts, metallogenic zones). Anthropogenic contamination by both hazardous elements and organic xenobiotic substances occurs only in some parts of these severely immission-impacted regions.

Ochratoxin A and citrinin loads in stored wheat grains: impact of grain dust and possible prediction using ergosterol measurement.

PubMed

Tangni, E K; Pussemier, L

2006-02-01

Crop storage should be carried out under hygienic conditions to ensure safe products, but sometimes grain dust which has settled from previous storage may be left over and incorporated to the following stored grains. This paper describes the results obtained using a lab model developed in order to assess the impact of grain dust incorporation for its direct contribution as a contaminant but also as an inoculum in stored wheat. Settled grain dust (4 samples) released from Belgian grain storages were collected and analysed by HPLC for ergosterol, ochratoxin A (OTA) and citrinin (CIT) content. For OTA and for ergosterol, there was a high degree of variability in concentrations found in the dust samples (from 17.3-318 ng g(-1) and from 39-823 microg g(-1), respectively) whilst for CIT, the range was less significant (from 137-344 ng g(-1)). Incorporation of grain dust into wheat storage contributed to an increase in the concentrations of mycotoxins in the stored grain. Dust acts as a contaminant and as an inoculum. According to these two ways, patterns of mycotoxin generation vary with the nature of the mycotoxin, the mycotoxigenic potential of dust and the water activity of the wheat. OTA and CIT showed a very versatile image when considering the amounts of toxins produced under the selected experimental conditions. The development of a robust tool to forecast the mycotoxigenicity of dust was based on the determination of ergosterol content as a general marker of fungal biomass. Present results suggest that this predictive tool would only be valid for predicting the contamination level of CIT and OTA at reasonable moisture content (14-20%). The potential risk of having highly contaminated batches from stock to stock may thus occur and this paper discusses possible pathways leading to OTA and CIT contamination either under wet or dry storage conditions. We therefore, recommend taking precautionary measures not only by controlling and maintaining moisture at a reasonable level during storage of the raw materials but also by paying more attention to the cleaning of the stores before loading in the new harvests.

Mercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife

USGS Publications Warehouse

Eagles-Smith, Collin A.; Wiener, James G.; Eckley, Chris S.; Willacker, James J.; Evers, David C.; Marvin-DiPasquale, Mark C.; Obrist, Daniel; Fleck, Jacob; Aiken, George R.; Lepak, Jesse M.; Jackson, Allyson K.; Webster, Jackson; Stewart, Robin; Davis, Jay; Alpers, Charles N.; Ackerman, Joshua T.

2016-10-15

Western North America is a region defined by extreme gradients in geomorphology and climate, which support a diverse array of ecological communities and natural resources. The region also has extreme gradients in mercury (Hg) contamination due to a broad distribution of inorganic Hg sources. These diverse Hg sources and a varied landscape create a unique and complex mosaic of ecological risk from Hg impairment associated with differential methylmercury (MeHg) production and bioaccumulation. Understanding the landscape-scale variation in the magnitude and relative importance of processes associated with Hg transport, methylation, and MeHg bioaccumulation requires a multidisciplinary synthesis that transcends small-scale variability. The Western North America Mercury Synthesis compiled, analyzed, and interpreted spatial and temporal patterns and drivers of Hg and MeHg in air, soil, vegetation, sediments, fish, and wildlife across western North America. This collaboration evaluated the potential risk from Hg to fish, and wildlife health, human exposure, and examined resource management activities that influenced the risk of Hg contamination. This paper integrates the key information presented across the individual papers that comprise the synthesis. The compiled information indicates that Hg contamination is widespread, but heterogeneous, across western North America. The storage and transport of inorganic Hg across landscape gradients are largely regulated by climate and land-cover factors such as plant productivity and precipitation. Importantly, there was a striking lack of concordance between pools and sources of inorganic Hg, and MeHg in aquatic food webs. Additionally, water management had a widespread influence on MeHg bioaccumulation in aquatic ecosystems, whereas mining impacts where relatively localized. These results highlight the decoupling of inorganic Hg sources with MeHg production and bioaccumulation. Together the findings indicate that developing efforts to control MeHg production in the West may be particularly beneficial for reducing food web exposure instead of efforts to simply control inorganic Hg sources.

Mercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife

USGS Publications Warehouse

Eagles-Smith, Collin A.; Wiener, James G.; Eckley, Chris S.; Willacker, James J.; Evers, David C.; Marvin-DiPasquale, Mark C.; Obrist, Daniel; Fleck, Jacob; Aiken, George R.; Lepak, Jesse M.; Jackson, Allyson K.; Webster, Jackson; Stewart, Robin; Davis, Jay; Alpers, Charles N.; Ackerman, Joshua T.

2016-01-01

Western North America is a region defined by extreme gradients in geomorphology and climate, which support a diverse array of ecological communities and natural resources. The region also has extreme gradients in mercury (Hg) contamination due to a broad distribution of inorganic Hg sources. These diverse Hg sources and a varied landscape create a unique and complex mosaic of ecological risk from Hg impairment associated with differential methylmercury (MeHg) production and bioaccumulation. Understanding the landscape-scale variation in the magnitude and relative importance of processes associated with Hg transport, methylation, and MeHg bioaccumulation requires a multidisciplinary synthesis that transcends small-scale variability. The Western North America Mercury Synthesis compiled, analyzed, and interpreted spatial and temporal patterns and drivers of Hg and MeHg in air, soil, vegetation, sediments, fish, and wildlife across western North America. This collaboration evaluated the potential risk from Hg to fish, and wildlife health, human exposure, and examined resource management activities that influenced the risk of Hg contamination. This paper integrates the key information presented across the individual papers that comprise the synthesis. The compiled information indicates that Hg contamination is widespread, but heterogeneous, across western North America. The storage and transport of inorganic Hg across landscape gradients are largely regulated by climate and land-cover factors such as plant productivity and precipitation. Importantly, there was a striking lack of concordance between pools and sources of inorganic Hg, and MeHg in aquatic food webs. Additionally, water management had a widespread influence on MeHg bioaccumulation in aquatic ecosystems, whereas mining impacts where relatively localized. These results highlight the decoupling of inorganic Hg sources with MeHg production and bioaccumulation. Together the findings indicate that developing efforts to control MeHg production in the West may be particularly beneficial for reducing food web exposure instead of efforts to simply control inorganic Hg sources.

Development of new multilocus variable number of tandem repeat analysis (MLVA) for Listeria innocua and its application in a food processing plant.

PubMed

Takahashi, Hajime; Ohshima, Chihiro; Nakagawa, Miku; Thanatsang, Krittaporn; Phraephaisarn, Chirapiphat; Chaturongkasumrit, Yuphakhun; Keeratipibul, Suwimon; Kuda, Takashi; Kimura, Bon

2014-01-01

Listeria innocua is an important hygiene indicator bacterium in food industries because it behaves similar to Listeria monocytogenes, which is pathogenic to humans. PFGE is often used to characterize bacterial strains and to track contamination source. However, because PFGE is an expensive, complicated, time-consuming protocol, and poses difficulty in data sharing, development of a new typing method is necessary. MLVA is a technique that identifies bacterial strains on the basis of the number of tandem repeats present in the genome varies depending on the strains. MLVA has gained attention due to its high reproducibility and ease of data sharing. In this study, we developed a MLVA protocol to assess L. innocua and evaluated it by tracking the contamination source of L. innocua in an actual food manufacturing factory by typing the bacterial strains isolated from the factory. Three VNTR regions of the L. innocua genome were chosen for use in the MLVA. The number of repeat units in each VNTR region was calculated based on the results of PCR product analysis using capillary electrophoresis (CE). The calculated number of repetitions was compared with the results of the gene sequence analysis to demonstrate the accuracy of the CE repeat number analysis. The developed technique was evaluated using 60 L. innocua strains isolated from a food factory. These 60 strains were classified into 11 patterns using MLVA. Many of the strains were classified into ST-6, revealing that this MLVA strain type can contaminate each manufacturing process in the factory. The MLVA protocol developed in this study for L. innocua allowed rapid and easy analysis through the use of CE. This technique was found to be very useful in hygiene control in factories because it allowed us to track contamination sources and provided information regarding whether the bacteria were present in the factories.

Moderately reverberant learning ultrasonic pinch panel.

PubMed

Nikolovski, Jean-Pierre

2013-10-01

Tactile sensing is widely used in human-computer interfaces. However, mechanical integration of touch technologies is often perceived as difficult by engineers because it often limits the freedom of style or form factor requested by designers. Recent work in active ultrasonic touch technologies has made it possible to transform thin glass plates, metallic sheets, or plastic shells into interactive surfaces. The method is based on a learning process of touch-induced, amplitude-disturbed diffraction patterns. This paper proposes, first, an evolution in the design with multiple dipole transducers that improves touch sensitivity or maximum panel size by a factor of ten, and improves robustness and usability in moderately reverberant panels, and second, defines a set of acoustic variables in the signal processing for the evaluation of sensitivity and radiating features. For proof of concept purposes, the design and process are applied to 3.2- and 6-mm-thick glass plates with variable damping conditions. Transducers are bonded to only one short side of the rectangular substrates. Measurements show that the highly sensitive free lateral sides are perfectly adapted for pinch-touch and pinch-slide interactions. The advantage of relative versus absolute touch disturbance measurement is discussed, together with tolerance to abutting contaminants.

Arsenic in Water Resources of the Southern Pampa Plains, Argentina

PubMed Central

Paoloni, Juan D.; Sequeira, Mario E.; Espósito, Martín E.; Fiorentino, Carmen E.; Blanco, María del C.

2009-01-01

Confronted with the need for accessible sources of good quality water and in view of the fact that the threat to public health posed by arsenic occurs mainly through the ingestion of contaminated drinking water, the presence and distribution of arsenic was evaluated in the southern Pampa Plains of Bahía Blanca district in Argentina. The findings show variable concentrations of arsenic in a complex distribution pattern. Complementary information is provided on the behavior of the groundwater resource and its salinity in terms of dissolved ions. Groundwater is the most severely affected, 97% of the samples exceeding the guideline value for arsenic in drinking water as recommended by the WHO (Guidelines for Drinking Water Quality, 2004). and showing maximum concentrations of up to 0.30 mg/L. Informing those responsible for preventive medicine and alerting the community at large will facilitate measures to mitigate exposure and ensure the safety of drinking water. PMID:19936127

Chronic radiation exposure modifies temporal dynamics of cytogenetic but not reproductive indicators in Scots pine populations.

PubMed

Geras'kin, Stanislav; Oudalova, Alla; Kuzmenkov, Alexey; Vasiliyev, Denis

2018-04-18

Over a period of 13 years (2003-2015), reproductive and cytogenetic effects are investigated in Scots pine populations growing in the Bryansk region of Russia radioactively contaminated as a result of the Chernobyl accident. In reference populations, the frequencies of cytogenetic abnormalities are shown to change with time in a cyclic manner. In chronically exposed populations, the cyclic patterns in temporal dynamics of cytogenetic abnormalities appear to be disturbed. In addition, a tendency to decrease in the frequencies of cytogenetic abnormalities with time as well as an increase in their variability with dose rate is revealed. In contrast, no significant impact of chronic radiation exposure on the time dynamics of reproductive indexes is detected. Finally, long-term observations on chronically exposed Scots pine populations revealed qualitative differences in the temporal dynamics of reproductive and cytogenetic indicators. Copyright © 2018 Elsevier Ltd. All rights reserved.

Does the Madden-Julian Oscillation influence aerosol variability?

NASA Astrophysics Data System (ADS)

Tian, Baijun; Waliser, Duane E.; Kahn, Ralph A.; Li, Qinbin; Yung, Yuk L.; Tyranowski, Tomasz; Geogdzhayev, Igor V.; Mishchenko, Michael I.; Torres, Omar; Smirnov, Alexander

2008-06-01

We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using multiple, global satellite aerosol products: aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite MJO analysis indicates that large variations in the TOMS AI and MODIS/AVHRR AOT are found over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is weak but the background aerosol level is high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The MODIS/AVHRR pattern is consistent with ground-based Aerosol Robotic Network data. These results indicate that the MJO and its associated cloudiness, rainfall, and circulation variability systematically influence the variability in remote sensing aerosol retrieval results. Several physical and retrieval algorithmic factors that may contribute to the observed aerosol-rainfall relationships are discussed. Preliminary analysis indicates that cloud contamination in the aerosol retrievals is likely to be a major contributor to the observed relationships, although we cannot exclude possible contributions from other physical mechanisms. Future research is needed to fully understand these complex aerosol-rainfall relationships.

Space-temporal analysis of Chagas disease and its environmental and demographic risk factors in the municipality of Barcarena, Pará, Brazil.

PubMed

Sousa, Alcinês da Silva; Palácios, Vera Regina da Cunha Menezes; Miranda, Claúdia do Socorro; Costa, Rodrigo Junior Farias da; Catete, Clistenes Pamplona; Chagasteles, Eugenia Janis; Pereira, Alba Lucia Ribeiro Raithy; Gonçalves, Nelson Veiga

2017-01-01

Chagas disease is a parasitosis considered a serious problem of public health. In the municipality of Barcarena, Pará, from 2007 to 2014, occurred the highest prevalence of this disease in Brazil. To analyze the disease distribution related to epidemiological, environmental and demographic variables, in the area and period of the study. Epidemiological and demographic data of Barcarena Health Department and satellite images from the National Institute For Space Research (INPE) were used. The deforestation data were obtained through satellite image classification, using artificial neural network. The statistical significance was done with the χ2 test, and the spatial dependence tests among the variables were done using Kernel and Moran techniques. The epidemiological curve indicated a disease seasonal pattern. The major percentage of the cases were in male, brown skin color, adult, illiterate, urban areas and with probable oral contamination. It was confirmed the spatial dependence of the disease cases with the different types of deforestation identified in the municipality, as well as agglomerations of cases in urban and rural areas. Discussion: The disease distribution did not occur homogeneously, possibly due to the municipality demographic dynamics, with intense migratory flows that generates the deforestation. Different relationships among the variables studied and the occurrence of the disease in the municipality were observed. The technologies used were satisfactory to construct the disease epidemiological scenarios.

The Signature of Southern Hemisphere Atmospheric Circulation Patterns in Antarctic Precipitation

PubMed Central

Thompson, David W. J.; van den Broeke, Michiel R.

2017-01-01

Abstract We provide the first comprehensive analysis of the relationships between large‐scale patterns of Southern Hemisphere climate variability and the detailed structure of Antarctic precipitation. We examine linkages between the high spatial resolution precipitation from a regional atmospheric model and four patterns of large‐scale Southern Hemisphere climate variability: the southern baroclinic annular mode, the southern annular mode, and the two Pacific‐South American teleconnection patterns. Variations in all four patterns influence the spatial configuration of precipitation over Antarctica, consistent with their signatures in high‐latitude meridional moisture fluxes. They impact not only the mean but also the incidence of extreme precipitation events. Current coupled‐climate models are able to reproduce all four patterns of atmospheric variability but struggle to correctly replicate their regional impacts on Antarctic climate. Thus, linking these patterns directly to Antarctic precipitation variability may allow a better estimate of future changes in precipitation than using model output alone. PMID:29398735

Regional risk assessment for contaminated sites part 2: ranking of potentially contaminated sites.

PubMed

Pizzol, Lisa; Critto, Andrea; Agostini, Paola; Marcomini, Antonio

2011-11-01

Environmental risks are traditionally assessed and presented in non spatial ways although the heterogeneity of the contaminants spatial distributions, the spatial positions and relations between receptors and stressors, as well as the spatial distribution of the variables involved in the risk assessment, strongly influence exposure estimations and hence risks. Taking into account spatial variability is increasingly being recognized as a further and essential step in sound exposure and risk assessment. To address this issue an innovative methodology which integrates spatial analysis and a relative risk approach was developed. The purpose of this methodology is to prioritize sites at regional scale where a preliminary site investigation may be required. The methodology aimed at supporting the inventory of contaminated sites was implemented within the spatial decision support sYstem for Regional rIsk Assessment of DEgraded land, SYRIADE, and was applied to the case-study of the Upper Silesia region (Poland). The developed methodology and tool are both flexible and easy to adapt to different regional contexts, allowing the user to introduce the regional relevant parameters identified on the basis of user expertise and regional data availability. Moreover, the used GIS functionalities, integrated with mathematical approaches, allow to take into consideration, all at once, the multiplicity of sources and impacted receptors within the region of concern, to assess the risks posed by all contaminated sites in the region and, finally, to provide a risk-based ranking of the potentially contaminated sites. Copyright © 2011. Published by Elsevier Ltd.

Influence of ecological factors and of land use on mercury levels in fish in the Tapajós River basin, Amazon.

PubMed

Sampaio da Silva, D; Lucotte, M; Paquet, S; Davidson, R

2009-05-01

Mercury (Hg) contamination of riparian communities and of environmental compartments of the Amazon can be directly related to the occupation of the territory. The objective of this study was to identify the characteristics of aquatic environments that are associated with high levels of Hg in ichthyofauna. Our research aimed at determining the influence of variables related to fish ecology, types of aquatic environment, fishing activities by local riparian populations, and watershed use on the levels of contamination of ichthyofauna. Six sites were sampled during two distinct periods of the hydrological cycle: at the beginning of descending waters and during low waters. We focused on ten dominant fish species representing four trophic levels: Curimata inornata, Geophagus proximus, Schizodon vittatum, Leporinus fasciatus, Anostomoides laticeps, Hemiodus unimaculatus, Caenotropus labyrinthicus, Hoplias malabaricus, Plagioscion squamosissimus, Acestrorhynchus falcirostris. The study sites, which included lotic and lentic habitats, are exploited year-round by local riparian communities. Spatial variations in Hg contamination in ichthyofauna were determined by factorial analysis of variance taking into account fish diets, seasons, and sampling sites. Multiple regressions were used to check the influence of ecological and anthropogenic variables and variables related to watershed uses, on Hg levels in key species representing the four trophic groups. Each variable was checked independently. Next, multiple regressions were used to verify the concomitant influence of selected variables. Independently of the study site and the phase of the hydrologic cycle, fish Hg contamination followed the trend piscivores>omnivores>herbivores>detritivores. In all the aquatic study sites, Hg levels measured in predatory species were often higher than the 500 ng/g fresh weight threshold. Mean Hg levels in key species were significantly higher during descending waters in lotic environments, and during low waters in lentic environments. Data from this study demonstrated that simple models based on watershed use and on easily obtained variables such as the suspended particulate matter (SPM) load and SPM Hg concentrations, number of inhabitants, habitat types, and the stage in the hydrological cycle enable very good prediction of Hg levels in fish. Our cartographical data clearly showed that the watershed site with the highest aquatic vegetation cover (6% of the open water body) and with the lowest forest cover (62% of the land) corresponded to the highest Hg concentrations in fish. Conversely, the watershed site with 94% forest cover and 1% aquatic vegetation corresponded to the lowest levels Hg concentrations in fish. These results suggest that land uses of watersheds play a key role in the level of Hg contamination of local ichthyofauna.

Transcript patterns of Phanerochaete chrysosporium genes in organopollutant contaminated soils and in wood

Treesearch

Amber Vanden Wymelenberg; Bernard Janse; Jill Gaskell; Diane Dietrich; Marcelo Vallim; Dan Cullen

1998-01-01

We describe here recent methods for quantitative assessment of specific P. chrysosporium mRNAs in organopollutant contaminated soils and in Aspen wood chips. Magnetic capture techniques were used to rapidly purify poly(A)-RNA, and quantitative RT-PCR protocols were developed for all known lignin peroxidase (lip) and cellobiohydrolase (cbh1) genes. The methodology is...

Impacts of road salts on leaching behavior of lead contaminated soil.

PubMed

Wu, Jingjing; Kim, Hwidong

2017-02-15

Research was conducted to explore the effects of road salts on lead leaching from lead contaminated soil samples that were collected in an old residence area in Erie, PA. The synthetic precipitate leaching procedure (SPLP) test was employed to evaluate lead leaching from one of the lead contaminated soils in the presence of various levels of road salts (5%, 10%, 20%, 30% and 40%). The results of the leaching test showed that lead leaching dramatically increased as the road salt content increased as a result of the formation of lead-chloride complexes, but different lead leaching patterns were observed in the presence of NaCl- and CaCl 2 -based road salts at a high content of road salts (>20%). Additional leaching tests that include 30% road salts and different soil samples showed a variety of leaching patterns by soil samples. The sequential extraction of each soil sample showed that a high fraction of organic matter bound lead was associated with lead contamination. The higher the fraction of organic matter bound lead contained in soil, the greater the effects of calcium on reducing lead leaching, observations showed. Copyright © 2016 Elsevier B.V. All rights reserved.

Combining chemometric tools for assessing hazard sources and factors acting simultaneously in contaminated areas. Case study: "Mar Piccolo" Taranto (South Italy).

PubMed

Mali, Matilda; Dell'Anna, Maria Michela; Notarnicola, Michele; Damiani, Leonardo; Mastrorilli, Piero

2017-10-01

Almost all marine coastal ecosystems possess complex structural and dynamic characteristics, which are influenced by anthropogenic causes and natural processes as well. Revealing the impact of sources and factors controlling the spatial distributions of contaminants within highly polluted areas is a fundamental propaedeutic step of their quality evaluation. Combination of different pattern recognition techniques, applied to one of the most polluted Mediterranean coastal basin, resulted in a more reliable hazard assessment. PCA/CA and factorial ANOVA were exploited as complementary techniques for apprehending the impact of multi-sources and multi-factors acting simultaneously and leading to similarities or differences in the spatial contamination pattern. The combination of PCA/CA and factorial ANOVA allowed, on one hand to determine the main processes and factors controlling the contamination trend within different layers and different basins, and, on the other hand, to ascertain possible synergistic effects. This approach showed the significance of a spatially representative overview given by the combination of PCA-CA/ANOVA in inferring the historical anthropogenic sources loading on the area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microplastic contamination of river beds significantly reduced by catchment-wide flooding

NASA Astrophysics Data System (ADS)

Hurley, Rachel; Woodward, Jamie; Rothwell, James J.

2018-04-01

Microplastic contamination of the oceans is one of the world's most pressing environmental concerns. The terrestrial component of the global microplastic budget is not well understood because sources, stores and fluxes are poorly quantified. We report catchment-wide patterns of microplastic contamination, classified by type, size and density, in channel bed sediments at 40 sites across urban, suburban and rural river catchments in northwest England. Microplastic contamination was pervasive on all river channel beds. We found multiple urban contamination hotspots with a maximum microplastic concentration of approximately 517,000 particles m-2. After a period of severe flooding in winter 2015/16, all sites were resampled. Microplastic concentrations had fallen at 28 sites and 18 saw a decrease of one order of magnitude. The flooding exported approximately 70% of the microplastic load stored on these river beds (equivalent to 0.85 ± 0.27 tonnes or 43 ± 14 billion particles) and eradicated microbead contamination at 7 sites. We conclude that microplastic contamination is efficiently flushed from river catchments during flooding.

