Aquatic Plant Control Research Program: Effects of Submersed Aquatic Macrophytes on Physical and Chemical Properties of Surrounding Water

DTIC Science & Technology

1988-12-01

synthetic activity of populations of epiphytes. Photosynthesis in these algae was potentially stimulated by nutrients lost from senescing portions of... photosynthesis in both studied systems were evidenced not only by daytime accumulation of DO but also by concomitant increases in pH. The same has been...declining rates of net photosynthesis during late morning and early afternoon. 43. Decreases in both conductivity and calcium concentration noted in Eau

Effects of seawater acidification on the early development of sea urchin Glyptocidaris crenularis

NASA Astrophysics Data System (ADS)

Zhan, Yaoyao; Hu, Wanbin; Duan, Lizhu; Liu, Minbo; Zhang, Weijie; Chang, Yaqing; Li, Cong

2017-10-01

In this study, we evaluated the effects of CO2-induced seawater acidification on fertilization, embryogenesis and early larval development in the sea urchin Glyptocidaris crenularis, that inhabits subtidal coastal areas in northern China. The range in seawater pH used in experiments was based on the projections of the Intergovernmental Panel on Climate Change (IPCC), to the year 2100. A natural seawater treatment (pHnbs=7.98±0.03) and three laboratory-controlled acidified treatments (OA1, ΔpHnbs=-0.3 units; OA2, ΔpHnbs=-0.4 units; OA3, ΔpHnbs=-0.5 units) were used in experiments. Results show that: (1) there was a negative effect of seawater acidification on fertilization and on the percentage of abnormal fertilized eggs; (2) the size of early cleavage stage embryos decreased in a dose-dependent manner with decreasing pH; (3) both the hatching rate of blastulae and the survival rate of four-armed pluteus larvae decreased as pH declined; (4) larval abnormalities including asymmetrical development, changes in the length of skeletal elements, and corroded spicules were observed in all seawater acidified-treatments compared with the control. These data indicate that seawater acidification has a negative impact on the early development of G. crenularis, and supports the hypothesis that the response of echinoderms to ocean acidification (OA) varies among species. Further research is required to clarify the specific cellular mechanisms involved.

Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model

PubMed Central

Krissansen-Totton, Joshua; Arney, Giada N.

2018-01-01

The early Earth’s environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0–50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from 6.6−0.4+0.6 (2σ) at 4.0 Ga to 7.0−0.5+0.7 (2σ) at the Archean–Proterozoic boundary, and to 7.9−0.2+0.1 (2σ) at the Proterozoic–Phanerozoic boundary. This evolution is driven by the secular decline of pCO2, which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering. PMID:29610313

Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model

NASA Astrophysics Data System (ADS)

Krissansen-Totton, Joshua; Arney, Giada N.; Catling, David C.

2018-04-01

The early Earth’s environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0–50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from 6.6‑0.4+0.6 (2σ) at 4.0 Ga to 7.0‑0.5+0.7 (2σ) at the Archean–Proterozoic boundary, and to 7.9‑0.2+0.1 (2σ) at the Proterozoic–Phanerozoic boundary. This evolution is driven by the secular decline of pCO2, which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering.

Rapid regional recovery from sulfate and nitrate pollution in streams of the western Czech Republic - Comparison to other recovering areas

USGS Publications Warehouse

Majer, V.; Kram, P.; Shanley, J.B.

2005-01-01

Hydrochemical changes between 1991 and 2001 were assessed based on two synoptic stream surveys from the 820-km2 region of the Slavkov Forest and surrounding area, western Czech Republic. Marked declines of sulfate, nitrate, chloride, calcium and magnesium in surface waters were compared with other areas of Europe and North America recovering from acidification. Declines of sulfate concentration in the Slavkov Forest (-30 ??eq L-1 yr-1) were more dramatic than declines reported from other sites. However, these dramatic declines of strong acid anions did not generate a widespread increase of stream water pH in the Slavkov Forest. Only the most acidic streams experienced a slight increase of pH by 0.5 unit. An unexpected decline of stream water pH occurred in slightly alkaline streams. ?? 2004 Elsevier Ltd. All rights reserved.

Early fundoplication is associated with slower decline in lung function after lung transplantation in patients with gastroesophageal reflux disease.

PubMed

Biswas Roy, Sreeja; Elnahas, Shaimaa; Serrone, Rosemarie; Haworth, Cassandra; Olson, Michael T; Kang, Paul; Smith, Michael A; Bremner, Ross M; Huang, Jasmine L

2018-06-01

Gastroesophageal reflux disease (GERD) is prevalent after lung transplantation. Fundoplication slows lung function decline in patients with GERD, but the optimal timing of fundoplication is unknown. We retrospectively reviewed patients who underwent fundoplication after lung transplantion at our center from April 2007 to July 2014. Patients were divided into 2 groups: early fundoplication (<6 months after lung transplantation) and late fundoplication (≥6 months after lung transplantation). Annual decline in percent predicted forced expiratory volume in 1 second (FEV 1 ) was analyzed. Of the 251 patients who underwent lung transplantation during the study period with available pH data, 86 (34.3%) underwent post-transplantation fundoplication for GERD. Thirty of 86 (34.9%) had early fundoplication and 56 of 86 (65.1%) had late fundoplication. Median time from lung transplantation to fundoplication was 4.6 months (interquartile range, 2.0-5.2) and 13.8 months (interquartile range, 9.0-16.1) for the early and late groups, respectively. The median DeMeester score was comparable between groups. One-, 3-, and 5-year actuarial survival rates in the early group were 90%, 70%, and 70%, respectively; in the late group, these rates were 91%, 66%, and 66% (log rank P = .60). Three- and 5-year percent predicted FEV 1 was lower in the late group by 8.9% (95% confidence interval, -30.2 to 12.38; P = .46) and 40.7% (95% confidence interval, -73.66 to -7.69; P = .019). A linear mixed model showed a 5.7% lower percent predicted FEV 1 over time in the late fundoplication group (P < .001). In this study, patients with early fundoplication had a higher FEV 1 5 years after lung transplantation. Early fundoplication might protect against GERD-induced lung damage in lung transplant recipients with GERD. Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Water Quality Conditions in Upper Klamath and Agency Lakes, Oregon, 2006

USGS Publications Warehouse

Lindenberg, Mary K.; Hoilman, Gene; Wood, Tamara M.

2008-01-01

The U.S. Geological Survey Upper Klamath Lake water quality monitoring program gathered information from multiparameter continuous water quality monitors, physical water samples, dissolved oxygen production and consumption experiments, and meteorological stations during the June-October 2006 field season. The 2006 study area included Agency Lake and all of Upper Klamath Lake. Seasonal patterns in water quality were similar to those observed in 2005, the first year of the monitoring program, and were closely related to bloom dynamics of the cyanobacterium (blue-green alga) Aphanizomenon flos-aquae (AFA) in the two lakes. High dissolved oxygen and pH conditions in both lakes before the bloom declined in July, which coincided with seasonal high temperatures and resulted in seasonal lows in dissolved oxygen and decreased pH. Dissolved oxygen and pH in Upper Klamath and Agency Lakes increased again after the bloom recovered. Seasonal low dissolved oxygen and decreased pH coincided with seasonal highs in ammonia and orthophosphate concentrations. Seasonal maximum daily average temperatures were higher and minimum dissolved oxygen concentrations were lower in 2006 than in 2005. Conditions potentially harmful to fish were influenced by seasonal patterns in bloom dynamics and bathymetry. Potentially harmful low dissolved oxygen and high un-ionized ammonia concentrations occurred mostly at the deepest sites in the Upper Klamath Lake during late July, coincident with a bloom decline. Potentially harmful pH conditions occurred mostly at sites outside the deepest parts of the lake in July and September, coincident with a heavy bloom. Instances of possible gas bubble formation, inferred from dissolved oxygen data, were estimated to occur frequently in shallow areas of Upper Klamath and Agency Lakes simultaneously with potentially harmful pH conditions. Comparison of the data from monitors in nearshore areas and monitors near the surface of the water column in the open waters of Upper Klamath Lake revealed few differences in water quality dynamics. Median daily temperatures were higher in nearshore areas, and dissolved oxygen concentrations were periodically higher as well during periods of high AFA bloom. Differences between the two areas in water quality conditions potentially harmful to fish were not statistically significant (p < 0.05). Chlorophyll a concentrations varied temporally and spatially throughout Upper Klamath Lake. Chlorophyll a concentrations indicated an algal bloom in late June and early July that was followed by an algae bloom decline in late July and early August and a subsequent recovery in mid-August. Sites in the deepest part of the lake, where some of the highest chlorophyll a concentrations were observed, were the same sites where the lowest dissolved oxygen concentrations and the highest un-ionized ammonia concentrations were recorded during the bloom decline, indicating cell senescence. Total phosphorus concentrations limited the initial algal bloom in late June and early July. The rate of net dissolved oxygen production (that is, production in excess of community respiration) and consumption (due to community respiration) in the lake water column as measured in light and dark bottles, respectively, ranged from 2.79 to -2.14 milligrams of oxygen per liter per hour. Net production rate generally correlated positively with chlorophyll a concentration, except episodically at a few sites where high chlorophyll a concentrations resulted in self-shading that inhibited photosynthesis. The depth of photic zone was inversely correlated with chlorophyll a concentration. Calculations of a 24-hour change in dissolved oxygen concentration indicated that oxygen-consuming processes predominated at the deep trench sites and oxygen-producing processes predominated at the shallow sites. In addition, calculations of the 24-hour change in dissolved oxygen indicate that oxygen-consuming processes in the water column di

Influence of early diagenesis on the vertical distribution of metal forms in sediments of Bohai Bay, China.

PubMed

Lu, Xueqiang; Zhang, Yan; Liu, Honglei; Xing, Meinan; Shao, Xiaolong; Zhao, Feng; Li, Xiaojuan; Liu, Qiongqiong; Yu, Dan; Yuan, Xuezhu; Yuan, Min

2014-11-15

The influence of early diagenesis on the vertical distribution of metal forms in the sediments of Bohai Bay was discussed in this paper. The results showed that the concentrations were: Al > Fe ≈ Ca > Mn > Cr > Zn > Cu > Pb > Cd. In vertical distribution, the forms of Cr and Pb were stable from the top to the bottom. However, the exchangeable forms and acid-extracted forms of Cd, Cu and Zn presented an obvious declining trend. The metals would be transformed to more stable forms during the early-diagenesis process. Further analysis found that early diagenesis can change the sedimentary environment, affecting pH, oxidation-reduction potential (ORP), total dissolved solid (TDS) and the structure of organic matter (OM), all main factors influencing metal forms in the sediments of Bohai Bay. Copyright © 2014 Elsevier Ltd. All rights reserved.

A method for early determination of meat ultimate pH.

