Direct uptake of soil nitrogen by mosses

PubMed Central

Ayres, Edward; van der Wal, René; Sommerkorn, Martin; Bardgett, Richard D

2006-01-01

Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques (15N). Both species exhibited increased concentrations of shoot 15N when exposed to either soil- or wet deposition-derived 15N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated. PMID:17148384

Direct uptake of soil nitrogen by mosses.

PubMed

Ayres, Edward; van der Wal, René; Sommerkorn, Martin; Bardgett, Richard D

2006-06-22

Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques (15N). Both species exhibited increased concentrations of shoot 15N when exposed to either soil- or wet deposition-derived 15N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated.

Soil Methane uptake Model (MeMo): a process based model for global methane consumption by soils

NASA Astrophysics Data System (ADS)

Murguia-Flores, F.; Arndt, S.; Ganesan, A.; Hornibrook, E. R. C.; Murray-Tortarolo, G.

2016-12-01

Atmospheric methane (CH4) is a powerful greenhouse gas, responsible for 20% of global warming. The only terrestrial and biological sink is the uptake in the soils by methanotrophic bacteria, however there is large spatial and temporal heterogeneity in the magnitude of this sink. One way to provide a global understanding of this process is by using a mathematical model to simulate the mechanisms of the underlying physical and biological drivers. Here we present the soil Methane uptake Model (MeMo) a process-based model for the global methane consumption by soils. We have built on previous models by Ridgwell et al., (1999) and Curry et al., (2007), by making several advances. First, a general analytical solution of the one-dimensional diffusion-reaction equation was implemented that accounts for a maximum uptake depth and for a CH4 flux coming from below the surface (i.e. CH4 production in the soil). Secondly, we revisited and improved the effect of nitrogen inhibition, soil moisture and soil temperature on CH4 uptake in the light of newly available data and advances in our understanding of these drivers. Using observed forcing data, we estimated a global mean CH4 uptake of 31.2±1.2 Tg y-1 for the period 1990-2009 with an increasing trend of 0.1 Tg y-2. Our model represented the latitudinal pattern of uptake shown by field observations, with the highest uptake per unit area occurring over dry tropical forest and the lowest uptake in the polar desert. The highest seasonality occurred in the Northern Hemisphere, showing that the main driver of variability in a given year is from a combination of temperature and soil moisture. Our model showed that CH4 uptake is reduced from previous studies by approximately 10% at the regions with the highest nitrogen deposition: East Asia and Europe. Finally, our results suggest that more field measurements are needed to improve the modelling of the process, such as the basal oxidation rate for different ecosystems, the Q10

Influence of Ca and pH on the uptake and effects of Cd in Folsomia candida exposed to simplified soil solutions.

PubMed

Ardestani, Masoud M; Ortiz, Maria Diez; van Gestel, Cornelis A M

2013-08-01

The present study sought to quantify the components of a biotic ligand model (BLM) for the effects of Cd on Folsomia candida (Collembola). Assuming that soil porewater is the main route of exposure and to exclude the effects of soil particles on metal availability, animals were exposed for 7 d to different Cd concentrations between 0.1 mM and 100 mM in simplified soil solutions at different Ca concentrations (0.2 mM, 0.8 mM, 3.2 mM, and 12.8 mM) or at different pH (5.0, 6.0, and 7.0). Higher Ca concentrations decreased the toxicity of Cd (adult survival) in test solutions, whereas toxicity was slightly lower at pH 7 and 6 than at pH 5, suggesting a mitigating effect of Ca and to a lesser extent pH on Cd toxicity to F. candida. Internal Cd concentrations in the animals increased with increasing exposure level but were significantly reduced by increasing Ca concentrations and were not significantly affected by pH. By using Langmuir isotherms, binding constants for Cd, Ca, and protons and the fraction of binding sites occupied by Cd were calculated and used to predict effects of Cd on survival. Predicted toxicity showed a good agreement with measured responses when Ca and pH were used as separate factors or combined together. The present study shows indications of protective effects of Ca but less of protons on the toxicity and uptake of Cd in F. candida on exposure to simplified soil solutions, which can be described using the principles of a biotic ligand model. Copyright © 2013 SETAC.

Uptake of HNO3 on aviation kerosene and aircraft engine soot: influences of H2O or/and H2SO4.

PubMed

Loukhovitskaya, Ekaterina E; Talukdar, Ranajit K; Ravishankara, A R

2013-06-13

The uptake of HNO3 on aviation kerosene soot (TC-1 soot) was studied in the absence and presence of water vapor at 295 and 243 K. The influence of H2SO4 coating of the TC-1 soot surface on HNO3 uptake was also investigated. Only reversible uptake of HNO3 was observed. HONO and NO2, potential products of reactive uptake of HNO3, were not observed under any conditions studied here. The uptake of nitric acid increased slightly with relative humidity (RH). Coating of the TC-1 soot surface with sulfuric acid decreased the uptake of HNO3 and did not lead to displacement of H2SO4 from the soot surface. A limited set of measurements was carried out on soot generated by aircraft engine combustor (E-soot) with results similar to those on TC-1 soot. The influence of water on HNO3 uptake on E-soot appeared to be more pronounced than on TC-1 soot. Our results suggest that HNO3 loss in the upper troposphere due to soot is not significant except perhaps in aircraft exhaust plumes. Our results also suggest that HNO3 is not converted to either NO2 or HONO upon its uptake on soot in the atmosphere.

Measuring and modeling three-dimensional water uptake of a growing faba bean (Vicia faba) within a soil column

NASA Astrophysics Data System (ADS)

Huber, Katrin; Koebernick, Nicolai; Kerkhofs, Elien; Vanderborght, Jan; Javaux, Mathieu; Vetterlein, Doris; Vereecken, Harry

2014-05-01

water uptake by the roots in the lower and wetter compartments. By comparing transpiration rates of experiments with and without additional paraffin layers, we were able to quantify restrictions of plant growth to available soil water. [1] Javaux, M., T. Schröder, J. Vanderborght, and H. Vereecken (2008), Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake, Vadose Zone Journal, 7(3), 1079-1079. [2] Stingaciu, L., H. Schulz, A. Pohlmeier, S. Behnke, H. Zilken, M. Javaux, H. Vereecken (2013), In Situ Root System Architecture Extraction from Magnetic Resonance Imaging for Water Uptake Modeling, Vadose Zone Journal, 12(1). [3] Koebernick, N., U. Weller, K. Huber, S. Schlüter, H.-J. Vogel, R. Jahn; H. Vereecken, D. Vetterlein, In situ visualisation and quantification of root-system architecture and growth with X-ray CT, Manuscript submitted for publication.

134Cs uptake by four plant species and Cs-K relations in the soil-plant system as affected by Ca(OH)2 application to an acid soil.

PubMed

Massas, I; Skarlou, V; Haidouti, C; Giannakopoulou, F

2010-03-01

Three rates of Ca(OH)(2) were applied to an acid soil and the (134)Cs uptake by radish, cucumber, soybean and sunflower plants was studied. The (134)Cs concentration in all plant species was reduced from 1.6-fold in the sunflower seeds to 6-fold in the soybean vegetative parts at the higher Ca(OH)(2) rate. Potassium (K) concentration in plants was also reduced, but less effectively. The significantly decreased (134)Cs-K soil to plant distribution factors (D.F.) clearly suggest a stronger effect of soil liming on (134)Cs than on K plant uptake. This observation was discussed in terms of ionic interactions in the soil matrix and within the plants. The results also indicated that the increased Ca(2+) concentration in the exchange phase and in the soil solution along with the improved root activity, due to the soil liming, enhanced the immobilization of (134)Cs in the soil matrix and consequently lowered the (134)Cs availability for plant uptake. 2009 Elsevier Ltd. All rights reserved.

The effect of tissue structure and soil chemistry on trace element uptake in fossils

NASA Astrophysics Data System (ADS)

Hinz, Emily A.; Kohn, Matthew J.

2010-06-01

Trace element profiles for common divalent cations (Sr, Zn, Ba), rare-earth elements (REE), Y, U, and Th were measured in fossil bones and teeth from the c. 25 ka Merrell locality, Montana, USA, by using laser-ablation ICP-MS. Multiple traverses in teeth were transformed into 2-D trace element maps for visualizing structural influences on trace element uptake. Trace element compositions of different soils from the fossil site were also analyzed by solution ICP-MS, employing progressive leaches that included distilled H 2O, 0.1 M acetic acid, and microwave digestion in concentrated HCl-HNO 3. In teeth, trace element uptake in enamel is 2-4 orders of magnitude slower than in dentine, forming an effective trace element barrier. Uptake in dentine parallel to the dentine-enamel interface is enhanced by at least 2 orders of magnitude compared to transverse, causing trace element "plumes" down the tooth core. In bone, U, Ba and Sr are nearly homogeneous, implying diffusivities ˜5 orders of magnitude faster than in enamel and virtually complete equilibration with host soils. In contrast all REE show strong depletions inward, with stepwise linear segments in log-normal or inverse complementary error function plots; these data require a multi-medium diffusion model, with about 2 orders of magnitude difference in slowest vs. fastest diffusivities. Differences in REE diffusivities in bone (slow) vs. dentine (fast) reflect different partition coefficients ( Kd's). Although acid leaches and bulk digestion of soils yield comparable fossil-soil Kd's among different elements, natural solutions are expected to be neutral to slightly basic. Distilled H 2O leachates instead reveal radically different Kd's in bone for REE than for U-Sr-Ba, suggest orders of magnitude lower effective diffusivities for REE, and readily explain steep vs. flat profiles for REE vs. U-Sr-Ba, respectively. Differences among REE Kd's and diffusivities may explain inward changes in Ce anomalies. Acid washes

Major controlling factors and prediction models for arsenic uptake from soil to wheat plants.

PubMed

Dai, Yunchao; Lv, Jialong; Liu, Ke; Zhao, Xiaoyan; Cao, Yingfei

2016-08-01

The application of current Chinese agriculture soil quality standards fails to evaluate the land utilization functions appropriately due to the diversity of soil properties and plant species. Therefore, the standards should be amended. A greenhouse experiment was conducted to investigate arsenic (As) enrichment in various soils from 18 Chinese provinces in parallel with As transfer to 8 wheat varieties. The goal of the study was to build and calibrate soil-wheat threshold models to forecast the As threshold of wheat soils. In Shaanxi soils, Wanmai and Jimai were the most sensitive and insensitive wheat varieties, respectively; and in Jiangxi soils, Zhengmai and Xumai were the most sensitive and insensitive wheat varieties, respectively. Relationships between soil properties and the bioconcentration factor (BCF) were built based on stepwise multiple linear regressions. Soil pH was the best predictor of BCF, and after normalizing the regression equation (Log BCF=0.2054 pH- 3.2055, R(2)=0.8474, n=14, p<0.001), we obtained a calibrated model. Using the calibrated model, a continuous soil-wheat threshold equation (HC5=10((-0.2054 pH+2.9935))+9.2) was obtained for the species-sensitive distribution curve, which was built on Chinese food safety standards. The threshold equation is a helpful tool that can be applied to estimate As uptake from soil to wheat. Copyright © 2016 Elsevier Inc. All rights reserved.

Unexpected stimulation of soil methane uptake as emergent property of agricultural soils following bio-based residue application.

PubMed

Ho, Adrian; Reim, Andreas; Kim, Sang Yoon; Meima-Franke, Marion; Termorshuizen, Aad; de Boer, Wietse; van der Putten, Wim H; Bodelier, Paul L E

2015-10-01

Intensification of agriculture to meet the global food, feed, and bioenergy demand entail increasing re-investment of carbon compounds (residues) into agro-systems to prevent decline of soil quality and fertility. However, agricultural intensification decreases soil methane uptake, reducing, and even causing the loss of the methane sink function. In contrast to wetland agricultural soils (rice paddies), the methanotrophic potential in well-aerated agricultural soils have received little attention, presumably due to the anticipated low or negligible methane uptake capacity in these soils. Consequently, a detailed study verifying or refuting this assumption is still lacking. Exemplifying a typical agricultural practice, we determined the impact of bio-based residue application on soil methane flux, and determined the methanotrophic potential, including a qualitative (diagnostic microarray) and quantitative (group-specific qPCR assays) analysis of the methanotrophic community after residue amendments over 2 months. Unexpectedly, after amendments with specific residues, we detected a significant transient stimulation of methane uptake confirmed by both the methane flux measurements and methane oxidation assay. This stimulation was apparently a result of induced cell-specific activity, rather than growth of the methanotroph population. Although transient, the heightened methane uptake offsets up to 16% of total gaseous CO2 emitted during the incubation. The methanotrophic community, predominantly comprised of Methylosinus may facilitate methane oxidation in the agricultural soils. While agricultural soils are generally regarded as a net methane source or a relatively weak methane sink, our results show that methane oxidation rate can be stimulated, leading to higher soil methane uptake. Hence, even if agriculture exerts an adverse impact on soil methane uptake, implementing carefully designed management strategies (e.g. repeated application of specific residues) may

H 2-saturation of high affinity H 2-oxidizing bacteria alters the ecological niche of soil microorganisms unevenly among taxonomic groups

DOE PAGES

Piché-Choquette, Sarah; Tremblay, Julien; Tringe, Susannah G.; ...

2016-03-10

Soil microbial communities are continuously exposed to H 2 diffusing into the soil from the atmosphere. N 2-fixing nodules represent a peculiar microniche in soil where H 2 can reach concentrations up to 20,000 fold higher than in the global atmosphere (0.530 ppmv). In this study, we investigated the impact of H 2 exposure on soil bacterial community structure using dynamic microcosm chambers simulating soil H 2 exposure from the atmosphere and N 2-fixing nodules. Biphasic kinetic parameters governing H 2 oxidation activity in soil changed drastically upon elevated H 2 exposure, corresponding to a slight but significant decay ofmore » high affinity H 2-oxidizing bacteria population, accompanied by an enrichment or activation of microorganisms displaying low-affinity for H 2. In contrast to previous studies that unveiled limited response by a few species, the relative abundance of 958 bacterial ribotypes distributed among various taxonomic groups, rather than a few distinct taxa, was influenced by H 2 exposure. Furthermore, correlation networks showed important alterations of ribotype covariation in response to H 2 exposure, suggesting that H 2 affects microbe-microbe interactions in soil. Taken together, our results demonstrate that H 2-rich environments exert a direct influence on soil H 2-oxidizing bacteria in addition to indirect effects on other members of the bacterial communities.« less

H2-saturation of high affinity H2-oxidizing bacteria alters the ecological niche of soil microorganisms unevenly among taxonomic groups

PubMed Central

Piché-Choquette, Sarah; Tremblay, Julien; Tringe, Susannah G.

2016-01-01

Soil microbial communities are continuously exposed to H2 diffusing into the soil from the atmosphere. N2-fixing nodules represent a peculiar microniche in soil where H2 can reach concentrations up to 20,000 fold higher than in the global atmosphere (0.530 ppmv). In this study, we investigated the impact of H2 exposure on soil bacterial community structure using dynamic microcosm chambers simulating soil H2 exposure from the atmosphere and N2-fixing nodules. Biphasic kinetic parameters governing H2 oxidation activity in soil changed drastically upon elevated H2 exposure, corresponding to a slight but significant decay of high affinity H2-oxidizing bacteria population, accompanied by an enrichment or activation of microorganisms displaying low-affinity for H2. In contrast to previous studies that unveiled limited response by a few species, the relative abundance of 958 bacterial ribotypes distributed among various taxonomic groups, rather than a few distinct taxa, was influenced by H2 exposure. Furthermore, correlation networks showed important alterations of ribotype covariation in response to H2 exposure, suggesting that H2 affects microbe-microbe interactions in soil. Taken together, our results demonstrate that H2-rich environments exert a direct influence on soil H2-oxidizing bacteria in addition to indirect effects on other members of the bacterial communities. PMID:26989620

Impact of soil water regime on degradation and plant uptake behaviour of the herbicide isoproturon in different soil types.

PubMed

Grundmann, Sabine; Doerfler, Ulrike; Munch, Jean Charles; Ruth, Bernhard; Schroll, Reiner

2011-03-01

The environmental fate of the worldwide used herbicide isoproturon was studied in four different, undisturbed lysimeters in the temperate zone of Middle Europe. To exclude climatic effects due to location, soils were collected at different regions in southern Germany and analyzed at a lysimeter station under identical environmental conditions. (14)C-isoproturon mineralization varied between 2.59% and 57.95% in the different soils. Barley plants grown on these lysimeters accumulated (14)C-pesticide residues from soil in partially high amounts and emitted (14)CO(2) in an extent between 2.01% and 13.65% of the applied (14)C-pesticide. Plant uptake and (14)CO(2) emissions from plants were inversely linked to the mineralization of the pesticide in the various soils: High isoproturon mineralization in soil resulted in low plant uptake whereas low isoproturon mineralization in soil resulted in high uptake of isoproturon residues in crop plants and high (14)CO(2) emission from plant surfaces. The soil water regime was identified as an essential factor that regulates degradation and plant uptake of isoproturon whereby the intensity of the impact of this factor is strongly dependent on the soil type. Copyright © 2010 Elsevier Ltd. All rights reserved.