Integrated methodology for assessing the HCH groundwater pollution at the multi-source contaminated mega-site Bitterfeld/Wolfen.

PubMed

Wycisk, Peter; Stollberg, Reiner; Neumann, Christian; Gossel, Wolfgang; Weiss, Holger; Weber, Roland

2013-04-01

A large-scale groundwater contamination characterises the Pleistocene groundwater system of the former industrial and abandoned mining region Bitterfeld/Wolfen, Eastern Germany. For more than a century, local chemical production and extensive lignite mining caused a complex contaminant release from local production areas and related dump sites. Today, organic pollutants (mainly organochlorines) are present in all compartments of the environment at high concentration levels. An integrated methodology for characterising the current situation of pollution as well as the future fate development of hazardous substances is highly required to decide on further management and remediation strategies. Data analyses have been performed on regional groundwater monitoring data from about 10 years, containing approximately 3,500 samples, and up to 180 individual organic parameters from almost 250 observation wells. Run-off measurements as well as water samples were taken biweekly from local creeks during a period of 18 months. A kriging interpolation procedure was applied on groundwater analytics to generate continuous distribution patterns of the nodal contaminant samples. High-resolution geological 3-D modelling serves as a database for a regional 3-D groundwater flow model. Simulation results support the future fate assessment of contaminants. A first conceptual model of the contamination has been developed to characterise the contamination in regional surface waters and groundwater. A reliable explanation of the variant hexachlorocyclohexane (HCH) occurrence within the two local aquifer systems has been derived from the regionalised distribution patterns. Simulation results from groundwater flow modelling provide a better understanding of the future pollutant migration paths and support the overall site characterisation. The presented case study indicates that an integrated assessment of large-scale groundwater contaminations often needs more data than only from local groundwater monitoring. The developed methodology is appropriate to assess POP-contaminated mega-sites including, e.g. HCH deposits. Although HCH isomers are relevant groundwater pollutants at this site, further organochlorine pollutants are present at considerably higher levels. The study demonstrates that an effective evaluation of the current situation of contamination as well as of the related future fate development requires detailed information of the entire observed system.

Temporal stability of Escherichia coli concentration patterns in two irrigation ponds in Maryland

USDA-ARS?s Scientific Manuscript database

Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. We hypothesized that there is a temporally stable pattern of E.coli concentrations ...

EVALUATION OF GROUNDWATER FLOW PATTERNS AROUND A DUAL-SCREENED GROUNDWATER CIRCULATION WELL

EPA Science Inventory

Dual-screened groundwater circulation wells (GCWs) can be used to remove contaminant mass and to mix reagents in situ. GCWs are so named because they force water in a circular pattern between injection and extraction screens. The radial extent, flux and direction of the effective...

Temporal Asthma Patterns Using Repeated Questionnaires over 13 Years in a Large French Cohort of Women

PubMed Central

Sanchez, Margaux; Bousquet, Jean; Le Moual, Nicole; Jacquemin, Bénédicte; Clavel-Chapelon, Françoise; Humbert, Marc; Kauffmann, Francine; Tubert-Bitter, Pascale; Varraso, Raphaëlle

2013-01-01

Variable expression is one aspect of the heterogeneity of asthma. We aimed to define a variable pattern, which is relevant in general health epidemiological cohorts. Our objectives were to assess whether: 1) asthma patterns defined using simple asthma questions through repeated measurements could reflect disease variability 2) these patterns may further be classified according to asthma severity/control. Among 70,428 French women, we used seven questionnaires (1992–2005) and a comprehensive reimbursement database (2004–2009) to define three reliable asthma patterns based on repeated positive answers to the ever asthma attack question: “never asthma” (n = 64,061); “inconsistent” (“yes” followed by “no”, n = 3,514); “consistent” (fully consistent positive answers, n = 2,853). The “Inconsistent” pattern was related to both long-term (childhood-onset asthma with remission in adulthood) and short-term (reported asthma attack in the last 12 months, associated with asthma medication) asthma variability, showing that repeated questions are relevant markers of the variable expression of asthma. Furthermore, in this pattern, the number of positive responses (1992–2005) predicted asthma drug consumption in subsequent years, a marker of disease severity. The “Inconsistent” pattern is a phenotype that may capture the variable expression of asthma. Repeated answers, even to a simple question, are too often neglected. PMID:23741466

Short-term variability and predictors of urinary pentachlorophenol levels in Ohio preschool children

EPA Science Inventory

Pentachlorophenol (PCP) is a persistent and ubiquitous environmental contaminant. No published data exist on the temporal variability or important predictors of urinary PCP concentrations in young children. In this further analysis of study data, we have examined the associations...

TEMPORAL VARIABILITY OF ENTEROCOCCI SPECIES IN STREAMS IMPACTED BY CATTLE FECAL CONTAMINATION

EPA Science Inventory

Temporal variability in the gastrointestinal flora of animals impacting water resources with fecal material can be one of the factors producing low source identification rates when applying microbial source tracking (MST) methods. Our objective is to identify and compare the temp...

Impacts of maintenance dredged material disposal on macrobenthic structure and secondary productivity.

PubMed

Bolam, S G; Barry, J; Bolam, T; Mason, C; Rumney, H S; Thain, J E; Law, R J

2011-10-01

The results of a monitoring programme to assess the spatial impacts associated with ongoing dredged material disposal activity at a dispersive, coastal disposal site (southwest UK) are described. Benthic impacts were assessed using benthic community structure and secondary productivity estimates. Analyses of univariate indices (including secondary production) and multivariate community structure revealed differences between stations inside and those outside the disposal site were minimal. Generally, stations within and outside the disposal site were characterised by the same species. Regression models indicated that the variability in biological structure and secondary production was predominantly accounted for by natural variables (e.g., depth, sediment granulometry) with only a small amount of residual variability being due to contaminant variables. Thus, the elevated levels of certain contaminants in the vicinity of the disposal area were not sufficient to result in significant ecological or ecotoxicological changes. We ascribe such findings partly to the dispersive nature of the disposal site. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

The effect of Piriformospora indica on the root development of maize (Zea mays L.) and remediation of petroleum contaminated soil.

PubMed

Zamani, Javad; Hajabbasi, Mohammad Ali; Alaie, Ebrahim; Sepehri, Mozhgan; Leuchtmann, Adrian; Schulin, Rainer

2016-01-01

As the depth of soil petroleum contamination can vary substantially under field conditions, a rhizotron experiment was performed to investigate the influence of endophyte, P. indica, on maize growth and degradation of petroleum components in a shallow and a deep-reaching subsurface layer of a soil. For control, a treatment without soil contamination was also included. The degree in contamination and the depth to which it extended had a strong effect on the growth of the plant roots. Contaminated soil layers severely inhibited root growth thus many roots preferred to bypass the shallow contaminated layer and grow in the uncontaminated soil. While the length and branching pattern of these roots were similar to those of uncontaminated treatment. Inoculation of maize with P. indica could improve root distribution and root and shoot growth in all three contamination treatments. This inoculation also enhanced petroleum degradation in soil, especially in the treatment with deep-reaching contamination, consequently the accumulation of petroleum hydrocarbons (PAHs) in the plant tissues were increased.

Implementation of a 3D Coupled Hydrodynamic and Contaminant Fate Model for PCDD/Fs in Thau Lagoon (France): The Importance of Atmospheric Sources of Contamination

PubMed Central

Dueri, Sibylle; Marinov, Dimitar; Fiandrino, Annie; Tronczyński, Jacek; Zaldívar, José-Manuel

2010-01-01

A 3D hydrodynamic and contaminant fate model was implemented for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Thau lagoon. The hydrodynamic model was tested against temperature and salinity measurements, while the contaminant fate model was assessed against available data collected at different stations inside the lagoon. The model results allow an assessment of the spatial and temporal variability of the distribution of contaminants in the lagoon, the seasonality of loads and the role of atmospheric deposition for the input of PCDD/Fs. The outcome suggests that air is an important source of PCDD/Fs for this ecosystem, therefore the monitoring of air pollution is very appropriate for assessing the inputs of these contaminants. These results call for the development of integrated environmental protection policies. PMID:20617040

Evidence for a Time-Invariant Phase Variable in Human Ankle Control

PubMed Central

Gregg, Robert D.; Rouse, Elliott J.; Hargrove, Levi J.; Sensinger, Jonathon W.

2014-01-01

Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms). In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control. PMID:24558485

Effect of acute stress on plasma beta-corticosterone, estradiol-17 beta and testosterone concentrations in juvenile American alligators collected from three sites within the Kissimmee-Everglades drainage basin in Florida (USA).

PubMed

Gunderson, M P; Kools, S A E; Milnes, M R; Guillette, L J

2003-07-01

The effect of acute stress on plasma beta-corticosterone (B), testosterone (T) and estradiol-17beta (E2) concentrations in juvenile alligators collected from sites with varying sediment contaminants was examined in this study. Dramatic increases in plasma B concentrations were observed in alligators from all of the sites after 2 h of capture although females from the intermediate contaminant site exhibited a significantly lower percentage increase in B than females from the other two sites. Males from the site with the highest contaminant levels exhibited elevated initial B concentrations relative to the other sites. This pattern was not observed after 2 h of restraint. Females from the highest contaminant site exhibited depressed initial T when compared to the other sites although this pattern was not observed after 2 h of restraint. Neither E2 nor T decreased after 2 h in females, whereas T concentrations decreased in all males over the same time period. The variance associated with these endpoints was also examined to determine whether it could serve as a more sensitive marker for perturbations of the endocrine system and stress response. Females from the higher and intermediate contaminant sites exhibited the lowest and highest standard errors (respectively) associated with 2 h plasma B concentrations with no differences among mean concentrations suggesting a perturbation of the stress response in these animals that was not detected by examining the means. We concluded that the environmental contaminants could be acting as stressors, leading to the observed differences.

Tissue contaminants and associated transcriptional response in trout liver from high elevation lakes of Washington

USGS Publications Warehouse

Moran, P.W.; Aluru, N.; Black, R.W.; Vijayan, M.M.

2007-01-01

The consistent cold temperatures and large amount of precipitation in the Olympic and Cascade ranges of Washington State are thought to enhance atmospheric deposition of contaminants. However, little is known about contaminant levels in organisms residing in these remote high elevation lakes. We measured total mercury and 28 organochlorine compounds in trout collected from 14 remote lakes in the Olympic, Mt. Rainer, and North Cascades National Parks. Mercury was detected in trout from all lakes sampled (15 to 262 ??g/kg ww), while two organochlorines, total polychlorinated biphenyls (tPCB) and dichlorodiphenyldichloroethylene (DDE), were also detected in these fish tissues (<25 ??g/kg ww). In sediments, organochlorine levels were below detection, while median total and methyl mercury were 30.4 and 0.34 ??g/ kg dry weight (ww), respectively. Using fish from two lakes, representing different contaminant loading levels (Wilcox lake: high; Skymo lake: low), we examined transcriptional response in the liver using a custom-made low-density targeted rainbow trout cDNA microarray. We detected significant differences in liver transcriptional response, including significant changes in metabolic, endocrine, and immune-related genes, in fish collected from Wilcox Lake compared to Skymo Lake. Overall, our results suggest that local urban areas contribute to the observed contaminant patterns in these high elevation lakes, while the transcriptional changes point to a biological response associated with exposure to these contaminants in fish. Specifically, the gene expression pattern leads us to hypothesize a role for mercury in disrupting the metabolic and reproductive pathways in fish from high elevation lakes in western Washington. ?? 2007 American Chemical Society.

Effect of tidal fluctuations on contaminant transfer to the ocean

USGS Publications Warehouse

Licata, I.L.; Langevin, C.D.; Dausman, A.M.

2007-01-01

Variable-density groundwater flow was simulated to examine the effects that tide has on the coastward migration of a contaminant through a freshwater/saltwater interface and toward a coastal ocean boundary. Simulated ocean tides did not significantly affect the total contaminant mass input to the ocean; however, the difference in tidal and non-tidal simulated concentrations could be as much as 15%. It may be possible to numerically approximate the tidal-driven hydraulic transients in transport models that do not explicitly include tides by locally increasing dispersivity. Copyright ?? 2007 IAHS Press.

Urban legacies and soil management affect the concentration and speciation of trace metals in Los Angeles community garden soils.

PubMed

Clarke, Lorraine Weller; Jenerette, G Darrel; Bain, Daniel J

2015-02-01

Heavy metals in urban soils can compromise human health, especially in urban gardens, where gardeners may ingest contaminated dust or crops. To identify patterns of urban garden metal contamination, we measured concentrations and bioavailability of Pb, As, and Cd in soils associated with twelve community gardens in Los Angeles County, CA. This included sequential extractions to partition metals among exchangeable, reducible, organic, or residual fractions. Proximity to road increased all metal concentrations, suggesting vehicle emissions sources. Reducible Pb increased with neighborhood age, suggesting leaded paint as a likely pollutant source. Exchangeable Cd and As both increased with road proximity. Only cultivated soils showed an increase in exchangeable As with road proximity, potentially due to reducing humic acid interactions while Cd bioavailability was mitigated by organic matter. Understanding the geochemical phases and metal bioavailability allows incorporation of contamination patterns into urban planning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dispersal of micro-organisms in commercial defeathering systems.

PubMed

Allen, V M; Tinker, D B; Hinton, M H; Wathes, C M

2003-03-01

1. The extent of cross contamination between carcases and the dispersal of micro-organisms to the environs during defeathering was measured in a commercial processing plant. 2. Defeathering reduced the numbers of a marker organism, a nalidixic acid-resistant strain of Escherichia coli K12, on inoculated carcases but dispersed the organism on to preceding and following carcases. 3. The pattern of microbial dispersal during defeathering was similar for naturally occurring bacteria on the carcase, for example, total aerobic counts and counts of presumptive coliforms, suggesting that the marker organism mimics the natural situation realistically. 4. The majority of feathers, together with micro-organisms, were removed during the first 10 s of the defeathering process, which was completed in 45 s, indicating that control measures to minimise cross contamination would be most effective if applied in the early stages of the process. 5. The method of defeathering used by the machine influenced the pattern of microbial dispersal and the extent of cross contamination to other carcases on the same processing line.

Patterns in benthic populations in the Milford Haven waterway following the 'Sea Empress' oil spill with special reference to amphipods.

PubMed

Nikitik, Christopher C S; Robinson, Andrew W

2003-09-01

The macrobenthic fauna of the Milford Haven Waterway was studied in detail following the 'Sea Empress' oil spill in 1996. Contamination patterns indicated heaviest contamination of sediments by oil to have occurred in the lower reaches of the waterway, although water borne hydrocarbons are likely to have penetrated throughout the Haven. Generally, the communities showed little impact of contamination by oil, although some changes were evident at the population level. A decline in the amphipod fauna was observed throughout the Haven, with the genera Ampelisca and Harpinia and the family Isaeidae particularly affected. This was accompanied by increases in both the diversity and abundance of polychaete populations as opportunist species took advantage of the decline of the amphipod fauna. However, within five years of the spill the amphipod fauna has shown clear signs of recovery. The use of the polychaete/amphipod ratio as an indicator of oil pollution is discussed.

A two-in-one process for reliable graphene transistors processed with photo-lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahlberg, P.; Hinnemo, M.; Song, M.

2015-11-16

Research on graphene field-effect transistors (GFETs) has mainly relied on devices fabricated using electron-beam lithography for pattern generation, a method that has known problems with polymer contaminants. GFETs fabricated via photo-lithography suffer even worse from other chemical contaminations, which may lead to strong unintentional doping of the graphene. In this letter, we report on a scalable fabrication process for reliable GFETs based on ordinary photo-lithography by eliminating the aforementioned issues. The key to making this GFET processing compatible with silicon technology lies in a two-in-one process where a gate dielectric is deposited by means of atomic layer deposition. During thismore » deposition step, contaminants, likely unintentionally introduced during the graphene transfer and patterning, are effectively removed. The resulting GFETs exhibit current-voltage characteristics representative to that of intrinsic non-doped graphene. Fundamental aspects pertaining to the surface engineering employed in this work are investigated in the light of chemical analysis in combination with electrical characterization.« less

Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital

PubMed Central

2013-01-01

Introduction Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. Objective To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital. Methodology Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. Result: A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44×104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Conclusion Bacterial contamination of the stethoscope was significant. The isolates were potential pathogens and resistant to multiple classes of antibiotics. Stethoscope is potential vehicle in the transmission of infections between patients and Healthcare Workers. Stethoscope diaphragm should be disinfected before and after each patient contact. PMID:24330702

Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital.

PubMed

Shiferaw, Teklu; Beyene, Getenet; Kassa, Tesfaye; Sewunet, Tsegaye

2013-12-13

Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital. Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44×104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Bacterial contamination of the stethoscope was significant. The isolates were potential pathogens and resistant to multiple classes of antibiotics. Stethoscope is potential vehicle in the transmission of infections between patients and Healthcare Workers. Stethoscope diaphragm should be disinfected before and after each patient contact.

Semi-quantitative evaluation of fecal contamination potential by human and ruminant sources using multiple lines of evidence.

PubMed

Stoeckel, Donald M; Stelzer, Erin A; Stogner, Robert W; Mau, David P

2011-05-01

Protocols for microbial source tracking of fecal contamination generally are able to identify when a source of contamination is present, but thus far have been unable to evaluate what portion of fecal-indicator bacteria (FIB) came from various sources. A mathematical approach to estimate relative amounts of FIB, such as Escherichia coli, from various sources based on the concentration and distribution of microbial source tracking markers in feces was developed. The approach was tested using dilute fecal suspensions, then applied as part of an analytical suite to a contaminated headwater stream in the Rocky Mountains (Upper Fountain Creek, Colorado). In one single-source fecal suspension, a source that was not present could not be excluded because of incomplete marker specificity; however, human and ruminant sources were detected whenever they were present. In the mixed-feces suspension (pet and human), the minority contributor (human) was detected at a concentration low enough to preclude human contamination as the dominant source of E. coli to the sample. Without the semi-quantitative approach described, simple detects of human-associated marker in stream samples would have provided inaccurate evidence that human contamination was a major source of E. coli to the stream. In samples from Upper Fountain Creek the pattern of E. coli, general and host-associated microbial source tracking markers, nutrients, and wastewater-associated chemical detections--augmented with local observations and land-use patterns--indicated that, contrary to expectations, birds rather than humans or ruminants were the predominant source of fecal contamination to Upper Fountain Creek. This new approach to E. coli allocation, validated by a controlled study and tested by application in a relatively simple setting, represents a widely applicable step forward in the field of microbial source tracking of fecal contamination. Copyright © 2011 Elsevier Ltd. All rights reserved.

Round-robin comparison of methods for the detection of human enteric viruses in lettuce.

PubMed

Le Guyader, Françoise S; Schultz, Anna-Charlotte; Haugarreau, Larissa; Croci, Luciana; Maunula, Leena; Duizer, Erwin; Lodder-Verschoor, Froukje; von Bonsdorff, Carl-Henrik; Suffredini, Elizabetha; van der Poel, Wim M M; Reymundo, Rosanna; Koopmans, Marion

2004-10-01

Five methods that detect human enteric virus contamination in lettuce were compared. To mimic multiple contaminations as observed after sewage contamination, artificial contamination was with human calicivirus and poliovirus and animal calicivirus strains at different concentrations. Nucleic acid extractions were done at the same time in the same laboratory to reduce assay-to-assay variability. Results showed that the two critical steps are the washing step and removal of inhibitors. The more reliable methods (sensitivity, simplicity, low cost) included an elution/concentration step and a commercial kit. Such development of sensitive methods for viral detection in foods other than shellfish is important to improve food safety.

UNDERSTANDING THE IMPACT OF ENVIRONMENTAL VARIABLES ON THE LEACHING OF MERCURY-CONTAMINATED MINE WASTES FROM THE SULFUR BANK MERCURY MINE, CLEAR LAKE, CA

EPA Science Inventory

For nearly a century, Clear Lake in northern California has received inputs of mercury (Hg) mining wastes trom the Sulfur Bank Mercury Mine (SBMM). About 1.2 million tons of Hg-contaminated overburden and mine tailings were distributed over a 50-ha surface area due to mining oper...

Model based estimation of sediment erosion in groyne fields along the River Elbe

NASA Astrophysics Data System (ADS)

Prohaska, Sandra; Jancke, Thomas; Westrich, Bernhard

2008-11-01

River water quality is still a vital environmental issue, even though ongoing emissions of contaminants are being reduced in several European rivers. The mobility of historically contaminated deposits is key issue in sediment management strategy and remediation planning. Resuspension of contaminated sediments impacts the water quality and thus, it is important for river engineering and ecological rehabilitation. The erodibility of the sediments and associated contaminants is difficult to predict due to complex time depended physical, chemical, and biological processes, as well as due to the lack of information. Therefore, in engineering practice the values for erosion parameters are usually assumed to be constant despite their high spatial and temporal variability, which leads to a large uncertainty of the erosion parameters. The goal of presented study is to compare the deterministic approach assuming constant critical erosion shear stress and an innovative approach which takes the critical erosion shear stress as a random variable. Furthermore, quantification of the effective value of the critical erosion shear stress, its applicability in numerical models, and erosion probability will be estimated. The results presented here are based on field measurements and numerical modelling of the River Elbe groyne fields.

Persistent organic pollutants in British Columbia grizzly bears: consequence of divergent diets.

PubMed

Christensen, Jennie R; MacDuffee, Misty; Macdonald, Robie W; Whiticar, Michael; Ross, Peter S

2005-09-15

Nitrogen and carbon stable isotope signatures in growing hair reveal that while some British Columbia grizzly bears (Ursus arctos horribilis) rely entirely on terrestrial foods, others switch in late summer to returning Pacific salmon (Oncorynchus spp.). Implications for persistent organic pollutant (POP) concentrations and patterns measured in the two feeding groups of grizzly bears were profound. While the bears consuming a higher proportion of terrestrial vegetation ("interior" grizzlies) exhibited POP patterns dominated bythe more volatile organochlorine (OC) pesticides and the heavier polybrominated diphenyl ethers (PBDEs: e.g., BDE-209), the bears consuming salmon were dominated by the more bioaccumulative POPs (e.g., DDT, chlordanes, and BDE-47). The ocean-salmon-bear pathway appeared to preferentially select for those contaminants with intermediate partitioning strength from water into lipid (log Kow approximately 6.5). This pattern reflects an optimum contaminant log Kow range for atmospheric transport, deposition into the marine environment, uptake into marine biota, accumulation through the food web, and retention in the bear tissues. We estimate that salmon deliver 70% of all OC pesticides, up to 85% of the lower brominated PBDE congeners, and 90% of PCBs found in salmon-eating grizzly bears, thereby inextricably linking these terrestrial predators to contaminants from the North Pacific Ocean.