PubMed

Young, O A; West, J; Hart, A L; van Otterdijk, F F H

2004-02-01

A patented method of rapidly determining the ultimate pH from approximate glycolytic potential of muscles of slaughtered animals has been devised. The method is based on the rapid hydrolysis of muscle glycogen to glucose by the enzyme amyloglucosidase and subsequent measurement of the liberated glucose. In acetate buffer at pH 4.5, glucose concentration can be determined in 30 s with domestic meters for diabetes control. The meter response differed from that of glucose in blood, but was linear with concentration. In slurries comprising homogenised meat in acetate buffer and added glucose, a similar linear response was obtained. Amyloglucosidase was capable of rapidly hydrolysing glycogen to glucose in such slurries. In the 24 h following slaughter, a decrease in glycogen, as determined by glucose, occurred in parallel with the decline in pH. At the same time, lactate progressively accumulated as expected. Values for the approximate glycolytic potential and (by calibration) ultimate pH, were obtained on prerigor muscle within 7 min of muscle sampling in an industrial environment. The method is suitable for on-line application in beef abattoirs particularly those employing hot boning where ultimate must be known at the grading point.

Decoupling between the response of coral calcifying fluid pH and calcification to ocean acidification.

PubMed

Comeau, S; Cornwall, C E; McCulloch, M T

2017-08-08

Evaluating the factors responsible for differing species-specific sensitivities to declining seawater pH is central to understanding the mechanisms via which ocean acidification (OA) affects coral calcification. We report here the results of an experiment comparing the responses of the coral Acropora yongei and Pocillopora damicornis to differing pH levels (8.09, 7.81, and 7.63) over an 8-week period. Calcification of A. youngei was reduced by 35% at pH 7.63, while calcification of P. damicornis was unaffected. The pH in the calcifying fluid (pH cf ) was determined using δ 11 B systematics, and for both species pH cf declined slightly with seawater pH, with the decrease being more pronounced in P. damicornis. The dissolved inorganic carbon concentration at the site of calcification (DIC cf ) was estimated using geochemical proxies (B/Ca and δ 11 B) and found to be double that of seawater DIC, and increased in both species as seawater pH decreased. As a consequence, the decline of the saturation state at the site of calcification (Ω cf ) with OA was partially moderated by the DIC cf increase. These results highlight that while pH cf , DIC cf and Ω cf are important in the mineralization process, some corals are able to maintain their calcification rates despite shifts in their calcifying fluid carbonate chemistry.

Trends in Seawater Boron-based Proxies during the Late Paleocene and Early Eocene Associated with Long-term Warming

NASA Astrophysics Data System (ADS)

Harper, D. T.; Penman, D. E.; Hoenisch, B.; Zachos, J. C.

2014-12-01

Boron isotopes (δ11B) and boron/calcium ratios (B/Ca) in tests of planktic foraminifera are controlled by equilibrium reactions between boron and carbon species in seawater, and thus represent important proxies of past marine carbonate chemistry. Indeed, the recent application of these boron-based proxies to fossil shells of planktic foraminifera from cores spanning the Paleocene-Eocene Thermal Maximum (PETM; 56Ma, an abrupt global warming and ocean acidification event) reveal a decline of ~0.3 in the pH of the mixed-layer [1], an anomaly that is well within the range of estimates based on the observed shoaling of the carbonate compensation depth (CCD) [2, and references therein]. The PETM occurred superimposed on a long-term warming trend that initiated in the Late Paleocene and continued into the Early Eocene (LPEE; 53-59Ma). The magnitude of warming [3] and deepening of the CCD [4] indicate that the LPEE was driven by a rise in pCO2 nearly equivalent to that of the PETM [5]. Here we extend the PETM record of boron-based proxies at IODP Site 1209 across the LPEE, in conjunction with stable carbon and oxygen isotopes in planktic foraminifera, in order to better constrain the long-term changes in pH and carbonate chemistry that accompanied the suggested rise in atmospheric CO2. The 20kyr resolution B/Ca record shows a long-term decline of ~25% during the LPEE, as well as subtle 400kyr cycles associated with eccentricity that mirror those observed in δ13C, and thus might reflect on changes in pH. The lower resolution δ11B record exhibits little change during the Late Paleocene before decreasing step-wise to lower values following the PETM, indicating that either pH in the upper ocean did not change significantly prior to the PETM, despite warming and inferred pCO2 increase, or changes in δ11Bseawater compensated for pH driven changes. As verification of these observations at Site 1209, complementary B/Ca and δ11B records are being generated for Atlantic IODP Sites 1262 and 1263. [1] Penman et al. 2014. Paleoceanography. [2] Palike et al. 2012. Nature. [3] Zachos et al. 2001. Science. [4] Leon-Rodriguez and Dickens 2010. Palaeogeogrphy, Palaeoclimatology, and Palaeoecology. [5] Komar, Zeebe and Dickens 2013. Paleoceanography.

Interactive effects of ocean acidification, elevated temperature, and reduced salinity on early-life stages of the pacific oyster.

PubMed

Ko, Ginger W K; Dineshram, R; Campanati, Camilla; Chan, Vera B S; Havenhand, Jon; Thiyagarajan, Vengatesen

2014-09-02

Ocean acidification (OA) effects on larvae are partially attributed for the rapidly declining oyster production in the Pacific Northwest region of the United States. This OA effect is a serious concern in SE Asia, which produces >80% of the world's oysters. Because climate-related stressors rarely act alone, we need to consider OA effects on oysters in combination with warming and reduced salinity. Here, the interactive effects of these three climate-related stressors on the larval growth of the Pacific oyster, Crassostrea gigas, were examined. Larvae were cultured in combinations of temperature (24 and 30 °C), pH (8.1 and 7.4), and salinity (15 psu and 25 psu) for 58 days to the early juvenile stage. Decreased pH (pH 7.4), elevated temperature (30 °C), and reduced salinity (15 psu) significantly delayed pre- and post-settlement growth. Elevated temperature lowered the larval lipid index, a proxy for physiological quality, and negated the negative effects of decreased pH on attachment and metamorphosis only in a salinity of 25 psu. The negative effects of multiple stressors on larval metamorphosis were not due to reduced size or depleted lipid reserves at the time of metamorphosis. Our results supported the hypothesis that the C. gigas larvae are vulnerable to the interactions of OA with reduced salinity and warming in Yellow Sea coastal waters now and in the future.

Impact of seawater carbonate chemistry on the calcification of marine bivalves

NASA Astrophysics Data System (ADS)

Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

2015-01-01

Bivalve calcification, particular of the early larval stages is highly sensitive to the change of ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no and [HCO3-] and pH only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. Therefore, the availability of [HCO3-] combined with favorable environmental pH determines calcification rate and an equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better understand the physiological processes and their underlying genetics that govern inorganic carbon assimilation for calcification.

Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

NASA Technical Reports Server (NTRS)

DesMarais, David J.; Chang, Sherwood (Technical Monitor)

1997-01-01

Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

NASA Technical Reports Server (NTRS)

Vessey, J. K.; Henry, L. T.; Chaillou, S.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1990-01-01

Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.

Larvae of the coral eating crown-of-thorns starfish, Acanthaster planci in a warmer-high CO2 ocean.

PubMed

Kamya, Pamela Z; Dworjanyn, Symon A; Hardy, Natasha; Mos, Benjamin; Uthicke, Sven; Byrne, Maria

2014-11-01

Outbreaks of crown-of-thorns starfish (COTS), Acanthaster planci, contribute to major declines of coral reef ecosystems throughout the Indo-Pacific. As the oceans warm and decrease in pH due to increased anthropogenic CO2 production, coral reefs are also susceptible to bleaching, disease and reduced calcification. The impacts of ocean acidification and warming may be exacerbated by COTS predation, but it is not known how this major predator will fare in a changing ocean. Because larval success is a key driver of population outbreaks, we investigated the sensitivities of larval A. planci to increased temperature (2-4 °C above ambient) and acidification (0.3-0.5 pH units below ambient) in flow-through cross-factorial experiments (3 temperature × 3 pH/pCO2 levels). There was no effect of increased temperature or acidification on fertilization or very early development. Larvae reared in the optimal temperature (28 °C) were the largest across all pH treatments. Development to advanced larva was negatively affected by the high temperature treatment (30 °C) and by both experimental pH levels (pH 7.6, 7.8). Thus, planktonic life stages of A. planci may be negatively impacted by near-future global change. Increased temperature and reduced pH had an additive negative effect on reducing larval size. The 30 °C treatment exceeded larval tolerance regardless of pH. As 30 °C sea surface temperatures may become the norm in low latitude tropical regions, poleward migration of A. planci may be expected as they follow optimal isotherms. In the absence of acclimation or adaptation, declines in low latitude populations may occur. Poleward migration will be facilitated by strong western boundary currents, with possible negative flow-on effects on high latitude coral reefs. The contrasting responses of the larvae of A. planci and those of its coral prey to ocean acidification and warming are considered in context with potential future change in tropical reef ecosystems. © 2014 John Wiley & Sons Ltd.

Long-Term Trends in Calcifying Plankton and pH in the North Sea

PubMed Central

Beare, Doug; McQuatters-Gollop, Abigail; van der Hammen, Tessa; Machiels, Marcel; Teoh, Shwu Jiau; Hall-Spencer, Jason M.

2013-01-01

Relationships between six calcifying plankton groups and pH are explored in a highly biologically productive and data-rich area of the central North Sea using time-series datasets. The long-term trends show that abundances of foraminiferans, coccolithophores, and echinoderm larvae have risen over the last few decades while the abundances of bivalves and pteropods have declined. Despite good coverage of pH data for the study area there is uncertainty over the quality of this historical dataset; pH appears to have been declining since the mid 1990s but there was no statistical connection between the abundance of the calcifying plankton and the pH trends. If there are any effects of pH on calcifying plankton in the North Sea they appear to be masked by the combined effects of other climatic (e.g. temperature), chemical (nutrient concentrations) and biotic (predation) drivers. Certain calcified plankton have proliferated in the central North Sea, and are tolerant of changes in pH that have occurred since the 1950s but bivalve larvae and pteropods have declined. An improved monitoring programme is required as ocean acidification may be occurring at a rate that will exceed the environmental niches of numerous planktonic taxa, testing their capacities for acclimation and genetic adaptation. PMID:23658686

Comparison of arterial and venous blood gases and the effects of analysis delay and air contamination on arterial samples in patients with chronic obstructive pulmonary disease and healthy controls.

PubMed

O'Connor, T M; Barry, P J; Jahangir, A; Finn, C; Buckley, B M; El-Gammal, A

2011-01-01

Arterial blood gases (ABGs) are often sampled incorrectly, leading to a 'mixed' or venous sample. Delays in analysis and air contamination are common. We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO₂ associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO₂ in all samples, including those that were immediately analyzed. Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO₂, indicating that air-contaminated ABGs should be discarded. Copyright © 2010 S. Karger AG, Basel.