Improving prediction of metal uptake by Chinese cabbage (Brassica pekinensis L.) based on a soil-plant stepwise analysis.

PubMed

Zhang, Sha; Song, Jing; Gao, Hui; Zhang, Qiang; Lv, Ming-Chao; Wang, Shuang; Liu, Gan; Pan, Yun-Yu; Christie, Peter; Sun, Wenjie

2016-11-01

It is crucial to develop predictive soil-plant transfer (SPT) models to derive the threshold values of toxic metals in contaminated arable soils. The present study was designed to examine the heavy metal uptake pattern and to improve the prediction of metal uptake by Chinese cabbage grown in agricultural soils with multiple contamination by Cd, Cu, Ni, Pb, and Zn. Pot experiments were performed with 25 historically contaminated soils to determine metal accumulation in different parts of Chinese cabbage. Different soil bioavailable metal fractions were determined using different extractants (0.43M HNO3, 0.01M CaCl2, 0.005M DTPA, and 0.01M LWMOAs), soil moisture samplers, and diffusive gradients in thin films (DGT), and the fractions were compared with shoot metal uptake using both direct and stepwise multiple regression analysis. The stepwise approach significantly improved the prediction of metal uptake by cabbage over the direct approach. Strongly pH dependent or nonlinear relationships were found for the adsorption of root surfaces and in root-shoot uptake processes. Metals were linearly translocated from the root surface to the root. Therefore, the nonlinearity of uptake pattern is an important explanation for the inadequacy of the direct approach in some cases. The stepwise approach offers an alternative and robust method to study the pattern of metal uptake by Chinese cabbage (Brassica pekinensis L.). Copyright © 2016. Published by Elsevier B.V.

Experimental warming of a mountain tundra increases soil CO2 effluxes and enhances CH4 and N2O uptake at Changbai Mountain, China

PubMed Central

Zhou, Yumei; Hagedorn, Frank; Zhou, Chunliang; Jiang, Xiaojie; Wang, Xiuxiu; Li, Mai-He

2016-01-01

Climatic warming is expected to particularly alter greenhouse gas (GHG) emissions from soils in cold ecosystems such as tundra. We used 1 m2 open-top chambers (OTCs) during three growing seasons to examine how warming (+0.8–1.2 °C) affects the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from alpine tundra soils. Results showed that OTC warming increased soil CO2 efflux by 141% in the first growing season and by 45% in the second and third growing season. The mean CH4 flux of the three growing seasons was −27.6 and −16.7 μg CH4-C m−2h−1 in the warmed and control treatment, respectively. Fluxes of N2O switched between net uptake and emission. Warming didn’t significantly affect N2O emission during the first and the second growing season, but stimulated N2O uptake in the third growing season. The global warming potential of GHG was clearly dominated by soil CO2 effluxes (>99%) and was increased by the OTC warming. In conclusion, soil temperature is the main controlling factor for soil respiration in this tundra. Climate warming will lead to higher soil CO2 emissions but also to an enhanced CH4 uptake with an overall increase of the global warming potential for tundra. PMID:26880107

Variability of Deuterium Fractionation Associated With Soil Uptake of Atmospheric Molecular Hydrogen

NASA Astrophysics Data System (ADS)

Rahn, T.; Randerson, J. T.; Eiler, J.

2005-12-01

Molecular hydrogen (H2) is the second most abundant reduced gas in the atmosphere (after methane) with a globally averaged mixing ratio of ~530 nmol/mol. Its largest sources are photochemical oxidation of methane and non-methane hydrocarbons with other recognized sources that include biomass burning, fossil fuel burning, nitrogen fixation, and ocean degassing. These sources are balanced by reaction of H2 with hydroxyl radicals (~25%) in the atmosphere and by deposition at the terrestrial soil surface (~75%). As with other atmospheric trace gases, the stable isotopic content of H2 has the potential to help quantify the various aspects of its production and destruction. The average deuterium content of H2 is dDH2 = ~130 ‰ relative to Standard Mean Ocean Water. While recent studies have begun to elucidate the deuterium content of the individual sources of H2 and the fractionation associated with hydroxyl oxidation has been well established in the laboratory, there are still few data documenting the fractionation associated with soil uptake. We measured the fractionation associated with soil uptake in May, June and August of 2002 in three upland ecosystems that were part of an Alaskan fire chronosequence. Fire occurred at these sites in 1999, 1987, and ~1920. Grasses and herbaceous vegetation establish initially after fire and are gradually replaced by deciduous trees and finally by evergreen trees and moss. All three sites were in interior Alaska near the town of Delta Junction (63° 54'N, 145° 40'W). Fluxes were measured with a Plexiglas flux chamber (8 liter volume) with a manifold of four ~400 ml double-valved glass flasks in parallel and a diaphragm pump for circulation (5 SLPM). Flasks were continuously flushed by the circulating system and isolated sequentially; they were then returned to the laboratory at Caltech for subsequent analysis. In the field, the chamber was seated on Plexiglas collars that were installed prior to initiating the study and left in

Cadmium dynamics in soil pore water and uptake by rice: Influences of soil-applied selenite with different water managements.

PubMed

Wan, Yanan; Camara, Aboubacar Younoussa; Yu, Yao; Wang, Qi; Guo, Tianliang; Zhu, Lina; Li, Huafen

2018-05-11

Cadmium (Cd) in rice grains is a potential threat to human health. This study investigated the effects of selenite fertilisation (0 mg kg -1 , 0.5 mg kg -1 , and 1.0 mg kg -1 ) on soil solution Cd dynamics and rice uptake. Rice was grown in two Cd-contaminated soils in Jiangxi and Hunan Provinces under two different sets of conditions: aerobic and flooded. The experiments were conducted in pots. The plants were harvested at the seedling stage and at maturity to determine their Cd levels. Soil solutions were also extracted during the growing season to monitor Cd dynamics. The results showed that in the Jiangxi soil (pH 5.25), Cd concentrations in the soil solutions, seedlings, and mature rice plants were higher under aerobic than under flooded water management conditions. In the Hunan soil (pH 7.26), however, flooding decreased Cd levels in the rice seedlings but not in mature plants. Selenite additions to the Hunan soil decreased Cd concentrations in the soil solutions and in the mature rice plants. These effects were not observed for the solutions or the plants from Jiangxi soil amended with selenite. Relative to the control treatment, 0.5 mg kg -1 selenite decreased the rice grain Cd content by 45.2% and 67.7% under aerobic and flooding conditions, respectively. The results demonstrated that water management regimes affected rice Cd uptake more effectively in Jiangxi than in Hunan soil, whereas selenite addition was more effective in Hunan than in Jiangxi soil. Selenite addition was also more effective at reducing rice grain Cd levels when it was applied under flooding than under aerobic conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cadmium and Zn availability as affected by pH manipulation and its assessment by soil extraction, DGT and indicator plants.

PubMed

Muhammad, Iqbal; Puschenreiter, Markus; Wenzel, Walter W

2012-02-01

Manipulation of soil pH by soil additives and / or rhizosphere processes may enhance the efficiency of metal phytoextraction. Here we report on the effect of nitric acid additions to four polluted soils on Cd and Zn concentrations in soil solution (C(soln)) and 0.005M Ca(NO(3))(2) extracts, and related changes in the diffusive fluxes and resupply of the metals as assessed by diffusive gradients in thin films (DGT). The responses of these chemical indicators of bioavailability were compared to metal uptake in two indicator plant species, common dandelion (Taraxacum officinale F.H. Wigg) and narrow leaf plantain (Plantago lanceolata L.) grown for 75days in a pot experiment. Lowering soil pH increased C(soln), the 0.005M Ca(NO(3))(2)-soluble fractions and the DGT-measured Cd and Zn concentrations (C(DGT)) in the experimental soils. This was associated with enhanced uptake of Cd and Zn on soils acidified to pH 4.5 whereas plants did not survive at pH 3.5. Toxicity along with decreased kinetics of metal resupply (calculated by the 2D DIFS model) in the strong acidification treatment suggests that moderate acidification is more appropriate to enhance the phytoextraction process. Each of the chemical indicators of bioavailability predicted well (R(2)>0.70) the Cd and Zn concentrations in plantain shoots but due to metal toxicity not for dandelion. Concentration factors, i.e. the ratio between metal concentrations in shoots and in soil solution (CF) indicate that Cd and Zn uptake in plantain was not limited by diffusion which may explain that DGT did not perform better than C(soln). However, DGT is expected to predict plant uptake better in diffusion-limited conditions such as in the rhizosphere of metal-accumulating phytoextraction crops. Copyright © 2011 Elsevier B.V. All rights reserved.

Zinc-arsenic interactions in soil: Solubility, toxicity and uptake.

PubMed

Kader, Mohammed; Lamb, Dane T; Wang, Liang; Megharaj, Mallavarapu; Naidu, Ravi

2017-11-01

Arsenic (As) and zinc (Zn) are common co-contaminants in mining impacted soils. Their interaction on solubility and toxicity when present concurrently is not well understood in natural systems. The aim of this study was to observe their interaction in solubility (soil-solution), bioaccumulation (shoot uptake) and toxicity to cucumber (Cucumis sativa L) conducting 4 weeks pot study in 5 different soils spiked with As (0, 2, 4, 8 to 1024 mg kg -1 ) individually and with Zn at two phytotoxic doses. The As pore-water concentration was significantly reduced (df = 289, Adjusted R 2  = 0.84, p < 0.01) in the presence of Zn in the whole dataset, whereas Zn and Zn 2+ activity in pore-water was reduced significantly only in the two alkaline soils. This outcome may be due to adsorption/surface precipitation or tertiary bridging complexation. No homogenous precipitation of zinc arsenate could be established using electron microscopy, XRD or even equilibrium calculations. For bioaccumulation phase, no significant effect of Zn on As uptake was observed except acidic MG soil whereas, Zn uptake was significantly reduced (p < 0.05) by As in whole dataset. However, an additive response was observed mostly except acidic MG soil. The synergistic response (more than additive) was predominant in this soil for a wide range of inhibition concentration (0-80%) at both Zn EC10 and EC50 levels. Since additive response is mostly considered in risk assessment for mixtures, precautions should be implemented for assessment of toxicity for As-Zn mixture in acidic soil due to their synergistic response in some soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crop uptake and extractability of cadmium in soils naturally high in metals at different pH levels

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

Singh, B.R.; Almas, A.; Narwal, R.P.

1995-12-01

A greenhouse experiment was conducted for three years to study the effect of different pH levels on metal concentrations in plants and the cadmium (Cd) extractability by DTPA and NH{sub 4}NO{sub 3}. The soils used were an alum shale (clay loam) and a moraine (loam), which were adjusted to pH levels of 5.5, 6.5, 7.0, and 7.5. Wheat (Triticum aestivum), carrot (Daucus carota L.), and lettuce (Lactuca sativa) were grown as test crops. Crop yields were not consistently affected at increasing soil pH levels. The concentration of Cd in plant species decreased with increasing soil pH in both soils andmore » in all three years. Significant concentration differences between soil pH levels were only seen in wheat and carrot crops. Increasing soil pH also decreased the nickel (Ni) and zinc (Zn) concentrations in plants in the first year crop but the copper (Cu) concentration was not consistently affected by soil pH. The effect of pH was more pronounced in the moraine then the alum shale soil. The DTPA-and NH{sub 4}NO{sub 3}-extractable Cd was decreased with the increasing soil pH and the pH effect was more pronounced with NH{sub 4}NO{sub 3} extractable Cd. Both extractants were found equally effective in relation to the Cd concentration in plants in this study. 33 refs., 2 figs., 7 tabs.« less

Soil CO2 venting as one of the mechanisms for tolerance of Zn deficiency by rice in flooded soils.

PubMed

Affholder, Marie-Cecile; Weiss, Dominik J; Wissuwa, Matthias; Johnson-Beebout, Sarah E; Kirk, Guy J D

2017-12-01

We sought to explain rice (Oryza sativa) genotype differences in tolerance of zinc (Zn) deficiency in flooded paddy soils and the counter-intuitive observation, made in earlier field experiments, that Zn uptake per plant increases with increasing planting density. We grew tolerant and intolerant genotypes in a Zn-deficient flooded soil at high and low planting densities and found (a) plant Zn concentrations and growth increased with planting density and more so in the tolerant genotype, whereas the concentrations of other nutrients decreased, indicating a specific effect on Zn uptake; (b) the effects of planting density and genotype on Zn uptake could only be explained if the plants induced changes in the soil to make Zn more soluble; and (c) the genotype and planting density effects were both associated with decreases in dissolved CO 2 in the rhizosphere soil solution and resulting increases in pH. We suggest that the increases in pH caused solubilization of soil Zn by dissolution of alkali-soluble, Zn-complexing organic ligands from soil organic matter. We conclude that differences in venting of soil CO 2 through root aerenchyma were responsible for the genotype and planting density effects. © 2017 John Wiley & Sons Ltd.

Influence of soil pH on the toxicity of zinc oxide nanoparticles to the terrestrial isopod Porcellionides pruinosus.

PubMed

Tourinho, Paula S; van Gestel, Cornelis A M; Lofts, Stephen; Soares, Amadeu M V M; Loureiro, Susana

2013-12-01

The effects of soil pH on the toxicity of ZnO nanoparticles (NPs) to the terrestrial isopod Porcellionides pruinosus were evaluated. Isopods were exposed to a natural soil amended with CaCO3 to reach 3 different pH(CaCl2) levels (4.5, 6.2, and 7.3) and to standard LUFA 2.2 soil (pH 5.5) spiked with ZnO NPs (30 nm), non-nano ZnO (200 nm), and ionic Zn as ZnCl₂. Toxicity was expressed based on total Zn concentration in soil, as well as total Zn and free Zn²⁺ ion concentrations in porewater. Compared with ZnO-spiked soils, the ZnCl₂-spiked soils had lower pH and higher porewater Ca²⁺ and Zn levels. Isopod survival did not differ between Zn forms and soils, but survival was higher for isopods exposed to ZnO NPs at pH 4.5. Median effect concentrations (EC50s) for biomass change showed similar trends for all Zn forms in all soils, with higher values at intermediate pH. Median lethal concentration (LC50) and EC50 values based on porewater Zn or free Zn ion concentrations were much lower for ZnO than for ionic zinc. Zn body concentrations increased in a dose-related manner, but no effect of soil pH was found. It is suggested not only that dissolved or free Zn in porewater contributed to uptake and toxicity, but also that oral uptake (i.e., ingestion of soil particles) could be an important additional route of exposure. © 2013 SETAC.

A Coupled Soil-Atmosphere Model of H2O2 on Mars

NASA Technical Reports Server (NTRS)

Bullock, Mark A.; Stoker, Carol R.; Mckay, Christopher P.; Zent, Aaron P.

1994-01-01

The Viking Gas Chromatograph Mass Spectrometer failed to detect organic compounds on Mars, and both the Viking Labeled Release and the Viking Gas Exchange experiments indicated a reactive soil surface. These results have led to the widespread belief that there are oxidants in the martian soil. Since H2O2 is produced by photochemical processes in the atmosphere of Mars, and has been shown in the laboratory to reproduce closely the Viking LR results, it is a likely candidate for a martian soil oxidant. Here, we report on the results of a coupled soil/atmosphere transport model for H202 on Mars. Upon diffusing into the soil, its concentration is determined by the extent to which it is adsorbed and by the rate at which it is catalytically destroyed. An analytical model for calculating the distribution of H202 in the martian atmosphere and soil is developed. The concentration of H202 in the soil is shown to go to zero at a finite depth, a consequence of the nonlinear soil diffusion equation. The model is parameterized in terms of an unknown quantity, the lifetime of H202 against heterogeneous catalytic destruction in the soil. Calculated concentrations are compared with a H202 concentration of 30 nmoles/cu cm, inferred from the Viking Labeled Release experiment. A significant result of this model is that for a wide range of H202 lifetimes (up to 105 years), the extinction depth was found to be less than 3 m. The maximum possible concentration in the top 4 cm is calculated to be approx. 240 nmoles/cu cm, achieved with lifetimes of greater than 1000 years. Concentrations higher than 30 nmoles/cu cm require lifetimes of greater than 4.3 terrestrial years. For a wide range of H202 lifetimes, it was found that the atmospheric concentration is only weakly coupled with soil loss processes. Losses to the soil become significant only when lifetimes are less than a few hours. If there are depths below which H202 is not transported, it is plausible that organic compounds

The effect of elevated CO2 and temperature on nutrient uptake by plants grown in basaltic soil

NASA Astrophysics Data System (ADS)

Villasenor Iribe, E.; Dontsova, K.; Juarez, S.; Le Galliard, J. F.; Chollet, S.; Llavata, M.; Massol, F.; Barré, P.; Gelabert, A.; Daval, D.; Troch, P.; Barron-Gafford, G.; Van Haren, J. L. M.; Ferrière, R.