Classification of Partial Discharge Measured under Different Levels of Noise Contamination.

PubMed

Jee Keen Raymond, Wong; Illias, Hazlee Azil; Abu Bakar, Ab Halim

2017-01-01

Cable joint insulation breakdown may cause a huge loss to power companies. Therefore, it is vital to diagnose the insulation quality to detect early signs of insulation failure. It is well known that there is a correlation between Partial discharge (PD) and the insulation quality. Although many works have been done on PD pattern recognition, it is usually performed in a noise free environment. Also, works on PD pattern recognition in actual cable joint are less likely to be found in literature. Therefore, in this work, classifications of actual cable joint defect types from partial discharge data contaminated by noise were performed. Five cross-linked polyethylene (XLPE) cable joints with artificially created defects were prepared based on the defects commonly encountered on site. Three different types of input feature were extracted from the PD pattern under artificially created noisy environment. These include statistical features, fractal features and principal component analysis (PCA) features. These input features were used to train the classifiers to classify each PD defect types. Classifications were performed using three different artificial intelligence classifiers, which include Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Support Vector Machine (SVM). It was found that the classification accuracy decreases with higher noise level but PCA features used in SVM and ANN showed the strongest tolerance against noise contamination.

Processing Conditions, Rice Properties, Health and Environment

PubMed Central

Roy, Poritosh; Orikasa, Takahiro; Okadome, Hiroshi; Nakamura, Nobutaka; Shiina, Takeo

2011-01-01

Rice is the staple food for nearly two-thirds of the world’s population. Food components and environmental load of rice depends on the rice form that is resulted by different processing conditions. Brown rice (BR), germinated brown rice (GBR) and partially-milled rice (PMR) contains more health beneficial food components compared to the well milled rice (WMR). Although the arsenic concentration in cooked rice depends on the cooking methods, parboiled rice (PBR) seems to be relatively prone to arsenic contamination compared to that of untreated rice, if contaminated water is used for parboiling and cooking. A change in consumption patterns from PBR to untreated rice (non-parboiled), and WMR to PMR or BR may conserve about 43–54 million tons of rice and reduce the risk from arsenic contamination in the arsenic prone area. This study also reveals that a change in rice consumption patterns not only supply more food components but also reduces environmental loads. A switch in production and consumption patterns would improve food security where food grains are scarce, and provide more health beneficial food components, may prevent some diseases and ease the burden on the Earth. However, motivation and awareness of the environment and health, and even a nominal incentive may require for a method switching which may help in building a sustainable society. PMID:21776212

Spray deposition inside tree canopies from a newly developed variable-rate air assisted sprayer

USDA-ARS?s Scientific Manuscript database

Conventional spray applications in orchards and ornamental nurseries are not target-oriented, resulting in significant waste of pesticides and contamination of the environment. To address this problem, a variable-rate air-assisted sprayer implementing laser scanning technology was developed to apply...

Development of variable-rate precision spraying systems for tree crop production

USDA-ARS?s Scientific Manuscript database

Excessive pesticides are often applied to target and non-target areas in orchards and nurseries, resulting in greater production costs, worker exposure to unnecessary pesticide risks, and adverse contamination of the environment. To improve spray application efficiency, two types of variable-rate pr...

RNAi control of aflatoxins in peanut plants, a multifactorial system

USDA-ARS?s Scientific Manuscript database

RNA-interference (RNAi)-mediated control of aflatoxin contamination in peanut plants is a multifactorial and hyper variable system. The use of RNAi biotechnology to silence single genes in plants has inherently high-variability among transgenic events. Also the level of expression of small interfe...

40 CFR 761.389 - Testing parameter requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... variable testing parameters described in this section which may be used in the validation study. The conditions demonstrated in the validation study for these variables shall become the required conditions for.... During the validation study, use the same ratio of contaminated surface area to soak solvent volume as...

40 CFR 761.389 - Testing parameter requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... variable testing parameters described in this section which may be used in the validation study. The conditions demonstrated in the validation study for these variables shall become the required conditions for.... During the validation study, use the same ratio of contaminated surface area to soak solvent volume as...

40 CFR 761.389 - Testing parameter requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... variable testing parameters described in this section which may be used in the validation study. The conditions demonstrated in the validation study for these variables shall become the required conditions for.... During the validation study, use the same ratio of contaminated surface area to soak solvent volume as...

The role of Spartina maritima and Sarcocornia fruticosa on trace metals retention in Ria Formosa, Portugal

NASA Astrophysics Data System (ADS)

Moreira da Silva, Manuela; Duarte, Duarte; Isidoro, Jorge; Chícharo, Luís

2013-04-01

Over the last years, phytoremediation has become an increasingly recognized pathway for contaminant removal from water and shallow soils. Assessing the phytoremediation potential of wetlands is complex due to variable conditions of hydrology, soil/sediment types, plant species diversity, growing season and water chemistry. Physico-chemical properties of wetlands provide many positive attributes for remediating contaminants. Saltmarsh plants can sequestrate and inherently tolerate high metal concentrations found in saltmarsh sediments. An increasing number of studies have been carried out to understand the role of halophyte vegetation on retention, biovailability and remediation of the pollutants in coastal areas (estuaries and lagoons). It is already known that the accumulation capacity and the pattern of metal distribution in the plant tissues vary among plant species, namely monocotyledonous and dicotyledonous, and with sediment characteristics. During the last decades, there has been a large increase in urbanization and industrialization of the area surrounding Ria Formosa. Due to this reality, anthropogenic contaminants, including trace metals, are transported via untreated sewage and agricultural effluents to several parts of the lagoon. The dominant producers are Spartina maritima (Poales: Poaceae) and Sarcocornia fruticosa (Caryophyllales: Chenopodiaceae), appearing in pure stands respectively in the lower and in the upper saltmarshes. The aim of this work was to survey, comparatively, the role of S. maritima and S. fruticosa on minor and trace element (Ag, Cd, Cu, Cr, Mo, Ni, Pb and Zn), contents and distribution amongst sediment and plant tissues. Both S. maritima and S. fruticosa could fix metals from the surrounding belowground environment and accumulate metals, mainly in roots (also in rhizomes in the case of the former). Metal translocation to aerial parts of the plants was, in general, residual.

Monitoring and modeling wetland chloride concentrations in relationship to oil and gas development

USGS Publications Warehouse

Post van der Burg, Max; Tangen, Brian A.

2015-01-01

Extraction of oil and gas via unconventional methods is becoming an important aspect of energy production worldwide. Studying the effects of this development in countries where these technologies are being widely used may provide other countries, where development may be proposed, with some insight in terms of concerns associated with development. A fairly recent expansion of unconventional oil and gas development in North America provides such an opportunity. Rapid increases in energy development in North America have caught the attention of managers and scientists as a potential stressor for wildlife and their habitats. Of particular concern in the Northern Great Plains of the U.S. is the potential for chloride-rich produced water associated with unconventional oil and gas development to alter the water chemistry of wetlands. We describe a landscape scale modeling approach designed to examine the relationship between potential chloride contamination in wetlands and patterns of oil and gas development. We used a spatial Bayesian hierarchical modeling approach to assess multiple models explaining chloride concentrations in wetlands. These models included effects related to oil and gas wells (e.g. age of wells, number of wells) and surficial geology (e.g. glacial till, outwash). We found that the model containing the number of wells and the surficial geology surrounding a wetland best explained variation in chloride concentrations. Our spatial predictions showed regions of localized high chloride concentrations. Given the spatiotemporal variability of regional wetland water chemistry, we do not regard our results as predictions of contamination, but rather as a way to identify locations that may require more intensive sampling or further investigation. We suggest that an approach like the one outlined here could easily be extended to more of an adaptive monitoring approach to answer questions about chloride contamination risk that are of interest to managers.

Arctic sea-ice variability and its implication to the path of pollutants under a changing climate

NASA Astrophysics Data System (ADS)

Castro-Morales, K.; Gerdes, R.; Riemann-Campe, K.; Köberle, C.; Losch, M.

2012-04-01

The increasing concentration of pollutants from anthropogenic origin in the Arctic atmosphere, water, sediments and biota has been evident during the last decade. The sea-ice is an important vehicle for pollutants in the Arctic Ocean. Pollutants are taken up by precipitation and dry atmospheric deposition over the snow and ice cover during winter and released to the ocean during melting. Recent changes in the sea-ice cover of the Arctic Ocean affect the fresh water balance and the oceanic circulation, and with it, the fate of pollutants in the system. The Arctic Ocean is characterized by complex dynamics and strong stratification. Thus, to evaluate the current and future changes in the Arctic circulation high-resolution models are needed. As part of the EU FP7 project ArcRisk (under the scope of the IPY), we use a high resolution regional sea-ice-ocean coupled model covering the Arctic Ocean and the subpolar North Atlantic based on the Massachusetts Institute of Technology - circulation model (MITgcm). Under realistic atmospheric forcing we obtain hindcast results of circulation patterns for the period 1990 - 2010 for validation of the model. We evaluate possible consequences on the pathways and transport of contaminants by downscaling future climate scenario runs available in the coupled model intercomparison project (CMIP3) for the following fifty years. Particular interest is set in the Barents Sea. In this shallow region strong river runoff, sea-ice delivered from the interior of the Arctic Ocean and warm waters from the North Atlantic current are main sources of contaminants. Under a changing climate, a higher input of contaminants delivered to surface waters is expected, remaining in the interior of the Arctic Ocean in a strongly stratified water column remaining.

Aiming for the stomach and hitting the heart: Dissociable triggers and sources for disgust reactions

PubMed Central

Shenhav, Amitai; Mendes, Wendy Berry

2014-01-01

Disgust reactions can be elicited using stimuli that engender orogastric rejection (e.g., pus and vomit; Core Disgust stimuli), but also using images of bloody injuries or medical procedures (e.g., surgeries; Blood-[Body] Boundary Violation [B-BV] Disgust stimuli). These two types of disgust reaction are believed to be connected by a common evolutionary function of avoiding either food- or blood-borne contaminants. However, reactions to the category of bloody injuries are typically conflated with reactions to the potential pain being experienced by the victim. This may explain why the two forms of ‘disgust,’ though similarly communicated (through self-report and facial expressions) evince different patterns of physiological reactivity. We therefore tested whether the communicative similarities and physiological dissimilarities would hold when markers of potential contamination in the latter category are removed, leaving only painful injuries that lack blood or explicit body-envelope violations. Participants viewed films that depicted imagery associated with (1) core disgust, (2) painful injuries, or (3) neutral scenes while we measured facial, cardiovascular, and gastric reactivity, respectively. Whereas communicative measures (self-report and facial muscles) suggested that participants experienced increased disgust for both core disgust and painful injuries, peripheral physiology dissociated the two: core disgust decreased normal gastric activity and painful-injury disgust decelerated heart rate and increased heart rate variability. These findings suggest that expressions of disgust toward bodily injuries may reflect a fundamentally different affective response than those evoked by core disgust, and that this (cardiovascularly-mediated) response may in fact be more closely tied to pain-perceptions (or empathy) rather than contaminant-laden stimuli. PMID:24219399

Performance of food safety management systems in poultry meat preparation processing plants in relation to Campylobacter spp. contamination.

PubMed

Sampers, Imca; Jacxsens, Liesbeth; Luning, Pieternel A; Marcelis, Willem J; Dumoulin, Ann; Uyttendaele, Mieke

2010-08-01

A diagnostic instrument comprising a combined assessment of core control and assurance activities and a microbial assessment instrument were used to measure the performance of current food safety management systems (FSMSs) of two poultry meat preparation companies. The high risk status of the company's contextual factors, i.e., starting from raw materials (poultry carcasses) with possible high numbers and prevalence of pathogens such as Campylobacter spp., requires advanced core control and assurance activities in the FSMS to guarantee food safety. The level of the core FSMS activities differed between the companies, and this difference was reflected in overall microbial quality (mesophilic aerobic count), presence of hygiene indicators (Enterobacteriaceae, Staphylococcus aureus, and Escherichia coli), and contamination with pathogens such as Salmonella, Listeria monocytogenes, and Campylobacter spp. The food safety output expressed as a microbial safety profile was related to the variability in the prevalence and contamination levels of Campylobacter spp. in poultry meat preparations found in a Belgian nationwide study. Although a poultry meat processing company could have an advanced FSMS in place and a good microbial profile (i.e., lower prevalence of pathogens, lower microbial numbers, and less variability in microbial contamination), these positive factors might not guarantee pathogen-free products. Contamination could be attributed to the inability to apply effective interventions to reduce or eliminate pathogens in the production chain of (raw) poultry meat preparations.

Hydrochemical profiles in urban groundwater systems: New insights into contaminant sources and pathways in the subsurface from legacy and emerging contaminants.

PubMed

White, D; Lapworth, D J; Stuart, M E; Williams, P J

2016-08-15

It has long been known that groundwaters beneath urban areas carry a fingerprint from urban activities but finding a consistent tracer for anthropogenic influence has proved elusive. The varied sources of urban contaminants means that a single consistent and inexpensive means of tracing the fate of urban contaminants is not generally possible and multiple tracers are often required to understand the contaminant sources and pathways in these complex systems. This study has utilized a combination of micro-organic (MO) contaminants and inorganic hydrochemistry to trace recharge pathways and quantify the variability of groundwater quality in multi-level piezometers in the city of Doncaster, UK. A total of 23 MOs were detected during this study, with more compounds consistently detected during higher groundwater table conditions highlighting the importance of sampling under different hydrological conditions. Four of the compounds detected are EU Water Framework Directive priority substances: atrazine, simazine, naphthalene and DEHP, with a maximum concentration of 0.18, 0.03, 0.2, 16μg/l respectively. Our study shows that the burden of the banned pesticide atrazine persists in the Sherwood Sandstone and is detected at two of the three study sites. Emerging contaminants are seen throughout the borehole profiles and provide insights into transient pathways for contaminant migration in the sub-surface. Long term changes in inorganic hydrochemistry show possible changes in contaminant input or the dissolution of minerals. Nitrate was detected above 50mg/l but on the whole nitrate concentrations have declined in the intervening years either due to a reduction of nitrate application at the surface or a migration of peak nitrate concentrations laterally or to greater depth. This study shows that multiple tracers together with multi-level piezometers can give a better resolution of contaminant pathways and variable flow regimes within the relatively uncomplicated aquifer of the Sherwood Sandstone compared with single long screened wells. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The pattern of Campylobacter contamination on broiler farms; external and internal sources.

PubMed

Battersby, T; Whyte, P; Bolton, D J

2016-04-01

The aim of this study was to apply the most sensitive molecular techniques in combination with culture-based methods to characterize broiler farms in terms of the timeline ('appearance' and 'pattern') of Campylobacter contamination prior to and post detection in the birds. Faecal and environmental samples were collected from three broiler farms (two flocks per farm). Real-time PCR was used to test for the presence of Campylobacter. Culture-based methods (enrichment and direct plating) were also applied and isolates were subject to a range of confirmatory tests before speciation (multiplex PCR). All flocks were colonized by Campylobacter before first thin and a similar pattern of Campylobacter contamination was observed; (day -1) a range of external and internal samples real-time PCR positive but culture negative; (day 0) chicks negative; (6-9 days pre-detection in the birds) internal samples (feeders, drinkers, barrier and/or bird weigh) culture positive and (post broiler infection) increasing concentrations of Campylobacter in internal samples but also on the tarmac apron and anteroom. It was concluded that; (i) vertical transmission did not occur; (ii) the environment was a potential source of Campylobacter; (iii) testing areas frequented by all birds (e.g. feeders and drinkers), may offer an opportunity for early Campylobacter detection and (iv) once the broilers are infected with Campylobacter, these bacteria are spread from the birds, through the anteroom to the areas surrounding the broiler house, highlighting the need for improved biosecurity. This study has established the pattern of Campylobacter contamination on broiler farms, identified an early detection opportunity, highlighted the need to better understand the role of viable but nonculturable Campylobacter in the ecology of Campylobacter on broiler farms and demonstrated the need for improved biosecurity to prevent the spread of Campylobacter from within the house to the surrounding environment. © 2016 The Society for Applied Microbiology.

Variability And Uncertainty Analysis Of Contaminant Transport Model Using Fuzzy Latin Hypercube Sampling Technique

NASA Astrophysics Data System (ADS)

Kumar, V.; Nayagum, D.; Thornton, S.; Banwart, S.; Schuhmacher2, M.; Lerner, D.

2006-12-01

Characterization of uncertainty associated with groundwater quality models is often of critical importance, as for example in cases where environmental models are employed in risk assessment. Insufficient data, inherent variability and estimation errors of environmental model parameters introduce uncertainty into model predictions. However, uncertainty analysis using conventional methods such as standard Monte Carlo sampling (MCS) may not be efficient, or even suitable, for complex, computationally demanding models and involving different nature of parametric variability and uncertainty. General MCS or variant of MCS such as Latin Hypercube Sampling (LHS) assumes variability and uncertainty as a single random entity and the generated samples are treated as crisp assuming vagueness as randomness. Also when the models are used as purely predictive tools, uncertainty and variability lead to the need for assessment of the plausible range of model outputs. An improved systematic variability and uncertainty analysis can provide insight into the level of confidence in model estimates, and can aid in assessing how various possible model estimates should be weighed. The present study aims to introduce, Fuzzy Latin Hypercube Sampling (FLHS), a hybrid approach of incorporating cognitive and noncognitive uncertainties. The noncognitive uncertainty such as physical randomness, statistical uncertainty due to limited information, etc can be described by its own probability density function (PDF); whereas the cognitive uncertainty such estimation error etc can be described by the membership function for its fuzziness and confidence interval by ?-cuts. An important property of this theory is its ability to merge inexact generated data of LHS approach to increase the quality of information. The FLHS technique ensures that the entire range of each variable is sampled with proper incorporation of uncertainty and variability. A fuzzified statistical summary of the model results will produce indices of sensitivity and uncertainty that relate the effects of heterogeneity and uncertainty of input variables to model predictions. The feasibility of the method is validated to assess uncertainty propagation of parameter values for estimation of the contamination level of a drinking water supply well due to transport of dissolved phenolics from a contaminated site in the UK.

Mental contamination: The effects of religiosity.

PubMed

Bilekli, Ilgun; Inozu, Mujgan

2018-03-01

Mental contamination, which occurs in the absence of contact with a contaminant, has a moral element. Previous studies evoked feelings of mental contamination via listening to a scenario, which described a non-consensual kiss. Since mental contamination has a moral element, we tested the effects of the level of religiosity on feelings of mental contamination and related variables in an experimental design. Female undergraduates of high religiosity (n = 48) and low religiosity (n = 44) were randomly assigned to listen to one of two audio recordings involving a consensual or non-consensual kiss from a man described as moral. Mental contamination feelings were evoked successfully in both groups. Effects of scenario condition and religiosity level were seen in mental contamination and related negative feelings. Participants who imagined a non-consensual kiss reported greatest feelings of mental contamination, and internal and external negative feelings. More importantly, high religiosity resulted in greater feelings of mental contamination, internal negative feelings, as well as urges to wash and actual washing behaviors. The current study was conducted on non-clinical Muslim females. This limits the generalization of the findings to the wider population. Mental contamination and related feelings can be seen in different forms at different levels of religiosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rainfall pattern variability as climate change impact in The Wallacea Region

NASA Astrophysics Data System (ADS)

Pujiastuti, I.; Nurjani, E.

2018-04-01

The objective of the study is to observe the characteristic variability of rainfall pattern in the city located in every rainfall type, local (Kendari), monsoon (Manado), and equatorial (Palu). The result will be compared to determine which has the most significantly precipitation changing due to climate change impact. Rainfall variability in Indonesia illustrates precipitation variation thus the important variability is the variability of monthly rainfall. Monthly precipitation data for the period of 1961-2010 are collected from Indonesian Agency for Meteorological, Climatological, and Geophysical Agency. This data is calculated with the normal test statistical method to analyze rainfall variability. The result showed the pattern of trend and variability of rainfall in every city with the own characteristic which determines the rainfall type. Moreover, there is comparison of rainfall pattern changing between every rainfall type. This information is useful for climate change mitigation and adaptation strategies especially in water resource management form precipitation as well as the occurrence of meteorological disasters.

Processing-Dependent and Clonal Contamination Patterns of Listeria monocytogenes in the Cured Ham Food Chain Revealed by Genetic Analysis.

PubMed

Morganti, Marina; Scaltriti, Erika; Cozzolino, Paolo; Bolzoni, Luca; Casadei, Gabriele; Pierantoni, Marco; Foni, Emanuela; Pongolini, Stefano

2016-02-01

The quantitative and qualitative patterns of environmental contamination by Listeria monocytogenes were investigated in the production chain of dry-cured Parma ham. Standard arrays of surfaces were sampled in processing facilities during a single visit per plant in the three compartments of the food chain, i.e., ham production (19 plants) and postproduction, which was divided into deboning (43 plants) and slicing (25 plants) steps. The numbers of sampled surfaces were 384 in ham production, with 25 positive for L. monocytogenes, and 1,084 in postproduction, with 83 positives. Statistical analysis of the prevalence of contaminated surfaces showed that in ham production, contamination was higher at the beginning of processing and declined significantly toward the end, while in postproduction, prevalence rose toward the end of processing. Prevalence was higher in the deboning facilities than in slicing facilities and was dependent on the type of surface (floor/drainage > clothing > equipment). The qualitative pattern of contamination was investigated through an analysis of the survey isolates and a set of isolates derived from routine monitoring, including longitudinal isolations. Pulsed-field gel electrophoresis (PFGE) and whole-genome single-nucleotide polymorphism (SNP) analysis revealed a remarkable clonality of L. monocytogenes within plants, with the detection of 16 plant-specific clones out of 17 establishments with multiple isolates. Repeated detections of clonal isolates >6 months apart were also observed. Six was the maximum number of between-isolate differences in core SNPs observed within these clones. Based on the same six-SNP threshold, three clusters of clonal isolates, shared by six establishments, were also identified. The spread of L. monocytogenes within and between plants, as indicated by its clonal behavior, is a matter of concern for the hygienic management of establishments. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

PROMISE: a tool to identify genomic features with a specific biologically interesting pattern of associations with multiple endpoint variables.