Microbial inoculation of alfalfa haylage: ensiling characteristics and milk production response when fed to early lactation dairy cows.

PubMed

Kent, B A; Arambel, M J; Winsryg, M D; Walters, J L

1989-09-01

Third-cutting alfalfa hay harvested at bud stage and wilted to approximately 65% moisture was treated with a live bacterial inoculant at the rate of 300,000 cfu/g fresh alfalfa. Treated alfalfa was packed in polyethylene bags. Samples were taken at time of ensiling and d 1, 2, 3, 4, 7, and 28 postensiling. Mean pH was lower in the treated haylage (5.09 and 5.71 for treatment and control, respectively). Mean temperatures were higher in the treated haylage (30.0 and 28.0 degrees C for treatment and control, respectively). Mold count, water-soluble carbohydrate, alpha amino nitrogen, CP, and ADF were not affected by treatment. Regardless of treatment, pH, mold counts, and water-soluble carbohydrates declined with time. There was no significant difference between treatments for DM intake, milk production, and milk composition.

The declining interest in an academic career

PubMed Central

Sauermann, Henry

2017-01-01

There is increasing evidence that science & engineering PhD students lose interest in an academic career over the course of graduate training. It is not clear, however, whether this decline reflects students being discouraged from pursuing an academic career by the challenges of obtaining a faculty job or whether it reflects more fundamental changes in students’ career goals for reasons other than the academic labor market. We examine this question using a longitudinal survey that follows a cohort of PhD students from 39 U.S. research universities over the course of graduate training to document changes in career preferences and to explore potential drivers of such changes. We report two main results. First, although the vast majority of students start the PhD interested in an academic research career, over time 55% of all students remain interested while 25% lose interest entirely. In addition, 15% of all students were never interested in an academic career during their PhD program, while 5% become more interested. Thus, the declining interest in an academic career is not a general phenomenon across all PhD students, but rather reflects a divergence between those students who remain highly interested in an academic career and other students who are no longer interested in one. Second, we show that the decline we observe is not driven by expectations of academic job availability, nor by related factors such as postdoctoral requirements or the availability of research funding. Instead, the decline appears partly due to the misalignment between students’ changing preferences for specific job attributes on the one hand, and the nature of the academic research career itself on the other. Changes in students’ perceptions of their own research ability also play a role, while publications do not. We discuss implications for scientific labor markets, PhD career development programs, and science policy. PMID:28922403

The declining interest in an academic career.

PubMed

Roach, Michael; Sauermann, Henry

2017-01-01

There is increasing evidence that science & engineering PhD students lose interest in an academic career over the course of graduate training. It is not clear, however, whether this decline reflects students being discouraged from pursuing an academic career by the challenges of obtaining a faculty job or whether it reflects more fundamental changes in students' career goals for reasons other than the academic labor market. We examine this question using a longitudinal survey that follows a cohort of PhD students from 39 U.S. research universities over the course of graduate training to document changes in career preferences and to explore potential drivers of such changes. We report two main results. First, although the vast majority of students start the PhD interested in an academic research career, over time 55% of all students remain interested while 25% lose interest entirely. In addition, 15% of all students were never interested in an academic career during their PhD program, while 5% become more interested. Thus, the declining interest in an academic career is not a general phenomenon across all PhD students, but rather reflects a divergence between those students who remain highly interested in an academic career and other students who are no longer interested in one. Second, we show that the decline we observe is not driven by expectations of academic job availability, nor by related factors such as postdoctoral requirements or the availability of research funding. Instead, the decline appears partly due to the misalignment between students' changing preferences for specific job attributes on the one hand, and the nature of the academic research career itself on the other. Changes in students' perceptions of their own research ability also play a role, while publications do not. We discuss implications for scientific labor markets, PhD career development programs, and science policy.

Status of soil acidification in North America

USGS Publications Warehouse

Fenn, M.E.; Huntington, T.G.; Mclaughlin, S.B.; Eagar, C.; Gomez, A.; Cook, R.B.

2006-01-01

Forest soil acidification and depletion of nutrient cations have been reported for several forested regions in North America, predominantly in the eastern United States, including the northeast and in the central Appalachians, but also in parts of southeastern Canada and the southern U.S. Continuing regional inputs of nitrogen and sulfur are of concern because of leaching of base cations, increased availability of soil Al, and the accumulation and ultimate transmission of acidity from forest soils to streams. Losses of calcium from forest soils and forested watersheds have now been documented as a sensitive early indicator and a functionally significant response to acid deposition for a wide range of forest soils in North America. For red spruce, a clear link has been established between acidic deposition, alterations in calcium and aluminum supplies and increased sensitivity to winter injury. Cation depletion appears to contribute to sugar maple decline on some soils, specifically the high mortality rates observed in northern Pennsylvania over the last decade. While responses to liming have not been systematically examined in North America, in a study in Pennsylvania, restoring basic cations through liming increased basal area growth of sugar maple and levels of calcium and magnesium in soil and foliage. In the San Bernardino Mountains in southern California near the west coast, the pH of the A horizon has declined by at least 2 pH units (to pH 4.0-4.3) over the past 30 years, with no detrimental effects on bole growth; presumably, because of the Mediterranean climate, base cation pools are still high and not limiting for plant growth.

Manipulating the dietary cation-anion difference via drenching to early-lactation dairy cows grazing pasture.

PubMed

Roche, J R; Petch, S; Kay, J K

2005-01-01

Diets offered to grazing dairy cows can vary considerably in their dietary cation-anion difference (DCAD) and are often well in excess of what has been considered optimal. The effects of a range of DCAD on the health and production of pasture-based dairy cows in early lactation was examined in a randomized block design. Four groups of 8 cows were offered a generous allowance of pasture (45 +/- 6 kg/d of dry matter (DM) per cow) for 35 d and achieved mean pasture intakes of approximately 17 kg/d of DM per cow. Cows were drenched twice daily with varying combinations of mineral compounds to alter the DCAD. Dietary cation-anion difference ranged from +23 to +88 mEq/100 g of DM. A linear increase in blood pH and HCO(3)(-) concentration and blood base excess, and a curvilinear increase in the pH of urine with increasing DCAD indicated a nonrespiratory effect of DCAD on metabolic acid-base balance. Plasma concentrations of Mg, K, and Cl declined as DCAD increased, whereas Na concentration increased. Urinary excretion of Ca decreased linearly as DCAD increased, although the data suggest that the decline may be curvilinear. These results in conjunction with the increased concentrations of ionized Ca suggest that intestinal absorption of Ca or bone resorption, or both, increased as DCAD declined. Dry matter intake, as measured using indigestible markers, was not significantly affected by DCAD. However, the linear increase in the yield of linolenic acid, vaccenic acid, and cis-9, trans-11 conjugated linoleic acid in milk, as DCAD increased is consistent with a positive effect of DCAD on DM intake. Increasing DCAD did not significantly affect milk yield or milk protein, but the concentration and yield of milk fat linearly increased with increasing DCAD. The increased milk fat yield was predominantly a result of increased de novo synthesis in the mammary epithelial cells, although an increase in the yield of preformed fatty acids also occurred. Milk production results suggest that DCAD for optimal production on pasture diets may be higher than the +20 mEq/100 g of DM previously identified for total mixed rations.

Effects of increased pCO2 and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, Sepia officinalis

NASA Astrophysics Data System (ADS)

Lacoue-Labarthe, T.; Martin, S.; Oberhänsli, F.; Teyssié, J.-L.; Markich, S.; Jeffree, R.; Bustamante, P.

2009-05-01

Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we are testing the effects of pH and temperature through a crossed (3×2) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the hatchlings weight at the end of development implying egg swelling process and embryo growth disturbances. The lower pH of incubation seawater of eggs, the more the hatchlings accumulated 110m Ag in their tissues. The 109Cd CF decreased with increasing pH and 65Zn CF reached the maximal values pH 7.85, independent of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and the embryo metabolism. To the best of our knowledge, this is one of the first studies on the ocean acidification and ocean warming consequences on the metal uptake in marine organisms, stimulating further interest to evaluate the likely ecotoxicological impact of the global change on the early-life stage of the cuttlefish.

Effects of Multiple Stressors on Red Abalone (Haliotis rufescens) Fertilization Success

NASA Astrophysics Data System (ADS)

Boch, C. A.; Aalto, E.; De Leo, G.; Litvin, S.; Lovera, C.; Micheli, F.; Woodson, C. B.; Monismith, S. G.; Barry, J. P.

2016-02-01

Acidification, hypoxia, and ocean warming are escalating threats in the world's coastal waters, with potentially severe consequences for marine life and ocean-based economies. In particular, eastern boundary current ecosystems, including the California Current Large Marine Ecosystem (CCLME), are experiencing large-scale declines in pH and dissolved oxygen (DO)—with the latter linked to changes in thermal stratification and shoaling of the oxygen minimum zone. To examine the consequences of ocean acidification and other climate-related changes in oceanographic conditions on nearshore marine populations within the CCLME, we are assessing the potential effects of current and future upwelling-type conditions on the population dynamics of the red abalone (Haliotis rufescens), with a focus on sensitive early life history phases (e.g., fertilization, larval development, and juvenile growth and survival) expected to be important determinants of population dynamics. Here, we present the first experimental results on the impacts of combined exposures of low pH and low DO on abalone fertilization success. Our results show that abalone fertilization success is significantly reduced when the gametes are exposed to a decrease in seawater pH from 8.0 to 7.2. Furthermore, low pH in combination with hypoxic exposure—e.g., a decrease in dissolved oxygen from 6 mg/L DO to 1 mg/L DO—does not further decrease fertilization rates, suggesting a lack of synergistic or additive effects of these multiple stressors on the reduction of fertilization success. Although the focus of this study is to characterize the effects of multiple stressors on the early life history of abalone, the implications of these results are expected to be relevant for a variety of marine taxa with similar reproductive modes.

Using Clinical Research Networks to Assess Severity of an Emerging Influenza Pandemic.