2017-12-01

Mineral weathering is an important process in soil formation. The interactions between the hydrologic, geologic and atmospheric cycles often determine the rate at which weathering occurs. Elements and nutrients weathered from the soil by water can be removed from soils in the runoff and seepage, but they can also remain in situ as newly precipitated secondary minerals or in biomass as a result of plant uptake. Here we present data from an experiment that was conducted at the controlled environment facility, Ecotron Ile-de-France (Saint-Pierre-les-Nemours, France) that studied mineral weathering and plant growth in granular basaltic material with high glass content that is being used to simulate soil in large scale Biosphere 2 Landscape Evolution Observatory (LEO) project. The experiment used 3 plant types: velvet mesquite (Prosopis velutina), green spangletop (Leptochloa dubia), and alfalfa (Medicago sativa), which were grown under varying temperature and CO2 conditions. We hypothesized that plants grown under warmer, higher CO2 conditions would have larger nutrient concentrations as more mineral weathering would occur. Results of plant digestions and analysis showed that plant concentrations of lithogenic elements were significantly influenced by the plant type and were different between above- and below-ground parts of the plant. Temperature and CO2 treatment effects were less pronounced, but we observed significant temperature effect on plant uptake. A number of major and trace elements showed increase in concentration with increase in temperature at elevated atmospheric CO2. Effect was observed both in the shoots and in the roots, but more significant differences were observed in the shoots. Results presented here indicate that climate change would have strong effect on plant uptake and mobility of weathered elements during soil formation and give further evidence of interactions between abiotic and biological processes in terrestrial ecosystems.

Effect of hydration status on pesticide uptake in anurans following exposure to contaminated soils.

PubMed

Glinski, Donna A; Henderson, W Matthew; Van Meter, Robin J; Purucker, S Thomas

2018-06-01

In this study, the impact of hydration status on dermal uptake of pesticides in two species of amphibians is examined. Absorption of pesticides in anurans occurs primarily through a highly vascularized dermal seat patch; however, pesticides can also enter through the superficial dermis following exposure. Despite the growing body of literature on dermal exposure in amphibians, little is known on how hydration status influences uptake. Thus, the objective of this study was to investigate the influence of hydration status on absorption of pesticides (atrazine, triadimefon, metolachlor, chlorothalonil, and imidacloprid) in southern leopard frogs (Lithobates sphenocephala) and Fowler's toads (Anaxyrus fowleri). Amphibian treatments included dehydration periods of 0, 2, 4, 6, 8, or 10 h prior to exposure to pesticide-contaminated soils for 8 h. Following exposure, soil and whole-body homogenates were extracted and analyzed by LC-MS/MS. Dehydration time was then regressed against post-exposure concentrations to infer the impact of dehydration on dermal pesticide uptake. Increased dehydration time resulted in significantly lowered pesticide concentrations in both species (F 6, 293  = 67.66, p = 0.007) for the five pesticides studied. This phenomenon could be due to an energy and/or dilution effect.

Impacts of industrial waste resources on maize (Zea mays L.) growth, yield, nutrients uptake and soil properties.

PubMed

Singh, Satnam; Young, Li-Sen; Shen, Fo-Ting; Young, Chiu-Chung

2014-10-01

Discharging untreated highly acidic (pH<4.0), organic and nutrients rich monosodium glutamate wastewater (MW), and highly alkaline (pH>10.0) paper-mill wastewater (PW) causes environmental pollution. When acidity of MW neutralized (pH 6.5±0.1) with PW and lime (treatments represented as MW+PW and MW+Lime), then MW may be utilized as a potential source of nutrients and organic carbon for sustainable food production. Objectives of this study were to compare the effects of PW and lime neutralized MW and chemical fertilizers on maize (Zea mays L. cv. Snow Jean) plant growth, yield, nutrients uptake, soil organic matter and humic substances. The field experiment was carried out on maize using MW at 6000 L ha(-1). Impacts of the MW application on maize crop and soil properties were evaluated at different stages. At harvest, plant height, and plant N and K uptake were higher in MW treatment. Leaf area index at 60 days after sowing, plant dry matter accumulation at harvest, and kernels ear(-1) and 100-kernel weight were higher in MW+Lime treatment. Kernel N, P, K, Mn, Fe and Zn, and plant Zn uptake were highest in MW+Lime. Plant Fe uptake, and soil organic matter and humic substances were highest in MW+PW. The MW+PW and MW+Lime treatments exhibited comparable results with chemically fertilized treatment. The MW acidity neutralized with lime showed positive impacts on growth, yield and nutrients uptake; nevertheless, when MW pH neutralized with PW has an additional benefit on increase in soil organic matter and humic substances. Copyright © 2014. Published by Elsevier Ltd.

Uptake and metabolism of 10:2 fluorotelomer alcohol in soil-earthworm (Eisenia fetida) and soil-wheat (Triticum aestivum L.) systems.

PubMed

Zhao, Shuyan; Zhu, Lingyan

2017-01-01

The behavior of 10:2 fluorotelomer alcohol (10:2 FTOH) in the systems of soil-earthworm (Eisenia fetida), soil-wheat (Triticum aestivum L.) and soil-earthworm-wheat, including degradation in soil, uptake and metabolism in wheat and earthworms were investigated. Several perfluorocarboxylic acids (PFCAs) as degradation products of 10:2 FTOH were identified in the soil, plant and earthworms. 10:2 FTOH could be biodegraded to perfluorooctanoate (PFOA), perfluorononanate (PFNA) and perfluorodecanoate (PFDA) in soil in the absence or presence of wheat/earthworms, and PFDA was the predominant metabolite. Accumulation of initial 10:2 FTOH and its metabolites were observed in the wheat and earthworms, suggesting that 10:2 FTOH could be bioaccumulated in wheat and earthworms and biotransformed to the highly stable PFCAs. Perfluoropentanoic acid (PFPeA), perfluorohexanoic (PFHxA) and PFDA were detected in wheat root, while PFDA and perfluoroundecanoic acid (PFUnDA) were detected in shoot. PFNA and PFDA were determined in earthworms and the concentration of PFDA was much higher. The presence of earthworms and/or plant stimulated the microbial degradation of 10:2 FTOH in soil. The results supplied important evidence that degradation of 10:2 FTOH was an important potential source of PFCAs in the environment and in biota. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatial 2D distribution of the proportion of soil phosphorus uptake by maize and soybean caused by tillage and fertilization

NASA Astrophysics Data System (ADS)

Li, Haixiao; Mollier, Alain; Ziadi, Noura; Messiga, Aimé Jean; Parent, Leon-Étienne; Morel, Christian

2017-04-01

Plant-available soil phosphorus (P) accumulates primarily in the topsoil due to P fertilization and P released from crop residues. In contrast with conventional tillage (moldboard plough, MP), conservation tillage [e.g. no-till, (NT)] often leads to higher P concentrations in the topsoil mainly due to the absence of mixing between soil, fertilizer, and crop residues. Our objective was to estimate the proportion of P uptake from a given soil mass across the soil profile under maize and soybean as the product of root surface density proportions and local plant-available soil P. This study was conducted on a long-term field experiment initiated in 1992 in southern Quebec, Canada, and established on a clay-loam soil under MP and NT systems. The experiment was factorially treated with three P doses (0, 17.5 and 35 kg P ha-1 applied as triple superphosphate on maize at 5 cm depth and at 5 cm on one side of the crop row). Soil was sampled at flowering stage at five depths (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and three horizontal distances perpendicular to the crop row (5, 15 and 25 cm) in 2014 and 2015 to map a grid soil P availability to plants, e.g. phosphate ion concentrations in solution and the time-dependent amount of phosphate ions that can equilibrate- solution by diffusion, root distribution, and consequently crop P uptake, which was calculated as the fraction of plant-available soil P intercepted by surface roots. In general, NT tended to have higher soil P status in the upper soil layer and lower soil P status in the deeper soil layer compared to MP ; confirming previous results obtained from the same experimental site. This variation along the soil profile was significantly affected by sampling distance to crop row with higher concentration observed at 5-cm distance mainly because of the placement of P fertilizers. The 2D distribution of P uptake depended on tillage practice and P fertilization. There was higher proportions of P uptake from the 0-10 and 0

Plant-uptake of uranium: Hydroponic and soil system studies

USGS Publications Warehouse

Ramaswami, A.; Carr, P.; Burkhardt, M.

2001-01-01

Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus giganteus), Spring Vetch (Vicia sativa), Hairy Vetch (Vicia villosa), Juniper (Juniperus monosperma), Indian Mustard (Brassica juncea), and Bush Bean (Phaseolus nanus). Plant performance was evaluated both in terms of the percent uranium extracted from the three systems, as well as the biological absorption coefficient (BAC) that normalized uranium uptake to plant biomass. Study results indicate that uranium extraction efficiency decreased sharply across hydroponic, sandy and organic soil systems, indicating that soil organic matter sequestered uranium, rendering it largely unavailable for plant uptake. These results indicate that site-specific soils must be used to screen plants for uranium extraction capability; plant behavior in hydroponic systems does not correlate well with that in soil systems. One plant species, Juniper, exhibited consistent uranium extraction efficiencies and BACs in both sandy and organic soils, suggesting unique uranium extraction capabilities.

Roles of H2 uptake hydrogenases in Shigella flexneri acid tolerance

PubMed Central

McNorton, Mykeshia M.

2012-01-01

Hydrogenases play many roles in bacterial physiology, and use of H2 by the uptake-type enzymes of animal pathogens is of particular interest. Hydrogenases have never been studied in the pathogen Shigella, so targeted mutant strains were individually generated in the two Shigella flexneri H2-uptake enzymes (Hya and Hyb) and in the H2-evolving enzyme (Hyc) to address their roles. Under anaerobic fermentative conditions, a Hya mutant strain (hya) was unable to oxidize H2, while a Hyb mutant strain oxidized H2 like the wild-type. A hyc strain oxidized more exogenously added hydrogen than the parent. Fluorescence ratio imaging with dye JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide) showed that the parent strain generated a membrane potential 15 times greater than hya. The hya mutant was also by far the most acid-sensitive strain, being even more acid-sensitive than a mutant strain in the known acid-combating glutamate-dependent acid-resistance pathway (GDAR pathway). In severe acid-challenge experiments, the addition of glutamate to hya restored survivability, and this ability was attributed in part to the GDAR system (removes intracellular protons) by mutant strain (e.g. hya/gadBC double mutant) analyses. However, mutant strain phenotypes indicated that a larger portion of the glutamate-rescued acid tolerance was independent of GadBC. The acid tolerance of the hya strains was aided by adding chloride ions to the growth medium. The whole-cell Hya enzyme became more active upon acid exposure (20 min), based on assays of hyc. Indeed, the very high rates of Shigella H2 oxidation by Hya in acid can supply each cell with 2.4×108 protons min−1. Electrons generated from Hya-mediated H2 oxidation at the inner membrane likely counteract cytoplasmic positive charge stress, while abundant proton pools deposited periplasmically likely repel proton influx during severe acid stress. PMID:22628482

Effects of soil pH and aluminum on plant respiration

Treesearch

Rakesh Minocha; Subhash C. Minocha

2005-01-01

Interactions among external (soil) pH, cellular pH, and their effects on respiratory metabolism are complex. While the effects of changes in the apoplastic pH on the cytosolic pH are not clearly understood, pH directly affects enzymatic reactions in the cell, and pH-regulated ion uptake has profound indirect effects on cellular respiratory metabolism. A major...

Uptakes of Cs and Sr on San Joaquin soil measured following ASTM method C1733.

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

Ebert, W.L.; Petri, E.T.

2012-04-04

Series of tests were conducted following ASTM Standard Procedure C1733 to evaluate the repeatability of the test and the effects of several test parameters, including the solution-to-soil mass ratio, test duration, pH, and the concentrations of contaminants in the solution. This standard procedure is recommended for measuring the distribution coefficient (K{sub d}) of a contaminant in a specific soil/groundwater system. One objective of the current tests was to identify experimental conditions that can be used in future interlaboratory studies to determine the reproducibility of the test method. This includes the recommendation of a standard soil, the range of contaminant concentrationsmore » and solution matrix, and various test parameters. Quantifying the uncertainty in the distribution coefficient that can be attributed to the test procedure itself allows the differences in measured values to be associated with differences in the natural systems being studied. Tests were conducted to measure the uptake of Cs and Sr dissolved as CsCl and Sr(NO{sub 3}){sub 2} in a dilute NaHCO{sub 3}/SiO{sub 2} solution (representing contaminants in a silicate groundwater) by a NIST standard reference material of San Joaquin soil (SRM 2709a). Tests were run to measure the repeatability of the method and the sensitivity of the test response to the reaction time, the mass of soil used (at a constant soil-to-solution ratio), the solution pH, and the contaminant concentration. All tests were conducted in screw-top Teflon vessels at 30 C in an oven. All solutions were passed through a 0.45-{mu}m pore size cellulose acetate membrane filter and stabilized with nitric acid prior to analysis with inductively-coupled plasma mass spectrometry (ICP-MS). Scoping tests with soil in demineralized water resulted in a solution pH of about 8.0 and the release of small amounts of Sr from the soil. Solutions were made with targeted concentrations of 1 x 10{sup -6} m, 1 x 10{sup -5} m, 2.5 x 10{sup

Metal(loid)-resistant bacteria reduce wheat Cd and As uptake in metal(loid)-contaminated soil.

PubMed

Wang, Xiao-Han; Luo, Wei-Wei; Wang, Qi; He, Lin-Yan; Sheng, Xia-Fang

2018-06-05

This study characterized the effect of the metal(loid)-resistant bacteria Ralstonia eutropha Q2-8 and Exiguobacterium aurantiacum Q3-11 on Cd and As accumulation in wheat grown in Cd- and As-polluted soils (1 mg kg -1 of Cd + 40 mg kg -1 of As and 2 mg kg -1 of Cd + 60 mg kg -1 of As). The influence of strains Q2-8 and Q3-11 on water-soluble Cd and As and NH 4 + concentration and pH in the soil filtrate were also analyzed. Inoculation with these strains significantly reduced wheat plant Cd (12-32%) and As (9-29%) uptake and available Cd (15-28%) and As (22-38%) contents in rhizosphere soils compared to the controls. Furthermore, these strains significantly increased the relative abundances of the arsM bacterial As metabolism gene and of Fe- and Mn-oxidizing Leptothrix species in rhizosphere soils. Notably, these strains significantly reduced water-soluble Cd and As concentrations and increased pH and NH 4 + concentration in the soil filtrate. These results suggest that these strains increased soil pH and the abundance of genes possibly involved in metal(loid) unavailability, resulting in reduced wheat Cd and As accumulation and highlight the possibility of using bacteria for in situ remediation and safe production of wheat or other food crops in metal(loid)-polluted soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ethanol stimulates glucose uptake and translocation of GLUT-4 in H9c2 myotubes via a Ca(2+)-dependent mechanism.

PubMed

Yu, B; Schroeder, A; Nagy, L E

2000-12-01

Short-term exposure to ethanol impairs glucose homeostasis, but the effects of ethanol on individual components of the glucose disposal pathway are not known. To understand the mechanisms by which ethanol disrupts glucose homeostasis, we have investigated the direct effects of ethanol on glucose uptake and translocation of GLUT-4 in H9c2 myotubes. Short-term treatment with 12.5-50 mM ethanol increased uptake of 2-deoxyglucose by 1.8-fold in differentiated myotubes. Pretreatment of H9c2 myotubes with 100 nM wortmannin, an inhibitor of phosphatidylinositol 3-kinase, had no effect on ethanol-induced increases in 2-deoxyglucose uptake. In contrast, preincubation with 25 microM dantrolene, an inhibitor of Ca(2+) release from the sarcoplasmic reticulum, blocked the stimulation of 2-deoxyglucose uptake by ethanol. Increased 2-deoxyglucose uptake after ethanol treatment was associated with a decrease in small intracellular GLUT-4 vesicles and an increase in GLUT-4 localized at the cell surface. In contrast, ethanol had no effect on the quantity of GLUT-1 and GLUT-3 at the plasma membrane. These data demonstrate that physiologically relevant concentrations of ethanol disrupt the trafficking of GLUT-4 in H9c2 myotubes resulting in translocation of GLUT-4 to the plasma membrane and increased glucose uptake.

Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

DOE PAGES

Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; ...

2016-03-21

Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO 2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States foundmore » soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, >800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. Furthermore, while COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.« less

Mechanisms for the increase in phosphorus uptake of waterlogged plants: soil phosphorus availability, root morphology and uptake kinetics.

PubMed

Rubio, Gerardo; Oesterheld, Martín; Alvarez, Carina R; Lavado, Raúl S

1997-10-01

Waterlogging frequently reduces plant biomass allocation to roots. This response may result in a variety of alterations in mineral nutrition, which range from a proportional lowering of whole-plant nutrient concentration as a result of unchanged uptake per unit of root biomass, to a maintenance of nutrient concentration by means of an increase in uptake per unit of root biomass. The first objective of this paper was to test these two alternative hypothetical responses. In a pot experiment, we evaluated how plant P concentration of Paspalum dilatatum, (a waterlogging-tolerant grass from the Flooding Pampa, Argentina) was affected by waterlogging and P supply and how this related to changes in root-shoot ratio. Under both soil P levels waterlogging reduced root-shoot ratios, but did not reduce P concentration. Thus, uptake of P per unit of root biomass increased under waterlogging. Our second objective was to test three non-exclusive hypotheses about potential mechanisms for this increase in P uptake. We hypothesized that the greater P uptake per unit of root biomass was a consequence of: (1) an increase in soil P availability induced by waterlogging; (2) a change in root morphology, and/or (3) an increase in the intrinsic uptake capacity of each unit of root biomass. To test these hypotheses we evaluated (1) changes in P availability induced by waterlogging; (2) specific root length of waterlogged and control plants, and (3) P uptake kinetics in excised roots from waterlogged and control plants. The results supported the three hypotheses. Soil P avail-ability was higher during waterlogging periods, roots of waterlogged plants showed a morphology more favorable to nutrient uptake (finer roots) and these roots showed a higher physiological capacity to absorb P. The results suggest that both soil and plant mechanisms contributed to compensate, in terms of P nutrition, for the reduction in allocation to root growth. The rapid transformation of the P uptake system is

Regional investigations of soil and overburden analysis and plant uptake of metals

USGS Publications Warehouse

Gough, L.P.

1984-01-01

Regional studies on the bioavailability of metals at native and disturbed sites were conducted over the past seven years by the USGS. The work was concentrated in the Fort Union, Powder River, and Green River coal resource regions where measures of extractable metals in soils were found to have limited use in predicting metal levels in plants. Correlations between Cu, Fe, and Zn in plants and extractable (DTPA, EDTA, and oxalate) or total levels in native A- and C-horizons of soil were occasionally significant. A simple linear model is generally not adequate, however, in estimating element uptake by plants. Prediction capabilities were improved when a number of soil chemical and physical parameters were included as independent variables in a stepwise linear multiple regression analysis; however, never more than 54% of the total variability in the data was explained by the equations for these metals. Soil pH was the most important variable relating soil chemistry to plant chemistry. This relation was always positive and apparently a response to soil levels of metal carbonates and not Fe and Mn oxides. Studies that compared the metal uptake by rehabilitation species to extractable (DTPA) metal levels in mice soils produced similar results. ?? 1984 Science and Technology Letters.

Phosphorus in global agricultural soils: spatially explicit modelling of soil phosphorus and crop uptake for 1900 to 2010

NASA Astrophysics Data System (ADS)

Zhang, J.; Beusen, A.; Bouwman, L.; Apeldoorn, D. V.; Yu, C.

2016-12-01

Phosphorus (P) plays a vital role in global crop production and food security. To explore the global P status of soils, in this study we developed a spatially explicit version of a two-pool dynamic soil P model at 0.5°resolution. With this model, we analyzed the historical changes of soil P inputs (including manure and inorganic P fertilizer) from 1900 to 2010, reproduced the historical crop P uptake, calculated the phosphorus use efficiency (PUE) and conducted a comprehensive inventory of soil P pools and P budgets (deficit and surplus) in global soils under croplands. Our results suggest that the spatially explicit model is capable of simulating the long-term soil P budget changes and crop uptake, with model simulations closely matching historical P uptake for cropland in all countries. The global P inputs from fertilizers and manure increased from 2 Tg P in 1900 to 23 Tg P in 2010 with great variation across different regions and countries of the world. The magnitude of crop uptake has also changed rapidly over the 20th century: according to our model, crop P uptake per hectare in Western Europe increased by more than three times while the total soil P stock per hectare increased by close to 37% due to long-term P surplus application, with a slight decrease in recent years. Croplands in China (total P per hectare slight decline during 1900-1970, +34% since 1970) and India (total P per hectare gradual increase by 14% since 1900, 6% since 1970) are currently in the phase of accumulation.The total soil P content per hectare in Sub-Saharan Africa has slightly decreased since 1900.Our model is a promising tool to analyze the changes in the soil P status and the capacity of soils to supply P to crops, including future projections of required nutrient inputs.

Drivers of Phosphorus Uptake by Barley Following Secondary Resource Application

PubMed Central

Brod, Eva; Øgaard, Anne Falk; Krogstad, Tore; Haraldsen, Trond Knapp; Frossard, Emmanuel; Oberson, Astrid

2016-01-01

Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake is still poorly understood. Using radioactive-labeling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal, and wood ash were studied as P uptake by barley after 44 days and compared with those of water-soluble mineral P (MinP) and an unfertilized control (NoP) in a pot experiment with an agricultural soil containing little available P at two soil pH levels, approximately pH 5.3 (unlimed soil) and pH 6.2 (limed soil). In a parallel incubation experiment, the effects of the secondary resources on physicochemical and microbial soil processes were studied. The results showed that the relative agronomic efficiency compared with MinP decreased in the order: manure ≥fish sludge ≥wood ash ≥meat bone meal. The solubility of inorganic P in secondary resources was the main driver for P uptake by barley (Hordeum vulgare). The effects of secondary resources on physicochemical and microbial soil processes were of little overall importance. Application of organic carbon with manure resulted in microbial P immobilization and decreased uptake by barley of P derived from the soil. On both soils, P uptake by barley was best explained by a positive linear relationship with the H2O + NaHCO3-soluble inorganic P fraction in fertilizers or by a linear negative relationship with the HCl-soluble inorganic P fraction in fertilizers. PMID:27243015

Microbiology and Moisture Uptake of Desert Soils

NASA Astrophysics Data System (ADS)

Kress, M. E.; Bryant, E. P.; Morgan, S. W.; Rech, S.; McKay, C. P.

2005-12-01

We have initiated an interdisciplinary study of the microbiology and water content of desert soils to better understand microbial activity in extreme arid environments. Water is the one constituent that no organism can live without; nevertheless, there are places on Earth with an annual rainfall near zero that do support microbial ecosystems. These hyperarid deserts (e.g. Atacama and the Antarctic Dry Valleys) are the closest terrestrial analogs to Mars, which is the subject of future exploration motivated by the search for life beyond Earth. We are modeling the moisture uptake by soils in hyperarid environments to quantify the environmental constraints that regulate the survival and growth of micro-organisms. Together with the studies of moisture uptake, we are also characterizing the microbial population in these soils using molecular and culturing methods. We are in the process of extracting DNA from these soils using MoBio extraction kits. This DNA will be used as a template to amplify bacterial and eukaryotic ribosomal DNA to determine the diversity of the microbial population. We also have been attempting to determine the density of organisms by culturing on one-half strength R2A agar. The long-range goal of this research is to identify special adaptations of terrestrial life that allow them to inhabit extreme arid environments, while simultaneously quantifying the environmental parameters that enforce limits on these organisms' growth and survival.

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were <0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were < 0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

Microscale Investigations of Soil Heterogeneity: Impacts on Zinc Retention and Uptake in Zinc-Contaminated Soils

DOE PAGES

Rosenfeld, Carla E.; Chaney, Rufus L.; Tappero, Ryan V.; ...

2017-03-17

Here, metal contaminants in soils can persist for millennia, causing lasting negative impacts on local ecosystems. Long-term contaminant bioavailability is related to soil pH and to the strength and stability of solid-phase associations. We combined physical density separation with synchrotron-based microspectroscopy to reduce solid-phase complexity and to study Zn speciation in field-contaminated soils. We also investigated Zn uptake in two Zn-hyperaccumulating ecotypes of Noccaea caerulescens (Ganges and Prayon). Soils were either moderately contaminated (500–800 mg Zn kg –1 via contaminated biosolids application) or grossly enriched (26,000 mg Zn kg –1 via geogenic enrichment). Soils were separated using sodium polytungstate intomore » three fractions: light fraction (LF) (<1.6 g cm –3), medium fraction (MF) (1.6–2.8 g cm –3), and heavy fraction (HF) (>2.8 g cm –3). Approximately 45% of the total Zn was associated with MF in biosolids-contaminated soils. From these data, we infer redistribution to the MF after biosolids application because Zn in biosolids is principally associated with HF and LF. Our results suggest that increasing proportions of HF-associated Zn in soils may be related to greater relative Zn removal by Zn hyperaccumulating plants. Using density fractions enabled assessment of Zn speciation on a microscale despite incomplete fractionation. Analyzing both density fractions and whole soils revealed certain phases (e.g., ZnS, Zn coprecipitated with Fe oxides) that were not obvious in all analyses, indicating multiple views of the same soils enable a more complete understanding of Zn speciation.« less

Soil solution Zn and pH dynamics in non-rhizosphere soil and in the rhizosphere of Thlaspi caerulescens grown in a Zn/Cd-contaminated soil.

PubMed

Luo, Y M; Christie, P; Baker, A J

2000-07-01

Temporal changes in soil solution properties and metal speciation were studied in non-rhizosphere soil and in the rhizosphere of the hyperaccumulator Thlaspi caerulescens J. & C. Presl (population from Prayon, Belgium) grown in a Zn- and Cd-contaminated soil. This paper focuses on soil solution Zn and pH dynamics during phytoextraction. The concentration of Zn in both non-rhizosphere and rhizosphere soil solutions decreased from 23 mg/l at the beginning to 2 mg/l at the end of the experiment (84 days after transplanting of seedlings), mainly due to chemical sorption. There was no significant difference in overall Zn concentration between the planted and the unplanted soil solutions (P > 0.05). Soil solution pH decreased initially and then increased slightly in both planted and unplanted soil zones. From 60 to 84 days after transplanting, the pH of the rhizosphere soil solution was higher than that of non-rhizosphere soil solution (P<0.05). Zn uptake by the hyperaccumulator plants was 8.8 mg per pot (each containing 1 kg oven-dry soil) on average. The data indicate that the potential of T. caerulescens to remove Zn from contaminated soil may not be related to acidification of the rhizosphere.

Mechanistic insights from DGT and soil solution measurements on the uptake of Ni and Cd by radish.

PubMed

Luo, Jun; Cheng, Hao; Ren, Jinghua; Davison, William; Zhang, Hao

2014-07-01

This work tests the previously proposed hypothesis that plant uptake of metals is determined dominantly by diffusional controlled or plant limiting uptake mechanisms at, respectively, low and high metal concentrations. Radish (Raphanus sativus) was grown in 13 soils spiked with Ni (10 and 100 mg kg(-1)) and Cd (0.5 and 4 mg kg(-1)) for 4 weeks to investigate the mechanisms affecting plant uptake. Soil solution concentrations, Css, of Ni and Cd were measured, along with the DGT interfacial concentration, CDGT, and the derived effective concentration in soil solution, CE. Free ion activities, aNi(2+) and aCd(2+), were obtained using WHAM 6. Although there was a poor relationship between Ni in radish roots and either Css or aNi(2+) in unamended soils, the distribution of data could be rationalized in terms of the extent of release of Ni from the soil solid phase, as identified by DGT and soil solution measurements. By contrast Ni in radish was linearly related to CE, demonstrating diffusion limited uptake. For soils amended with high concentrations of Ni, linear relationships were obtained for Ni in radish plotted against, Css, aNi(2+), and CE, consistent with the plant controlling uptake. For Ni the hypothesis concerning dominant diffusional and plant limiting uptake mechanisms was demonstrated. Poor relationships between Cd in radish and Css, aCd(2+), and CE, irrespective of amendment by Cd, showed the importance of factors other than diffusional supply, such as rhizosphere and inhibitory processes, and that fulfilment of this hypothesis is plant and metal specific.

Effect of arbuscular mycorrhizal (AM) fungi on 137Cs uptake by plants grown on different soils.

PubMed

Vinichuk, M; Mårtensson, A; Ericsson, T; Rosén, K

2013-01-01

The potential use of mycorrhiza as a bioremediation agent for soils contaminated by radiocesium was evaluated in a greenhouse experiment. The uptake of (137)Cs by cucumber, perennial ryegrass, and sunflower after inoculation with a commercial arbuscular mycorrhizal (AM) product in soils contaminated with (137)Cs was investigated, with non-mycorrhizal quinoa included as a "reference" plant. The effect of cucumber and ryegrass inoculation with AM fungi on (137)Cs uptake was inconsistent. The effect of AM fungi was most pronounced in sunflower: both plant biomass and (137)Cs uptake increased on loamy sand and loamy soils. The total (137)Cs activity accumulated within AM host sunflower on loamy sand and loamy soils was 2.4 and 3.2-fold higher than in non-inoculated plants. Although the enhanced uptake of (137)Cs by quinoa plants on loamy soil inoculated by the AM fungi was observed, the infection of the fungi to the plants was not confirmed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characteristics of (3H)2-Deoxyglucose Uptake by Slices of Rat Cerebral Cortex

DTIC Science & Technology

1983-05-17

phlorizin or by phloretin , two compounds known to inhibit glucose transport by kidney and by erythrocytes, respectively. Net [-̂ H]2-de- oxyglucose uptake...Hexoses 53 17. The Effect of Phlorizin and Phloretin on Net [3H]2-Deoxy- glucose Transport by Slices of Cerebral Cortex 55 18. The Effect of Sodium...LeFevre, 1961). Transport by erythrocytes is not dependent on sodium (Silverman, 1976). Transport is, however, sensitive to inhibition by phloretin

Influence of soil properties and phosphate addition on arsenic uptake from polluted soils by velvetgrass (Holcus lanatus).

PubMed

Lewińska, K; Karczewska, A

2013-01-01

Four kinds of soil material were used in a pot experiment with velvetgrass (Holcus lanatus). Two unpolluted soils: sand (S) and loam (L) were spiked with sodium arsenite (As II) and arsenate (As V), to obtain total arsenic (As) concentrations of 500 mg As kg(-1). Two other soils (ZS I, ZS III), containing 3320 and 5350 mg As kg(-1), were collected from Zloty Stok where gold and arsenic ores were mined and processed for several centuries. The effects of phosphate addition on plants growth and As uptake were investigated. Phosphate was applied to soils in the form of NH4H2PO4 at the rate 0.2 g P/kg. Average concentrations of arsenic in the shoots of velvetgrass grown in spiked soils S and L without P amendment were in the range 18-210 mg As kg(-1) d.wt., whereas those in plants grown on ZS I and ZS II soils were considerably lower, and varied in the range 11-52 mg As kg(-1) d.wt. The addition of phosphate caused a significant increase in plant biomass and therefore the total amounts of As taken up by plants, however, the differences in As concentrations in the shoots of velvetgrass amended and non-amended with phosphate were not statistically significant.