PubMed

Pounds, Stan; Cheng, Cheng; Cao, Xueyuan; Crews, Kristine R; Plunkett, William; Gandhi, Varsha; Rubnitz, Jeffrey; Ribeiro, Raul C; Downing, James R; Lamba, Jatinder

2009-08-15

In some applications, prior biological knowledge can be used to define a specific pattern of association of multiple endpoint variables with a genomic variable that is biologically most interesting. However, to our knowledge, there is no statistical procedure designed to detect specific patterns of association with multiple endpoint variables. Projection onto the most interesting statistical evidence (PROMISE) is proposed as a general procedure to identify genomic variables that exhibit a specific biologically interesting pattern of association with multiple endpoint variables. Biological knowledge of the endpoint variables is used to define a vector that represents the biologically most interesting values for statistics that characterize the associations of the endpoint variables with a genomic variable. A test statistic is defined as the dot-product of the vector of the observed association statistics and the vector of the most interesting values of the association statistics. By definition, this test statistic is proportional to the length of the projection of the observed vector of correlations onto the vector of most interesting associations. Statistical significance is determined via permutation. In simulation studies and an example application, PROMISE shows greater statistical power to identify genes with the interesting pattern of associations than classical multivariate procedures, individual endpoint analyses or listing genes that have the pattern of interest and are significant in more than one individual endpoint analysis. Documented R routines are freely available from www.stjuderesearch.org/depts/biostats and will soon be available as a Bioconductor package from www.bioconductor.org.

Faecal contamination of drinking water in a Brazilian shanty town: importance of household storage and new human faecal marker testing.

PubMed

Copeland, Curtis C; Beers, Benjamin B; Thompson, Meghan R; Fitzgerald, Relana P; Barrett, Leah J; Sevilleja, Jesus E; Alencar, Sayonara; Lima, Aldo A M; Guerrant, Richard L

2009-06-01

Worldwide, contaminated drinking water poses a major health threat, particularly to child development. Diarrhoea represents a large part of the water-related disease burden and enteric infections have been linked to nutritional and growth shortfalls as well as long-term physical and cognitive impairment in children. Previous studies detailed the frequency of infection and the consequences for child health in a shanty town in north-east Brazil. To determine the frequency of contaminated water, we measured faecal contamination in primary drinking water samples from 231 randomly selected households. Risk for contamination was compared across source and storage types. Nearly a third of the study households (70/231: 30.3%) had contaminated drinking water; the source with the highest frequency of contamination was well water (23/24: 95.8%). For tap water, the type of storage had a significant effect on the susceptibility to contamination (chi(2) = 12.090; p = 0.007). The observed pattern of contamination demonstrated the relative potential contributions of both source and storage. With evidence that supports the inclusion of source and storage in water quality surveys, this study, like others, suggests that contaminated drinking water in storage vessels may be an important factor for the documented diarrhoea disease burden in the Brazilian shanty town.

Land use and climate variability amplify carbon, nutrient, and contaminant pulses: a review with management implications

EPA Science Inventory

Nonpoint source pollution from agriculture and urbanization is increasing globally at the same time that climate extremes have increased in frequency and intensity. We review over 160 studies and show how the interaction between land use and climate variability alters the magnit...

Variability of water quality across headwater catchments with distinct soils and hydrologic systems in central Missouri

USDA-ARS?s Scientific Manuscript database

Surface water and groundwater contamination by herbicides and fertilizers continues to be a major water quality problem in central Missouri. The purpose of this study was to examine spatial variability of water quality among three different headwater catchments – Goodwater Creek Experimental Watersh...

TEMPORAL AND SPATIAL VARIABILITY OF FECAL INDICATOR BACTERIA: IMPLICATIONS FOR THE APPLICATION OF MST METHODOLOGIES TO DIFFERENTIATE SOURCES OF FECAL CONTAMINATION

EPA Science Inventory

Temporal variability in the gastrointestinal flora of animals impacting water resources with fecal material can be one of the factors producing low source identification rates when applying microbial source tracking (MST) methods. Understanding how bacterial species and genotype...

Spatiotemporal variability of inorganic nutrients during wastewater effluent dominated streamflow conditions in Indian Creek, Johnson County, Kansas, 2012–15

USGS Publications Warehouse

Foster, Guy M.; Graham, Jennifer L.; Williams, Thomas J.; King, Lindsey R.

2016-10-31

Nutrients, particularly nitrogen and phosphorus, are a leading cause of water-quality impairment in Kansas and the Nation. Indian Creek is one of the most urban drainage basins in Johnson County, Kansas, and environmental and biological conditions are affected by contaminants from point and other urban sources. The Johnson County Douglas L. Smith Middle Basin (hereinafter Middle Basin) wastewater treatment facility (WWTF) is the largest point-source discharge on Indian Creek. A second facility, the Tomahawk Creek WWTF, discharges into Indian Creek approximately 11.6 kilometers downstream from the Middle Basin WWTF. To better characterize the spatiotemporal variability of nutrients in Indian Creek, the U.S. Geological Survey, in cooperation with the Kansas Department of Health and Environment and Johnson County Wastewater, collected high-resolution spatial and temporal (a large number of samples collected over the entire reach or at single locations over a long period of time) inorganic nutrient (nitrate plus nitrite and orthophosphorus) data using a combination of discrete samples and sensor-measured data during 2012 through 2015.Nutrient patterns observed in Indian Creek along the upstream-downstream gradient during wastewater effluent dominated streamflow conditions were largely affected by the WWTFs and by travel time of the parcels of water. Nitrate plus nitrite concentrations in the Middle Basin WWTF effluent and at downstream sites varied by as much as 6 milligrams per liter over a 24-hour period. The cyclical variability in the Middle Basin WWTF effluent generated a nitrate plus nitrite pulse that could be tracked for approximately 11.5 kilometers downstream in Indian Creek, until the effect was masked by the Tomahawk Creek WWTF effluent discharge. All longitudinal surveys showed the same general patterns along the upstream-downstream gradient, though streamflows, wastewater effluent contributions to streamflow, and nutrient concentrations spanned a wide range. Differences in orthophosphorus and nitrate plus nitrite patterns were clear along the upstream-downstream gradient in Indian Creek, and orthophosphorus concentrations were not as variable as nitrate plus nitrite concentrations. In general, nitrate plus nitrite concentrations decreased downstream from the Middle Basin WWTF to minima near the confluence with Tomahawk Creek, increased downstream from the Tomahawk Creek WWTF, and then varied little within the study reach. Orthophosphorus concentrations generally decreased downstream from the Middle Basin WWTF.Despite the marked variability in nitrate plus nitrite concentrations caused by the Middle Basin WWTF effluent discharges, decreases in nitrate plus nitrite concentrations were discernable along the study reach between the two WWTFs. Decreases in nitrate plus nitrite concentrations along study reach were less variable than the cyclical variability typically measured, reiterating the effect of the Middle Basin WWTF effluent discharges on the spatiotemporal variability of nitrate plus nitrite in Indian Creek. Although decreases and rates of change in nitrate plus nitrite concentration were similar between the upper and lower reaches of Indian Creek, relations with initial nitrate plus nitrite concentrations and seasonal patterns were different between the upper (from College to the Marty study sites) and lower reaches (from Marty to the Mission Farms study sites) and did not reflect patterns observed for the overall reach. Quantifying the decreases in nitrate plus nitrite concentration caused by dilution and other in-stream processes were beyond the scope of this study, and were limited by available data. The data that are available suggest that dilution and other in-stream processes play a role in decreasing nitrate plus nitrite concentrations downstream from the Middle Basin WWTF in Indian Creek.Analysis of the spatiotemporal variability of nutrients focused on below-normal and normal streamflow conditions, when streamflow and nutrient conditions in Indian Creek were largely controlled by WWTF effluent flows and nutrient removal processes. Spatial and temporal data indicate there are decreases in nutrient concentrations along the upstream-downstream gradient in Indian Creek, but quantifying decreases is complicated by the variability in nutrient concentrations caused by the WWTFs. During below-normal and normal streamflow conditions, Indian Creek nutrient concentrations downstream from the Middle Basin WWTF primarily reflect effluent concentrations in the hours or days before depending on relative distance downstream.

Advances in Dynamic Transport of Organic Contaminants in Karst Groundwater Systems

NASA Astrophysics Data System (ADS)

Padilla, I. Y.; Vesper, D.; Alshawabkeh, A.; Hellweger, F.

2011-12-01

Karst groundwater systems develop in soluble rocks such as limestone, and are characterized by high permeability and well-developed conduit porosity. These systems provide important freshwater resources for human consumption and ecological integrity of streams, wetlands, and coastal zones. The same characteristics that make karst aquifers highly productive make them highly vulnerable to contamination. As a result, karst aquifers serve as an important route for contaminants exposure to humans and wildlife. Transport of organic contaminants in karst ground-water occurs in complex pathways influenced by the flow mechanism predominating in the aquifer: conduit-flow dominated systems tend to convey solutes rapidly through the system to a discharge point without much attenuation; diffuse-flow systems, on the other hand, can cause significant solute retardation and slow movement. These two mechanisms represent end members of a wide spectrum of conditions found in karst areas, and often a combination of conduit- and diffuse-flow mechanisms is encountered, where both flow mechanisms can control the fate and transport of contaminants. This is the case in the carbonate aquifers of northern Puerto Rico. This work addresses advances made on the characterization of fate and transport processes in karst ground-water systems characterized by variable conduit and/or diffusion dominated flow under high- and low-flow conditions. It involves laboratory-scale physical modeling and field-scale sampling and historical analysis of contaminant distribution. Statistical analysis of solute transport in Geo-Hydrobed physical models shows the heterogeneous character of transport dynamics in karstic units, and its variability under different flow regimes. Field-work analysis of chlorinated volatile organic compounds and phthalates indicates a large capacity of the karst systems to store and transmit contaminants. This work is part of the program "Puerto Rico Testsite for Exploring Contamination Threats (PRoTECT)" supported by the National Institute of Environmental Health Sciences (NIEHS, Grant Award No. P42ES017198).

Contamination and spatial variation of heavy metals in the soil-rice system in Nanxun County, Southeastern China.

PubMed

Zhao, Keli; Fu, Weijun; Ye, Zhengqian; Zhang, Chaosheng

2015-01-28

There is an increasing concern about heavy metal contamination in farmland in China and worldwide. In order to reveal the spatial features of heavy metals in the soil-rice system, soil and rice samples were collected from Nanxun, Southeastern China. Compared with the guideline values, elevated concentrations of heavy metals in soils were observed, while heavy metals in rice still remained at a safe level. Heavy metals in soils and rice had moderate to strong spatial dependence (nugget/sill ratios: 13.2% to 49.9%). The spatial distribution of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in soils illustrated that their high concentrations were located in the southeast part. The high concentrations of cadmium (Cd) in soils were observed in the northeast part. The accumulation of all the studied metals is related to the long-term application of agrochemicals and industrial activities. Heavy metals in rice showed different spatial distribution patterns. Cross-correlograms were produced to quantitatively determine the spatial correlation between soil properties and heavy metals composition in rice. The pH and soil organic matter had significant spatial correlations with the concentration of heavy metals in rice. Most of the selected variables had clear spatial correlation ranges for heavy metals in rice, which could be further applied to divide agricultural management zones.

A site-specific farm-scale GIS approach for reducing groundwater contamination by pesticides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mulla, D.J.; Perillo, C.A.; Cogger, C.G.

1996-05-01

It has been proposed to vary pesticide applications by patterns in surface organic C to reduce the potential for contamination of groundwater. To evaluate the feasibility of this {open_quotes}precision farming{close_quotes} approach, data for carbofuran concentrations from 57 locations sampled to a depth of 180 cm were fit to the convective-dispersive equation. Fitted values for pore water velocity (v) ranged from 0.17 to 1.92 cm d{sup -1}, with a mean of 0.68 cm d{sup -1}. Values for dispersion (D) ranged from 0.29 to 13.35 cm{sup 2} d{sup -1}, with a mean of 2.57. With this data, risks of pesticide leaching weremore » estimated at each location using the attenuation factor (AF) model, and a dispersion based leached factor (LF) model. Using the AF model gave two locations with a very high pesticide leaching risk, 6 with a low risk, and 2 with no risk. Using the LF model, 6 had a high risk, 13 had a medium risk, 18 had a low risk, and 20 had no risk. Pesticide leaching risks were not correlated with any measured surface soil properties. Much of the variability in leaching risk was because of velocity variations, so it would be incorrect to assume that surface organic C content controls the leaching risk. 30 refs., 1 fig., 3 tabs.« less

Influence of land use and meteorological factors on the spatial distribution of Toxocara canis and Toxocara cati eggs in soil in urban areas.

PubMed

Gao, Xiang; Wang, Hongbin; Li, Jianxin; Qin, Hongyu; Xiao, Jianhua

2017-01-15

Soil which has been contaminated by Toxocara spp. eggs is considered as one of the main infection sources of Toxocariasis in animals and humans. The present study conducted a detailed investigation into the spatial patterns of Toxocara canis (T. canis) and Toxocara cati (T. cati) eggs in soil in urban area of northeastern Mainland China, and assessed the inter-relationships between meteorological factors, land use and the distribution of the Toxocara spp. eggs. Polymerase chain reaction (PCR) was used for the determination of T. canis and T. cati eggs contamination in soil samples. Between April 2014 and May 2015, 9420 soil samples were subjected to PCR examination and 7027 sheep (74.6%) were determined to be positive for T. canis and T. cati eggs. Subsequently, we evaluated the effect of land use, and meteorological factors on the spatial distribution of T. canis and T. cati eggs based on a maximum entropy model. Jackknife analysis revealed that the area of residential land, wood and grass land and precipitation may influence the occurrence of T. canis and T. cati eggs in soil. Our findings indicate that land use and meteorological factors may be important variables affecting transmission of Toxocariasis and should be taken into account in the development of future surveillance programmes for Toxocariasis. Copyright © 2016 Elsevier B.V. All rights reserved.

Bunburra Rockhole: Exploring the geology of a new differentiated asteroid

NASA Astrophysics Data System (ADS)

Benedix, G. K.; Bland, P. A.; Friedrich, J. M.; Mittlefehldt, D. W.; Sanborn, M. E.; Yin, Q.-Z.; Greenwood, R. C.; Franchi, I. A.; Bevan, A. W. R.; Towner, M. C.; Perrotta, G. C.; Mertzman, S. A.

2017-07-01

Bunburra Rockhole is the first recovered meteorite of the Desert Fireball Network. We expanded a bulk chemical study of the Bunburra Rockhole meteorite to include major, minor and trace element analyses, as well as oxygen and chromium isotopes, in several different pieces of the meteorite. This was to determine the extent of chemical heterogeneity and constrain the origin of the meteorite. Minor and trace element analyses in all pieces are exactly on the basaltic eucrite trend. Major element analyses show a slight deviation from basaltic eucrite compositions, but not in any systematic pattern. New oxygen isotope analyses on 23 pieces of Bunburra Rockhole shows large variation in both δ17O and δ18O, and both are well outside the HED parent body fractionation line. We present the first Cr isotope results of this rock, which are also distinct from HEDs. Detailed computed tomographic scanning and back-scattered electron mapping do not indicate the presence of any other meteoritic contaminant (contamination is also unlikely based on trace element chemistry). We therefore conclude that Bunburra Rockhole represents a sample of a new differentiated asteroid, one that may have more variable oxygen isotopic compositions than 4 Vesta. The fact that Bunburra Rockhole chemistry falls on the eucrite trend perhaps suggests that multiple objects with basaltic crusts accreted in a similar region of the Solar System.

Mercury contamination in fish in midcontinent great rivers of the united states: Importance of species traits and environmental factors

USGS Publications Warehouse

Walters, D.M.; Blocksom, K.A.; Lazorchak, J.M.; Jicha, T.; Angradi, T.R.; Bolgrien, D.W.

2010-01-01

We measured mercury (Hg) concentrations in whole fish from the Upper Mississippi, Missouri, and Ohio Rivers to characterize the extent and magnitude of Hg contamination and to identify environmental factors influencing Hg accumulation. Concentrations were generally lower (80% of values between 20?200 ng g1 wet weight) than those reported for other regions (e.g., upper Midwest and Northeast U.S.). Mercury exceeded the risk threshold for belted kingfisher (Ceryle alcyon, the most sensitive species considered) in 33?75% of river length and 1?7% of river length for humans. Concentrations were lower in the Missouri than in the Mississippi and Ohio Rivers, consistent with continental-scale patterns in atmospheric Hg deposition. Body size and trophic guild were the best predictors of Hg concentrations, which were highest in large-bodied top predators. Site geochemical and landscape properties were weakly related with fish Hg. Moreover, relationships often ran contrary to conventional wisdom, and the slopes of the relationships (positive or negative) were inconsistent among fish guilds and rivers. For example, sulfate is positively associated with fish Hg concentrations but was negatively correlated with Hg in five of six regression models of tissue concentrations. Variables such as pH, acid neutralizing capacity, and total phosphorus did not occur at levels associated with high fish Hg concentrations, partially explaining the relatively low Hg values we observed. ?? 2010 American Chemical Society.

The Survey of Cronobacter spp. (formerly Enterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012.

PubMed

Pei, Xiao Yan; Yan, Lin; Zhu, Jiang Hui; Li, Ning; Guo, Yun Chang; Fu, Ping; Jia, Hua Yun; Zhang, Xiu Li; Yang, Xiao Rong; Yang, Da Jin

2016-02-01

To determine Cronobacter spp. contamination in infant and follow-up powdered formula in China. All of 2282 samples were collected from the retail markets in China from January 2012 to December 2012, and analyzed for Cronobacter spp. by the Chinese National Food Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI and SpeI restriction enzymes. Cronobacter spp. strains were isolated from 25 samples, and the positive rates in infant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization of Cronobacter spp. to elucidate genetic diversity revealed only three pairs of Cronobacter spp. out of 25 having the same PFGE patterns. The current investigation indicated a lower positive rate of Cronobacter spp. in the powdered formula in China. This evidence suggested contamination originating from multiple different sources during the manufacturing process. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Fumigation of a laboratory-scale HVAC system with hydrogen peroxide for decontamination following a biological contamination incident.

PubMed

Meyer, K M; Calfee, M W; Wood, J P; Mickelsen, L; Attwood, B; Clayton, M; Touati, A; Delafield, R

2014-03-01

To evaluate hydrogen peroxide vapour (H2 O2 ) for its ability to inactivate Bacillus spores within a laboratory-scale heating, ventilation and air-conditioning (HVAC) duct system. Experiments were conducted in a closed-loop duct system, constructed of either internally lined or unlined galvanized metal. Bacterial spores were aerosol-deposited onto 18-mm-diameter test material coupons and strategically placed at several locations within the duct environment. Various concentrations of H2 O2 and exposure times were evaluated to determine the sporicidal efficacy and minimum exposure needed for decontamination. For the unlined duct, high variability was observed in the recovery of spores between sample locations, likely due to complex, unpredictable flow patterns within the ducts. In comparison, the lined duct exhibited a significant desorption of the H2 O2 following the fumigant dwell period and thus resulted in complete decontamination at all sampling locations. These findings suggest that decontamination of Bacillus spore-contaminated unlined HVAC ducts by hydrogen peroxide fumigation may require more stringent conditions (higher concentrations, longer dwell duration) than internally insulated ductwork. These data may help emergency responders when developing remediation plans during building decontamination. © 2013 The Society for Applied Microbiology This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Contamination and Spatial Variation of Heavy Metals in the Soil-Rice System in Nanxun County, Southeastern China

PubMed Central

Zhao, Keli; Fu, Weijun; Ye, Zhengqian; Zhang, Chaosheng

2015-01-01

There is an increasing concern about heavy metal contamination in farmland in China and worldwide. In order to reveal the spatial features of heavy metals in the soil-rice system, soil and rice samples were collected from Nanxun, Southeastern China. Compared with the guideline values, elevated concentrations of heavy metals in soils were observed, while heavy metals in rice still remained at a safe level. Heavy metals in soils and rice had moderate to strong spatial dependence (nugget/sill ratios: 13.2% to 49.9%). The spatial distribution of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in soils illustrated that their high concentrations were located in the southeast part. The high concentrations of cadmium (Cd) in soils were observed in the northeast part. The accumulation of all the studied metals is related to the long-term application of agrochemicals and industrial activities. Heavy metals in rice showed different spatial distribution patterns. Cross-correlograms were produced to quantitatively determine the spatial correlation between soil properties and heavy metals composition in rice. The pH and soil organic matter had significant spatial correlations with the concentration of heavy metals in rice. Most of the selected variables had clear spatial correlation ranges for heavy metals in rice, which could be further applied to divide agricultural management zones. PMID:25635917

PCDD/Fs and PCBs in seafood species from Moreton Bay, Queensland, Australia.

PubMed

Matthews, V; Päpke, O; Gaus, C

2008-01-01

Previous studies have identified elevated levels of polychlorinated dibenzo-p-dioxins (PCDDs) in sediments and megafauna (dugongs and green turtles) in the marine environment of southeast Queensland, Australia. Little information exists, however, regarding the levels of PCDDs, polychlorinated dibenzofurans (PCDFs) and related polychlorinated biphenyls (PCBs) in seafood from this area. This study aims to establish baseline information on PCDD/F and PCB contamination in a range of seafood species from Moreton Bay and to investigate contaminant variability due to harvesting season, size, habitat location and trophic level. In addition, different seafood extraction methods were tested to evaluate their impact on lipid yields and contaminant concentration. Overall, the median TEQ(DF&PCB) levels in seafood from Moreton Bay were elevated compared to background levels in Australian marine/estuarine and retail fish. However, TEQ(DF&PCB) levels of most seafood analysed were below the respective EU maximum limits. High inter- and intraspecies variability was observed, which could be partially attributed to differences in trophic level, season harvested and habitat location.

Observations of Local Positive Low Cloud Feedback Patterns and Their Role in Internal Variability and Climate Sensitivity

NASA Astrophysics Data System (ADS)

Yuan, Tianle; Oreopoulos, Lazaros; Platnick, Steven E.; Meyer, Kerry

2018-05-01

Modeling studies have shown that cloud feedbacks are sensitive to the spatial pattern of sea surface temperature (SST) anomalies, while cloud feedbacks themselves strongly influence the magnitude of SST anomalies. Observational counterparts to such patterned interactions are still needed. Here we show that distinct large-scale patterns of SST and low-cloud cover (LCC) emerge naturally from objective analyses of observations and demonstrate their close coupling in a positive local SST-LCC feedback loop that may be important for both internal variability and climate change. The two patterns that explain the maximum amount of covariance between SST and LCC correspond to the Interdecadal Pacific Oscillation and the Atlantic Multidecadal Oscillation, leading modes of multidecadal internal variability. Spatial patterns and time series of SST and LCC anomalies associated with both modes point to a strong positive local SST-LCC feedback. In many current climate models, our analyses suggest that SST-LCC feedback strength is too weak compared to observations. Modeled local SST-LCC feedback strength affects simulated internal variability so that stronger feedback produces more intense and more realistic patterns of internal variability. To the extent that the physics of the local positive SST-LCC feedback inferred from observed climate variability applies to future greenhouse warming, we anticipate significant amount of delayed warming because of SST-LCC feedback when anthropogenic SST warming eventually overwhelm the effects of internal variability that may mute anthropogenic warming over parts of the ocean. We postulate that many climate models may be underestimating both future warming and the magnitude of modeled internal variability because of their weak SST-LCC feedback.