PubMed

Simonsen, Lone; Higgs, Elizabeth; Taylor, Robert J; Wentworth, Deborah; Cozzi-Lepri, Al; Pett, Sarah; Dwyer, Dominic E; Davey, Richard; Lynfield, Ruth; Losso, Marcelo; Morales, Kathleen; Glesby, Marshall J; Weckx, Jozef; Carey, Dianne; Lane, Cliff; Lundgren, Jens

2018-05-08

Early clinical severity assessments during the 2009 influenza A H1N1 pandemic (pH1N1) overestimated clinical severity due to selection bias and other factors. We retrospectively investigated how to use data from the International Network for Strategic Initiatives in Global HIV Trials, a global clinical influenza research network, to make more accurate case fatality ratio (CFR) estimates early in a future pandemic, an essential part of pandemic response. We estimated the CFR of medically attended influenza (CFRMA) as the product of probability of hospitalization given confirmed outpatient influenza and the probability of death given hospitalization with confirmed influenza for the pandemic (2009-2011) and post-pandemic (2012-2015) periods. We used literature survey results on health-seeking behavior to convert that estimate to CFR among all infected persons (CFRAR). During the pandemic period, 5.0% (3.1%-6.9%) of 561 pH1N1-positive outpatients were hospitalized. Of 282 pH1N1-positive inpatients, 8.5% (5.7%-12.6%) died. CFRMA for pH1N1 was 0.4% (0.2%-0.6%) in the pandemic period 2009-2011 but declined 5-fold in young adults during the post-pandemic period compared to the level of seasonal influenza in the post-pandemic period 2012-2015. CFR for influenza-negative patients did not change over time. We estimated the 2009 pandemic CFRAR to be 0.025%, 16-fold lower than CFRMA. Data from a clinical research network yielded accurate pandemic severity estimates, including increased severity among younger people. Going forward, clinical research networks with a global presence and standardized protocols would substantially aid rapid assessment of clinical severity. NCT01056354 and NCT010561.

Lack of chlorpromazine effect on skeletal muscle metabolism after ischemia and a short reperfusion period.

PubMed

Piccinato, Carlos E; Salles Roselino, José E; Massuda, Carlos A; Cherri, Jesualdo

2004-01-01

The great resistance of muscle to ischemia was used to study blood flow-dependent phenomena produced by anesthetic drugs in this condition. A short reperfusion period was used in order to favor metabolic changes indicative of an effect of chlorpromazine (CPZ) on blood flow. Gracilis muscles of dogs were submitted to 5 h of ischemia and 30 min of reperfusion. CPZ-treated animals were injected I.V. (2 mg/kg) 10 min before the beginning of ischemia. Biopsies provided the material for tissue measurements. Lactate content and pH were determined in blood samples collected from a muscle efferent vein. In both the CPZ-treated and nontreated groups, ischemia induced a decline in muscle glycogen content, with a corresponding increase in muscle lactate and a decrease in mitochondrial respiratory control ratio. After 30 min of reperfusion, tissue levels of lactate did not attain preischemic values but showed a clear decline in the two experimental groups, evidencing the reversible state of the muscle. All other metabolic parameters remained unchanged. Mitochondrial respiratory control remained functional during ischemia and reperfusion. Blood pH displayed similar changes in both groups. There was no metabolic indication that the drug affected blood flow during early reperfusion and/or of a greater sensitivity of muscle endothelial cells to anesthetic drugs. Copyright 2004 Wiley-Liss, Inc.

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

Landry, L.G.; Pell, E.J.

Hybrid poplar clones exposed to ozone exhibit symptoms of accelerated senescence, including early decline in activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). The authors examined the hypothesis that ozone-induced reduction in rubisco occurred as a result of increased protease activity. To test this hypothesis, saplings of Populus maximowizii x trichocarpa were exposed to 0.08 {mu}l/l ozone, 4 h/day, from initiation of sample leaf expansion to foliar abscission. Periodically throughout the treatment the sample leaf was analyzed for chlorophyll content, total protein content, rubisco activity, and proteolytic activity at pH 4.5 and 7.8. At the time of peak rubisco activity, protein was subjectmore » to SDS-PAGE to quantify rubisco. Total protein content of sample leaves was unaffected by ozone treatment. Proteolysis measured under acidic conditions was lower in ozone-treated than control plants throughout the exposure. Proteolysis determined under alkaline conditions only revealed decreases in the second half of the experiment. Ozone induced a more rapid decline in rubisco activity than occurred in control tissue. Quantitative effects of rubisco reflected results of activity assays. It did not appear that enhanced proteolysis could explain the ozone-induced accelerated decline in rubisco.« less

34 CFR 303.405 - Parent right to decline service.

Code of Federal Regulations, 2011 CFR

2011-07-01

... members will accept or decline any early intervention service under this part in accordance with State law, and may decline such a service after first accepting it, without jeopardizing other early intervention... AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION EARLY INTERVENTION PROGRAM FOR INFANTS AND...

Cerebral Metabolic Alterations in Rats With Diabetic Ketoacidosis

PubMed Central

Glaser, Nicole; Yuen, Natalie; Anderson, Steven E.; Tancredi, Daniel J.; O'Donnell, Martha E.

2010-01-01

OBJECTIVE Cerebral edema is a life-threatening complication of diabetic ketoacidosis (DKA) in children. Recent data suggest that cerebral hypoperfusion and activation of cerebral ion transporters may be involved, but data describing cerebral metabolic alterations during DKA are lacking. RESEARCH DESIGN AND METHODS We evaluated 50 juvenile rats with DKA and 21 normal control rats using proton and phosphorus magnetic resonance spectroscopy (MRS). MRS measured cerebral intracellular pH and ratios of metabolites including ATP/inorganic phosphate (Pi), phosphocreatine (PCr)/Pi, N-acetyl aspartate (NAA)/creatine (Cr), and lactate/Cr before and during DKA treatment. We determined the effects of treatment with insulin and intravenous saline with or without bumetanide, an inhibitor of Na-K-2Cl cotransport, using ANCOVA with a 2 × 2 factorial study design. RESULTS Cerebral intracellular pH was decreased during DKA compared with control (mean ± SE difference −0.13 ± 0.03; P < 0.001), and lactate/Cr was elevated (0.09 ± 0.02; P < 0.001). DKA rats had lower ATP/Pi and NAA/Cr (−0.32 ± 0.10, P = 0.003, and −0.14 ± 0.04, P < 0.001, respectively) compared with controls, but PCr/Pi was not significantly decreased. During 2-h treatment with insulin/saline, ATP/Pi, PCr/Pi, and NAA/Cr declined significantly despite an increase in intracellular pH. Bumetanide treatment increased ATP/Pi and PCr/Pi and ameliorated the declines in these values with insulin/saline treatment. CONCLUSIONS These data demonstrate that cerebral metabolism is significantly compromised during DKA and that further deterioration occurs during early DKA treatment—consistent with possible effects of cerebral hypoperfusion and reperfusion injury. Treatment with bumetanide may help diminish the adverse effects of initial treatment with insulin/saline. PMID:20028943

A nocturnal decline of salivary pH associated with airway hyperresponsiveness in asthma.

PubMed

Watanabe, Masanari; Sano, Hiroyuki; Tomita, Katsuyuki; Yamasaki, Akira; Kurai, Jun; Hasegawa, Yasuyuki; Igishi, Tadashi; Okazaki, Ryota; Tohda, Yuji; Burioka, Naoto; Shimizu, Eiji

2010-08-01

Salivary pH is associated with esophageal acid reflux and neutralization of esophageal acid. In this study, we assessed the association between nocturnal decline of salivary pH and airway hyperresponsiveness. Salivary pH was serially assessed in 9 patients with mild asthma (7 men and 2 women; mean age 33.3 years; mean %predicted FEV(1.0) 89.4%) and 10 healthy volunteers (6 men and 4 women; mean age 31.2 years) using a pH indicator tape. The buffering capacity of saliva was defined as the median effective dose (ED(50)) for acidification of saliva with 0.01 N HCl, and airway responsiveness was defined as the dose of methacholine producing a 35% fall in Grs (PD(35)-Grs). There was a significant correlation between the values obtained from the pH indicator tape and those obtained from the electrometric pH meter. Using the indicator tape for sequential monitoring, we observed a nocturnal fall (ΔpH) in salivary pH in all subjects. A significant correlation was found between airway hyperresponsiveness (PD(35)-Grs) and either ΔpH or ED(50) in mildly asthmatic patients. Vagal reflux dysfunction might contribute to nocturnal salivary pH as well as to airway hyperresponsiveness in mild asthmatics.

Examination of the effect of ageing and temperature at rigor on colour stability of lamb meat.

PubMed

Hopkins, D L; Lamb, T A; Kerr, M J; van de Ven, R J; Ponnampalam, E N

2013-10-01

A study of factors (ageing period, rigor temperature and vitamin E level) impacting on the colour stability of lamb m. longissimus thoracis et lumborum (LL) during 3 days of simulated retail display was undertaken. The LL were taken from 84 lambs from 3 slaughters. Slices of LL were measured fresh (24h post-mortem) or after ageing for 5 days in vacuum packaging. The oxy/met ratio (630/580 nm), declined with display time, and increased with increasing temperature at pH6.0. Redness (a*) values also declined with display time and a reduction in redness values was observed as LL pH at 24h post-mortem and/or pH at 18°C increased. There was no effect of ageing period or vitamin E level on the oxy/met ratio or a* values when the vitamin E level averaged 3.76 mg/kg LL. These results suggest that maximising vitamin E levels in lambs and achieving a moderate rate of pH decline will optimise colour stability irrespective of ageing period. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Early pulmonary vascular disease in preterm infants at risk for bronchopulmonary dysplasia.

PubMed

Mourani, Peter M; Sontag, Marci K; Younoszai, Adel; Miller, Joshua I; Kinsella, John P; Baker, Christopher D; Poindexter, Brenda B; Ingram, David A; Abman, Steven H

2015-01-01

Pulmonary hypertension (PH) is associated with poor outcomes among preterm infants with bronchopulmonary dysplasia (BPD), but whether early signs of pulmonary vascular disease are associated with the subsequent development of BPD or PH at 36 weeks post-menstrual age (PMA) is unknown. To prospectively evaluate the relationship of early echocardiogram signs of pulmonary vascular disease in preterm infants to the subsequent development of BPD and late PH (at 36 wk PMA). Prospectively enrolled preterm infants with birthweights 500-1,250 g underwent echocardiogram evaluations at 7 days of age (early) and 36 weeks PMA (late). Clinical and echocardiographic data were analyzed to identify early risk factors for BPD and late PH. A total of 277 preterm infants completed echocardiogram and BPD assessments at 36 weeks PMA. The median gestational age at birth and birthweight of the infants were 27 weeks and 909 g, respectively. Early PH was identified in 42% of infants, and 14% were diagnosed with late PH. Early PH was a risk factor for increased BPD severity (relative risk, 1.12; 95% confidence interval, 1.03-1.23) and late PH (relative risk, 2.85; 95% confidence interval, 1.28-6.33). Infants with late PH had greater duration of oxygen therapy and increased mortality in the first year of life (P < 0.05). Early pulmonary vascular disease is associated with the development of BPD and with late PH in preterm infants. Echocardiograms at 7 days of age may be a useful tool to identify infants at high risk for BPD and PH.

Leaching potential of pervious concrete and immobilization of Cu, Pb and Zn using pervious concrete.