Effects of elevated CO2 on soil organic matter turnover and plant nitrogen uptake: First results from a dual labeling mesocosm experiment

NASA Astrophysics Data System (ADS)

Eder, Lucia Muriel; Weber, Enrico; Schrumpf, Marion; Zaehle, Sönke

2017-04-01

The response of plant growth to elevated concentrations of CO2 (eCO2) is often constrained by plant nitrogen (N) uptake. To overcome potential N limitation, plants may invest photosynthetically fixed carbon (C) into N acquiring strategies, including fine root biomass, root exudation, or C allocation to mycorrhizal fungi. In turn, these strategies may affect the decomposition of soil organic matter, leading to uncertainties in net effects of eCO2 on C storage. To gain more insight into these plant-soil C-N-interactions, we combined C and N stable isotope labeling in a mesocosm experiment. Saplings of Fagus sylvatica L. were exposed to a 13CO2 enriched atmosphere at near ambient (380 ppm) or elevated (550 ppm) CO2 concentrations for four months of the vegetation period in 2016. Aboveground and belowground net CO2 fluxes were measured separately and the 13C label enabled partitioning of total soil CO2 efflux into old, soil derived and new, plant-derived C. We used ingrowth cores to assess effects of eCO2on belowground C allocation and plant N uptake in more detail and in particular we evaluated the relative importance of ectomycorrhizal associations. In the soil of each sapling, ingrowth cores with different mesh sizes allowed fine roots or only mycorrhizal hyphae to penetrate. In one type of ingrowth core each, we incorporated fine root litter that was enriched in 15N. Additionally, total N uptake was estimated by using 15N enriched saplings and unlabeled control plants. We found that eCO2 increased aboveground net CO2 exchange rates by 19% and total soil respiration by 11%. The eCO2 effect for GPP and also for NPP was positive (+23% and +11%, respectively). By combining gaseous C fluxes with data on new and old C stocks in bulk soil and plants through destructive harvesting in late autumn 2016, we will be able to infer net effects of eCO2 on the fate of C in these mesocosms. Biomass allocation patterns can reveal physiological responses to high C availability under

Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake.

PubMed

Markewitz, Daniel; Devine, Scott; Davidson, Eric A; Brando, Paulo; Nepstad, Daniel C

2010-08-01

*Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. *The current study utilized a 1999-2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil. *Simulations with root uptake compensation had a relative root mean square error (RRMSE) of 11% at 0-40 cm and < 5% at 350-1150 cm. The simulated contribution of deep root uptake under the control was c. 20% of water demand from 250 to 550 cm and c. 10% from 550 to 1150 cm. Furthermore, in years 2 (2001) and 3 (2002) of throughfall exclusion, deep root uptake increased as soil moisture was available but then declined to near zero in deep layers in 2003 and 2004. *Deep root uptake was limited despite high VWC (i.e. > 0.30 cm(3) cm(-3)). This limitation may partly be attributable to high residual water contents (theta(r)) in these high-clay (70-90%) soils or due to high soil-to-root resistance. The ability of deep roots and soils to contribute increasing amounts of water with extended drought will be limited.

Root Water Uptake and Soil Moisture Pattern Dynamics - Capturing Connections, Controls and Causalities

NASA Astrophysics Data System (ADS)

Blume, T.; Heidbuechel, I.; Hassler, S. K.; Simard, S.; Guntner, A.; Stewart, R. D.; Weiler, M.

2015-12-01

We hypothesize that there is a shift in controls on landscape scale soil moisture patterns when plants become active during the growing season. Especially during the summer soil moisture patterns are not only controlled by soils, topography and related abiotic site characteristics but also by root water uptake. Root water uptake influences soil moisture patterns both in the lateral and vertical direction. Plant water uptake from different soil depths is estimated based on diurnal fluctuations in soil moisture content and was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographic positions and types of vegetation. Vegetation types include pasture, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture and soil temperature profiles, matrix potential, piezometers and sapflow sensors as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. The analysis of soil moisture patterns over time indicates a shift in regime depending on season. Depth profiles of root water uptake show strong differences between different forest stands, with maximum depths ranging between 50 and 200 cm. Temporal dynamics of signal strength within the profile furthermore suggest a locally shifting spatial distribution of root water uptake depending on water availability. We will investigate temporal thresholds (under which conditions spatial patterns of root water uptake become most distinct) as well as landscape controls on soil moisture and root water uptake dynamics.

Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation.

PubMed

Sallach, J Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

2015-02-01

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

Uptake of explosives from contaminated soil by vegetation at the Joliet Army Ammunition Plant

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

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D.

1994-06-01

This study examines the uptake of explosives by vegetation growing on soils contaminated by 2,4,6-trinitrotoluene (TNT) in Group 61 at the Joliet Army Ammunition Plant (JAAP). Plant materials and soil from the root zone were sampled and analyzed to determine TNT uptake under natural field conditions. Standard USATHAMA methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. No- explosives were detected in the aboveground portion of any plant sample. However, results indicate that TNT, 2-aminodinitrotoluene (2-ADNT), and/or 4-ADNT were present in some root samples. The presence of 2-ADNT and 4-ADNT increases the likelihoodmore » that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.« less

Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

PubMed Central

Blankinship, Joseph C.; Marchus, Kenneth; Lucero, Delores M.; Sickman, James O.; Schimel, Joshua P.

2016-01-01

Nitric oxide (NO) is an important trace gas and regulator of atmospheric photochemistry. Theory suggests moist soils optimize NO emissions, whereas wet or dry soils constrain them. In drylands, however, NO emissions can be greatest in dry soils and when dry soils are rewet. To understand how aridity and vegetation interact to generate this pattern, we measured NO fluxes in a California grassland, where we manipulated vegetation cover and the length of the dry season and measured [δ15-N]NO and [δ18-O]NO following rewetting with 15N-labeled substrates. Plant N uptake reduced NO emissions by limiting N availability. In the absence of plants, soil N pools increased and NO emissions more than doubled. In dry soils, NO-producing substrates concentrated in hydrologically disconnected microsites. Upon rewetting, these concentrated N pools underwent rapid abiotic reaction, producing large NO pulses. Biological processes did not substantially contribute to the initial NO pulse but governed NO emissions within 24 h postwetting. Plants acted as an N sink, limiting NO emissions under optimal soil moisture. When soils were dry, however, the shutdown in plant N uptake, along with the activation of chemical mechanisms and the resuscitation of soil microbial processes upon rewetting, governed N loss. Aridity and vegetation interact to maintain a leaky N cycle during periods when plant N uptake is low, and hydrologically disconnected soils favor both microbial and abiotic NO-producing mechanisms. Under increasing rates of atmospheric N deposition and intensifying droughts, NO gas evasion may become an increasingly important pathway for ecosystem N loss in drylands. PMID:27114523

pH-dependent phytoavailability and speciation of tungsten (W) in soil affecting growth and N nutrition of soy (Glycine max)

NASA Astrophysics Data System (ADS)

Oburger, Eva; Vergara Cid, Carolina; Preiner, Julian; Hu, Junjian; Hann, Stephan; Wanek, Wolfgang; Richter, Andreas

2017-04-01

Tungsten (W) is an economically important transition metal that finds a broad scope of applications ranging from household appliances to high-end technology goods. However, in the past decades, increasing industrial and military use of W-based products (particularly ammunition, as well as drilling, milling and cutting tools) opened new pathways of W into natural systems and raise the need for a better understanding of the behavior of W in the environment. Soils play an important role in controlling the bioavailability of pollutants and their entry into the food web via plant uptake as they serve as filter and buffer systems. However, compared to other trace metals, knowledge about the fate of W in the plant-soil environment is rather sketchy. The chemical alikeness of W and molybdenum (Mo) suggests not only similar, typical anionic behaviour in soil but also a potential negative effect of W on important plant physiological processes that require Mo. We examined how soil pH dependent solubility and W speciation affected biomass production, W and nutrient uptake by soy (Glycine max cv Primus) and the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N2 fixation (nitrogenase). Increased solubility of mainly monomeric W in high pH soils resulted in increased W plant uptake, demonstrating a greater risk of entry of W into the food web in alkaline soils. Symbiotic nitrogen fixation was able to compensate for reduced nitrate reductase activity until W soil solution concentrations became too phytotoxic, indicating a more efficient detoxification/compartmentalization mechanism in nodules than in soy leaves. The increasing presence of polymeric W species observed in low pH soils spiked with high W concentrations resulted in decreased W uptake but simultaneously had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our results demonstrate the importance of soil pH for

Involvement of Silicon Influx Transporter OsNIP2;1 in Selenite Uptake in Rice1[W][OA

PubMed Central

Zhao, Xue Qiang; Mitani, Namiki; Yamaji, Naoki; Shen, Ren Fang; Ma, Jian Feng

2010-01-01

Rice (Oryza sativa) as a staple food, provides a major source of dietary selenium (Se) for humans, which essentially requires Se, however, the molecular mechanism for Se uptake is still poorly understood. Herein, we show evidence that the uptake of selenite, a main bioavailable form of Se in paddy soils, is mediated by a silicon (Si) influx transporter Lsi1 (OsNIP2;1) in rice. Defect of OsNIP2;1 resulted in a significant decrease in the Se concentration of the shoots and xylem sap when selenite was given. However, there was no difference in the Se concentration between the wild-type rice and mutant of OsNIP2;1 when selenate was supplied. A short-term uptake experiment showed that selenite uptake greatly increased with decreasing pH in the external solution. Si as silicic acid did not inhibit the Se uptake from selenite in both rice and yeast (Saccharomyces cerevisiae) at low pHs. Expression of OsNIP2;1 in yeast enhanced the selenite uptake at pH 3.5 and 5.5 but not at pH 7.5. On the other hand, defect of Si efflux transporter Lsi2 did not affect the uptake of Se either from selenite or selenate. Taken together, our results indicate that Si influx transporter OsNIP2;1 is permeable to selenite. PMID:20498338

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

NASA Astrophysics Data System (ADS)

Murguia-Flores, Fabiola; Arndt, Sandra; Ganesan, Anita L.; Murray-Tortarolo, Guillermo; Hornibrook, Edward R. C.

2018-06-01

Soil bacteria known as methanotrophs are the sole biological sink for atmospheric methane (CH4), a potent greenhouse gas that is responsible for ˜ 20 % of the human-driven increase in radiative forcing since pre-industrial times. Soil methanotrophy is controlled by a plethora of factors, including temperature, soil texture, moisture and nitrogen content, resulting in spatially and temporally heterogeneous rates of soil methanotrophy. As a consequence, the exact magnitude of the global soil sink, as well as its temporal and spatial variability, remains poorly constrained. We developed a process-based model (Methanotrophy Model; MeMo v1.0) to simulate and quantify the uptake of atmospheric CH4 by soils at the global scale. MeMo builds on previous models by Ridgwell et al. (1999) and Curry (2007) by introducing several advances, including (1) a general analytical solution of the one-dimensional diffusion-reaction equation in porous media, (2) a refined representation of nitrogen inhibition on soil methanotrophy, (3) updated factors governing the influence of soil moisture and temperature on CH4 oxidation rates and (4) the ability to evaluate the impact of autochthonous soil CH4 sources on uptake of atmospheric CH4. We show that the improved structural and parametric representation of key drivers of soil methanotrophy in MeMo results in a better fit to observational data. A global simulation of soil methanotrophy for the period 1990-2009 using MeMo yielded an average annual sink of 33.5 ± 0.6 Tg CH4 yr-1. Warm and semi-arid regions (tropical deciduous forest and open shrubland) had the highest CH4 uptake rates of 602 and 518 mg CH4 m-2 yr-1, respectively. In these regions, favourable annual soil moisture content ( ˜ 20 % saturation) and low seasonal temperature variations (variations < ˜ 6 °C) provided optimal conditions for soil methanotrophy and soil-atmosphere gas exchange. In contrast to previous model analyses, but in agreement with recent observational data

Decreased N2O reduction by low soil pH causes high N2O emissions in a riparian ecosystem.

PubMed

Van den Heuvel, R N; Bakker, S E; Jetten, M S M; Hefting, M M

2011-05-01

Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils. © 2011 Blackwell Publishing Ltd.

Simulations and field observations of root water uptake in plots with different soil water availability.

NASA Astrophysics Data System (ADS)

Cai, Gaochao; Vanderborght, Jan; Couvreur, Valentin; Javaux, Mathieu; Vereecken, Harry

2015-04-01

Root water uptake is a main process in the hydrological cycle and vital for water management in agronomy. In most models of root water uptake, the spatial and temporal soil water status and plant root distributions are required for water flow simulations. However, dynamic root growth and root distributions are not easy and time consuming to measure by normal approaches. Furthermore, root water uptake cannot be measured directly in the field. Therefore, it is necessary to incorporate monitoring data of soil water content and potential and root distributions within a modeling framework to explore the interaction between soil water availability and root water uptake. But, most models are lacking a physically based concept to describe water uptake from soil profiles with vertical variations in soil water availability. In this contribution, we present an experimental setup in which root development, soil water content and soil water potential are monitored non-invasively in two field plots with different soil texture and for three treatments with different soil water availability: natural rain, sheltered and irrigated treatment. Root development is monitored using 7-m long horizontally installed minirhizotubes at six depths with three replicates per treatment. The monitoring data are interpreted using a model that is a one-dimensional upscaled version of root water uptake model that describes flow in the coupled soil-root architecture considering water potential gradients in the system and hydraulic conductances of the soil and root system (Couvreur et al., 2012). This model approach links the total root water uptake to an effective soil water potential in the root zone. The local root water uptake is a function of the difference between the local soil water potential and effective root zone water potential so that compensatory uptake in heterogeneous soil water potential profiles is simulated. The root system conductance is derived from inverse modelling using

Probing the Release and Uptake of Water in α-MnO 2 · xH 2O

DOE PAGES

Yang, Zhenzhen; Ford, Denise C.; Park, Joong Sun; ...

2016-12-27

Alpha-MnO 2 is of interest as a cathode material for 3 V lithium batteries and as an electrode/electrocatalyst for higher energy, hybrid Li-ion/Li–O 2 systems. It has a structure with large tunnels that contain stabilizing cations such as Ba 2+, K + , NH 4 + , and H3O + (or water, H 2O). When stabilized by H 3O + /H 2O, the protons can be ion-exchanged with lithium to produce a Li 2O-stabilized α-MnO 2 structure. It has been speculated that the electrocatalytic process in Li–O 2 cells may be linked to the removal of lithium and oxygen frommore » the host α-MnO 2 structure during charge, and their reintroduction during discharge. In this investigation, hydrated α-MnO 2 was used, as a first step, to study the release and uptake of oxygen in α-MnO 2. Temperature-resolved in situ synchrotron X-ray diffraction (XRD) revealed a nonlinear, two-stage, volume change profile, which with the aide of X-ray absorption near-edge spectroscopy (XANES), redox titration, and density functional theory (DFT) calculations, is interpreted as the release of water from the α-MnO 2 tunnels. The two stages correspond to H 2O release from intercalated H 2O species at lower temperatures and H 3O + species at higher temperature. Thermogravimetric analysis confirmed the release of oxygen from α-MnO 2 in several stages during heating–including surface water, occluded water, and structural oxygen–and in situ UV resonance Raman spectroscopy corroborated the uptake and release of tunnel water by revealing small shifts in frequencies during the heating and cooling of α-MnO 2. Lastly, DFT calculations revealed the likelihood of disordered water species in binding sites in α-MnO 2 tunnels and a facile diffusion process.« less

[Effects of sulfur on transformation of selenium in soil and uptake of selenium in rape].

PubMed

Liu, Xin-wei; Duan, Bi-huil; Xia, Quan-jie; Jiao, Wei; Guo, Zai-hua; Hu, Cheng-xiao; Zhao, Zhu-qing

2014-09-01

The high-quality, high-yield rape (Brassica napus L. cv. Xiangnongyou 571) was chosen as the experimental material to undergo seedling stage soil cultivation and solution cultivation. This study was aimed to investigate the effects of sulfur (S) on the fraction and species of amend selenium (Se) in soil by applying S fertilizer, and to reveal the mechanism through which S controls the Se uptake of rape. The results showed that applications of both Se at 5 mg.kg-1 and S at 150 mg.kg-1 could provide some boost to rape growth, however such boost was unremarkable; S application could significantly reduce Se content in shoots and roots by as much as 64. 0% and 39. 1% , respectively; S application could significantly decrease the pH value and increase the organic matter content by as much as 0. 65 units and 1.76 g.kg-1 , respectively; S application could significantly decrease soluble Se and Fe/Mn oxide-bound Se, and significantly increase organic matter-bound Se, however, there was no remarkable effect on exchangeable and residual Se. S could significantly decrease the content of Se(IV) in the soluble Se and significantly increase the content of Se(IV) in the exchangeable Se, with remarkable decrease in Se(VI) content in both fractions, and no remarkable effect on Se(II). S had a profound effect on the uptake of Se by rape seedlings when Se( IV) and Se( VI) were applied. The Se contents in shoot and root of the Se( VI)-treated rape were 7.3 and 3.2 times respectively as high as that of the Se( IV)-treated rape, while with a S rate of 2 mmolL-1, their Se contents were lower than 32.6% and 8.7% of that of the Se(IV)-treated rape. In conclusion, in addition to improving crop growth, appropriate amount of S fertilizer could also reduce soil pH and increase organic content, causing available Se in soil to be Fe/Mn oxide-bound and organic matter-bound, and retarding its transformation to Se( VI), thus reducing Se uptake by rape. This has significant value for regulation of Se

Changes in soil moisture drive soil methane uptake along a fire regeneration chronosequence in a eucalypt forest landscape.