Environmentally benign semiconductor processing for dielectric etch

NASA Astrophysics Data System (ADS)

Liao, Marci Yi-Ting

Semiconductor processing requires intensive usage of chemicals, electricity, and water. Such intensive resource usage leaves a large impact on the environment. For instance, in Silicon Valley, the semiconductor industry is responsible for 80% of the hazardous waste sites contaminated enough to require government assistance. Research on environmentally benign semiconductor processing is needed to reduce the environmental impact of the semiconductor industry. The focus of this dissertation is on the environmental impact of one aspect of semiconductor processing: patterning of dielectric materials. Plasma etching of silicon dioxide emits perfluorocarbons (PFCs) gases, like C2F6 and CF4, into the atmosphere. These gases are super global warming/greenhouse gases because of their extremely long atmospheric lifetimes and excellent infrared absorption properties. We developed the first inductively coupled plasma (ICP) abatement device for destroying PFCs downstream of a plasma etcher. Destruction efficiencies of 99% and 94% can be obtained for the above mentioned PFCs, by using O 2 as an additive gas. Our results have lead to extensive modeling in academia as well as commercialization of the ICP abatement system. Dielectric patterning of hi-k materials for future device technology brings different environment challenges. The uncertainty of the hi-k material selection and the patterning method need to be addressed. We have evaluated the environmental impact of three different dielectric patterning methods (plasma etch, wet etch and chemical-mechanical polishing), as well as, the transistor device performances associated with the patterning methods. Plasma etching was found to be the most environmentally benign patterning method, which also gives the best device performance. However, the environmental concern for plasma etching is the possibility of cross-contamination from low volatility etch by-products. Therefore, mass transfer in a plasma etcher for a promising hi-k dielectric material, ZrO2, was studied. A novel cross-contamination sampling technique was developed, along with a mass transfer model.

Exposure assessment of environmental organic chemicals at contaminated sites: a multicompartment modelling approach.

PubMed

Matthies, M

2003-04-11

For the prevention of future damages from chemicals at large contaminated sites, all transfer pathways leading to the exposure of man and vulnerable ecosystems have to be taken into account. For organic contaminants, the uptake into vegetation is the major entry route for the transfer into the food chains. Lipophilic substances are taken up by roots but are not translocated with the transpiration stream. Atmospheric background concentrations have a significant impact on foliage contamination due to the effective gaseous and particle deposition. Vegetables can also be contaminated after irrigation with contaminated water supplied by groundwater wells. By means of a multicompartment model, the various uptake processes into roots and foliage as well as the transformation and translocation processes are described and the concentration pattern resulting from daily irrigation with methyl-t-butyl ether in the edible parts is simulated. The results demonstrate the advantage of a dynamic multicompartment model over the static environmental quality standard approach in terms of derivation of possible exposure reduction measures for organic chemicals.

A cross-study analysis of prenatal exposures to environmental contaminants and the epigenome: support for stress-responsive transcription factor occupancy as a mediator of gene-specific CpG methylation patterning

PubMed Central

Martin, Elizabeth M.; Fry, Rebecca C.

2016-01-01

Abstract A biological mechanism by which exposure to environmental contaminants results in gene-specific CpG methylation patterning is currently unknown. We hypothesize that gene-specific CpG methylation is related to environmentally perturbed transcription factor occupancy. To test this hypothesis, a database of 396 genes with altered CpG methylation either in cord blood leukocytes or placental tissue was compiled from 14 studies representing assessments of six environmental contaminants. Subsequently, an in silico approach was used to identify transcription factor binding sites enriched among the genes with altered CpG methylation in relationship to the suite of environmental contaminants. For each study, the sequences of the promoter regions (representing −1000 to +500 bp from the transcription start site) of all genes with altered CpG methylation were analyzed for enrichment of transcription factor binding sites. Binding sites for a total of 56 unique transcription factors were identified to be enriched within the promoter regions of the genes. Binding sites for the Kidney-Enriched Krupple-like Factor 15, a known responder to endogenous stress, were enriched ( P  < 0.001–0.041) among the genes with altered CpG methylation associated for five of the six environmental contaminants. These data support the transcription factor occupancy theory as a potential mechanism underlying environmentally-induced gene-specific CpG methylation. PMID:27066266

XBAER-derived aerosol optical thickness from OLCI/Sentinel-3 observation

NASA Astrophysics Data System (ADS)

Mei, Linlu; Rozanov, Vladimir; Vountas, Marco; Burrows, John P.; Richter, Andreas

2018-02-01

A cloud identification algorithm used for cloud masking, which is based on the spatial variability of reflectances at the top of the atmosphere in visible wavelengths, has been developed for the retrieval of aerosol properties by MODIS. It is shown that the spatial pattern of cloud reflectance, as observed from space, is very different from that of aerosols. Clouds show a high spatial variability in the scale of a hundred metres to a few kilometres, whereas aerosols in general are homogeneous. The concept of spatial variability of reflectances at the top of the atmosphere is mainly applicable over the ocean, where the surface background is sufficiently homogeneous for the separation between aerosols and clouds. Aerosol retrievals require a sufficiently accurate cloud identification to be able to mask these ground scenes. However, a conservative mask will exclude strong aerosol episodes and a less conservative mask could introduce cloud contamination that biases the retrieved aerosol optical properties (e.g. aerosol optical depth and effective radii). A detailed study on the effect of cloud contamination on aerosol retrievals has been performed and parameters are established determining the threshold value for the MODIS aerosol cloud mask (3×3-STD) over the ocean. The 3×3-STD algorithm discussed in this paper is the operational cloud mask used for MODIS aerosol retrievals over the ocean.A prolonged pollution haze event occurred in the northeast part of China during the period 16-21 December 2016. To assess the impact of such events, the amounts and distribution of aerosol particles, formed in such events, need to be quantified. The newly launched Ocean Land Colour Instrument (OLCI) onboard Sentinel-3 is the successor of the MEdium Resolution Imaging Spectrometer (MERIS). It provides measurements of the radiance and reflectance at the top of the atmosphere, which can be used to retrieve the aerosol optical thickness (AOT) from synoptic to global scales. In this study, the recently developed AOT retrieval algorithm eXtensible Bremen AErosol Retrieval (XBAER) has been applied to data from the OLCI instrument for the first time to illustrate the feasibility of applying XBAER to the data from this new instrument. The first global retrieval results show similar patterns of aerosol optical thickness, AOT, to those from MODIS and MISR aerosol products. The AOT retrieved from OLCI is validated by comparison with AERONET observations and a correlation coefficient of 0.819 and bias (root mean square) of 0.115 is obtained. The haze episode is well captured by the OLCI-derived AOT product. XBAER is shown to retrieve AOT well from the observations of MERIS and OLCI.

The effects of ingested petroleum on the maphthalene-metabolizing properties of the liver tissue in seawater-adapted mallard ducks (Anas platyrhynchos)

USGS Publications Warehouse

Gorsline, J.; Holmes, W.N.; Cronshaw, J.

1981-01-01

Hepatic mixed function oxidase activities were estimated in seawater-adapted mallard ducks (Anas platyrhynchos) that had been consuming food contaminated with one of five different types of crude oil. After 50 days of exposure to contaminated food, enzyme activities of liver microsomal preparations were assessed in terms of their naphthalenemetabolizing properties in vitro. Although dose-dependent increases in the total hepatic enzyme activities (nmole naphthalene metabolized per minute per unit mass body weight) were observed in birds consuming food contaminated with each type of crude oil, three patterns of response were apparent. Crude oils from South Louisiana and Kuwait stimulated large and significant increases in the specific activity of the enzyme system (nmole naphthalene metabolized per minute per unit mass microsomal protein), whereas little or no increase in either microsomal protein content or relative liver weight were observed. In contrast, two crude oils from Santa Barbara, Calif., induced only small increases in specific activity but significant increases occurred in hepatic microsomal protein concentration and relative liver weight. The crude oil from Prudhoe Bay, Ala., evoked intermediate patterns of response. The possible significance of these data is discussed in relation to the survival of seabirds consuming petroleum-contaminated food and drinking water.

Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp.

PubMed

Liu, Cheng; Hofstra, Nynke; Franz, Eelco

2013-05-15

The likelihood of leafy green vegetable (LGV) contamination and the associated pathogen growth and survival are strongly related to climatic conditions. Particularly temperature increase and precipitation pattern changes have a close relationship not only with the fate and transport of enteric bacteria, but also with their growth and survival. Using all relevant literature, this study reviews and synthesises major impacts of climate change (temperature increases and precipitation pattern changes) on contamination sources (manure, soil, surface water, sewage and wildlife) and pathways of foodborne pathogens (focussing on Escherichia coli O157 and Salmonella spp.) on pre-harvested LGVs. Whether climate change increases their prevalence depends not only on the resulting local balance of the positive and negative impacts but also on the selected regional climate change scenarios. However, the contamination risks are likely to increase. This review shows the need for quantitative modelling approaches with scenario analyses and additional laboratory experiments. This study gives an extensive overview of the impacts of climate change on the contamination of pre-harvested LGVs and shows that climate change should not be ignored in food safety management and research. Copyright © 2013 Elsevier B.V. All rights reserved.

A meta-analysis and statistical modelling of nitrates in groundwater at the African scale

NASA Astrophysics Data System (ADS)

Ouedraogo, Issoufou; Vanclooster, Marnik

2016-06-01

Contamination of groundwater with nitrate poses a major health risk to millions of people around Africa. Assessing the space-time distribution of this contamination, as well as understanding the factors that explain this contamination, is important for managing sustainable drinking water at the regional scale. This study aims to assess the variables that contribute to nitrate pollution in groundwater at the African scale by statistical modelling. We compiled a literature database of nitrate concentration in groundwater (around 250 studies) and combined it with digital maps of physical attributes such as soil, geology, climate, hydrogeology, and anthropogenic data for statistical model development. The maximum, medium, and minimum observed nitrate concentrations were analysed. In total, 13 explanatory variables were screened to explain observed nitrate pollution in groundwater. For the mean nitrate concentration, four variables are retained in the statistical explanatory model: (1) depth to groundwater (shallow groundwater, typically < 50 m); (2) recharge rate; (3) aquifer type; and (4) population density. The first three variables represent intrinsic vulnerability of groundwater systems to pollution, while the latter variable is a proxy for anthropogenic pollution pressure. The model explains 65 % of the variation of mean nitrate contamination in groundwater at the African scale. Using the same proxy information, we could develop a statistical model for the maximum nitrate concentrations that explains 42 % of the nitrate variation. For the maximum concentrations, other environmental attributes such as soil type, slope, rainfall, climate class, and region type improve the prediction of maximum nitrate concentrations at the African scale. As to minimal nitrate concentrations, in the absence of normal distribution assumptions of the data set, we do not develop a statistical model for these data. The data-based statistical model presented here represents an important step towards developing tools that will allow us to accurately predict nitrate distribution at the African scale and thus may support groundwater monitoring and water management that aims to protect groundwater systems. Yet they should be further refined and validated when more detailed and harmonized data become available and/or combined with more conceptual descriptions of the fate of nutrients in the hydrosystem.

Occurrence and origin of Escherichia coli in water and sediments at two public swimming beaches at Lake of the Ozarks State Park, Camden County, Missouri, 2011-13

USGS Publications Warehouse

Wilson, Jordan L.; Schumacher, John G.; Burken, Joel G.

2014-01-01

In the past several years, the Missouri Department of Natural Resources has closed two popular public beaches, Grand Glaize Beach and Public Beach 1, at Lake of the Ozarks State Park in Osage Beach, Missouri when monitoring results exceeded the established Escherichia coli (E. coli) standard. As a result of the beach closures, the U.S. Geological Survey and Missouri University of Science and Technology, in cooperation with the Missouri Department of Natural Resources, led an investigation into the occurrence and origins of E. coli at Grand Glaize Beach and Public Beach 1. The study included the collection of more than 1,300 water, sediment, and fecal source samples between August 2011 and February 2013 from the two beaches and vicinity. Spatial and temporal patterns of E. coli concentrations in water and sediments combined with measurements of environmental variables, beach-use patterns, and Missouri Department of Natural Resources water-tracing results were used to identify possible sources of E. coli contamination at the two beaches and to corroborate microbial source tracking (MST) sampling efforts. Results from a 2011 reconnaissance sampling indicate that water samples from Grand Glaize Beach cove contained significantly larger E. coli concentrations than adjacent coves and were largest at sites at the upper end of Grand Glaize Beach cove, indicating a probable local source of E. coli contamination within the upper end of the cove. Results from an intensive sampling effort during 2012 indicated that E. coli concentrations in water samples at Grand Glaize Beach cove were significantly larger in ankle-deep water than waist-deep water, trended downward during the recreational season, significantly increased with an increase in the total number of bathers at the beach, and were largest during the middle of the day. Concentrations of E. coli in nearshore sediment (sediment near the shoreline) at Grand Glaize Beach were significantly larger in foreshore samples (samples collected above the shoreline) than in samples collected in ankle-deep water below the shoreline, significantly larger in the left and middle areas of the beach than the right area, and substantially larger than similar studies at E. coli- contaminated beaches on Lake Erie in Ohio. Concentrations of E. coli in the water column also were significantly larger after resuspension of sediments. Results of MST indicate a predominance of waterfowl-associated markers in nearshore sediments at Grand Glaize Beach consistent with frequent observations of goose and vulture fecal matter in sediment, especially on the left and middle areas of the beach. The combination of spatial and temporal sampling and MST indicate that an important source of E. coli contamination at Grand Glaize Beach during 2012 was E. coli released into the water column by bathers resuspending E. coli-contaminated sediments, especially during high-use days early in the recreational season.

The magnitude of variability produced by methods used to estimate annual stormwater contaminant loads for highly urbanised catchments.

PubMed

Beck, H J; Birch, G F

2013-06-01

Stormwater contaminant loading estimates using event mean concentration (EMC), rainfall/runoff relationship calculations and computer modelling (Model of Urban Stormwater Infrastructure Conceptualisation--MUSIC) demonstrated high variability in common methods of water quality assessment. Predictions of metal, nutrient and total suspended solid loadings for three highly urbanised catchments in Sydney estuary, Australia, varied greatly within and amongst methods tested. EMC and rainfall/runoff relationship calculations produced similar estimates (within 1 SD) in a statistically significant number of trials; however, considerable variability within estimates (∼50 and ∼25 % relative standard deviation, respectively) questions the reliability of these methods. Likewise, upper and lower default inputs in a commonly used loading model (MUSIC) produced an extensive range of loading estimates (3.8-8.3 times above and 2.6-4.1 times below typical default inputs, respectively). Default and calibrated MUSIC simulations produced loading estimates that agreed with EMC and rainfall/runoff calculations in some trials (4-10 from 18); however, they were not frequent enough to statistically infer that these methods produced the same results. Great variance within and amongst mean annual loads estimated by common methods of water quality assessment has important ramifications for water quality managers requiring accurate estimates of the quantities and nature of contaminants requiring treatment.

Assessing groundwater quality in Greece based on spatial and temporal analysis.

PubMed

Dokou, Zoi; Kourgialas, Nektarios N; Karatzas, George P

2015-12-01

The recent industrial growth together with the urban expansion and intensive agriculture in Greece has increased groundwater contamination in many regions of the country. In order to design successful remediation strategies and protect public health, it is very important to identify those areas that are most vulnerable to groundwater contamination. In this work, an extensive contamination database from monitoring wells that cover the entire Greek territory during the last decade (2000-2008) was used in order to study the temporal and spatial distribution of groundwater contamination for the most common and serious anionic and cationic trace element pollutants (heavy metals). Spatial and temporal patterns and trends in the occurrence of groundwater contamination were also identified highlighting the regions where the higher groundwater contamination rates have been detected across the country. As a next step, representative contaminated aquifers in Greece, which were identified by the above analysis, were selected in order to analyze the specific contamination problem in more detail. To this end, geostatistical techniques (various types of kriging, co-kriging, and indicator kriging) were employed in order to map the contaminant values and the probability of exceeding critical thresholds (set as the parametric values of the contaminant of interest in each case). The resulting groundwater contamination maps could be used as a useful tool for water policy makers and water managers in order to assist the decision-making process.

Consumption of organic meat does not diminish the carcinogenic potential associated with the intake of persistent organic pollutants (POPs).

PubMed

Hernández, Ángel Rodríguez; Boada, Luis D; Mendoza, Zenaida; Ruiz-Suárez, Norberto; Valerón, Pilar F; Camacho, María; Zumbado, Manuel; Almeida-González, Maira; Henríquez-Hernández, Luis A; Luzardo, Octavio P

2017-02-01

Numerous studies have shown an epidemiological link between meat consumption and the incidence of cancer, and it has been suggested that this relationship may be motivated by the presence of carcinogenic contaminants on it. Among the most frequently detected contaminants in meat are several types of persistent organic pollutants (POPs), and it is well known that many of them are carcinogenic. On the other hand, an increasing number of consumers choose to feed on what are perceived as healthier foods. Thus, the number of consumers of organic food is growing. However, environmental contamination by POPs is ubiquitous, and it is therefore unlikely that the practices of organic food production are able to prevent this contamination. To test this hypothesis, we acquired 76 samples of meat (beef, chicken, and lamb) of two modes of production (organic and conventional) and quantified their levels of 33 carcinogenic POPs. On this basis, we determined the human meat-related daily dietary exposure to these carcinogens using as a model a population with a high consumption of meat, such as the Spanish population. The maximum allowable meat consumption for this population and the carcinogenic risk quotients associated with the current pattern of consumption were calculated. As expected, no sample was completely free of carcinogenic contaminants, and the differences between organically and conventionally produced meats were minimal. According to these results, the current pattern of meat consumption exceeded the maximum limits, which are set according to the levels of contaminations, and this is associated with a relevant carcinogenic risk. Strikingly, the consumption of organically produced meat does not diminish this carcinogenic risk, but on the contrary, it seems to be even higher, especially that associated with lamb consumption.

Electric discharge for treatment of trace contaminants

NASA Technical Reports Server (NTRS)

Flamm, D. L.; Wydeven, T. J. (Inventor)

1978-01-01

A radio frequency glow discharge reactor is described for removing trace oxidizable contaminants from an oxygen bearing atmosphere. The reaction chamber is defined by an inner metal electrode facing a dielectric backed by an outer conductive electrode. In one embodiment, a conductive liquid forms the conductor of an outer electrode and cools the dielectric. A resonator coupled to a variable radio frequency source generates the high voltages for creating a glow discharge in the chamber at a predetermined pressure whereby the trace contaminants are oxidized into a few simple non-toxic products that may be easily recovered. The corresponding process for removal of trace contaminants from an oxygen-bearing atmosphere with high efficiency independent of the concentration level is also disclosed.

Drinking water incidents due to chemical contamination in England and Wales, 2006-2008.

PubMed

Paranthaman, Karthikeyan; Harrison, Henrietta

2010-12-01

Contamination of drinking water by microbiological and chemical agents can lead to adverse health effects. In England and Wales, the Chemicals Hazards and Poisons Division (CHaPD) of the Health Protection Agency provides expert advice on the consequences to public health of chemical contamination incidents affecting drinking water. In this study, we extracted data from the National Database on the type and nature of drinking water contamination events reported to the CHaPD between 2006 and 2008. Eighty-two incidents with confirmed chemical contamination were identified. Among the 70 incidents where data was available, 40% (28/70) of incidents related to contamination of drinking water provided by private suppliers, 31% (22/70) were due to contamination occurring close to the point of consumption (i.e. near consumer) and 29% (20/70) related to incidents where public water supplies were identified as the contaminated source. For the majority of incidents, little or no information was available on the critical exposure variables such as duration of contamination and actual or estimates of the population affected. Reassuringly, the levels of exposure in most incidents were considered unlikely to cause serious immediate or long term ill health effects. Recording of exposure data for reported contamination incidents needs to be improved.

Spatial and Seasonal Dynamics of Water Environmental Capacity in Mountainous Rivers of the Southeastern Coast, China

PubMed Central

Jiang, Jingang; Jing, Changwei

2018-01-01

The south-east littoral is one of the most populous and developed regions in China suffering from serious water pollution problems, and the Xian-Jiang Basin in the mid of this region is among the most polluted watersheds. Critical information is needed but lacking for improved pollution control and water quality assessment, among which water environmental capacity (WEC) is the most important variable but is difficult to calculate. In this study, a one-dimensional water quality model combined with a matrix calculation algorithm was first developed and calibrated with in-situ observations in the Xian-Jiang basin. Then, the model was applied to analyze the spatial and temporal patterns of WEC of the entire basin. The results indicated that, in 2015, the total pollutant discharges into the river reached 6719.68 t/yr, 488.12 t/yr, and 128.57 t/yr for COD, NH3-N and TP, respectively. The spatial pattern suggested a strong correlation between these water contaminants and industrial enterprises, residential areas, and land-use types in the basin. Furthermore, it was noticed that there was a significant seasonal pattern in WEC that the dry season pollution is much greater than that in the plum season, while that in the typhoon season appears to be the weakest among all seasons. The WEC differed significantly among the 24 sub-basins during the dry season but varied to a smaller extent in other seasons, suggesting differential complex spatial-temporal dependency of the WEC. PMID:29315265

Variations of sediment toxicity in a tidal estuary: a case study of the South Passage, Changjiang (Yangtze) Estuary.