PubMed

Solpuker, U; Sheets, J; Kim, Y; Schwartz, F W

2014-06-01

This paper investigates the leaching potential of pervious concrete and its capacity for immobilizing Cu, Pb and Zn, which are common contaminants in urban runoff. Batch experiments showed that the leachability of Cu, Pb and Zn increased when pH<8. According to PHREEQC equilibrium modeling, the leaching of major ions and trace metals was mainly controlled by the dissolution/precipitation and surface complexation reactions, respectively. A 1-D reactive transport experiment was undertaken to better understand how pervious concrete might function to attenuate contaminant migration. A porous concrete block was sprayed with low pH water (pH=4.3±0.1) for 190 h. The effluent was highly alkaline (pH~10 to 12). In the first 50 h, specific conductance and trace-metal were high but declined towards steady state values. PHREEQC modeling showed that mixing of interstitial alkaline matrix waters with capillary pore water was required in order to produce the observed water chemistry. The interstitial pore solutions seem responsible for the high pH values and relatively high concentrations of trace metals and major cations in the early stages of the experiment. Finally, pervious concrete was sprayed with a synthetic contaminated urban runoff (10 ppb Cu, Pb and Zn) with a pH of 4.3±0.1 for 135 h. It was found that Pb immobilization was greater than either Cu or Zn. Zn is the most mobile among three and also has the highest variation in the observed degree of immobilization. Copyright © 2014 Elsevier B.V. All rights reserved.

Factors Influencing Trends in pH in the Wootton et al. (2008) Dataset

EPA Science Inventory

In this report, the dataset collected by Wootton at Tatoosh Island during 2000 through 2010 is analyzed to assess whether the apparent rapid decline in the pH data can be explained by other more localized processes. Specifically, we focused on the role of river discharge on pH l...

Oxygen, pH, and Eh microprofiles around submerged macrophyte Vallisneria natans response to growing stages

NASA Astrophysics Data System (ADS)

Dong, B.; Wang, G. X.; Yu, H. G.

2017-08-01

The periphyton, attached to the surfaces of submerged plants, has important effects on plant growth and development in eutrophic waters. Periphyton complicates the microenvironment of diffusive boundary layer around submerged plants. We researched periphyton characteristics, oxygen (O2), pH, and Eh microprofiles at various growing stages of Vallisneria natans. The results suggested that during the growing period of V. natans, O2 concentration and pH decreased from 0 to 2 mm above the leaf surface, whereas the Eh increased. As V. natans grew, O2 and pH gradually increased until they peaked during stable growing stages, while the Eh decreased. However, during the decline stage, O2 and pH gradually decreased, and Eh increased. To summarise, O2 and pH showed a unimodal pattern in response to the life cycle of V. natans, with the maximum levels during the stable growth stage and the minimum levels during the rapid growth and decline stages. Our study demonstrated that V. natans growth induced steep gradients in O2 concentrations, pH, and Eh at the DBL by increasing the layer’s thickness, macrophyte photosynthetic capacity, and periphyton biomass in eutrophic waters.

Organohalide Respiration with Chlorinated Ethenes under Low pH Conditions

DOE PAGES

Yang, Yi; Cápiro, Natalie L.; Marcet, Tyler F.; ...

2017-06-30

Bioremediation at chlorinated solvent sites often leads to groundwater acidification due to electron donor fermentation and enhanced dechlorination activity. The microbial reductive dechlorination process is robust at circumneutral pH, but activity declines at groundwater pH values below 6.0. Consistent with this observation, the activity of tetrachloroethene (PCE) dechlorinating cultures declined at pH 6.0 and was not sustained in pH 5.5 medium, with one notable exception. Sulf urospirillum multivorans dechlorinated PCE to cis-1,2-dichloroethene (cDCE) in pH 5.5 medium and maintained this activity upon repeated transfers. Microcosms established with soil and aquifer materials from five distinct locations dechlorinated PCE-to-ethene at pH 5.5more » and pH 7.2. Dechlorination to ethene was maintained following repeated transfers at pH 7.2, but no ethene was produced at pH 5.5, and only the transfer cultures derived from the Axton Cross Superfund (ACS) microcosms sustained PCE dechlorination to cDCE as a final product. 16S rRNA gene amplicon sequencing of pH 7.2 and pH 5.5 ACS enrichments revealed distinct microbial communities, with the dominant dechlorinator being Dehalococcoides in pH 7.2 and Sulf urospirillum in pH 5.5 cultures. PCE-to-trichloroethene- (TCE-) and PCE-to-cDCEdechlorinating isolates obtained from the ACS pH 5.5 enrichment shared 98.6%, and 98.5% 16S rRNA gene sequence similarities to Sulf urospirillum multivorans. Lastly, these findings imply that sustained Dehalococcoides activity cannot be expected in low pH (i.e., ≤ 5.5) groundwater, and organohalide-respiring Sulf urospirillum spp. are key contributors to in situ PCE reductive dechlorination under low pH conditions.« less

Organohalide Respiration with Chlorinated Ethenes under Low pH Conditions

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

Yang, Yi; Cápiro, Natalie L.; Marcet, Tyler F.

Bioremediation at chlorinated solvent sites often leads to groundwater acidification due to electron donor fermentation and enhanced dechlorination activity. The microbial reductive dechlorination process is robust at circumneutral pH, but activity declines at groundwater pH values below 6.0. Consistent with this observation, the activity of tetrachloroethene (PCE) dechlorinating cultures declined at pH 6.0 and was not sustained in pH 5.5 medium, with one notable exception. Sulf urospirillum multivorans dechlorinated PCE to cis-1,2-dichloroethene (cDCE) in pH 5.5 medium and maintained this activity upon repeated transfers. Microcosms established with soil and aquifer materials from five distinct locations dechlorinated PCE-to-ethene at pH 5.5more » and pH 7.2. Dechlorination to ethene was maintained following repeated transfers at pH 7.2, but no ethene was produced at pH 5.5, and only the transfer cultures derived from the Axton Cross Superfund (ACS) microcosms sustained PCE dechlorination to cDCE as a final product. 16S rRNA gene amplicon sequencing of pH 7.2 and pH 5.5 ACS enrichments revealed distinct microbial communities, with the dominant dechlorinator being Dehalococcoides in pH 7.2 and Sulf urospirillum in pH 5.5 cultures. PCE-to-trichloroethene- (TCE-) and PCE-to-cDCEdechlorinating isolates obtained from the ACS pH 5.5 enrichment shared 98.6%, and 98.5% 16S rRNA gene sequence similarities to Sulf urospirillum multivorans. Lastly, these findings imply that sustained Dehalococcoides activity cannot be expected in low pH (i.e., ≤ 5.5) groundwater, and organohalide-respiring Sulf urospirillum spp. are key contributors to in situ PCE reductive dechlorination under low pH conditions.« less

Genetics and Genomics of Longitudinal Lung Function Patterns in Individuals with Asthma

PubMed Central

Yates, Katherine P.; Zhou, Xiaobo; Guo, Feng; Sternberg, Alice L.; Van Natta, Mark L.; Wise, Robert A.; Szefler, Stanley J.; Sharma, Sunita; Kho, Alvin T.; Cho, Michael H.; Croteau-Chonka, Damien C.; Castaldi, Peter J.; Jain, Gaurav; Sanyal, Amartya; Zhan, Ye; Lajoie, Bryan R.; Dekker, Job; Stamatoyannopoulos, John; Covar, Ronina A.; Zeiger, Robert S.; Adkinson, N. Franklin; Williams, Paul V.; Kelly, H. William; Grasemann, Hartmut; Vonk, Judith M.; Koppelman, Gerard H.; Postma, Dirkje S.; Raby, Benjamin A.; Houston, Isaac; Lu, Quan; Fuhlbrigge, Anne L.; Tantisira, Kelan G.; Silverman, Edwin K.; Tonascia, James; Strunk, Robert C.; Weiss, Scott T.

2016-01-01

Rationale: Patterns of longitudinal lung function growth and decline in childhood asthma have been shown to be important in determining risk for future respiratory ailments including chronic airway obstruction and chronic obstructive pulmonary disease. Objectives: To determine the genetic underpinnings of lung function patterns in subjects with childhood asthma. Methods: We performed a genome-wide association study of 581 non-Hispanic white individuals with asthma that were previously classified by patterns of lung function growth and decline (normal growth, normal growth with early decline, reduced growth, and reduced growth with early decline). The strongest association was also measured in two additional cohorts: a small asthma cohort and a large chronic obstructive pulmonary disease metaanalysis cohort. Interaction between the genomic region encompassing the most strongly associated single-nucleotide polymorphism and nearby genes was assessed by two chromosome conformation capture assays. Measurements and Main Results: An intergenic single-nucleotide polymorphism (rs4445257) on chromosome 8 was strongly associated with the normal growth with early decline pattern compared with all other pattern groups (P = 6.7 × 10−9; odds ratio, 2.8; 95% confidence interval, 2.0–4.0); replication analysis suggested this variant had opposite effects in normal growth with early decline and reduced growth with early decline pattern groups. Chromosome conformation capture experiments indicated a chromatin interaction between rs4445257 and the promoter of the distal CSMD3 gene. Conclusions: Early decline in lung function after normal growth is associated with a genetic polymorphism that may also protect against early decline in reduced growth groups. Clinical trial registered with www.clinicaltrials.gov (NCT00000575). PMID:27367781

Ocean acidification alters early successional coral reef communities and their rates of community metabolism.

PubMed

Noonan, Sam H C; Kluibenschedl, Anna; Fabricius, Katharina E

2018-01-01

Ocean acidification is expected to alter community composition on coral reefs, but its effects on reef community metabolism are poorly understood. Here we document how early successional benthic coral reef communities change in situ along gradients of carbon dioxide (CO2), and the consequences of these changes on rates of community photosynthesis, respiration, and light and dark calcification. Ninety standardised benthic communities were grown on PVC tiles deployed at two shallow-water volcanic CO2 seeps and two adjacent control sites in Papua New Guinea. Along the CO2 gradient, both the upward facing phototrophic and the downward facing cryptic communities changed in their composition. Under ambient CO2, both communities were dominated by calcifying algae, but with increasing CO2 they were gradually replaced by non-calcifying algae (predominantly green filamentous algae, cyanobacteria and macroalgae, which increased from ~30% to ~80% cover). Responses were weaker in the invertebrate communities, however ascidians and tube-forming polychaetes declined with increasing CO2. Differences in the carbonate chemistry explained a far greater amount of change in communities than differences between the two reefs and successional changes from five to 13 months, suggesting community successions are established early and are under strong chemical control. As pH declined from 8.0 to 7.8, rates of gross photosynthesis and dark respiration of the 13-month old reef communities (upper and cryptic surfaces combined) significantly increased by 10% and 20%, respectively, in response to altered community composition. As a consequence, net production remained constant. Light and dark calcification rates both gradually declined by 20%, and low or negative daily net calcification rates were observed at an aragonite saturation state of <2.3. The study demonstrates that ocean acidification as predicted for the end of this century will strongly alter reef communities, and will significantly change rates of community metabolism.

Ocean acidification alters early successional coral reef communities and their rates of community metabolism

PubMed Central

Kluibenschedl, Anna; Fabricius, Katharina E.