PubMed

Fest, Benedikt; Wardlaw, Tim; Livesley, Stephen J; Duff, Thomas J; Arndt, Stefan K

2015-11-01

Disturbance associated with severe wildfires (WF) and WF simulating harvest operations can potentially alter soil methane (CH4 ) oxidation in well-aerated forest soils due to the effect on soil properties linked to diffusivity, methanotrophic activity or changes in methanotrophic bacterial community structure. However, changes in soil CH4 flux related to such disturbances are still rarely studied even though WF frequency is predicted to increase as a consequence of global climate change. We measured in-situ soil-atmosphere CH4 exchange along a wet sclerophyll eucalypt forest regeneration chronosequence in Tasmania, Australia, where the time since the last severe fire or harvesting disturbance ranged from 9 to >200 years. On all sampling occasions, mean CH4 uptake increased from most recently disturbed sites (9 year) to sites at stand 'maturity' (44 and 76 years). In stands >76 years since disturbance, we observed a decrease in soil CH4 uptake. A similar age dependency of potential CH4 oxidation for three soil layers (0.0-0.05, 0.05-0.10, 0.10-0.15 m) could be observed on incubated soils under controlled laboratory conditions. The differences in soil CH4 uptake between forest stands of different age were predominantly driven by differences in soil moisture status, which affected the diffusion of atmospheric CH4 into the soil. The observed soil moisture pattern was likely driven by changes in interception or evapotranspiration with forest age, which have been well described for similar eucalypt forest systems in south-eastern Australia. Our results imply that there is a large amount of variability in CH4 uptake at a landscape scale that can be attributed to stand age and soil moisture differences. An increase in severe WF frequency in response to climate change could potentially increase overall forest soil CH4 sinks. © 2015 John Wiley & Sons Ltd.

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans

PubMed Central

2018-01-01

Increasing use of tungsten (W)-based products opened new pathways for W into environmental systems. Due to its chemical alikeness with molybdenum (Mo), W is expected to behave similarly to its “twin element”, Mo; however, our knowledge of the behavior of W in the plant–soil environment remains inadequate. The aim of this study was to investigate plant growth as well as W and nutrient uptake depending on soil chemical properties such as soil pH and texture. Soybean (Glycine max cv. Primus) was grown on two acidic soils differing in soil texture that were either kept at their natural soil pH (pH of 4.5–5) or limed (pH of ≥7) and amended with increasing concentrations of metallic W (control and 500 and 5000 mg kg–1). In addition, the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N2 fixation (nitrogenase) was also investigated. Our results showed that the risk of W entering the food web was significantly greater in high-pH soils due to increased solubility of mainly monomeric W. The effect of soil texture on W solubility and phytoavailability was less pronounced compared to soil pH. Particularly at intermediate W additions (W 500 mg kg–1), symbiotic nitrogen fixation was able to compensate for reduced leaf nitrate reductase activity. When W soil solution concentrations became too toxic (W 5000 mg kg–1), nodulation was more strongly inhibited than nitrogenase activity in the few nodules formed, suggesting a more-efficient detoxification and compartmentalization mechanism in nodules than in soybean leaves. The increasing presence of polymeric W species observed in low-pH soils spiked with high W concentrations resulted in decreased W uptake. Simultaneously, polymeric W species had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our study demonstrates the importance of accounting for soil pH in risk assessment studies of W in the plant–soil

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans.

PubMed

Oburger, Eva; Vergara Cid, Carolina; Preiner, Julian; Hu, Junjian; Hann, Stephan; Wanek, Wolfgang; Richter, Andreas

2018-06-05

Increasing use of tungsten (W)-based products opened new pathways for W into environmental systems. Due to its chemical alikeness with molybdenum (Mo), W is expected to behave similarly to its "twin element", Mo; however, our knowledge of the behavior of W in the plant-soil environment remains inadequate. The aim of this study was to investigate plant growth as well as W and nutrient uptake depending on soil chemical properties such as soil pH and texture. Soybean ( Glycine max cv. Primus) was grown on two acidic soils differing in soil texture that were either kept at their natural soil pH (pH of 4.5-5) or limed (pH of ≥7) and amended with increasing concentrations of metallic W (control and 500 and 5000 mg kg -1 ). In addition, the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N 2 fixation (nitrogenase) was also investigated. Our results showed that the risk of W entering the food web was significantly greater in high-pH soils due to increased solubility of mainly monomeric W. The effect of soil texture on W solubility and phytoavailability was less pronounced compared to soil pH. Particularly at intermediate W additions (W 500 mg kg -1 ), symbiotic nitrogen fixation was able to compensate for reduced leaf nitrate reductase activity. When W soil solution concentrations became too toxic (W 5000 mg kg -1 ), nodulation was more strongly inhibited than nitrogenase activity in the few nodules formed, suggesting a more-efficient detoxification and compartmentalization mechanism in nodules than in soybean leaves. The increasing presence of polymeric W species observed in low-pH soils spiked with high W concentrations resulted in decreased W uptake. Simultaneously, polymeric W species had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our study demonstrates the importance of accounting for soil pH in risk assessment studies of W in the plant-soil

Assessing cadmium exposure risks of vegetables with plant uptake factor and soil property.

PubMed

Yang, Yang; Chang, Andrew C; Wang, Meie; Chen, Weiping; Peng, Chi

2018-07-01

Plant uptake factors (PUFs) are of great importance in human cadmium (Cd) exposure risk assessment while it has been often treated in a generic way. We collected 1077 pairs of vegetable-soil samples from production fields to characterize Cd PUFs and demonstrated their utility in assessing Cd exposure risks to consumers of locally grown vegetables. The Cd PUFs varied with plant species and pH and organic matter content of soils. Once normalized PUFs against soil parameters, the PUFs distributions were log-normal in nature. In this manner, the PUFs were represented by definable probability distributions instead of a deterministic figure. The Cd exposure risks were then assessed using the normalized PUF based on the Monte Carlo simulation algorithm. Factors affecting the extent of Cd exposures were isolated through sensitivity analyses. Normalized PUF would illustrate the outcomes for uncontaminated and slightly contaminated soils. Among the vegetables, lettuce was potentially hazardous for residents due to its high Cd accumulation but low Zn concentration. To protect 95% of the lettuce production from causing excessive Cd exposure risks, pH of soils needed to be 5.9 and above. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ecosystem fluxes of hydrogen in a mid-latitude forest driven by soil microorganisms and plants

DOE PAGES

Meredith, Laura K.; Commane, Róisín; Keenan, Trevor F.; ...

2016-09-14

Molecular hydrogen (H 2 ) is an atmospheric trace gas with a large microbe-mediated soil sink, yet cycling of this compound throughout ecosystems is poorly understood. Measurements of the sources and sinks of H 2 in various ecosystems are sparse, resulting in large uncertainties in the global H 2 budget. Constraining the H 2 cycle is critical to understanding its role in atmospheric chemistry and climate. We measured H 2 fluxes at high frequency in a temperate mixed deciduous forest for 15 months using a tower-based flux-gradient approach to determine both the soil-atmosphere and the net ecosystem flux of H 2more » . We also found that Harvard Forest is a net H 2 sink (-1.4 ± 1.1 kg H 2  ha -1 ) with soils as the dominant H 2 sink (-2.0 ± 1.0 kg H 2  ha -1 ) and aboveground canopy emissions as the dominant H 2 source (+0.6 ± 0.8 kg H 2  ha -1 ). Aboveground emissions of H 2 were an unexpected and substantial component of the ecosystem H 2 flux, reducing net ecosystem uptake by 30% of that calculated from soil uptake alone. Soil uptake was highly seasonal (July maximum, February minimum), positively correlated with soil temperature and negatively correlated with environmental variables relevant to diffusion into soils (i.e., soil moisture, snow depth, snow density). Soil microbial H 2 uptake was correlated with rhizosphere respiration rates (r = 0.8, P  <  0.001), and H 2 metabolism yielded up to 2% of the energy gleaned by microbes from carbon substrate respiration. Here, we elucidate key processes controlling the biosphere–atmosphere exchange of H 2 and raise new questions regarding the role of aboveground biomass as a source of atmospheric H 2 and mechanisms linking soil H 2 and carbon cycling. Our results should be incorporated into modeling efforts to predict the response of the H 2 soil sink to changes in anthropogenic H 2 emissions and shifting soil conditions with climate and land-use change.« less

Ecosystem fluxes of hydrogen in a mid-latitude forest driven by soil microorganisms and plants

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

Meredith, Laura K.; Commane, Róisín; Keenan, Trevor F.

Molecular hydrogen (H 2 ) is an atmospheric trace gas with a large microbe-mediated soil sink, yet cycling of this compound throughout ecosystems is poorly understood. Measurements of the sources and sinks of H 2 in various ecosystems are sparse, resulting in large uncertainties in the global H 2 budget. Constraining the H 2 cycle is critical to understanding its role in atmospheric chemistry and climate. We measured H 2 fluxes at high frequency in a temperate mixed deciduous forest for 15 months using a tower-based flux-gradient approach to determine both the soil-atmosphere and the net ecosystem flux of H 2more » . We also found that Harvard Forest is a net H 2 sink (-1.4 ± 1.1 kg H 2  ha -1 ) with soils as the dominant H 2 sink (-2.0 ± 1.0 kg H 2  ha -1 ) and aboveground canopy emissions as the dominant H 2 source (+0.6 ± 0.8 kg H 2  ha -1 ). Aboveground emissions of H 2 were an unexpected and substantial component of the ecosystem H 2 flux, reducing net ecosystem uptake by 30% of that calculated from soil uptake alone. Soil uptake was highly seasonal (July maximum, February minimum), positively correlated with soil temperature and negatively correlated with environmental variables relevant to diffusion into soils (i.e., soil moisture, snow depth, snow density). Soil microbial H 2 uptake was correlated with rhizosphere respiration rates (r = 0.8, P  <  0.001), and H 2 metabolism yielded up to 2% of the energy gleaned by microbes from carbon substrate respiration. Here, we elucidate key processes controlling the biosphere–atmosphere exchange of H 2 and raise new questions regarding the role of aboveground biomass as a source of atmospheric H 2 and mechanisms linking soil H 2 and carbon cycling. Our results should be incorporated into modeling efforts to predict the response of the H 2 soil sink to changes in anthropogenic H 2 emissions and shifting soil conditions with climate and land-use change.« less

Evaluation of soil water stable isotope analysis by H2O(liquid)-H2O(vapor) equilibration method

NASA Astrophysics Data System (ADS)

Gralher, Benjamin; Stumpp, Christine

2014-05-01

Environmental tracers like stable isotopes of water (δ18O, δ2H) have proven to be valuable tools to study water flow and transport processes in soils. Recently, a new technique for soil water isotope analysis has been developed that employs a vapor phase being in isothermal equilibrium with the liquid phase of interest. This has increased the potential application of water stable isotopes in unsaturated zone studies as it supersedes laborious extraction of soil water. However, uncertainties of analysis and influencing factors need to be considered. Therefore, the objective of this study was to evaluate different methodologies of analysing stable isotopes in soil water in order to reduce measurement uncertainty. The methodologies included different preparation procedures of soil cores for equilibration of vapor and soil water as well as raw data correction. Two different inflatable sample containers (freezer bags, bags containing a metal layer) and equilibration atmospheres (N2, dry air) were tested. The results showed that uncertainties for δ18O were higher compared to δ2H that cannot be attributed to any specific detail of the processing routine. Particularly, soil samples with high contents of organic matter showed an apparent isotope enrichment which is indicative for fractionation due to evaporation. However, comparison of water samples obtained from suction cups with the local meteoric water line indicated negligible fractionation processes in the investigated soils. Therefore, a method was developed to correct the raw data reducing the uncertainties of the analysis.. We conclude that the evaluated method is advantageous over traditional methods regarding simplicity, resource requirements and sample throughput but careful consideration needs to be made regarding sample handling and data processing. Thus, stable isotopes of water are still a good tool to determine water flow and transport processes in the unsaturated zone.

Uptake of PAHs into polyoxymethylene and application to oil-soot (lampblack)-impacted soil samples.

PubMed

Hong, Lei; Luthy, Richard G

2008-05-01

Polyoxymethylene (POM) is a polymeric material used increasingly in passive sampling of hydrophobic organic contaminants such as PAHs and PCBs in soils and sediments. In this study, we examined the sorption behavior of 12 PAH compounds to POM and observed linear isotherms spanning two orders of magnitude of aqueous concentrations. Uptake kinetic studies performed in batch systems for up to 54 d with two different volume ratios of POM-to-aqueous phase were evaluated with coupled diffusion and mass transfer models to simulate the movement of PAHs during the uptake process and to assess the physicochemical properties and experimental conditions that control uptake rates. Diffusion coefficients of PAHs in POM were estimated to be well correlated with diffusants' molecular weights as D(POM) proportional, variant(MW)(-3), descending from 2.3 x 10(-10) cm(2) s(-1) for naphthalene to 7.0 x 10(-11) cm(2) s(-1) for pyrene. The uptake rates for PAHs with log K(ow)<5.8 were controlled by the POM phase and the hydrophobicity of PAH compounds. For more hydrophobic PAH compounds, the aqueous boundary layer played an increasingly important role in determining the overall mass transfer rate. The POM partitioning technique was demonstrated to agree well with two other procedures for measuring PAH soil-water distribution coefficients in oil-soot (lampblack) containing soil samples.

The role of soil pH on soil carbonic anhydrase activity

NASA Astrophysics Data System (ADS)

Sauze, Joana; Jones, Sam P.; Wingate, Lisa; Wohl, Steven; Ogée, Jérôme

2018-01-01

Carbonic anhydrases (CAs) are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O) of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2-H2O isotopic exchange rate (kiso) in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content) affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content) played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation) that varied with soil texture. The reasons for this offset are still unknown.

Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources.

PubMed

Keeping, Malcolm G

2017-01-01

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate

Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources

PubMed Central

Keeping, Malcolm G.

2017-01-01

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate

Biochar and manure affect calcareous soil and corn silage nutrient concentrations and uptake.

PubMed

Lentz, R D; Ippolito, J A

2012-01-01

Carbon-rich biochar derived from the pyrolysis of biomass can sequester atmospheric CO, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. To an irrigated calcareous soil, we applied stockpiled dairy manure (42 Mg ha dry wt) and hardwood-derived biochar (22.4 Mg ha), singly and in combination with manure, along with a control, yielding four treatments. Nitrogen fertilizer was applied when needed (based on preseason soil test N and crop requirements) in all plots and years, with N mineralized from added manure included in this determination. Available soil nutrients (NH-N; NO-N; Olsen P; and diethylenetriaminepentaacetic acid-extractable K, Mg, Na, Cu, Mn, Zn, and Fe), total C (TC), total N (TN), total organic C (TOC), and pH were evaluated annually, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5-fold increase in available soil Mn and a 1.4-fold increase in TC and TOC, whereas manure produced a 1.2- to 1.7-fold increase in available nutrients (except Fe), compared with controls. In 2009 biochar increased corn silage B concentration but produced no yield increase; in 2010 biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3-fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared with the control in 2010. The combined biochar-manure effects were not synergistic except in the case of available soil Mn. In these calcareous soils, biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are representative, they suggest that biochar applications to calcareous soils may lead to reduced N availability, requiring additional soil N inputs to maintain yield targets. Copyright © by the

Response of soil methane uptake to simulated nitrogen deposition and grazing management across three types of steppe in Inner Mongolia, China.

PubMed

Li, Xianglan; He, Hong; Yuan, Wenping; Li, Linghao; Xu, Wenfang; Liu, Wei; Shi, Huiqiu; Hou, Longyu; Chen, Jiquan; Wang, Zhiping

2018-01-15

The response of soil methane (CH 4 ) uptake to increased nitrogen (N) deposition and grazing management was studied in three types of steppe (i.e., meadow steppe, typical steppe, and desert steppe) in Inner Mongolia, China. The experiment was designed with four simulated N deposition rates such as 0, 50, 100, and 200kgNha -1 , respectively, under grazed and fenced management treatments. Results showed that the investigated steppes were significant sinks for CH 4 , with an uptake flux of 1.12-3.36kgha -1 over the grass growing season and that the magnitude of CH 4 uptake significantly (P<0.05) decreased with increasing N deposition rates. The soil CH 4 uptake rates were highest in the desert steppe, moderate in the typical steppe, and lowest in the meadow steppe. Compared with grazed plots, fencing increased the CH 4 uptake by 4.7-40.2% with a mean value of 20.2% across the three different steppe types. The responses of soil CH 4 uptake to N deposition in the continental steppe varied depending on the N deposition rate, steppe type, and grazing management. A significantly positive correlation between CH 4 uptake and soil temperature was found in this study, whereas no significant relationship between soil moisture and CH 4 uptake occurred. Our results may contribute to the improvement of model parameterization for simulating biosphere-atmosphere CH 4 exchange processes and for evaluating the climate change feedback on CH 4 soil uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

Biochar amendment reduces rice Cd uptake in polluted and unpolluted paddy soils: a long term field experiment

NASA Astrophysics Data System (ADS)

Bian, R.; Cui, L.; Pan, G.; Li, L.