PubMed

Gao, Jinjuan; Shi, Huahong; Dai, Zhijun; Mei, Xuefei

2015-06-01

Sediments in estuaries, especially those containing a large reservoir of contaminants released from urban and industrial activities, have had great impacts on benthic fauna and associated species. A better understanding of the toxicity of contaminants in estuarine sediments is of great significance to ecological assessments. Here, based on the collected sediments from neap to spring tides in the South Passage, Changjiang Estuary, the toxicity of the sediments was first studied using the frog embryo teratogenesis assay-Xenopus (FETAX). The results showed that the extracts of estuarine sediments induced multiple malformations in the embryos and that the phenotypes of malformation had two distinct patterns of variations corresponding to the tidal cycles. The phenotypes in the first pattern were dominated by hypopigmentation and edema of the heart, and the pattern was mainly controlled by fine-grained fractions. The phenotypes in the second pattern were dominated by edema of the heart and enlarged proctodeum, and it was mostly controlled by coarse-grain fractions. The sediment toxicity was higher during the spring and flood tides, which may be influenced by the grain size and sediment resuspension. Furthermore, obvious periodicities existed in the changes of the percentages of hatching (14-16 h and 6 h), enlarged proctodeum (15-18 h), and bent tail (5-7 h) due to the influence of tidal cycles. Moreover, our results also suggested that FETAX is an appropriate cost-effective biological monitoring tool to assess estuarine ecological health in contaminated sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Regulation of Spatiotemporal Patterns by Biological Variability: General Principles and Applications to Dictyostelium discoideum

PubMed Central

Grace, Miriam; Hütt, Marc-Thorsten

2015-01-01

Spatiotemporal patterns often emerge from local interactions in a self-organizing fashion. In biology, the resulting patterns are also subject to the influence of the systematic differences between the system’s constituents (biological variability). This regulation of spatiotemporal patterns by biological variability is the topic of our review. We discuss several examples of correlations between cell properties and the self-organized spatiotemporal patterns, together with their relevance for biology. Our guiding, illustrative example will be spiral waves of cAMP in a colony of Dictyostelium discoideum cells. Analogous processes take place in diverse situations (such as cardiac tissue, where spiral waves occur in potentially fatal ventricular fibrillation) so a deeper understanding of this additional layer of self-organized pattern formation would be beneficial to a wide range of applications. One of the most striking differences between pattern-forming systems in physics or chemistry and those in biology is the potential importance of variability. In the former, system components are essentially identical with random fluctuations determining the details of the self-organization process and the resulting patterns. In biology, due to variability, the properties of potentially very few cells can have a driving influence on the resulting asymptotic collective state of the colony. Variability is one means of implementing a few-element control on the collective mode. Regulatory architectures, parameters of signaling cascades, and properties of structure formation processes can be "reverse-engineered" from observed spatiotemporal patterns, as different types of regulation and forms of interactions between the constituents can lead to markedly different correlations. The power of this biology-inspired view of pattern formation lies in building a bridge between two scales: the patterns as a collective state of a very large number of cells on the one hand, and the internal parameters of the single cells on the other. PMID:26562406

PROMISE: a tool to identify genomic features with a specific biologically interesting pattern of associations with multiple endpoint variables

PubMed Central

Pounds, Stan; Cheng, Cheng; Cao, Xueyuan; Crews, Kristine R.; Plunkett, William; Gandhi, Varsha; Rubnitz, Jeffrey; Ribeiro, Raul C.; Downing, James R.; Lamba, Jatinder

2009-01-01

Motivation: In some applications, prior biological knowledge can be used to define a specific pattern of association of multiple endpoint variables with a genomic variable that is biologically most interesting. However, to our knowledge, there is no statistical procedure designed to detect specific patterns of association with multiple endpoint variables. Results: Projection onto the most interesting statistical evidence (PROMISE) is proposed as a general procedure to identify genomic variables that exhibit a specific biologically interesting pattern of association with multiple endpoint variables. Biological knowledge of the endpoint variables is used to define a vector that represents the biologically most interesting values for statistics that characterize the associations of the endpoint variables with a genomic variable. A test statistic is defined as the dot-product of the vector of the observed association statistics and the vector of the most interesting values of the association statistics. By definition, this test statistic is proportional to the length of the projection of the observed vector of correlations onto the vector of most interesting associations. Statistical significance is determined via permutation. In simulation studies and an example application, PROMISE shows greater statistical power to identify genes with the interesting pattern of associations than classical multivariate procedures, individual endpoint analyses or listing genes that have the pattern of interest and are significant in more than one individual endpoint analysis. Availability: Documented R routines are freely available from www.stjuderesearch.org/depts/biostats and will soon be available as a Bioconductor package from www.bioconductor.org. Contact: stanley.pounds@stjude.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:19528086

Spatiotemporal variability and differentiation between anthropogenic and natural contamination of heavy metals of surface water: a case study in the Cordillera Blanca, Peru

NASA Astrophysics Data System (ADS)

Guittard, A.; Baraer, M.; McKenzie, J. M.; Mark, B. G.; Fernandez, A.; Walsh, E.; Santos Perez, A.

2015-12-01

The Rio Santa, Peru, drains the western slopes of the glacierized Cordillera Blanca and provides water resources at almost all levels of the watershed. As it flows away from the valleys of the Cordillera Blanca, the Rio Santa takes out pollution from numerous sources, including acid mine drainage and natural sulfide oxidation by-products. The Rio Santa dry season discharge decline that is projected to be a consequence of glaciers retreat will probably have implications for the evolution of water pollution. This threat makes the characterization of the actual contamination mechanisms of primary importance. The present study focuses, first, on the spatiotemporal variability of heavy metal contamination across the entire Rio Santa Watershed and secondly on differentiating anthropogenic and natural contaminated sites. First, a macroscale sampling has been done during the summer 2013 to provide an overview of the contamination by trace metal, in water, suspended sediments and riverbed sediments. In addition, 30 water samples were taken from a point next to the city of Huaraz at a frequency of once every 2 weeks and analyzed for trace metals. Secondly, in order to identify hydrochemical contaminant origin dependant signatures in the Rio Santa watershed, 5 areas of known contamination origins were sampled during the summer 2014.Spatially speaking, we observed that most pollution is located in the south of the watershed, and that a large part of the arsenic that reaches the Santa in an aqueous phase does not make it to the outlet but remains trapped in the riverbed. Annual variation in water shows a very unusual fluctuation in Mn compare to other trace metal which are relatively stable. By differencing anthropogenic and natural sites and by considering glaciers melt and decrease water in future what would be the impact of the part of natural contaminated sites versus anthropogenic, mining and cities, on the water quality? Preliminary results show that anthropogenic sites show high level of As and Cd but natural contaminated sites show high level of Al, Fe and Mn.

Complex Controls on Groundwater Quality in Growing Mid-sized Cities: A Case Study Focused on Nitrate and Emerging Contaminants

NASA Astrophysics Data System (ADS)

Ohr, C. A.; Godsey, S.; Welhan, J. A.; Larson, D. M.; Lohse, K. A.; Finney, B.; Derryberry, D.

2015-12-01

Many regions rely on quality groundwater to support urban growth. Groundwater quality often responds in a complex manner to stressors such as land use change, climate change, or policy decisions. Urban growth patterns in mid-sized cities, especially ones that are growing urban centers in water-limited regions in the western US, control and are controlled by water availability and its quality. We present a case study from southeastern Idaho where urban growth over the past 20 years has included significant ex-urban expansion of houses that rely on septic systems rather than city sewer lines for their wastewater treatment. Septic systems are designed to mitigate some contaminants, but not others. In particular, nitrates and emerging contaminants, such as pharmaceuticals, are not removed by most septic systems. Thus, even well-maintained septic systems at sufficiently high densities can impact down gradient water quality. Here we present patterns of nitrate concentrations over the period from 1985-2015 from the Lower Portneuf River Valley in southeastern Idaho. Concentrations vary from 0.03 to 27.09 nitrate-nitrogen mg/L, with average values increasing significantly over the 30 year time period from 3.15 +/- 0.065 to 3.57 +/- 0.43 mg/L. We examine temporal changes in locations of nitrate hotspots, and present pilot data on emerging contaminants of concern. Initial results suggest that high nitrate levels are generally associated with higher septic densities, but that this pattern is influenced by legacy agricultural uses and strongly controlled by underlying aquifer properties. Future work will include more detailed hydrological modeling to predict changes in hotspot locations under potential climate change scenarios.

Synoptic sampling and principal components analysis to identify sources of water and metals to an acid mine drainage stream.

PubMed

Byrne, Patrick; Runkel, Robert L; Walton-Day, Katherine

2017-07-01

Combining the synoptic mass balance approach with principal components analysis (PCA) can be an effective method for discretising the chemistry of inflows and source areas in watersheds where contamination is diffuse in nature and/or complicated by groundwater interactions. This paper presents a field-scale study in which synoptic sampling and PCA are employed in a mineralized watershed (Lion Creek, Colorado, USA) under low flow conditions to (i) quantify the impacts of mining activity on stream water quality; (ii) quantify the spatial pattern of constituent loading; and (iii) identify inflow sources most responsible for observed changes in stream chemistry and constituent loading. Several of the constituents investigated (Al, Cd, Cu, Fe, Mn, Zn) fail to meet chronic aquatic life standards along most of the study reach. The spatial pattern of constituent loading suggests four primary sources of contamination under low flow conditions. Three of these sources are associated with acidic (pH <3.1) seeps that enter along the left bank of Lion Creek. Investigation of inflow water (trace metal and major ion) chemistry using PCA suggests a hydraulic connection between many of the left bank inflows and mine water in the Minnesota Mine shaft located to the north-east of the river channel. In addition, water chemistry data during a rainfall-runoff event suggests the spatial pattern of constituent loading may be modified during rainfall due to dissolution of efflorescent salts or erosion of streamside tailings. These data point to the complexity of contaminant mobilisation processes and constituent loading in mining-affected watersheds but the combined synoptic sampling and PCA approach enables a conceptual model of contaminant dynamics to be developed to inform remediation.

Synoptic sampling and principal components analysis to identify sources of water and metals to an acid mine drainage stream

USGS Publications Warehouse

Byrne, Patrick; Runkel, Robert L.; Walton-Day, Katie

2017-01-01

Combining the synoptic mass balance approach with principal components analysis (PCA) can be an effective method for discretising the chemistry of inflows and source areas in watersheds where contamination is diffuse in nature and/or complicated by groundwater interactions. This paper presents a field-scale study in which synoptic sampling and PCA are employed in a mineralized watershed (Lion Creek, Colorado, USA) under low flow conditions to (i) quantify the impacts of mining activity on stream water quality; (ii) quantify the spatial pattern of constituent loading; and (iii) identify inflow sources most responsible for observed changes in stream chemistry and constituent loading. Several of the constituents investigated (Al, Cd, Cu, Fe, Mn, Zn) fail to meet chronic aquatic life standards along most of the study reach. The spatial pattern of constituent loading suggests four primary sources of contamination under low flow conditions. Three of these sources are associated with acidic (pH <3.1) seeps that enter along the left bank of Lion Creek. Investigation of inflow water (trace metal and major ion) chemistry using PCA suggests a hydraulic connection between many of the left bank inflows and mine water in the Minnesota Mine shaft located to the north-east of the river channel. In addition, water chemistry data during a rainfall-runoff event suggests the spatial pattern of constituent loading may be modified during rainfall due to dissolution of efflorescent salts or erosion of streamside tailings. These data point to the complexity of contaminant mobilisation processes and constituent loading in mining-affected watersheds but the combined synoptic sampling and PCA approach enables a conceptual model of contaminant dynamics to be developed to inform remediation.

Can Geostatistical Models Represent Nature's Variability? An Analysis Using Flume Experiments

NASA Astrophysics Data System (ADS)

Scheidt, C.; Fernandes, A. M.; Paola, C.; Caers, J.

2015-12-01

The lack of understanding in the Earth's geological and physical processes governing sediment deposition render subsurface modeling subject to large uncertainty. Geostatistics is often used to model uncertainty because of its capability to stochastically generate spatially varying realizations of the subsurface. These methods can generate a range of realizations of a given pattern - but how representative are these of the full natural variability? And how can we identify the minimum set of images that represent this natural variability? Here we use this minimum set to define the geostatistical prior model: a set of training images that represent the range of patterns generated by autogenic variability in the sedimentary environment under study. The proper definition of the prior model is essential in capturing the variability of the depositional patterns. This work starts with a set of overhead images from an experimental basin that showed ongoing autogenic variability. We use the images to analyze the essential characteristics of this suite of patterns. In particular, our goal is to define a prior model (a minimal set of selected training images) such that geostatistical algorithms, when applied to this set, can reproduce the full measured variability. A necessary prerequisite is to define a measure of variability. In this study, we measure variability using a dissimilarity distance between the images. The distance indicates whether two snapshots contain similar depositional patterns. To reproduce the variability in the images, we apply an MPS algorithm to the set of selected snapshots of the sedimentary basin that serve as training images. The training images are chosen from among the initial set by using the distance measure to ensure that only dissimilar images are chosen. Preliminary investigations show that MPS can reproduce fairly accurately the natural variability of the experimental depositional system. Furthermore, the selected training images provide process information. They fall into three basic patterns: a channelized end member, a sheet flow end member, and one intermediate case. These represent the continuum between autogenic bypass or erosion, and net deposition.

Cross-contamination of foods and implications for food allergic patients.

PubMed

Taylor, Steve L; Baumert, Joseph L

2010-07-01

Cross-contamination presents a risk of unknown magnitude for food allergic consumers. Published cases likely represent the tip of a rather large iceberg. Cross-contamination can occur in homes, restaurants, food manufacturing plants, and on farms. The frequency of cross-contamination as the cause of accidental exposures to allergenic foods is unknown. Food allergic individuals can react to ingestion of trace levels of the offending food, although a highly variable range of threshold doses exist among populations of food allergic individuals. The magnitude of the risk posed to food allergic consumers by cross-contamination is characterized by the frequency of exposure to cross-contaminated foods, the dose of exposure, and the individual's threshold dose. The food and food service industry (and food preparers in homes as well) have the responsibility to provide and prepare foods that are safe for food allergic consumers, but quality of life may be improved with the recognition that safe (though very low) thresholds do exist.

Patterns of cross-contamination in a multispecies population genomic project: detection, quantification, impact, and solutions.

PubMed

Ballenghien, Marion; Faivre, Nicolas; Galtier, Nicolas

2017-03-29

Contamination is a well-known but often neglected problem in molecular biology. Here, we investigated the prevalence of cross-contamination among 446 samples from 116 distinct species of animals, which were processed in the same laboratory and subjected to subcontracted transcriptome sequencing. Using cytochrome oxidase 1 as a barcode, we identified a minimum of 782 events of between-species contamination, with approximately 80% of our samples being affected. An analysis of laboratory metadata revealed a strong effect of the sequencing center: nearly all the detected events of between-species contamination involved species that were sent the same day to the same company. We introduce new methods to address the amount of within-species, between-individual contamination, and to correct for this problem when calling genotypes from base read counts. We report evidence for pervasive within-species contamination in this data set, and show that classical population genomic statistics, such as synonymous diversity, the ratio of non-synonymous to synonymous diversity, inbreeding coefficient F IT , and Tajima's D, are sensitive to this problem to various extents. Control analyses suggest that our published results are probably robust to the problem of contamination. Recommendations on how to prevent or avoid contamination in large-scale population genomics/molecular ecology are provided based on this analysis.

Detection of aflatoxin and surface mould contaminated figs by using Fourier transform near-infrared reflectance spectroscopy.

PubMed

Durmuş, Efkan; Güneş, Ali; Kalkan, Habil

2017-01-01

Aflatoxins are toxic metabolites that are mainly produced by members of the Aspergillus section Flavi on many agricultural products. Certain agricultural products such as figs are known to be high risk products for aflatoxin contamination. Aflatoxin contaminated figs may show a bright greenish yellow fluorescence (BGYF) under ultraviolet (UV) light at a wavelength of 365 nm. Traditionally, BGYF positive figs are manually selected by workers. However, manual selection depends on the expertise level of the workers and it may cause them skin-related health problems due to UV radiation. In this study, we propose a non-invasive approach to detect aflatoxin and surface mould contaminated figs by using Fourier transform near-infrared (FT-NIR) reflectance spectroscopy. A classification accuracy of 100% is achieved for classifying the figs into aflatoxin contaminated/uncontaminated and surface mould contaminated/uncontaminated categories. In addition, a strong correlation has been found between aflatoxin and surface mould. Combined with pattern classification methods, the NIR spectroscopy can be used to detect aflatoxin contaminated figs non-invasively. Furthermore, a positive correlation between surface mould and aflatoxin contamination leads to a promising alternative indicator for the detection of aflatoxin-contaminated figs. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Environmental contaminants

USGS Publications Warehouse

Hoffman, D.J.; Rattner, B.A.; Scheunert, I.; Korte, F.; Shore, Richard F.; Rattner, Barnett A.

2001-01-01

The purpose of this chapter is to provide an overview of the ecotoxicology of major classes of environmental contaminants, with respect to sources, environmental chemistry, most likely routes of exposure, potential bioaccumulation and biomagification, mechanisms of toxicity, and effects on potentially vulnerable species of mammalian wildlife. Major contaminants reviewed were selected on the basis of their use patterns, availability and potential toxicity to wild mammals. These included pesticides used in agroecosystems (organochlorines, organophosphorus and carbamate compounds, anticoagulants, herbicides and fungicides), various organic pollutants (chlorobenzenes, chlorophenols, polychlorinated biphenyls, dibenzodioxins and dibenzofurans, and polycyclic aromatic hydrocarbons), heavy metals (lead, mercury, and cadmium), agricultural drainwater mixtures, leachates and radionuclides. Many of the above aspects of ecotoxicology and contaminants will be expanded upon in subsequent chapters of this book as they relate to distinct mammalian species and potential risk.

New insight on intergenerational attachment from a relationship-based analysis.

PubMed

Bailey, Heidi N; Tarabulsy, George M; Moran, Greg; Pederson, David R; Bento, Sandi

2017-05-01

Research on attachment transmission has focused on variable-centered analyses, where hypotheses are tested by examining linear associations between variables. The purpose of this study was to apply a relationship-centered approach to data analysis, where adult states of mind, maternal sensitivity, and infant attachment were conceived as being three components of a single, intergenerational relationship. These variables were assessed in 90 adolescent and 99 adult mother-infant dyads when infants were 12 months old. Initial variable-centered analyses replicated the frequently observed associations between these three core attachment variables. Relationship-based, latent class analyses then revealed that the most common pattern among young mother dyads featured maternal unresolved trauma, insensitive interactive behavior, and disorganized infant attachment (61%), whereas the most prevalent adult mother dyad relationship pattern involved maternal autonomy, sensitive maternal behavior, and secure infant attachment (59%). Three less prevalent relationship patterns were also observed. Moderation analyses revealed that the adolescent-adult mother distinction differentiated between secure and disorganized intergenerational relationship patterns, whereas experience of traumatic events distinguished between disorganized and avoidant patterns. Finally, socioeconomic status distinguished between avoidant and secure patterns. Results emphasize the value of a relationship-based approach, adding an angle of understanding to the study of attachment transmission.

DNAPL distribution in the source zone: Effect of soil structure and uncertainty reduction with increased sampling density

NASA Astrophysics Data System (ADS)

Pantazidou, Marina; Liu, Ke

2008-02-01

This paper focuses on parameters describing the distribution of dense nonaqueous phase liquid (DNAPL) contaminants and investigates the variability of these parameters that results from soil heterogeneity. In addition, it quantifies the uncertainty reduction that can be achieved with increased density of soil sampling. Numerical simulations of DNAPL releases were performed using stochastic realizations of hydraulic conductivity fields generated with the same geostatistical parameters and conditioning data at two sampling densities, thus generating two simulation ensembles of low and high density (three-fold increase) of soil sampling. The results showed that DNAPL plumes in aquifers identical in a statistical sense exhibit qualitatively different patterns, ranging from compact to finger-like. The corresponding quantitative differences were expressed by defining several alternative measures that describe the DNAPL plume and computing these measures for each simulation of the two ensembles. The uncertainty in the plume features under study was affected to different degrees by the variability of the soil, with coefficients of variation ranging from about 20% to 90%, for the low-density sampling. Meanwhile, the increased soil sampling frequency resulted in reductions of uncertainty varying from 7% to 69%, for low- and high-uncertainty variables, respectively. In view of the varying uncertainty in the characteristics of a DNAPL plume, remedial designs that require estimates of the less uncertain features of the plume may be preferred over others that need a more detailed characterization of the source zone architecture.

Models for nearly every occasion: Part I - One box models.

PubMed

Hewett, Paul; Ganser, Gary H

2017-01-01

The standard "well mixed room," "one box" model cannot be used to predict occupational exposures whenever the scenario involves the use of local controls. New "constant emission" one box models are proposed that permit either local exhaust or local exhaust with filtered return, coupled with general room ventilation or the recirculation of a portion of the general room exhaust. New "two box" models are presented in Part II of this series. Both steady state and transient models were developed. The steady state equation for each model, including the standard one box steady state model, is augmented with an additional factor reflecting the fraction of time the substance was generated during each task. This addition allows the easy calculation of the average exposure for cyclic and irregular emission patterns, provided the starting and ending concentrations are zero or near zero, or the cumulative time across all tasks is long (e.g., several tasks to a full shift). The new models introduce additional variables, such as the efficiency of the local exhaust to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). A structured procedure for calibrating a model to a work scenario is introduced that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of the generation rate and all of remaining unknown model variables.

Longitudinal prevalence and molecular typing of Escherichia coli O157:H7 by use of multiple-locus variable-number tandem-repeat analysis and pulsed-field gel electrophoresis in fecal samples collected from a range-based herd of beef cattle in California.

PubMed

Kondo, Sonoko; Hoar, Bruce R; Villanueva, Veronica; Mandrell, Robert E; Atwill, Edward R

2010-11-01

To evaluate seasonal patterns and risk factors for Escherichia coli O157:H7 in feces in a beef cattle herd and determine strain diversity and transition in E coli over time by use of multiple-locus variable-number tandem-repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). 456 samples of freshly passed feces collected over a 1-year period from cattle in a range-based cow-calf operation located in the foothills of the Sierra Nevada Mountains in California. E coli O157:H7 was recovered from feces by use of immunomagnetic separation and 2 selective media. Virulence factors were detected via reverse transcriptase-PCR assay. Escherichia coli O157:H7 isolates were subtyped with MLVA and PFGE. Prevalence estimates were calculated and significant risk factors determined. A dendrogram was constructed on the basis of results of MLVA typing. Overall prevalence estimate for E coli O157:H7 was 10.5%, with the prevalence lowest during the winter. Mean temperature during the 30 days before collection of samples was significantly associated with prevalence of E coli O157:H7 in feces. Nineteen MLVA and 12 PFGE types were identified. A seasonal pattern was detected for prevalence of E coli O157:H7 in feces collected from beef cattle in California. Subtyping via MLVA and PFGE revealed a diversity of E coli O157:H7 strains in a cow-calf operation and noteworthy turnover of predominant types. Given the importance of accurately determining sources of contamination in investigations of disease outbreaks in humans, MLVA combined with PFGE should be powerful tools for epidemiologists.