2018-01-01

Ocean acidification is expected to alter community composition on coral reefs, but its effects on reef community metabolism are poorly understood. Here we document how early successional benthic coral reef communities change in situ along gradients of carbon dioxide (CO2), and the consequences of these changes on rates of community photosynthesis, respiration, and light and dark calcification. Ninety standardised benthic communities were grown on PVC tiles deployed at two shallow-water volcanic CO2 seeps and two adjacent control sites in Papua New Guinea. Along the CO2 gradient, both the upward facing phototrophic and the downward facing cryptic communities changed in their composition. Under ambient CO2, both communities were dominated by calcifying algae, but with increasing CO2 they were gradually replaced by non-calcifying algae (predominantly green filamentous algae, cyanobacteria and macroalgae, which increased from ~30% to ~80% cover). Responses were weaker in the invertebrate communities, however ascidians and tube-forming polychaetes declined with increasing CO2. Differences in the carbonate chemistry explained a far greater amount of change in communities than differences between the two reefs and successional changes from five to 13 months, suggesting community successions are established early and are under strong chemical control. As pH declined from 8.0 to 7.8, rates of gross photosynthesis and dark respiration of the 13-month old reef communities (upper and cryptic surfaces combined) significantly increased by 10% and 20%, respectively, in response to altered community composition. As a consequence, net production remained constant. Light and dark calcification rates both gradually declined by 20%, and low or negative daily net calcification rates were observed at an aragonite saturation state of <2.3. The study demonstrates that ocean acidification as predicted for the end of this century will strongly alter reef communities, and will significantly change rates of community metabolism. PMID:29847575

Acid precipitation studies in Colorado and Wyoming: interim report of surveys of montane amphibians and water chemistry

USGS Publications Warehouse

Corn, Paul Stephen; Stolzenburg, William; Bury, R. Bruce

1989-01-01

Acid deposition may be detrimental or stressful to native populations of wildlife. Because many species of amphibians breed in shallow ponds created by spring rains or melting snow, they may be particularly vulnerable to the effects of acidification. From 1986 to 1988, we surveyed 105 locations in the central Rocky Mountains where amphibians had been recorded previously, and we found that two species of amphibians had experiences major losses. We found the northern leopard frog (Rana pipiens) at only 4 of 33 (12%) historically known localities, and the boreal toad (Bufo boreas) was present at 10 of 59 (17%) known localities. Three other species have not suffered region-wide declines. Tiger salamanders (Ambystoma tigrinum) and wood frogs (Rana sylvatica) were present at 45% and 69% of known localities respectively, and were observed at several localities were they had not been recorded previously. Chorus frogs (Pseudacris triseriata) suffered a catastrophic decline in population size in one population monitored since 1961, but regionally, this species was observed in 36 of 56 (64%) known localities and in another 19 localities where there were no previous records. Complete water chemistry was recorded for 41 localities, and pH was measured at 110 sites in total. Acid neutralizing capacity, pH, specific conductivity, and cation concentrations were negatively correlated with elevation. However, in mountain ponds and lakes, pH was rarely less than 6.0 during the amphibian breeding season. We tested the tolerance of embryos of the four species of frogs to low pH. The LC50 pH was 4.8 for chorus frogs, 4.4-4.7 for leopard frogs, 4.4-4.5 for boreal toads, and 4.2-4.3 for wood frogs. Survival of wood frog embryos declined when exposed to aluminum concentrations of 100 µg/L or greater, but boreal toad embryos survived exposure to aluminum concentrations of 400 µg/L. Acid deposition does not appear to be a major factor in the decline of leopard frogs and boreal toads. However, we have not yet investigated effects of sublethal pH on growth and development of tadpoles. Pollution remains suspect, but other factors, including natural fluctuations in population size, may account for the observed declines.

Impact of seawater carbonate chemistry on the calcification of marine bivalves

NASA Astrophysics Data System (ADS)

Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

2015-07-01

Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better understand the physiological processes and their underlying genetics that govern inorganic carbon assimilation for calcification.

Long-term evolution of highly alkaline steel slag drainage waters.

PubMed

Riley, Alex L; Mayes, William M

2015-07-01

The disposal of slag generated by the steel industry can have negative consequences upon the surrounding aquatic environment by the generation of high pH waters, leaching of potentially problematic trace metals, and rapid rates of calcite precipitation which smother benthic habitats. A 36-year dataset was collated from the long-term ambient monitoring of physicochemical parameters and elemental concentrations of samples from two steel slag leachate-affected watercourses in northern England. Waters were typified by elevated pH (>10), high alkalinity, and were rich in dissolved metals (e.g. calcium (Ca), aluminium (Al), and zinc (Zn)). Long-term trend analysis was performed upon pH, alkalinity, and Ca concentration which, in addition to Ca flux calculations, were used to highlight the longevity of pollution arising as a result of the dumping and subsequent leaching of steel slags. Declines in calcium and alkalinity have been modest over the monitoring period and not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50-80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible.

Effect of Early Referral to Specialist in Dementia on Institutionalization and Functional Decline: Findings from a Population-Based Study.

PubMed

Pimouguet, Clément; Le-Goff, Mélanie; Rizzuto, Debora; Berr, Claudine; Leffondré, Karen; Pérès, Karine; Dartigues, Jean FranÇois; Helmer, Catherine

2016-01-01

Although early diagnosis has been hypothesized to benefit both patients and caregivers, until now studies evaluating the effect of early dementia diagnosis are lacking. To investigate the influence of early specialist referral for dementia on the risk of institutionalization and functional decline in Activity of Daily Living (ADL). Incident dementia cases were screened in a prospective population-based cohort, the Three-City Study, and initial specialist consultation for cognitive complaint was assessed at dementia diagnosis. Proportional hazard regression and illness-death models were used to test the association between specialist referral and, respectively, institutionalization and functional decline. Only one third of the incident individuals with dementia had consulted a specialist for cognitive problems early (36%). After adjustment on potential confounders (including cognitive and functional decline) and competing risk of death, participants who had consulted a specialist early in the disease course presented a higher rate of being institutionalized than those who did not (Hazard Ratio = 2.00, 95% Confidence Interval (CI): 1.09- 3.64). But early specialist referral was not associated with further functional decline (HR = 1.09, 95% CI: 0.71- 1.67). Early specialist referral in dementia is associated with increased risk of institutionalization but not with functional decline in ADL. These findings suggest that early care referral in dementia may be a marker of concern for patients and/or caregivers; subsequent medical and social care could be suboptimal or inappropriate to allow patients to stay longer at home.

Limited toxicity of NH(x) pulses on an early and late successional tropical seagrass species: interactions with pH and light level.

PubMed

Christianen, M J A; van der Heide, T; Bouma, T J; Roelofs, J G M; van Katwijk, M M; Lamers, L P M

2011-07-01

Seagrasses have declined at a global scale due to light reduction and toxicity events, caused by eutrophication and increased sediment loading. Although several studies have tested effects of light reduction and toxicants on seagrasses, there is at present no information available on their interacting effects. In a full-factorial 5-day laboratory experiment, we studied short-term interactive effects of light conditions, pH and reduced nitrogen (NH(x)) in the water layer, mimicking pulses of river discharge, on the tropical early successional species Halodule uninervis and the late successional species Thalassia hemprichii. In contrast to recent results reported for the temperate species Zostera marina, increased NH(x) supply did not affect leaf mortality or photochemical efficiency in H. uninervis and in 7 out of 8 treatments for T. hemprichii. However, both tropical species demonstrated striking differences in nitrogen accumulation, free amino acid composition and free NH₃ accumulation. The increase in tissue nitrogen content was two times higher for H. uninervis than for T. hemprichii. Nitrogen stored as free amino acids (especially asparagine) only increased in H. uninervis. High pH only affected T. hemprichii, but only when not shaded, by doubling its free NH₃ concentrations, concomitantly decreasing its photosynthetic efficiency. Our results indicate that the early successional H. uninervis has higher tolerance to high NH(x) loads as compared to the late successional T. hemprichii. H. uninervis was better able to avoid toxic internal NH(x) levels by further assimilating glutamine into asparagine in contrast to T. hemprichii. Moreover, both tropical species seem to cope much better with high NH(x) than the temperate Z. marina. The implications for the distribution and succession of seagrass species under high nutrient loads are discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

Transcriptomic responses to ocean acidification in larval sea urchins from a naturally variable pH environment.

PubMed

Evans, Tyler G; Chan, Francis; Menge, Bruce A; Hofmann, Gretchen E

2013-03-01

Some marine ecosystems already experience natural declines in pH approximating those predicted with future anthropogenic ocean acidification (OA), the decline in seawater pH caused by the absorption of atmospheric CO2 . The molecular mechanisms that allow organisms to inhabit these low pH environments, particularly those building calcium carbonate skeletons, are unknown. Also uncertain is whether an enhanced capacity to cope with present day pH variation will confer resistance to future OA. To address these issues, we monitored natural pH dynamics within an intertidal habitat in the Northeast Pacific, demonstrating that upwelling exposes resident species to pH regimes not predicted to occur elsewhere until 2100. Next, we cultured the progeny of adult purple sea urchins (Strongylocentrotus purpuratus) collected from this region in CO2 -acidified seawater representing present day and near future ocean scenarios and monitored gene expression using transcriptomics. We hypothesized that persistent exposure to upwelling during evolutionary history will have selected for increased pH tolerance in this population and that their transcriptomic response to low pH seawater would provide insight into mechanisms underlying pH tolerance in a calcifying species. Resulting expression patterns revealed two important trends. Firstly, S. purpuratus larvae may alter the bioavailability of calcium and adjust skeletogenic pathways to sustain calcification in a low pH ocean. Secondly, larvae use different strategies for coping with different magnitudes of pH stress: initiating a robust transcriptional response to present day pH regimes but a muted response to near future conditions. Thus, an enhanced capacity to cope with present day pH variation may not translate into success in future oceans. © 2013 Blackwell Publishing Ltd.

CO2 leakage-induced vegetation decline is primarily driven by decreased soil O2.

PubMed

Zhang, Xueyan; Ma, Xin; Zhao, Zhi; Wu, Yang; Li, Yue

2016-04-15

To assess the potential risks of carbon capture and storage (CCS), studies have focused on vegetation decline caused by leaking CO2. Excess soil CO2 caused by leakage can affect soil O2 concentrations and soil pH, but how these two factors affect plant development remains poorly understood. This hinders the selection of appropriate species to mitigate potential negative consequences of CCS. Through pot experiments, we simulated CO2 leakage to examine its effects on soil pH and soil O2 concentrations. We subsequently assessed how maize growth responded to these changes in soil pH and O2. Decreased soil O2 concentrations significantly reduced maize biomass, and explained 69% of the biomass variation under CO2 leakage conditions. In contrast, although leaked CO2 changed soil pH significantly (from 7.32 to 6.75), it remained within the optimum soil pH range for maize growth. This suggests that soil O2 concentration, not soil pH, influences plant growth in these conditions. Therefore, in case of potential CO2 leakage risks, hypoxia-tolerant species should be chosen to improve plant survival, growth, and yield. Copyright © 2016 Elsevier Ltd. All rights reserved.