2012-04-01

The bioavailability of Cd in agricultural soils has been a great health concern due to the potential risk through exposure of agro-food produced in Cd-contaminated fields. Yet, rice subject to Cd contamination appears to have expanded at the last decade due to irrigation with waste water and chemical fertilization in south china. This is supposed to raise the Cd accumulation of rice grain. Therefore, techniques to reduce Cd mobility and plant uptake have been a urgent demand for food safety in China.A field experiment was performed in a high-polluted (HP), mid-pollute (MP) and unpolluted (UP) paddy soil with biochar(BC) amendment in 2011. BC was applied in HP, MP and UP in 2008, 2009, 2009 with the rates of 0, 10, 20, 40t ha-1 in HP, MP and 0, 40t ha-1 in UP. The experiment was monitored in 2011. It was observed that BC amendment did not affect rice grain yield but significantly increased soil pH by 0.58-0.77, 1.30 units in MP, UP and there was no difference in HP. The Cacl2 extracted Cd in soil was decreased by 18.1%-28.9% in HP, 49.3%-67.5% in MP and 83.1% in UP, respectively. Meanwhile, H2O extractable Cd in soil was decreased by 20.0%-31.7% in HP, 32.7%-44.2% in MP and 25.0% in UP, respectively. With the BC treatment, rice grain Cd concentration was decreased 4.7%-17.6% in HP, 35.9%-53.4% in MP. Especially in UP field, the rice grain Cd concentration was decreased from 0.22mg kg-1 to 0.07mg kg-1 which was below National standard (0.20mg kg-1) in China. The straw and root Cd contents were also significantly decreased with BC application. Therefore, BC amendment in polluted and unpolluted fields can sustainably reduce rice Cd uptake and it may offer a basic option to reduce Cd levels in rice. Keywords: Biochar, Cd, bioavailability, paddy soil, food safety

Arsenic-phosphorus interactions in the soil-plant-microbe system: Dynamics of uptake, suppression and toxicity to plants.

PubMed

Anawar, Hossain M; Rengel, Zed; Damon, Paul; Tibbett, Mark

2018-02-01

High arsenic (As) concentrations in the soil, water and plant systems can pose a direct health risk to humans and ecosystems. Phosphate (Pi) ions strongly influence As availability in soil, its uptake and toxicity to plants. Better understanding of As(V)-Pi interactions in soils and plants will facilitate a potential remediation strategy for As contaminated soils, reducing As uptake by crop plants and toxicity to human populations via manipulation of soil Pi content. However, the As(V)-Pi interactions in soil-plant systems are complex, leading to contradictory findings among different studies. Therefore, this review investigates the role of soil type, soil properties, minerals, Pi levels in soil and plant, Pi transporters, mycorrhizal association and microbial activities on As-Pi interactions in soils and hydroponics, and uptake by plants, elucidate the key mechanisms, identify key knowledge gaps and recommend new research directions. Although Pi suppresses As uptake by plants in hydroponic systems, in soils it could either increase or decrease As availability and toxicity to plants depending on the soil types, properties and charge characteristics. In soil, As(V) availability is typically increased by the addition of Pi. At the root surface, the Pi transport system has high affinity for Pi over As(V). However, Pi concentration in plant influences the As transport from roots to shoots. Mycorrhizal association may reduce As uptake via a physiological shift to the mycorrhizal uptake pathway, which has a greater affinity for Pi over As(V) than the root epidermal uptake pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of EDTA in arsenic mobilization and its uptake by maize grown on an As-polluted soil.

PubMed

Abbas, Mohamed H H; Abdelhafez, Ahmed A

2013-01-01

EDTA amendments are widely used for micronutrient fertilization in arid soils, besides their effectiveness in the remediation process of heavy metal from contaminated soils. However, the persistence of EDTA in arsenic contaminated soil may have further negative effects on the grown plants. To investigate the influences of EDTA on soil As, a pot experiment was conducted using a sandy clay loam As-polluted soil treated with gradual rates of EDTA (0, 1.0, 2.5 and 5 mmol kg(-1)) and planted with maize for two months. The key findings reveal that EDTA applications increased AB-DTPA extractable and water soluble As significantly. Such increases seemed to be the main reasons behind the increase in As uptake by maize plants as the addition of EDTA at the rates of 1.0, 2.5 and 5.0 mmol kg(-1) increased significantly As uptake by shoots 1.5, 2.4 and 3.0 folds, respectively compared to the untreated soil. On the other hand, As uptake by roots did not increase significantly except with the highest application rates of 2.5 and 5.0 mmol kg(-1). The results also show that arsenic translocation factor (TF) values were too low to attain successful phytoextraction. In conclusion, the bioavailable fraction of As is important to investigate the phytoextraction and phytotoxicity of As. Copyright © 2012 Elsevier Ltd. All rights reserved.

Afforestation neutralizes soil pH.

PubMed

Hong, Songbai; Piao, Shilong; Chen, Anping; Liu, Yongwen; Liu, Lingli; Peng, Shushi; Sardans, Jordi; Sun, Yan; Peñuelas, Josep; Zeng, Hui

2018-02-06

Soil pH regulates soil biogeochemical processes and has cascading effects on terrestrial ecosystem structure and functions. Afforestation has been widely adopted to increase terrestrial carbon sequestration and enhance water and soil preservation. However, the effect of afforestation on soil pH is still poorly understood and inconclusive. Here we investigate the afforestation-caused soil pH changes with pairwise samplings from 549 afforested and 148 control plots in northern China. We find significant soil pH neutralization by afforestation-afforestation lowers pH in relatively alkaline soil but raises pH in relatively acid soil. The soil pH thresholds (T pH ), the point when afforestation changes from increasing to decreasing soil pH, are species-specific, ranging from 5.5 (Pinus koraiensis) to 7.3 (Populus spp.) with a mean of 6.3. These findings indicate that afforestation can modify soil pH if tree species and initial pH are properly matched, which may potentially improve soil fertility and promote ecosystem productivity.

Soil organic matter-hydrogen peroxide dynamics in the treatment of contaminated soils and groundwater using catalyzed H2O2 propagations (modified Fenton's reagent).

PubMed

Bissey, Lauren L; Smith, Jeffrey L; Watts, Richard J

2006-07-01

The interactions between catalyzed H(2)O(2) propagations (CHP-i.e. modified Fenton's reagent) and soil organic matter (SOM) during the treatment of contaminated soils and groundwater was studied in a well-characterized surface soil. The fate of two fractions of SOM, particulate organic matter (POM) and nonparticulate organic matter (NPOM), during CHP reactions was evaluated using concentrations of hydrogen peroxide from 0.5 to 3M catalyzed by soluble iron (III), an iron (III)-ethylenediamine tetraacetic acid (EDTA) chelate, or naturally-occurring soil minerals. The destruction of total SOM in CHP systems was directly proportional to the hydrogen peroxide dosage, and was significantly greater at pH 3 than at neutral pH; furthermore, SOM destruction occurred predominantly in the NPOM fraction. At pH 3, SOM did not affect hydrogen peroxide decomposition rates or hydroxyl radical activity in CHP reactions. However, at neutral pH, increasing the mass of SOM decreased the hydrogen peroxide decomposition rate and increased the rate of hydroxyl radical generation in CHP systems. These results show that, while CHP reactions destroy some of the organic carbon pools, SOM does not have a significant effect on the CHP treatment of soils and groundwater.

Soil Fertility Status, Nutrient Uptake, and Maize (Zea mays L.) Yield Following Organic Matters and P Fertilizer Application on Andisol

NASA Astrophysics Data System (ADS)

Minardi, S.; Harieni, S.; Anasrullah, A.; Purwanto, H.

2017-04-01

Objective of this study were to elucidate effects of organic matters and P fertilizer application on soil fertility status, nutrient uptake and maize yield in the Andisol. This experiment consisted of two factors. The first factor comprised of four levels of organic matters input (without organic matter, manure, rice straw, and Gliricidia sepium leaves), with the application dosage 10 t.ha-1 and the second factor comprised of three levels of P fertilizer application (without P addition (control), 50 kg P2O5 ha-1, 100 kg P2O5 ha-1). Results of this study showed that organic matters and P fertilizer application improved soil fertility status, especially pH, soil organic C, cation exchange capacity (CEC), available P which resulted in an increase in P uptake that improve yield of maize. The highest yield of maize (corn cob) was obtained through application Gliricida sepium (8.40 t.ha-1), followed by manure (6.02 t.ha-1) and rice straw (5.87 t.ha-1). Application of 50 kg P2O5 Ha-1 yield was (5.76 t.ha-1) and application of 100 Kg P2O5 Ha-1 yield was (6.12 t.ha-1).

Drivers of methane uptake by montane forest soils in the Peruvian Andes

NASA Astrophysics Data System (ADS)

Jones, Sam; Diem, Torsten; Huaraca Quispe, Lidia; Cahuana, Adan; Meir, Patrick; Teh, Yit

2016-04-01

The exchange of methane between the soils of humid tropical forests and the atmosphere is relatively poorly documented. This is particularly true of montane settings where variations between uptake and emission of atmospheric methane have been observed. Whilst most of these ecosystems appear to function as net sinks for atmospheric methane, some act as considerable sources. In regions like the Andes, humid montane forests are extensive and a better understanding of the magnitude and controls on soil-atmosphere methane exchange is required. We report methane fluxes from upper montane cloud forest (2811 - 2962 m asl), lower montane cloud forest (1532 - 1786 m asl), and premontane forest (1070 - 1088 m asl) soils in south-eastern Peru. Between 1000 and 3000 m asl, mean annual air temperature and total annual precipitation decrease from 24 ° C and 5000 mm to 12 ° C and 1700 mm. The study region experiences a pronounced wet season between October and April. Monthly measurements of soil-atmosphere gas exchange, soil moisture, soil temperature, soil oxygen concentration, available ammonium and available nitrate were made from February 2011 in the upper and lower montane cloud forests and July 2011 in the premontane forest to June 2013. These soils acted as sinks for atmospheric methane with mean net fluxes for wet and dry season, respectively, of -2.1 (0.2) and -1.5 (0.1) mg CH4 m-2 d-1 in the upper montane forest; -1.5 (0.2) and -1.4 (0.1) mg CH4 m-2 d-1in the lower montane forest; and -0.3 (0.2) and -0.2 (0.2) mg CH4 m-2 d-1 in the premontane forest. Spatial variations among forest types were related to available nitrate and water-filled pore space suggesting that nitrate inhibition of oxidation or constraints on the diffusional supply of methane to methanotrophic communities may be important controls on methane cycling in these soils. Seasonality in methane exchange, with weaker uptake related to increased water-filled pore space and soil temperature during the wet

Americium-241 uptake by Bahiagrass as influenced by soil type, lime, and organic matter

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

Hoyt, G.D.; Adriano, D.C.

1979-07-01

Availability of /sup 241/Am to bahiagrass (Paspalum notatum), a major forage crop in the southeastern US, was studied under greenhouse conditions using two soil types, two rates of lime, and four rates of organic matter. The plants were grown in pots until three clippings were obtained. Americium-241 concentrations in plant tissues from the unlimed Dothan (24% clay) soil were, on the average, approximately twice as high as those from unlimed Troup (10% clay) soil. Lime significantly reduced /sup 241/Am uptake from both soils. The americium concentration ratios (americium concentration in dry plant tissue/average americium concentration in dry soil) for limedmore » treatments were, in general, one order of magnitude lower than those for unlimed treatments. Organic matter, added to the soils as bermuda grass hay, somewhat reduced /sup 241/Am uptake, especially when added at high rates in unlimed soils. The effect of lime on uptake could be attributed to immobilization of americium ions external to the roots as a result of decreased solubility of this radionuclide and/or antagonistic effect of increased calcium ion concentration in the soil solution on americium ions. The effect of organic matter on uptake could be attributed to its fixing capacity for metals.« less

Molybdenum uptake by forage crops grown on sewage sludge -- Amended soils in the field and greenhouse

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

McBride, M.B.; Richards, B.K.; Steenhuis, T.

2000-06-01

Molybdenum (Mo) is a plant-available element in soils that can adversely affect the health of farm animals. There is a need for more information on its uptake into forage crops from waste materials, such as sewage sludge, applied to agricultural land. Field and greenhouse experiments with several crops grown on long-term sewage sludge-amended soils as well as soils recently amended with dewatered (DW) and alkaline-stabilized (ALK) sludges indicated that Mo supplied from sludge is readily taken up by legumes in particular. Excessive uptake into red clover (Trifolium pratense L.) was seen in a soil that had been heavily amended withmore » sewage sludge 20 yr earlier, where the soil contained about 3 mg Mo/kg soil, three times the background soil concentration. The greenhouse and field studies indicated that Mo can have a long residual availability in sludge-amended soils. The effect of sludge application was to decrease Cu to Mo ratios in legume forages, canola (Brassica napus var. napus) and soybeans [Glycine max (L.) Merr.] below the recommended limit of 2:1 for ruminant diets, a consequence of high bioavailability of Mo and low uptake of Cu added in sludge. Molybdenum uptake coefficients (UCs) for ALK sludge were higher than for DW sludge, presumably due to the greater solubility of Mo measured in the more alkaline sludges and soils. Based on these UCs, it is tentatively recommended that cumulative Mo loadings on forages grown on nonacid soils should not exceed 1.0 kg/ha from ALK sludge or 4.0 kg/ha from DW sludge.« less

Conocarpus biochar as a soil amendment for reducing heavy metal availability and uptake by maize plants.

PubMed

Al-Wabel, Mohammad I; Usman, Adel R A; El-Naggar, Ahmed H; Aly, Anwar A; Ibrahim, Hesham M; Elmaghraby, Salem; Al-Omran, Abdulrasoul

2015-07-01

The objective of this study was to assess the use of Concarpus biochar as a soil amendment for reducing heavy metal accessibility and uptake by maize plants (Zea mays L.). The impacts of biochar rates (0.0, 1.0, 3.0, and 5.0% w/w) and two soil moisture levels (75% and 100% of field capacity, FC) on immobilization and availability of Fe, Mn, Zn, Cd, Cu and Pb to maize plants as well as its application effects on soil pH, EC, bulk density, and moisture content were evaluated using heavy metal-contaminated soil collected from mining area. The biochar addition significantly decreased the bulk density and increased moisture content of soil. Applying biochar significantly reduced NH4OAc- or AB-DTPA-extractable heavy metal concentrations of soils, indicating metal immobilization. Conocarpus biochar increased shoot dry biomass of maize plants by 54.5-102% at 75% FC and 133-266% at 100% FC. Moreover, applying biochar significantly reduced shoot heavy metal concentrations in maize plants (except for Fe at 75% FC) in response to increasing application rates, with a highest decrease of 51.3% and 60.5% for Mn, 28% and 21.2% for Zn, 60% and 29.5% for Cu, 53.2% and 47.2% for Cd at soil moisture levels of 75% FC and 100% FC, respectively. The results suggest that biochar may be effectively used as a soil amendment for heavy metal immobilization and in reducing its phytotoxicity.