Depth Stratification Leads to Distinct Zones of Manganese and Arsenic Contaminated Groundwater.

PubMed

Ying, Samantha C; Schaefer, Michael V; Cock-Esteb, Alicea; Li, Jun; Fendorf, Scott

2017-08-15

Providing access to safe drinking water is a global challenge, for which groundwater is increasingly being used throughout the world. However, geogenic contaminants limit the suitability of groundwater for domestic purposes over large geographic areas across most continents. Geogenic contaminants in groundwater are often evaluated individually, but here we demonstrate the need to evaluate multiple contaminants to ensure that groundwater is safe for human consumption and agricultural usage. We compiled groundwater chemical data from three aquifer regions across the world that have been reported to have widespread As and Mn contamination including the Glacial Aquifer in the U.S., the Ganges-Brahmaputra-Mehta Basin within Bangladesh, and the Mekong Delta in Cambodia, along with newly sampled wells in the Yangtze River Basin of China. The proportion of contaminated wells increase by up to 40% in some cases when both As and Mn contaminants are considered. Wilcoxon rank-sum analysis indicates that Mn contamination consistently occurs at significantly shallower depths than As contaminated wells in all regions. Arsenic concentrations in groundwater are well predicted by redox indicators (Eh and dissolved oxygen) whereas Mn shows no significant relationship with either parameter. These findings illustrate that the number of safe wells may be drastically overestimated in some regions when Mn contamination is not taken into account and that depth may be used as a distinguishing variable in efforts to predict the presence of groundwater contaminants regionally.

Observed distribution of radiocaesium contamination in shiitake lots and variability of test results.

PubMed

Tsuchiyama, Tomoyuki; Miyazaki, Hitoshi; Terada, Hisaya; Nakajima, Masahiro

2015-01-01

Shiitake mushrooms (Lentinula edodes) cultivated on bed-log are known to accumulate radiocaesium. Since the Fukushima-Diichi nuclear power plant accident (2011), the violation rate has been higher for log-cultivated shiitake than that for agricultural products or other foodstuffs. When testing shiitake mushrooms for radionuclide contamination, the validation of the sampling plan can be severely compromised by the heterogeneous contamination within shiitake lots. Currently, few data are available on the statistical properties of the radiocaesium contamination of log-cultivated shiitake. In this paper, shiitake lots contaminated by radiocaesium were identified and the distribution of the radiocaesium concentration within the lots investigated. The risk of misclassifying shiitake lots was predicted from the operating characteristic curve generated from Monte Carlo simulations and the performance of various sampling plans was evaluated. This study provides useful information for deciding on an acceptable level of misclassification risk.

Classification of Antibiotic Resistance Patterns of Indicator Bacteria by Discriminant Analysis: Use in Predicting the Source of Fecal Contamination in Subtropical Waters

PubMed Central

Harwood, Valerie J.; Whitlock, John; Withington, Victoria

2000-01-01

The antibiotic resistance patterns of fecal streptococci and fecal coliforms isolated from domestic wastewater and animal feces were determined using a battery of antibiotics (amoxicillin, ampicillin, cephalothin, chlortetracycline, oxytetracycline, tetracycline, erythromycin, streptomycin, and vancomycin) at four concentrations each. The sources of animal feces included wild birds, cattle, chickens, dogs, pigs, and raccoons. Antibiotic resistance patterns of fecal streptococci and fecal coliforms from known sources were grouped into two separate databases, and discriminant analysis of these patterns was used to establish the relationship between the antibiotic resistance patterns and the bacterial source. The fecal streptococcus and fecal coliform databases classified isolates from known sources with similar accuracies. The average rate of correct classification for the fecal streptococcus database was 62.3%, and that for the fecal coliform database was 63.9%. The sources of fecal streptococci and fecal coliforms isolated from surface waters were identified by discriminant analysis of their antibiotic resistance patterns. Both databases identified the source of indicator bacteria isolated from surface waters directly impacted by septic tank discharges as human. At sample sites selected for relatively low anthropogenic impact, the dominant sources of indicator bacteria were identified as various animals. The antibiotic resistance analysis technique promises to be a useful tool in assessing sources of fecal contamination in subtropical waters, such as those in Florida. PMID:10966379

Global linkages between teleconnection patterns and the terrestrial biosphere

NASA Astrophysics Data System (ADS)

Dahlin, Kyla M.; Ault, Toby R.

2018-07-01

Interannual variability in the global carbon cycle is largely due to variations in carbon uptake by terrestrial ecosystems, yet linkages between climate variability and variability in the terrestrial carbon cycle are not well understood at the global scale. Using a 30-year satellite record of semi-monthly leaf area index (LAI), we show that four modes of climate variability - El Niño/Southern Oscillation, the North Atlantic Oscillation, the Atlantic Meridional Mode, and the Indian Ocean Dipole Mode - strongly impact interannual vegetation growth patterns, with 68% of the land surface impacted by at least one of these teleconnection patterns, yet the spatial distribution of these impacts is heterogeneous. Considering the patterns' impacts by biome, none has an exclusively positive or negative relationship with LAI. Our findings imply that future changes in the frequency and/or magnitude of teleconnection patterns will lead to diverse changes to the terrestrial biosphere and the global carbon cycle.

Escherichia coli and enterococci at beaches in the Grand Traverse Bay, Lake Michigan: Sources, characteristics, and environmental pathways

USGS Publications Warehouse

Haack, S.K.; Fogarty, L.R.; Wright, C.

2003-01-01

This study quantified Escherichia coli(EC) and enterococci (ENT) in beach waters and dominant source materials, correlated these with ambient conditions, and determined selected EC genotypes and ENT phenotypes. Bathing-water ENT criteria were exceeded more frequently than EC criteria, providing conflicting interpretations of water quality. Dominant sources of EC and ENT were bird feces (108/d/bird), storm drains (107/d), and river water (1011/d); beach sands, shallow groundwater and detritus were additional sources. Beach-water EC genotypes and ENT phenotypes formed clusters with those from all source types, reflecting diffuse inputs. Some ENT isolates had phenotypes similar to those of human pathogens and/or exhibited high-level resistance to human-use antibiotics. EC and ENT concentrations were influenced by collection time and wind direction. There was a 48-72-h lag between rainfall and elevated EC concentrations at three southern shoreline beaches, but no such lag at western and eastern shoreline beaches, reflecting the influence of beach orientation with respect to cyclic (3-5 d) summer weather patterns. In addition to local contamination sources and processes, conceptual or predictive models of Great Lakes beach water quality should consider regional weather patterns, lake hydrodynamics, and the influence of monitoring method variables (time of day, frequency).

Toxicity Assessment of Contaminated Soils of Solid Domestic Waste Landfill

NASA Astrophysics Data System (ADS)

Pasko, O. A.; Mochalova, T. N.

2014-08-01

The paper delivers the analysis of an 18-year dynamic pattern of land pollutants concentration in the soils of a solid domestic waste landfill. It also presents the composition of the contaminated soils from different areas of the waste landfill during its operating period. The authors calculate the concentrations of the following pollutants: chrome, nickel, tin, vanadium, lead, cuprum, zinc, cobalt, beryllium, barium, yttrium, cadmium, arsenic, germanium, nitrate ions and petrochemicals and determine a consistent pattern of their spatial distribution within the waste landfill area as well as the dynamic pattern of their concentration. Test-objects are used in experiments to make an integral assessment of the polluted soil's impact on living organisms. It was discovered that the soil samples of an animal burial site are characterized by acute toxicity while the area of open waste dumping is the most dangerous in terms of a number of pollutants. This contradiction can be attributed to the synergetic effect of the polluted soil, which accounts for the regularities described by other researchers.

Landscape assessment of spatial Cs-137 connectivity patterns in arable land with gray loamy soils in the Bryansk Region (landscapes of the Opolje)

NASA Astrophysics Data System (ADS)

Linnik, Vitaly; Sokolov, Alexander; Saveliev, Anatoly; Mironenko, Iya

2017-04-01

As a result of the Chernobyl accident in 1986 landscapes of the Bryansk Region (Russia) were contaminated by Cs-137. In 1993 air-gamma survey with 100 m resolution was done in contaminated areas of the region, which revealed significant spatial heterogeneity of Cs-137 contamination. The initial "spotting" of contamination Cs-137, which in the spring of 1986 represented multi-scale complex patterns of contamination, was substantially transformed by 1993 as a result of erosion processes of various intensity. The purpose of this research was to obtain estimates of the transformation of initial Cs-137 patterns as influenced by different landscape factors. The study is based on the concept of sediment and hydrological connectivity. We apply GIS-based models considering lateral soil migration to analyze sediment cascade system. The study area is a test plot that has grey loamy soils (landscapes of the Opolje) with a size 10x16 km in the central part of the Bryansk Region, with more than 80% of the area under cultivation. Elevation levels are in the range of 140-210 m. Because of plowing, intense erosion processes have taken place. The slope angles in the lower parts of slopes reach 2-3 degrees. Maximum slopes in gullies reach 11,5 degrees. Cs-137 levels of contamination vary from 3,6 kBq/m2 to 35 3,6 kBq/m2. Over the past few decades the Cs-137 technique has been applied to determine net soil redistribution rates. It is applicable for medium long term (30 to 40 years) soil redistribution estimates. In this technique, the anthropogenic radionuclide Cs-137 is used as a sediment tracer from upland erosion studies to catchment sediment budgets, as well as to depositional areas in colluvial positions, valleys, river terraces, floodplains. The soil movement is primarily driven by water flow due to the gravity. The effect of gravity can be easily approximated using DEM derivatives. Cs-137 patterns have been investigated to estimate landscape connectivity and soil redistribution rates in different slope positions. In addition to the Cs-137 contamination, DEM parameters, such as slope angle, aspect, and different landscape indexes (wetness index etc.) have been estimated. Potential Cs-137 connectivity of hillslopes - floodplain or hillslopes -valley is characterized by lateral contributing area. To assess the relationship of Cs-137 with various landscape factors we used different statistical models. Analysis of the lateral redistribution of Cs-137 in the landscape is based on the assumption of primordial density in nonuniformity of Cs-137 deposition in different landscape positions. Relationship of Cs-137 connectivity for various landscape positions is presented. Fundamental differences of Cs-137 connectivity for slopes of southern and northern exposure are demonstrated.

Sporadic case of listeriosis associated with the consumption of a Listeria monocytogenes-contaminated 'Camembert' cheese.

PubMed

Gilot, P; Hermans, C; Yde, M; Gigi, J; Janssens, M; Genicot, A; André, P; Wauters, G

1997-09-01

Listeria monocytogenes is an intracellular gram-positive organism responsible for severe infections in both humans and animals. Whereas the food-borne transmission of listeriosis was demonstrated in several outbreaks, most cases of listeriosis occur sporadically and are rarely linked with consumption of contaminated foods. In this paper a case of septicaemia with L. monocytogenes in a 73-year-old immunocompromised man is described. Evidence for the association of this case of listeriosis with the consumption of a contaminated 'Camembert' cheese is provided by serotyping, esterase typing, DNA macrorestriction patterns analysis and level of virulence of the isolated strains for mice.

Occurrence of organic wastewater-indicator compounds in urban streams of the Atlanta area, Georgia, 2003-2006

USGS Publications Warehouse

Lawrence, Stephen J.; LaFontaine, Jacob H.

2010-01-01

The similarity in the pattern and distribution of OWICs in samples at sites upstream and downstream from known CSO outfalls indicates that CSOs were not the dominant source of OWICs during the study period. Other sources may include non-sewage discharges-both permitted, permitted but out of compliance, and non-permitted, contaminated groundwater from leaking sewer lines or septic systems, sanitary-sewer overflows, or dry-weather runoff from outdoor water use. These OWICs may be better suited for identifying sewage-contaminated groundwater than sewage-contaminated surface water because groundwater is not typically affected by the OWICs that are more common in urban runoff.

Surface contamination detection by means of near-infrared stimulation of thermal luminescence

NASA Astrophysics Data System (ADS)

Carrieri, Arthur H.; Roese, Erik S.

2006-02-01

A method for remotely detecting liquid chemical contamination on terrestrial surfaces is presented. Concurrent to irradiation by an absorbing near-infrared beam, the subject soil medium liberates radiance called thermal luminescence (TL) comprising middle-infrared energies (numir) that is scanned interferometrically in beam duration tau. Cyclic states of absorption and emission by the contaminant surrogate are rendered from a sequential differential-spectrum measurement [deltaS(numir,tau)] of the scanned TL. Detection of chemical warfare agent simulant wetting soil is performed in this manner, for example, through pattern recognition of its unique, thermally dynamic, molecular vibration resonance bands on display in the deltaS(numir,tau) metric.

LARGE-SCALE PATTERNS OF STREAMFLOW DISTURBANCE AND FISH COMMUNITIES IN UPPER MISSOURI RIVER BASIN, USA

EPA Science Inventory

Patterns of streamflow variability are likely to be a major organizing feature of the habitat template for stream fishes. Functional organization of stream communities has been linked to streamflow, especially to patterns of flow variability that describe the physical disturbanc...

LARGE-SCALE PATTERNS OF STREAMFLOW DISTURBANCE AND FISH ASSEMBLAGES IN UPPER MISSOURI RIVER BASIN, USA

EPA Science Inventory

Patterns of streamflow variability are likely to be a major organizing feature of the habitat template for stream fishes. Ecological organization of stream communities has been linked to streamflow, especially to patterns of flow variability that describe the physical disturbanc...

Classification of Partial Discharge Measured under Different Levels of Noise Contamination

PubMed Central

2017-01-01

Cable joint insulation breakdown may cause a huge loss to power companies. Therefore, it is vital to diagnose the insulation quality to detect early signs of insulation failure. It is well known that there is a correlation between Partial discharge (PD) and the insulation quality. Although many works have been done on PD pattern recognition, it is usually performed in a noise free environment. Also, works on PD pattern recognition in actual cable joint are less likely to be found in literature. Therefore, in this work, classifications of actual cable joint defect types from partial discharge data contaminated by noise were performed. Five cross-linked polyethylene (XLPE) cable joints with artificially created defects were prepared based on the defects commonly encountered on site. Three different types of input feature were extracted from the PD pattern under artificially created noisy environment. These include statistical features, fractal features and principal component analysis (PCA) features. These input features were used to train the classifiers to classify each PD defect types. Classifications were performed using three different artificial intelligence classifiers, which include Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Support Vector Machine (SVM). It was found that the classification accuracy decreases with higher noise level but PCA features used in SVM and ANN showed the strongest tolerance against noise contamination. PMID:28085953

Insights into biodegradation through depth-resolved microbial community functional and structural profiling of a crude-oil contaminant plume

USGS Publications Warehouse

Fahrenfeld, Nicole; Cozzarelli, Isabelle M.; Bailey, Zach; Pruden, Amy

2014-01-01

Small-scale geochemical gradients are a key feature of aquifer contaminant plumes, highlighting the need for functional and structural profiling of corresponding microbial communities on a similar scale. The purpose of this study was to characterize the microbial functional and structural diversity with depth across representative redox zones of a hydrocarbon plume and an adjacent wetland, at the Bemidji Oil Spill site. A combination of quantitative PCR, denaturing gradient gel electrophoresis, and pyrosequencing were applied to vertically sampled sediment cores. Levels of the methanogenic marker gene, methyl coenzyme-M reductase A (mcrA), increased with depth near the oil body center, but were variable with depth further downgradient. Benzoate degradation N (bzdN) hydrocarbon-degradation gene, common to facultatively anaerobic Azoarcus spp., was found at all locations, but was highest near the oil body center. Microbial community structural differences were observed across sediment cores, and bacterial classes containing known hydrocarbon degraders were found to be low in relative abundance. Depth-resolved functional and structural profiling revealed the strongest gradients in the iron-reducing zone, displaying the greatest variability with depth. This study provides important insight into biogeochemical characteristics in different regions of contaminant plumes, which will aid in improving models of contaminant fate and natural attenuation rates.

Temporary vs. Permanent Sub-slab Ports: A Comparative ...

EPA Pesticide Factsheets

Vapor intrusion (VI) is the migration of subsurface vapors, including radon and volatile organic compounds (VOCs), from the subsurface to indoor air. The VI exposure pathway extends from the contaminant source, which can be impacted soil, non-aqueous phase liquid, or contaminated groundwater, to indoor air-exposure points. Therefore, contaminated matrices may include groundwater, soil, soil gas, and indoor air. VOC contaminants of concern typically include halogenated solvents such as trichloroethene, tetrachloroethene, and chloroform, as well as petroleum hydrocarbons, such as the aromatic VOCs benzene, toluene, and xylenes. Radon is a colorless radioactive gas that is released by radioactive decay of radionuclides in rock and soil that migrate into homes through VI in a similar fashion to VOCs. This project focused on the performance of permanent versus temporary sub-slab sampling ports for the determination of VI of halogenated VOCs and radon into an unoccupied house. VOC and radon concentrations measured simultaneously in soil gas using collocated temporary and permanent ports appeared to be independent of the type of port. The variability between collocated temporary and permanent ports was much less than the spatial variability between different locations within a single residential duplex. The agreement of the majority of VOC and radon concentrations, 0–36% relative percent difference, and 2–19% relative standard deviation respectively, of each sub-sl

Influence of various factors on individual radiation exposure from the Chernobyl disaster.

PubMed

Zamostian, Pavlo; Moysich, Kirsten B; Mahoney, Martin C; McCarthy, Philip; Bondar, Alexandra; Noschenko, Andrey G; Michalek, Arthur M

2002-10-29

The explosion at the Chernobyl Nuclear Power Plant was one of the greatest known nuclear disasters of the 20th century. To reduce individual exposure to ionizing radiation the Soviet Union government introduced a number of counter-measures. This article presents a description of how historical events conspired to disrupt these efforts and affect residents in exposed areas. This study employed an extensive review of data on radionuclide deposition, contamination patterns and lifestyle characteristics. Data were obtained from the Ukraine Ministry of Health and the Ukraine Research Center for Radiation Medicine. Data are presented on annual contamination rates in selected locales as well as data on local food consumption patterns. Historical factors including economic and political circumstances are also highlighted. Results show the diminution of individual doses between 1987 and 1991 and then an increase between 1991 and 1994 and the relationship between this increase and changes in the lifestyle of the local population. A number of factors played direct and indirect roles in contributing to the populace's cumulative radiation exposure. Future post-contamination studies need to consider these factors when estimating individual exposures.

Children's exposure assessment: a review of factors influencing Children's exposure, and the data available to characterize and assess that exposure.

PubMed Central

Cohen Hubal, E A; Sheldon, L S; Burke, J M; McCurdy, T R; Berry, M R; Rigas, M L; Zartarian, V G; Freeman, N C

2000-01-01

We review the factors influencing children's exposure to environmental contaminants and the data available to characterize and assess that exposure. Children's activity pattern data requirements are demonstrated in the context of the algorithms used to estimate exposure by inhalation, dermal contact, and ingestion. Currently, data on children's exposures and activities are insufficient to adequately assess multimedia exposures to environmental contaminants. As a result, regulators use a series of default assumptions and exposure factors when conducting exposure assessments. Data to reduce uncertainty in the assumptions and exposure estimates are needed to ensure chemicals are regulated appropriately to protect children's health. To improve the database, advancement in the following general areas of research is required: identification of appropriate age/developmental benchmarks for categorizing children in exposure assessment; development and improvement of methods for monitoring children's exposures and activities; collection of activity pattern data for children (especially young children) required to assess exposure by all routes; collection of data on concentrations of environmental contaminants, biomarkers, and transfer coefficients that can be used as inputs to aggregate exposure models. PMID:10856019

Vagal-dependent nonlinear variability in the respiratory pattern of anesthetized, spontaneously breathing rats

PubMed Central

Dhingra, R. R.; Jacono, F. J.; Fishman, M.; Loparo, K. A.; Rybak, I. A.

2011-01-01

Physiological rhythms, including respiration, exhibit endogenous variability associated with health, and deviations from this are associated with disease. Specific changes in the linear and nonlinear sources of breathing variability have not been investigated. In this study, we used information theory-based techniques, combined with surrogate data testing, to quantify and characterize the vagal-dependent nonlinear pattern variability in urethane-anesthetized, spontaneously breathing adult rats. Surrogate data sets preserved the amplitude distribution and linear correlations of the original data set, but nonlinear correlation structure in the data was removed. Differences in mutual information and sample entropy between original and surrogate data sets indicated the presence of deterministic nonlinear or stochastic non-Gaussian variability. With vagi intact (n = 11), the respiratory cycle exhibited significant nonlinear behavior in templates of points separated by time delays ranging from one sample to one cycle length. After vagotomy (n = 6), even though nonlinear variability was reduced significantly, nonlinear properties were still evident at various time delays. Nonlinear deterministic variability did not change further after subsequent bilateral microinjection of MK-801, an N-methyl-d-aspartate receptor antagonist, in the Kölliker-Fuse nuclei. Reversing the sequence (n = 5), blocking N-methyl-d-aspartate receptors bilaterally in the dorsolateral pons significantly decreased nonlinear variability in the respiratory pattern, even with the vagi intact, and subsequent vagotomy did not change nonlinear variability. Thus both vagal and dorsolateral pontine influences contribute to nonlinear respiratory pattern variability. Furthermore, breathing dynamics of the intact system are mutually dependent on vagal and pontine sources of nonlinear complexity. Understanding the structure and modulation of variability provides insight into disease effects on respiratory patterning. PMID:21527661

Monitoring of Soil Contamination by Heavy Metals in the Impact Zone of Copper-Nickel Smelter on the Kola Peninsula

NASA Astrophysics Data System (ADS)

Kashulina, G. M.

2018-04-01

The results of landscape monitoring of the concentrations of acid-extractable Ni, Cu, Co, Mn, and Zn in soils of the local impact zone of the Severonikel industrial complex on the Kola Peninsula are discussed. The aim of monitoring studies was to reveal the spatial and temporal regularities of variation in the degree of soil contamination by heavy metals. In 2001-2011, the concentrations of acid-extractable compounds of the elements in the upper part of organic soil horizons around this plant exceeded their background concentrations by two orders of magnitude for Cu and Co and by three orders of magnitude for Ni. The degree of topsoil contamination with Ni, Cu, and Co generally corresponded to the distance of the plots from the contamination source and to the modern technogenic load. However, because of the long period of the emissions, their extreme amounts, and complex composition, indirect factors—the degree of technogenic soil degradation, the loss of soil organic matter, saturation of the surface soil layers by the contaminating metals, and competitive relationships between the elements—also affect soil contamination level. The concentrations of all the studied metals in the topsoil are characterized by considerable (1.5 to 7 times) variability in their long-term dynamics. The most important factors of this variability for Ni, Cu, and Co are the organic matter content of the samples and the amount of atmospheric precipitation in the year preceding the sampling. An inverse relationship between element concentrations in the soils and the amount of atmospheric precipitation attests to the dynamic nature and reversible character of the accumulation of heavy metals in the soils.