Predicting Effects of Coastal Acidification on Marine Bivalve ...

EPA Pesticide Factsheets

The partial pressure of carbon dioxide (pCO2) is increasing in the oceans and causing changes in seawater pH commonly described as ocean or coastal acidification. It is now well-established that, when reproduced in laboratory experiments, these increases in pCO2 can reduce survival and growth of early life stage bivalves. However, the effects that these impairments would have on whole populations of bivalves are unknown. In this study, these laboratory responses were incorporated into field-parameterized population models to assess population-level sensitivities to acidification for two northeast bivalve species with different life histories: Mercenaria mercenaria (hard clam) and Argopecten irradians (bay scallop). The resulting models permitted translation of laboratory pCO2 response functions into population-level responses to examine population sensitivity to future pCO2 changes. Preliminary results from our models indicate that if the current M. mercenaria negative population growth rate was attributed to the effects of pCO2 on early life stages, the population would decline at a rate of 50% per ten years at 420 microatmospheres (µatm) pCO2. If the current population growth rate was attributed to other additive factors (e.g., harvest, harmful algal blooms), M. mercenaria populations were predicted to decline at a rate of 50% per ten years at the preliminary estimate of 1010 µatm pCO2. The estimated population growth rate was positive for A. irradians,

Water-quality data from Upper Klamath and Agency Lakes, Oregon, 2009-10

USGS Publications Warehouse

Eldridge, D. Blake; Caldwell Eldridge, Sara L.; Schenk, Liam N.; Tanner, Dwight Q.; Wood, Tamara M.

2012-01-01

The U.S. Geological Survey Upper Klamath Lake water-quality monitoring program collected data from multiparameter continuous water-quality monitors, weekly water-quality samples, and meteorological stations during 2009 and 2010 from May through November each year. The results of these measurements and sample analyses, as well as quality-control data for the water-quality samples, are presented in this report for 14 sites on Upper Klamath Lake and 2 sites on Agency Lake. These 2 years of data demonstrate a contrast in the seasonal bloom of the dominant cyanobacterium, Aphanizomenon flos-aquae, that can be related to differences in the measured water quality and meteorological variables. Some of the significant findings from 2009 and 2010 are listed below. * Both 2009 and 2010 were characterized by two cyanobacteria blooms, but the blooms differed in timing and intensity. The first bloom in 2009 peaked in late June and at higher chlorophyll a concentrations at most sites than the first bloom in 2010, which peaked in mid-July. A major decline in the first 2009 bloom occurred in late July and was followed by a second bloom that peaked at most sites in mid-August and persisted through September. The decline of the weaker first bloom in 2010 occurred in early August and was followed by a more substantial second bloom that peaked between late August and early September at most sites. * Dissolved oxygen minima associated with bloom declines occurred approximately 2 weeks earlier in 2009 (mid-July) than in 2010 (early August). pH maxima associated with rapid bloom growth occurred in late June and again in mid-August in 2009 and in mid-July and late August in 2010. * In both years, the maxima for total phosphorus and total nitrogen concentrations coincided with the chlorophyll a maximum. The maxima for dissolved nutrient concentrations (orthophosphate, ammonia, and nitrite plus nitrate) coincided with the declines of the first blooms. * Total particulate carbon, total particulate nitrogen, and total particulate phosphorus concentrations were measured in 2009 only. The ratios of carbon to phosphorus and nitrogen to phosphorus in particulates were the highest of the entire season during the rapid growth phase of the first bloom and were the lowest of the season during the decline of the first bloom. These ratios increased with the onset of the second bloom in that year, but to a lesser degree. * Meteorological data show that 2009 was warmer (particularly in June and July), less windy, and more humid early in the season than 2010. The difference in water temperatures reflected the difference in air temperatures in that the lakes were warmer in 2009 than in 2010 starting in early May, when the sensors were deployed, through most of June. Water temperature peaked at a higher value in 2009, and there were more clear days in June 2009 than in June 2010.

Large natural pH, CO2 and O2 fluctuations in a temperate tidal salt marsh on diel, seasonal, and interannual time scales

USGS Publications Warehouse

Baumann, Hannes; Wallace, Ryan; Tagliaferri, Tristen N.; Gobler, Christopher J.

2014-01-01

Coastal marine organisms experience dynamic pH and dissolved oxygen (DO) conditions in their natural habitats, which may impact their susceptibility to long-term anthropogenic changes. Robust characterizations of all temporal scales of natural pH and DO fluctuations in different marine habitats are needed; however, appropriate time series of pH and DO are still scarce. We used multiyear (2008–2012), high-frequency (6 min) monitoring data to quantify diel, seasonal, and interannual scales of pH and DO variability in a productive, temperate tidal salt marsh (Flax Pond, Long Island, US). pHNBS and DO showed strong and similar seasonal patterns, with average (minimum) conditions declining from 8.2 (8.1) and 12.5 (11.4) mg l−1 at the end of winter to 7.6 (7.2) and 6.3 (2.8) mg l−1 in late summer, respectively. Concomitantly, average diel fluctuations increased from 0.22 and 2.2 mg l−1 (February) to 0.74 and 6.5 mg l−1 (August), respectively. Diel patterns were modulated by tides and time of day, eliciting the most extreme minima when low tides aligned with the end of the night. Simultaneous in situ pCO2 measurements showed striking fluctuations between ∼330 and ∼1,200 (early May), ∼2,200 (mid June), and ∼4,000 μatm (end of July) within single tidal cycles. These patterns also indicate that the marsh’s strong net heterotrophy influences its adjacent estuary by ‘outwelling’ acidified and hypoxic water during ebb tides. Our analyses emphasize the coupled and fluctuating nature of pH and DO conditions in productive coastal and estuarine environments, which have yet to be adequately represented by experiments.

Prognostic significance of an early decline in serum alpha-fetoprotein during chemotherapy for ovarian yolk sac tumors.

PubMed

de la Motte Rouge, Thibault; Pautier, Patricia; Genestie, Catherine; Rey, Annie; Gouy, Sébastien; Leary, Alexandra; Haie-Meder, Christine; Kerbrat, Pierre; Culine, Stéphane; Fizazi, Karim; Lhommé, Catherine

2016-09-01

The ovarian yolk sac tumor (OYST) is a very rare malignancy arising in young women. Our objective was to determine whether an early decline in serum alpha-fetoprotein (AFP) during chemotherapy has a prognostic impact. This retrospective study is based on prospectively recorded OYST cases at Gustave Roussy (Cancer Treatment Center). Survival curves were estimated using the Kaplan-Meier method. The serum AFP decline was calculated with the formula previously developed and validated in male patients with poor prognosis non-seminomatous germ cell tumors. Univariate and multivariate analyses were performed using the log-rank test and logistic regression, respectively. Data on AFP were available to calculate an early AFP decline in 57 patients. All patients had undergone surgery followed by chemotherapy. The 5-year overall survival (OS) and event-free survival (EFS) rates were 86% (95% CI: 74%-93%) and 84% (95% CI: 73%-91%), respectively. The disease stage, presence of ascites at presentation, use of the BEP regimen, serum AFP half-life and an early AFP decline were significantly predictive factors for OS and EFS in the univariate analysis. The OS rate was 100% and 49% (95% CI: 26%-72%) in patients with a favorable AFP decline and in those with an unfavorable decline, respectively (p<0.001). In the multivariate analysis, only the presence of ascites at diagnosis (RR=7.3, p=0.03) and an unfavorable early AFP decline (RR=16.9, p<0.01) were significant negative predictive factors for OS. An early AFP decline during chemotherapy is an independent prognostic factor in patients with OYSTs. No conflict of interest. Copyright © 2016. Published by Elsevier Inc.

Growth rates of three geographically separated strains of the ichthyotoxic Prymnesium parvum (Prymnesiophyceae) in response to six different pH levels

NASA Astrophysics Data System (ADS)

Lysgaard, Maria L.; Eckford-Soper, Lisa; Daugbjerg, Niels

2018-05-01

Continued anthropogenic carbon emissions are expected to cause a decline in global average pH of the oceans to a projected value of 7.8 by the end of the century. Understanding how harmful algal bloom (HAB) species will respond to lowered pH levels will be important when predicting future HAB events and their ecological consequences. In this study, we examined how manipulated pH levels affected the growth rate of three strains of Prymnesium parvum from North America, Denmark and Japan. Triplicate strains were grown under pH conditions ranging from 6.6 to 9.1 to simulate plausible future levels. Different tolerances were evident for all strains. Significantly higher growth rates were observed at pH 6.6-8.1 compared to growth rates at pH 8.6-9.1 and a lower pH limit was not observed. The Japanese strain (NIES-1017) had the highest maximum growth rate of 0.39 divisions day-1 at pH 6.6 but a low tolerance (0.22 divisions day-1) to high levels (pH 9.1) with growth declining markedly after pH 7.6. The Danish (SCCAP K-0081) and North American (UTEX LB 2797) strains had maximum growth rates of 0.26 and 0.35 divisions day-1, respectively between pH 6.6-8.1. Compared to the other two strains the Danish strain had a statistically lower growth rate across all pH treatments. Strain differences were either attributed to their provenance or the length of time the strain had been in culture.

Long photoperiods sustain high pH in Arctic kelp forests.

PubMed

Krause-Jensen, Dorte; Marbà, Núria; Sanz-Martin, Marina; Hendriks, Iris E; Thyrring, Jakob; Carstensen, Jacob; Sejr, Mikael Kristian; Duarte, Carlos M

2016-12-01

Concern on the impacts of ocean acidification on calcifiers, such as bivalves, sea urchins, and foraminifers, has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows. The metabolism of these habitats can lead to diel fluctuation in pH with increases during the day and declines at night, suggesting no net effect on pH at time scales longer than daily. We examined the capacity of subarctic and Arctic kelps to up-regulate pH in situ and experimentally tested the role of photoperiod in determining the capacity of Arctic macrophytes to up-regulate pH. Field observations at photoperiods of 15 and 24 hours in Greenland combined with experimental manipulations of photoperiod show that photoperiods longer than 21 hours, characteristic of Arctic summers, are conducive to sustained up-regulation of pH by kelp photosynthesis. We report a gradual increase in pH of 0.15 units and a parallel decline in pCO 2 of 100 parts per million over a 10-day period in an Arctic kelp forest over midsummer, with ample scope for continued pH increase during the months of continuous daylight. Experimental increase in CO 2 concentration further stimulated the capacity of macrophytes to deplete CO 2 and increase pH. We conclude that long photoperiods in Arctic summers support sustained up-regulation of pH in kelp forests, with potential benefits for calcifiers, and propose that this mechanism may increase with the projected expansion of Arctic vegetation in response to warming and loss of sea ice.

Changes in Forest Soil Properties in Different Successional Stages in Lower Tropical China

PubMed Central

Li, Yuelin; Yang, Fangfang; Ou, Yangxu; Zhang, Deqiang; Liu, Juxiu; Chu, Guowei; Zhang, Yaru; Otieno, Dennis; Zhou, Guoyi

2013-01-01

Background Natural forest succession often affects soil physical and chemical properties. Selected physical and chemical soil properties were studied in an old-growth forest across a forest successional series in Dinghushan Nature Reserve, Southern China. Methodology/Principal Findings The aim was to assess the effects of forest succession change on soil properties. Soil samples (0–20 cm depth) were collected from three forest types at different succession stages, namely pine (Pinus massoniana) forest (PMF), mixed pine and broadleaf forest (PBMF) and monsoon evergreen broadleaf forest (MEBF), representing early, middle and advanced successional stages respectively. The soil samples were analyzed for soil water storage (SWS), soil organic matter (SOM), soil microbial biomass carbon (SMBC), pH, NH4 +-N, available potassium (K), available phosphorus (P) and microelements (available copper (Cu), available zinc (Zn), available iron (Fe) and available boron (B)) between 1999 and 2009. The results showed that SWS, SOM, SMBC, Cu, Zn, Fe and B concentrations were higher in the advanced successional stage (MEBF stage). Conversely, P and pH were lower in the MEBF but higher in the PMF (early successional stage). pH, NH4 +-N, P and K declined while SOM, Zn, Cu, Fe and B increased with increasing forest age. Soil pH was lower than 4.5 in the three forest types, indicating that the surface soil was acidic, a stable trend in Dinghushan. Conclusion/Significance These findings demonstrated significant impacts of natural succession in an old-growth forest on the surface soil nutrient properties and organic matter. Changes in soil properties along the forest succession gradient may be a useful index for evaluating the successional stages of the subtropical forests. We caution that our inferences are drawn from a pseudo-replicated chronosequence, as true replicates were difficult to find. Further studies are needed to draw rigorous conclusions regarding on nutrient dynamics in different successional stages of forest. PMID:24244738

Early-life exposure to climate change impairs tropical shark survival.

PubMed

Rosa, Rui; Baptista, Miguel; Lopes, Vanessa M; Pegado, Maria Rita; Paula, José Ricardo; Trübenbach, Katja; Leal, Miguel Costa; Calado, Ricardo; Repolho, Tiago

2014-10-22

Sharks are one of the most threatened groups of marine animals worldwide, mostly owing to overfishing and habitat degradation/loss. Although these cartilaginous fish have evolved to fill many ecological niches across a wide range of habitats, they have limited capability to rapidly adapt to human-induced changes in their environments. Contrary to global warming, ocean acidification was not considered as a direct climate-related threat to sharks. Here we show, for the first time, that an early ontogenetic acclimation process of a tropical shark (Chiloscyllium punctatum) to the projected scenarios of ocean acidification (ΔpH = 0.5) and warming (+4°C; 30°C) for 2100 elicited significant impairments on juvenile shark condition and survival. The mortality of shark embryos at the present-day thermal scenarios was 0% both at normocapnic and hypercapnic conditions. Yet routine metabolic rates (RMRs) were significantly affected by temperature, pH and embryonic stage. Immediately after hatching, the Fulton condition of juvenile bamboo sharks was significantly different in individuals that experienced future warming and hypercapnia; 30 days after hatching, survival rapidly declined in individuals experiencing both ocean warming and acidification (up to 44%). The RMR of juvenile sharks was also significantly affected by temperature and pH. The impact of low pH on ventilation rates was significant only under the higher thermal scenario. This study highlights the need of experimental-based risk assessments of sharks to climate change. In other words, it is critical to directly assess risk and vulnerability of sharks to ocean acidification and warming, and such effort can ultimately help managers and policy-makers to take proactive measures targeting most endangered species. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Early-life exposure to climate change impairs tropical shark survival

PubMed Central

Rosa, Rui; Baptista, Miguel; Lopes, Vanessa M.; Pegado, Maria Rita; Ricardo Paula, José; Trübenbach, Katja; Leal, Miguel Costa; Calado, Ricardo; Repolho, Tiago

2014-01-01

Sharks are one of the most threatened groups of marine animals worldwide, mostly owing to overfishing and habitat degradation/loss. Although these cartilaginous fish have evolved to fill many ecological niches across a wide range of habitats, they have limited capability to rapidly adapt to human-induced changes in their environments. Contrary to global warming, ocean acidification was not considered as a direct climate-related threat to sharks. Here we show, for the first time, that an early ontogenetic acclimation process of a tropical shark (Chiloscyllium punctatum) to the projected scenarios of ocean acidification (ΔpH = 0.5) and warming (+4°C; 30°C) for 2100 elicited significant impairments on juvenile shark condition and survival. The mortality of shark embryos at the present-day thermal scenarios was 0% both at normocapnic and hypercapnic conditions. Yet routine metabolic rates (RMRs) were significantly affected by temperature, pH and embryonic stage. Immediately after hatching, the Fulton condition of juvenile bamboo sharks was significantly different in individuals that experienced future warming and hypercapnia; 30 days after hatching, survival rapidly declined in individuals experiencing both ocean warming and acidification (up to 44%). The RMR of juvenile sharks was also significantly affected by temperature and pH. The impact of low pH on ventilation rates was significant only under the higher thermal scenario. This study highlights the need of experimental-based risk assessments of sharks to climate change. In other words, it is critical to directly assess risk and vulnerability of sharks to ocean acidification and warming, and such effort can ultimately help managers and policy-makers to take proactive measures targeting most endangered species. PMID:25209942

Pulmonary Hypertension Surveillance

PubMed Central

Schieb, Linda J.; Ayala, Carma; Talwalkar, Anjali; Levant, Shaleah

2014-01-01

Pulmonary hypertension (PH) is an uncommon but progressive condition, and much of what we know about it comes from specialized disease registries. With expanding research into the diagnosis and treatment of PH, it is important to provide updated surveillance on the impact of this disease on hospitalizations and mortality. This study, which builds on previous PH surveillance of mortality and hospitalization, analyzed mortality data from the National Vital Statistics System and data from the National Hospital Discharge Survey between 2001 and 2010. PH deaths were identified using International Classification of Diseases, Tenth Revision codes I27.0, I27.2, I27.8, or I27.9 as any contributing cause of death on the death certificate. Hospital discharges associated with PH were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes 416.0, 416.8, or 416.9 as one of up to seven listed medical diagnoses. The decline in death rates associated with PH among men from 1980 to 2005 has reversed and now shows a significant increasing trend. Similarly, the death rates for women with PH have continued to increase significantly during the past decade. PH-associated mortality rates for those aged 85 years and older have accelerated compared with rates for younger age groups. There have been significant declines in PH-associated mortality rates for those with pulmonary embolism and emphysema. Rates of hospitalization for PH have increased significantly for both men and women during the past decade; for those aged 85 years and older, hospitalization rates have nearly doubled. Continued surveillance helps us understand and address the evolving trends in hospitalization and mortality associated with PH and PH-associated conditions, especially regarding sex, age, and race/ethnicity disparities. PMID:24700091

Growth decline and divergent tree ring isotopic composition (δ(13) C and δ(18) O) contradict predictions of CO2 stimulation in high altitudinal forests.

PubMed

Gómez-Guerrero, Armando; Silva, Lucas C R; Barrera-Reyes, Miguel; Kishchuk, Barbara; Velázquez-Martínez, Alejandro; Martínez-Trinidad, Tomás; Plascencia-Escalante, Francisca Ofelia; Horwath, William R

2013-06-01

Human-induced changes in atmospheric composition are expected to affect primary productivity across terrestrial biomes. Recent changes in productivity have been observed in many forest ecosystems, but low-latitude upper tree line forests remain to be investigated. Here, we use dendrochronological methods and isotopic analysis to examine changes in productivity, and their physiological basis, in Abies religiosa (Ar) and Pinus hartwegii (Ph) trees growing in high-elevation forests of central Mexico. Six sites were selected across a longitudinal transect (Transverse Volcanic Axis), from the Pacific Ocean toward the Gulf of Mexico, where mature dominant trees were sampled at altitudes ranging from 3200 to 4000 m asl. A total of 60 Ar and 84 Ph trees were analyzed to describe changes in growth (annual-resolution) and isotopic composition (decadal-resolution) since the early 1900s. Our results show an initial widespread increase in basal area increment (BAI) during the first half of the past century. However, BAI has decreased significantly since the 1950s with accentuated decline after the 1980s in both species and across sites. We found a consistent reduction in atmosphere to wood (13) C discrimination, resulting from increasing water use efficiency (20-60%), coinciding with rising atmospheric CO2 . Changes in (13) C discrimination were not followed, however, by shifts in tree ring δ(18) O, indicating site- and species-specific differences in water source or uptake strategy. Our results indicate that CO2 stimulation has not been enough to counteract warming-induced drought stress, but other stressors, such as progressive nutrient limitation, could also have contributed to growth decline. Future studies should explore the distinct role of resource limitation (water vs. nutrients) in modulating the response of high-elevation ecosystems to atmospheric change. © 2013 Blackwell Publishing Ltd.

Vulnerability of Coral Reefs to Bioerosion From Land-Based Sources of Pollution

NASA Astrophysics Data System (ADS)

Prouty, Nancy G.; Cohen, Anne; Yates, Kimberly K.; Storlazzi, Curt D.; Swarzenski, Peter W.; White, Darla

2017-12-01

Ocean acidification (OA), the gradual decline in ocean pH and [CO32-] caused by rising levels of atmospheric CO2, poses a significant threat to coral reef ecosystems, depressing rates of calcium carbonate (CaCO3) production, and enhancing rates of bioerosion and dissolution. As ocean pH and [CO32-] decline globally, there is increasing emphasis on managing local stressors that can exacerbate the vulnerability of coral reefs to the effects of OA. We show that sustained, nutrient rich, lower pH submarine groundwater discharging onto nearshore coral reefs off west Maui lowers the pH of seawater and exposes corals to nitrate concentrations 50 times higher than ambient. Rates of coral calcification are substantially decreased, and rates of bioerosion are orders of magnitude higher than those observed in coral cores collected in the Pacific under equivalent low pH conditions but living in oligotrophic waters. Heavier coral nitrogen isotope (δ15N) values pinpoint not only site-specific eutrophication, but also a sewage nitrogen source enriched in 15N. Our results show that eutrophication of reef seawater by land-based sources of pollution can magnify the effects of OA through nutrient driven-bioerosion. These conditions could contribute to the collapse of coastal coral reef ecosystems sooner than current projections predict based only on ocean acidification.