Detection by denaturing gradient gel electrophoresis of ammonia-oxidizing bacteria in microcosms of crude oil-contaminated mangrove sediments.

PubMed

dos Santos, A C F; Marques, E L S; Gross, E; Souza, S S; Dias, J C T; Brendel, M; Rezende, R P

2012-01-27

Currently, the effect of crude oil on ammonia-oxidizing bacterium communities from mangrove sediments is little understood. We studied the diversity of ammonia-oxidizing bacteria in mangrove microcosm experiments using mangrove sediments contaminated with 0.1, 0.5, 1, 2, and 5% crude oil as well as non-contaminated control and landfarm soil from near an oil refinery in Camamu Bay in Bahia, Brazil. The evolution of CO(2) production in all crude oil-contaminated microcosms showed potential for mineralization. Cluster analysis of denaturing gradient gel electrophoresis-derived samples generated with primers for gene amoA, which encodes the functional enzyme ammonia monooxygenase, showed differences in the sample contaminated with 5% compared to the other samples. Principal component analysis showed divergence of the non-contaminated samples from the 5% crude oil-contaminated sediment. A Venn diagram generated from the banding pattern of PCR-denaturing gradient gel electrophoresis was used to look for operational taxonomic units (OTUs) in common. Eight OTUs were found in non-contaminated sediments and in samples contaminated with 0.5, 1, or 2% crude oil. A Jaccard similarity index of 50% was found for samples contaminated with 0.1, 0.5, 1, and 2% crude oil. This is the first study that focuses on the impact of crude oil on the ammonia-oxidizing bacterium community in mangrove sediments from Camamu Bay.

Analysis of the interdecadal variability of summer precipitation in central Japan using a reconstructed 106 year long oxygen isotope record from tree ring cellulose

NASA Astrophysics Data System (ADS)

Kurita, Naoyuki; Nakatsuka, Takeshi; Ohnishi, Keiko; Mitsutani, Takumi; Kumagai, Tomo'omi

2016-10-01

We present a unique proxy for reconstructing the interannual variability of summer precipitation associated with the quasi-stationary front (Baiu front) in central Japan. The rainfall from the Baiu front has a relatively lower oxygen isotopic composition than other types of nonfrontal precipitation. The variability in the oxygen isotopes in summer rainfall is closely related to the Baiu frontal activity. In this study we used a mechanistic tree ring isotope model to reconstruct a 106 year long oxygen isotopic composition of precipitation during the early rainy season (June) based on the oxygen isotopic compositions of the annual rings of Chamaecyparis obtusa Endl trees from central Japan. The year-to-year variations of the isotopes over the most recent 25 years are associated with several teleconnection patterns that often lead to the Baiu precipitation anomalies in central Japan (such as the Pacific-Japan (PJ) pattern, Silk Road pattern, and wave train pattern along the polar jet). Yet none of these external forcing mechanisms apply further back in time. From the 1950s to 1980s, the interannual isotopic variability is predominantly related to local factors such as anomalous intensification/weakening of the Bonin High. Before the 1950s, the variability of the oxygen isotopic composition of precipitation is mainly associated with a wave train pattern along the polar jet. The isotopic variability is predominantly linked to the PJ pattern, while the PJ index is correlated with El Niño-Southern Oscillation. These findings suggest that the teleconnection patterns influencing Baiu precipitation variability vary according to interdecadal time scales during the twentieth century.

Weather patterns as a downscaling tool - evaluating their skill in stratifying local climate variables

NASA Astrophysics Data System (ADS)

Murawski, Aline; Bürger, Gerd; Vorogushyn, Sergiy; Merz, Bruno

2016-04-01

The use of a weather pattern based approach for downscaling of coarse, gridded atmospheric data, as usually obtained from the output of general circulation models (GCM), allows for investigating the impact of anthropogenic greenhouse gas emissions on fluxes and state variables of the hydrological cycle such as e.g. on runoff in large river catchments. Here we aim at attributing changes in high flows in the Rhine catchment to anthropogenic climate change. Therefore we run an objective classification scheme (simulated annealing and diversified randomisation - SANDRA, available from the cost733 classification software) on ERA20C reanalyses data and apply the established classification to GCMs from the CMIP5 project. After deriving weather pattern time series from GCM runs using forcing from all greenhouse gases (All-Hist) and using natural greenhouse gas forcing only (Nat-Hist), a weather generator will be employed to obtain climate data time series for the hydrological model. The parameters of the weather pattern classification (i.e. spatial extent, number of patterns, classification variables) need to be selected in a way that allows for good stratification of the meteorological variables that are of interest for the hydrological modelling. We evaluate the skill of the classification in stratifying meteorological data using a multi-variable approach. This allows for estimating the stratification skill for all meteorological variables together, not separately as usually done in existing similar work. The advantage of the multi-variable approach is to properly account for situations where e.g. two patterns are associated with similar mean daily temperature, but one pattern is dry while the other one is related to considerable amounts of precipitation. Thus, the separation of these two patterns would not be justified when considering temperature only, but is perfectly reasonable when accounting for precipitation as well. Besides that, the weather patterns derived from reanalyses data should be well represented in the All-Hist GCM runs in terms of e.g. frequency, seasonality, and persistence. In this contribution we show how to select the most appropriate weather pattern classification and how the classes derived from it are reflected in the GCMs.

Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake.

PubMed

Burger, Joanna

2013-01-01

Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency's oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals.

Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake

PubMed Central

Burger, Joanna

2013-01-01

Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency’s oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals. PMID:23914136

Improving surface-subsurface water budgeting for Brownfield study sites using high resolution satellite imagery

NASA Astrophysics Data System (ADS)

Dujardin, J.; Boel, S.; Anibas, C.; Batelaan, O.; Canters, F.

2009-04-01

Countries around the world have problems with contaminated brownfield sites as resulting from a relatively anarchic economical and industrial development during the 19th and 20th centuries. Since a few decades policy makers and stakeholders have become more aware of the risk posed by these sites because some of these sites present direct public hazards. Water is often the main vector of the mobility of contaminants. In order to propose remediation measures for the contaminated sites, it is required to describe and to quantify as accurately as possible the surface and subsurface water fluxes in the polluted site. In this research a modelling approach with integrated remote sensing analysis has been developed for accurately calculating water and contaminant fluxes on the polluted sites. Groundwater pollution in urban environments is linked to patterns of land use, so to identify the sources of contamination with great accuracy in urban environments it is essential to characterize the land cover in a detailed way. The use of high resolution spatial information is required because of the complexity of the urban land use. An object-oriented classification approach applied on high resolution satellite data has been adopted. Cluster separability analysis and visual interpretation of the image objects belonging to each cluster resulted in the selection of 8 land-cover categories (water, bare soil, meadow, mixed forest, grey urban surfaces, red roofs, bright roofs and shadow).To assign the image objects to one of the 8 selected classes a multiple layer perceptron (MLP) approach was adopted, using the NeuralWorks Predict software. After a post-classification shadow removal and a rule-based classification enhancement a kappa-value of 0.86 was obtained. Once the land cover was characterized, the groundwater recharge has been simulated using the spatially distributed WetSpass model and the subsurface water flow was simulated with GMS 6.0 in order to identify and budget the water fluxes on the brownfield. The obtained land use map shows to have a strong impact on the groundwater recharge, resulting in a high spatial variability. Simulated groundwater fluxes from brownfield to a receiving river where independently verified by measurements and simulation of groundwater-surface water interaction based on thermal gradients in the river bed. It is concluded that in order to better quantify total fluxes of contaminants from brownfields in the groundwater, remote sensing imagery can be operationally integrated in a modelling procedure. The developed methodology is applied to a case site in Vilvoorde, Brussels (Belgium).

Environmental effects on the shape variation of male ultraviolet patterns in the Brimstone butterfly ( Gonepteryx rhamni, Pieridae, Lepidoptera)

NASA Astrophysics Data System (ADS)

Pecháček, Pavel; Stella, David; Keil, Petr; Kleisner, Karel

2014-12-01

The males of the Brimstone butterfly ( Gonepteryx rhamni) have ultraviolet pattern on the dorsal surfaces of their wings. Using geometric morphometrics, we have analysed correlations between environmental variables (climate, productivity) and shape variability of the ultraviolet pattern and the forewing in 110 male specimens of G. rhamni collected in the Palaearctic zone. To start with, we subjected the environmental variables to principal component analysis (PCA). The first PCA axis (precipitation, temperature, latitude) significantly correlated with shape variation of the ultraviolet patterns across the Palaearctic. Additionally, we have performed two-block partial least squares (PLS) analysis to assess co-variation between intraspecific shape variation and the variation of 11 environmental variables. The first PLS axis explained 93 % of variability and represented the effect of precipitation, temperature and latitude. Along this axis, we observed a systematic increase in the relative area of ultraviolet colouration with increasing temperature and precipitation and decreasing latitude. We conclude that the shape variation of ultraviolet patterns on the forewings of male Brimstones is correlated with large-scale environmental factors.

Organochlorine residues and shell characteristics of roseate tern eggs, 1981

USGS Publications Warehouse

Custer, T.W.; Nisbet, I.C.T.; Krynitsky, A.J.

1983-01-01

Roseate Terns (Sterna dougallii ) breed in two areas in the Western Hemisphere: in northeastern North America between Long Island, New York, and Nova Scotia, and around the Caribbean Sea from the Florida Keys and the Bahamas to the Netherlands Lesser Antilles. The present paper reports the results of a survey of organochlorine residues in Roseate Terns in 1981. The main objectives of the survey were to determine the levels of organochlorine contamination in eggs of the Roseate Tern in its major colonies and to investigate whether changes in eggshell characteristics similar to those reported by Fox (1976) may have occurred in this species. A secondary objective was to determine geographic patterns of organochlorine contamination within the northeastern U.S. population of Roseate Terns and to compare them with patterns observed in Common Terns.

Exposure to Tetrachloroethylene-Contaminated Drinking Water and the Risk of Pregnancy Loss

PubMed Central

Aschengrau, Ann; Weinberg, Janice M.; Gallagher, Lisa G.; Winter, Michael R.; Vieira, Veronica M.; Webster, Thomas F.; Ozonoff, David M.

2010-01-01

There is little information on the impact of solvent-contaminated drinking water on pregnancy outcomes. This retrospective cohort study examined whether maternal exposure to tetrachloroethylene (PCE) - contaminated drinking water in the Cape Cod region of Massachusetts influenced the risk of clinically recognized pregnancy loss. The study identified exposed (n=959) and unexposed (1,087) women who completed a questionnaire on their residential and pregnancy histories, and confounding variables. Exposure was estimated using water distribution system modeling software. No meaningful associations were seen between PCE exposure level and the risk of clinically recognized pregnancy loss at the exposure levels experienced by the study population. Because PCE remains a common water contaminant, it is important to continue monitoring its impact on women and their pregnancies. PMID:20613966

Saltelli Global Sensitivity Analysis and Simulation Modelling to Identify Intervention Strategies to Reduce the Prevalence of Escherichia coli O157 Contaminated Beef Carcasses

PubMed Central

Brookes, Victoria J.; Jordan, David; Davis, Stephen; Ward, Michael P.; Heller, Jane

2015-01-01

Introduction Strains of Shiga-toxin producing Escherichia coli O157 (STEC O157) are important foodborne pathogens in humans, and outbreaks of illness have been associated with consumption of undercooked beef. Here, we determine the most effective intervention strategies to reduce the prevalence of STEC O157 contaminated beef carcasses using a modelling approach. Method A computational model simulated events and processes in the beef harvest chain. Information from empirical studies was used to parameterise the model. Variance-based global sensitivity analysis (GSA) using the Saltelli method identified variables with the greatest influence on the prevalence of STEC O157 contaminated carcasses. Following a baseline scenario (no interventions), a series of simulations systematically introduced and tested interventions based on influential variables identified by repeated Saltelli GSA, to determine the most effective intervention strategy. Results Transfer of STEC O157 from hide or gastro-intestinal tract to carcass (improved abattoir hygiene) had the greatest influence on the prevalence of contaminated carcases. Due to interactions between inputs (identified by Saltelli GSA), combinations of interventions based on improved abattoir hygiene achieved a greater reduction in maximum prevalence than would be expected from an additive effect of single interventions. The most effective combination was improved abattoir hygiene with vaccination, which achieved a greater than ten-fold decrease in maximum prevalence compared to the baseline scenario. Conclusion Study results suggest that effective interventions to reduce the prevalence of STEC O157 contaminated carcasses should initially be based on improved abattoir hygiene. However, the effect of improved abattoir hygiene on the distribution of STEC O157 concentration on carcasses is an important information gap—further empirical research is required to determine whether reduced prevalence of contaminated carcasses is likely to result in reduced incidence of STEC O157 associated illness in humans. This is the first use of variance-based GSA to assess the drivers of STEC O157 contamination of beef carcasses. PMID:26713610

Expression Analysis of Stress-Related Genes in Kernels of Different Maize (Zea mays L.) Inbred Lines with Different Resistance to Aflatoxin Contamination

PubMed Central

Jiang, Tingbo; Zhou, Boru; Luo, Meng; Abbas, Hamed K.; Kemerait, Robert; Lee, Robert Dewey; Scully, Brian T.; Guo, Baozhu

2011-01-01

This research examined the expression patterns of 94 stress-related genes in seven maize inbred lines with differential expressions of resistance to aflatoxin contamination. The objective was to develop a set of genes/probes associated with resistance to A. flavus and/or aflatoxin contamination. Ninety four genes were selected from previous gene expression studies with abiotic stress to test the differential expression in maize lines, A638, B73, Lo964, Lo1016, Mo17, Mp313E, and Tex6, using real-time RT-PCR. Based on the relative-expression levels, the seven maize inbred lines clustered into two different groups. One group included B73, Lo1016 and Mo17, which had higher levels of aflatoxin contamination and lower levels of overall gene expression. The second group which included Tex6, Mp313E, Lo964 and A638 had lower levels of aflatoxin contamination and higher overall levels of gene expressions. A total of six “cross-talking” genes were identified between the two groups, which are highly expressed in the resistant Group 2 but down-regulated in susceptible Group 1. When further subjected to drought stress, Tex6 expressed more genes up-regulated and B73 has fewer genes up-regulated. The transcript patterns and interactions measured in these experiments indicate that the resistant mechanism is an interconnected process involving many gene products and transcriptional regulators, as well as various host interactions with environmental factors, particularly, drought and high temperature. PMID:22069724

Thermotemporal dynamics of contaminant bacteria and antimicrobials in extended porcine semen.

PubMed

Althouse, G C; Pierdon, M S; Lu, K G

2008-11-01

Bacterial contamination of extended porcine semen has been associated with deleterious effects on both semen quality and sow fertility. Retrospective, prospective and in vitro studies were performed to delineate the prevalence and behavior of certain bacterial contaminants in extended semen, and antimicrobial pharmacodynamics in various semen diluents. Retrospective review of extended semen samples submitted from North American boar studs for microbiological screening at the University of Pennsylvania Reference Andrology Laboratory in 2005 and 2006 yielded bacteriospermia prevalence rates of 17% (144/832) and 26% (256/984), respectively. In a prospective study of regional boar studs, of 91 extended semen samples tested over 1-y, 29% were positive for bacteriospermia. Retrospective and prospective studies both showed that the preponderance of contaminant positive samples occurred during the fall months (P<0.05). To better understand behavior of select contaminant bacteria, generation intervals were determined for Serratia marcescens (SM) and Achromobacter xylosoxidans (AX) at 16, 22 and 37 degrees C. Generation times were temperature-dependent, with intervals decreasing two- to four-fold as incubation temperature increased. Growth patterns for SM, AX and Burkholderia cepacia were evaluated in various semen diluents. The different diluents exhibited constant or episodic patterns of growth within and among bacteria throughout the 5-d test period. Kill-time kinetics at 37 degrees C of several genera of bacteria in four semen diluents containing amoxicillin, gentamicin, tylosin, and lincomycin/spectinomycin (single drug or combination) ranged from 75 to over 360min, and was highly dependent (P<0.05) upon both type of bacteria and semen diluent.

On the construction, comparison, and variability of airsheds for interpreting semivolatile organic compounds in passively sampled air.

PubMed

Westgate, John N; Wania, Frank

2011-10-15

Air mass origin as determined by back trajectories often aids in explaining some of the short-term variability in the atmospheric concentrations of semivolatile organic contaminants. Airsheds, constructed by amalgamating large numbers of back trajectories, capture average air mass origins over longer time periods and thus have found use in interpreting air concentrations obtained by passive air samplers. To explore some of their key characteristics, airsheds for 54 locations on Earth were constructed and compared for roundness, seasonality, and interannual variability. To avoid the so-called "pole problem" and to simplify the calculation of roundness, a "geodesic grid" was used to bin the back-trajectory end points. Departures from roundness were seen to occur at all latitudes and to correlate significantly with local slope but no strong relationship between latitude and roundness was revealed. Seasonality and interannual variability vary widely enough to imply that static models of transport are not sufficient to describe the proximity of an area to potential sources of contaminants. For interpreting an air measurement an airshed should be generated specifically for the deployment time of the sampler, especially when investigating long-term trends. Samples taken in a single season may not represent the average annual atmosphere, and samples taken in linear, as opposed to round, airsheds may not represent the average atmosphere in the area. Simple methods are proposed to ascertain the significance of an airshed or individual cell. It is recommended that when establishing potential contaminant source regions only end points with departure heights of less than ∼700 m be considered.

Hydrology and human behavior: two key factors of diarrhea incidence in montane tropical humid areas

NASA Astrophysics Data System (ADS)

Boithias, Laurie; Choisy, Marc; Souliyaseng, Noy; Jourdren, Marine; Quet, Fabrice; Buisson, Yves; Thammahacksa, Chanthamousone; Silvera, Norbert; Latsachack, Keooudone; Sengtaheuanghoung, Oloth; Pierret, Alain; Rochelle-Newall, Emma; Becerra, Sylvia; Ribolzi, Olivier

2017-04-01

The global burden of diarrhea is a leading cause of morbidity and mortality worldwide. In montane areas of South-East Asia such as northern Laos, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads, and potential pathogen dissemination. In this study we hypothesized that climate factors combined with human behavior control diarrhea incidence, either because higher rainfall, leading to higher stream discharges, suspended sediment loads and Fecal Indicator Bacteria (FIB) counts, are associated with higher numbers of reported diarrhea cases during the rainy season, or because water shortage leads to the use of less safe water sources during the dry season. For this mixed methods approach, we conducted a retrospective time series analysis of meteorological variables (rainfall, air temperature), hydrological variables (discharge, suspended sediments, FIB counts, water temperature) at the outlet of 2 catchments in Northern Lao PDR, and the number of diarrheal disease cases reported in 6 health centers located in the Luang Prabang Province. We also examined the socio-behavioral factors potentially affecting vulnerability to the effect of the climate factors, such as drinking water sources and hygiene habits. We found the FIB Escherichia coli to be present all year long (100-1,000 MPN 100 mL-1) indicating that fecal contamination is ubiquitous and constant. We found that populations switch their water supply from wells to surface water during drought periods, the latter of which appear to be at higher risk of bacterial contamination than municipal water fountains. We thus found that water shortage in the Luang Prabang area triggers diarrhea peaks during the dry and hot season and that rainfall and aquifer refill ends the epidemic during the wet season. We thus found that anthropogenic drivers, such as hygiene practices, were at least as important as environmental drivers in determining the seasonal pattern of a diarrhea epidemic. For diarrheal disease risk monitoring, discharge or groundwater level can be considered as relevant proxies.

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Meta-analysis of radiocesium contamination data in Japanese forest trees over the period 2011-2013.

PubMed

Gonze, M-A; Calmon, P

2017-12-01

The fate and dispersion of radiocesium in forests affected by the Fukushima atmospheric fallouts have been efficiently characterized by Japanese scientists thanks to monitoring surveys of radioactive contents in contaminated soil, water, and vegetation samples at numerous sites. In this paper, we carry out a meta-analysis of the field surveys conducted over the period 2011-2013 in evergreen coniferous and deciduous broadleaf forests of Fukushima or neighboring prefectures. The review focuses on contamination data acquired in tree vegetation - about 1500 spatio-temporal measurements of concentrations, inventories and depuration fluxes - with a particular interest for organs that were directly exposed to the atmospheric fallouts and subjected to depuration mechanisms (foliage, branches and outer bark). To reduce the spatial variability between the sites, radioactive data were normalized by the total deposit estimated at each site. Our analysis highlights the overall consistency of field observations despite the variety of experimental protocols, disparate sampling periods, differences in the forest stand characteristics and variability of the atmospheric deposition conditions. Assuming that the sites conformed to the same dynamics (within the range of residual variability), we then derive, discuss, and compare the mean representative evolutions of radiocesium contamination in the two categories of forest. Thanks to a simple mass balance approach, we finally demonstrate that: (i) about 90% of the radiocesium deposit was intercepted by evergreen coniferous vegetation, (ii) 80% of the deposit was gradually transferred to the forest floor in 3years, according to a well characterized depuration kinetics, and (iii) about 4% was readily absorbed by the foliage and translocated to internal organs (inner bark, stem wood and roots) at a rate of about 10 -4 d -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Aflatoxin regulations and global pistachio trade: insights from social network analysis.

PubMed

Bui-Klimke, Travis R; Guclu, Hasan; Kensler, Thomas W; Yuan, Jian-Min; Wu, Felicia

2014-01-01

Aflatoxins, carcinogenic toxins produced by Aspergillus fungi, contaminate maize, peanuts, and tree nuts in many regions of the world. Pistachios are the main source of human dietary aflatoxins from tree nuts worldwide. Over 120 countries have regulations for maximum allowable aflatoxin levels in food commodities. We developed social network models to analyze the association between nations' aflatoxin regulations and global trade patterns of pistachios from 1996-2010. The main pistachio producing countries are Iran and the United States (US), which together contribute to nearly 75% of the total global pistachio market. Over this time period, during which many nations developed or changed their aflatoxin regulations in pistachios, global pistachio trade patterns changed; with the US increasingly exporting to countries with stricter aflatoxin standards. The US pistachio crop has had consistently lower levels of aflatoxin than the Iranian crop over this same time period. As similar trading patterns have also been documented in maize, public health may be affected if countries without aflatoxin regulations, or with more relaxed regulations, continually import crops with higher aflatoxin contamination. Unlike the previous studies on maize, this analysis includes a dynamic element, examining how trade patterns change over time with introduction or adjustment of aflatoxin regulations.