Conocarpus biochar as a soil amendment for reducing heavy metal availability and uptake by maize plants

PubMed Central

Al-Wabel, Mohammad I.; Usman, Adel R.A.; El-Naggar, Ahmed H.; Aly, Anwar A.; Ibrahim, Hesham M.; Elmaghraby, Salem; Al-Omran, Abdulrasoul

2014-01-01

The objective of this study was to assess the use of Concarpus biochar as a soil amendment for reducing heavy metal accessibility and uptake by maize plants (Zea mays L.). The impacts of biochar rates (0.0, 1.0, 3.0, and 5.0% w/w) and two soil moisture levels (75% and 100% of field capacity, FC) on immobilization and availability of Fe, Mn, Zn, Cd, Cu and Pb to maize plants as well as its application effects on soil pH, EC, bulk density, and moisture content were evaluated using heavy metal-contaminated soil collected from mining area. The biochar addition significantly decreased the bulk density and increased moisture content of soil. Applying biochar significantly reduced NH4OAc- or AB-DTPA-extractable heavy metal concentrations of soils, indicating metal immobilization. Conocarpus biochar increased shoot dry biomass of maize plants by 54.5–102% at 75% FC and 133–266% at 100% FC. Moreover, applying biochar significantly reduced shoot heavy metal concentrations in maize plants (except for Fe at 75% FC) in response to increasing application rates, with a highest decrease of 51.3% and 60.5% for Mn, 28% and 21.2% for Zn, 60% and 29.5% for Cu, 53.2% and 47.2% for Cd at soil moisture levels of 75% FC and 100% FC, respectively. The results suggest that biochar may be effectively used as a soil amendment for heavy metal immobilization and in reducing its phytotoxicity. PMID:26150758

Nutrient uptake by agricultural crops from biochar-amended soils: results from two field experiments in Austria

NASA Astrophysics Data System (ADS)

Karer, Jasmin; Zehetner, Franz; Kloss, Stefanie; Wimmer, Bernhard; Soja, Gerhard

2013-04-01

The use of biochar as soil amendment is considered as a promising agricultural soil management technique, combining carbon sequestration and soil fertility improvements. These expectations are largely founded on positive experiences with biochar applications to impoverished or degraded tropical soils. The validity of these results for soils in temperate climates needs confirmation from field experiments with typical soils representative for intensive agricultural production areas. Frequently biochar is mixed with other organic additives like compost. As these two materials interact with each other and each one may vary considerably in its basic characteristics, it is difficult to attribute the effects of the combined additive to one of its components and to a specific physico-chemical parameter. Therefore investigations of the amendment efficacy require the study of the pure components to characterize their specific behavior in soil. This is especially important for adsorption behavior of biochar for macro- and micronutrients because in soil there are multiple nutrient sinks that compete with plant roots for vital elements. Therefore this contribution presents results from a field amendment study with pure biochar that had the objective to characterize the macro- and microelement uptake of crops from different soils in two typical Austrian areas of agricultural production. At two locations in North and South-East Austria, two identical field experiments on different soils (Chernozem and Cambisol) were installed in 2011 with varying biochar additions (0, 30 and 90 t/ha) and two nitrogen levels. The biochar was a product from slow pyrolysis of wood (SC Romchar SRL). During the installation of the experiments, the biochar fraction of <2 mm was mixed with surface soil to a depth of 15 cm in plots of 33 m2 each (n=4). Barley (at the Chernozem soil) and maize (at the Cambisol) were cultivated according to standard agricultural practices. The highest crop yields at both

Microdialysis of Soil P: A means to mimic root uptake?

NASA Astrophysics Data System (ADS)

Schack-Kirschner, Helmer; Demand, Dominic; Lang, Friederike

2017-04-01

Standard procedures to assess P availability in soils are based on batch experiments with various extractants. However, in most soils P nutrition is less limited by bulk stocks but by slow diffusion of phosphate through the soil solution. More comparable to the root's approach is to strip phosphate locally from the solid phase by lowering the soil-solution concentration, which can be achieved by establishing an infinite diffusional sink, such as DGT. An alternative diffusive sampling technique is microdialysis (MD), well established in pharmacokinetics. Briefly, this method uses miniaturized flow-through probes where the perfusate gets in diffusive contact to the external solution by a semipermeable membrane. Important aspects of P supply to roots resemble MD sampling. This is not only the mostly diffusive transport, but also an elongated capillary tube-like geometry of absorption. The diameter of typical commercial MD probes is around 500μm. One additional inherent feature of microdialysis is the possibility to release low-molecular substances from the perfusate by diffusion into the matrix, such as carboxylates. However, microdialysis has yet not been used for P in soils. We tested microdialysis in topsoils of an acid beech forest, of an unfertilized grassland and of a fertilized crop site. Three perfusates have been used: 1 mM KNO3, electrolyte + 0.1 mM citric acid, and electrolyte + 1 mM citric acid. We observed rates of uptake into the probes in a range between 1.5*10-15 and 6.7*10-14 mol s-1cm-1 in case of no citrate addition. Surprisingly, these uptake rates were mostly independent of the bulk stocks. Citrate addition increased P yields only in the higher concentration but not in the forest soil. The order of magnitude of MD uptake rates from the soil samples matched root-length related uptake rates from other studies. The micro-radial citrate release in MD reflects the processes controlling phosphate mobilization in the rhizosphere better than measurements

Influence of root-water-uptake parameterization on simulated heat transport in a structured forest soil

NASA Astrophysics Data System (ADS)

Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir

2015-04-01

Coupled simulations of soil water flow and associated transport of substances have become a useful and increasingly popular tool of subsurface hydrology. Quality of such simulations is directly affected by correctness of its hydraulic part. When near-surface processes under vegetation cover are of interest, appropriate representation of the root water uptake becomes essential. Simulation study of coupled water and heat transport in soil profile under natural conditions was conducted. One-dimensional dual-continuum model (S1D code) with semi-separate flow domains representing the soil matrix and the network of preferential pathways was used. A simple root water uptake model based on water-potential-gradient (WPG) formulation was applied. As demonstrated before [1], the WPG formulation - capable of simulating both the compensatory root water uptake (in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers), and the root-mediated hydraulic redistribution of soil water - enables simulation of more natural soil moisture distribution throughout the root zone. The potential effect on heat transport in a soil profile is the subject of the present study. [1] Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154. The research was supported by the Czech Science Foundation Project No. 14-15201J.

Cadmium Sorption Characteristics of Soil Amendments and its Relationship with the Cadmium Uptake by Hyperaccumulator and Normal Plants in Amended Soils

PubMed Central

Sun, Yan; Wu, Qi-Tang; Lee, Charles C.C.; Li, Baoqin; Long, Xinxian

2013-01-01

In order to select appropriate amendments for cropping hyperaccumulator or normal plants on contaminated soils and establish the relationship between Cd sorption characteristics of soil amendments and their capacity to reduce Cd uptake by plants, batch sorption experiments with 11 different clay minerals and organic materials and a pot experiment with the same amendments were carried out. The pot experiment was conducted with Sedum alfredii and maize (Zea mays) in a co-cropping system. The results showed that the highest sorption amount was by montmorillonite at 40.82 mg/g, while mica was the lowest at only 1.83 mg/g. There was a significant negative correlation between the n value of Freundlich equation and Cd uptake by plants, and between the logarithm of the stability constant K of the Langmuir equation and plant uptake. Humic acids (HAs) and mushroom manure increased Cd uptake by S. alfredii, but not maize, thus they are suitable as soil amendments for the co-cropping S. alfredii and maize. The stability constant K in these cases was 0.14–0.16 L/mg and n values were 1.51–2.19. The alkaline zeolite and mica had the best fixation abilities and significantly decreased Cd uptake by the both plants, with K ≥ 1.49 L/mg and n ≥ 3.59. PMID:24912231

Characterization of H2S removal and microbial community in landfill cover soils.

PubMed

Xia, Fang-Fang; Zhang, Hong-Tao; Wei, Xiao-Meng; Su, Yao; He, Ruo

2015-12-01

H2S is a source of odors at landfills and poses a threat to the surrounding environment and public health. In this work, compared with a usual landfill cover soil (LCS), H2S removal and biotransformation were characterized in waste biocover soil (WBS), an alternative landfill cover material. With the input of landfill gas (LFG), the gas concentrations of CH4, CO2, O2, and H2S, microbial community and activity in landfill covers changed with time. Compared with LCS, lower CH4 and H2S concentrations were detected in the WBS. The potential sulfur-oxidizing rate and sulfate-reducing rate as well as the contents of acid-volatile sulfide, SO4(2-), and total sulfur in the WBS and LCS were all increased with the input of LFG. After exposure to LFG for 35 days, the sulfur-oxidizing rate of the bottom layer of the WBS reached 82.5 μmol g dry weight (d.w.)(-1) day(-1), which was 4.3-5.4 times of that of LCS. H2S-S was mainly deposited in the soil covers, while it escaped from landfills to the atmosphere. The adsorption, absorption, and biotransformation of H2S could lead to the decrease in the pH values of landfill covers; especially, in the LCS with low pH buffer capacity, the pH value of the bottom layer dropped to below 4. Pyrosequencing of 16S ribosomal RNA (rRNA) gene showed that the known sulfur-metabolizing bacteria Ochrobactrum, Paracoccus, Comamonas, Pseudomonas, and Acinetobacter dominated in the WBS and LCS. Among them, Comamonas and Acinetobacter might play an important role in the metabolism of H2S in the WBS. These findings are helpful to understand sulfur bioconversion process in landfill covers and to develop techniques for controlling odor pollution at landfills.

Sorption, Uptake, and Translocation of Pharmaceuticals across Multiple Interfaces in Soil Environment

NASA Astrophysics Data System (ADS)

Zhang, W.; Liu, C. H.; Bhalsod, G.; Zhang, Y.; Chuang, Y. H.; Boyd, S. A.; Teppen, B. J.; Tiedje, J. M.; Li, H.

2015-12-01

Pharmaceuticals are contaminants of emerging concern frequently detected in soil and water environments, raising serious questions on their potential impact on human and ecosystem health. Overuse and environmental release of antibiotics (i.e., a group of pharmaceuticals extensively used in human medicine and animal agriculture) pose enormous threats to the health of human, animal, and the environment, due to proliferation of antibiotic resistant bacteria. Recently, we have examined interactions of pharmaceuticals with soil geosorbents, bacteria, and vegetable crops in order to elucidate pathways of sorption, uptake, and translocation of pharmaceuticals across the multiple interfaces in soils. Sorption of pharmaceuticals by biochars was studied to assess the potential of biochar soil amendment for reducing the transport and bioavailability of antibiotics. Our preliminary results show that carbonaceous materials such as biochars and activated carbon had strong sorption capacities for antibiotics, and consequently decreased the uptake and antibiotic resistance gene expression by an Escherichia coli bioreporter. Thus, biochar soil amendment showed the potential for reducing selection pressure on antibiotic resistant bacteria. Additionally, since consumption of pharmaceutical-tainted food is a direct exposure pathway for humans, it is important to assess the uptake and accumulation of pharmaceuticals in food crops grown in contaminated soils or irrigated with reclaimed water. Therefore, we have investigated the uptake and accumulations of pharmaceuticals in greenhouse-grown lettuce under contrasting irrigation practices (i.e., overhead or surface irrigations). Preliminary results indicate that greater pharmaceutical concentrations were measured in overhead irrigated lettuce than in surface irrigated lettuce. This could have important implications when selecting irrigation scheme to use the reclaimed water for crop irrigation. In summary, proper soil and water management

Effects of continuous fertilization on bioavailability and fractionation of cadmium in soil and its uptake by rice (Oryza sativa L.).

PubMed

Huang, Qingqing; Yu, Yao; Wan, Yanan; Wang, Qi; Luo, Zhang; Qiao, Yuhui; Su, Dechun; Li, Huafen

2018-06-01

A four-year field trial was conducted in a rice paddy in southern China to determine the effects of continuous phosphate fertilizer, pig manure, chicken manure, and sewage sludge application on soil Cd accumulation in soil and Cd uptake by rice. The results showed that continuous application of fertilizers with higher Cd levels caused Cd to accumulate and redistribute in various soil fractions. In turn, these effects influenced Cd bioavailability in rice plants. After four years of phosphate fertilizer, pig manure, chicken manure, and sewage sludge application, the annual soil Cd accumulation rates were 0.007-0.032 mg kg -1 , 0.005-0.022 mg kg -1 , 0.002-0.013 mg kg -1 , and 0.032-0.087 mg kg -1 , respectively. Relative to the control, the pig- and chicken manure treatments significantly increased soil pH and reduced DTPA-extractable Cd (DTPA-Cd) and the exchangeable Cd fraction (Exc-Cd). In contrast, sewage sludge application significantly increased DTPA-Cd and Cd in all soil fractions. Phosphate fertilization had no significant effect on soil pH, DTPA-Cd, or Exc-Cd. Pearson's correlation coefficients showed that the rice grain Cd levels varied directly with DTPA-Cd, and Exc-Cd but inversely with soil pH. Pig- or chicken manure decreased rice grain Cd content, but sewage sludge increased both soil Cd availability and rice grain Cd uptake. Application of phosphate fertilizer had no significant effect on rice grain Cd content. The continuous use of organic- or phosphate fertilizer with elevated Cd content at high application rates may induce soil Cd accumulation and influence rice grain Cd accumulation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Phylogenetic and functional potential links pH and N2O emissions in pasture soils.

PubMed

Samad, Md Sainur; Biswas, Ambarish; Bakken, Lars R; Clough, Timothy J; de Klein, Cecile A M; Richards, Karl G; Lanigan, Gary J; Morales, Sergio E

2016-10-26

Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N 2 O and N 2 emissions. Soil pH regulates the reduction of N 2 O to N 2 , however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N 2 O emission ratio (N 2 O/(NO + N 2 O + N 2 )) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N 2 O emission ratio and community changes. Soil pH was negatively associated with N 2 O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir &nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N 2 O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N 2 O emission ratio through more efficient conversion of N 2 O to N 2 .

Phylogenetic and functional potential links pH and N2O emissions in pasture soils

NASA Astrophysics Data System (ADS)

Samad, M. D. Sainur; Biswas, Ambarish; Bakken, Lars R.; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

2016-10-01

Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2.

Phylogenetic and functional potential links pH and N2O emissions in pasture soils

PubMed Central

Samad, M. d. Sainur; Biswas, Ambarish; Bakken, Lars R.; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

2016-01-01

Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2. PMID:27782174

Effect of Soil pH Increase by Biochar on NO, N2O and N2 Production during Denitrification in Acid Soils

PubMed Central

Obia, Alfred; Cornelissen, Gerard; Mulder, Jan; Dörsch, Peter

2015-01-01

Biochar (BC) application to soil suppresses emission of nitrous- (N2O) and nitric oxide (NO), but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2) were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH) were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH. PMID:26397367

Effect of Soil pH Increase by Biochar on NO, N2O and N2 Production during Denitrification in Acid Soils.

PubMed

Obia, Alfred; Cornelissen, Gerard; Mulder, Jan; Dörsch, Peter

2015-01-01

Biochar (BC) application to soil suppresses emission of nitrous- (N2O) and nitric oxide (NO), but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2) were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH) were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH.

Fluoroethoxy-1,4-diphenethylpiperidine and piperazine derivatives: Potent and selective inhibitors of [3H]dopamine uptake at the vesicular monoamine transporter-2.

PubMed

Hankosky, Emily R; Joolakanti, Shyam R; Nickell, Justin R; Janganati, Venumadhav; Dwoskin, Linda P; Crooks, Peter A

2017-12-15

A small library of fluoroethoxy-1,4-diphenethyl piperidine and fluoroethoxy-1,4-diphenethyl piperazine derivatives were designed, synthesized and evaluated for their ability to inhibit [ 3 H]dopamine (DA) uptake at the vesicular monoamine transporter-2 (VMAT2) and dopamine transporter (DAT), [ 3 H]serotonin (5-HT) uptake at the serotonin transporter (SERT), and [ 3 H]dofetilide binding at the human-ether-a-go-go-related gene (hERG) channel. The majority of the compounds exhibited potent inhibition of [ 3 H]DA uptake at VMAT2, Ki changes in the nanomolar range (K i  = 0.014-0.073 µM). Compound 15d exhibited the highest affinity (K i  = 0.014 µM) at VMAT2, and had 160-, 5-, and 60-fold greater selectivity for VMAT2 vs. DAT, SERT and hERG, respectively. Compound 15b exhibited the greatest selectivity (>60-fold) for VMAT2 relative to all the other targets evaluated, and 15b had high affinity for VMAT2 (K i  = 0.073 µM). Compound 15b was considered the lead compound from this analog series due to its high affinity and selectivity for VMAT2. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatiotemporal dynamics of soil phosphorus and crop uptake in global cropland during the 20th century

NASA Astrophysics Data System (ADS)

Zhang, Jie; Beusen, Arthur H. W.; Van Apeldoorn, Dirk F.; Mogollón, José M.; Yu, Chaoqing; Bouwman, Alexander F.

2017-04-01

Phosphorus (P) plays a vital role in global crop production and food security. In this study, we investigate the changes in soil P pool inventories calibrated from historical countrywide crop P uptake, using a 0.5-by-0.5° spatially explicit model for the period 1900-2010. Globally, the total P pool per hectare increased rapidly between 1900 and 2010 in soils of Europe (+31 %), South America (+2 %), North America (+15 %), Asia (+17 %), and Oceania (+17 %), while it has been stable in Africa. Simulated crop P uptake is influenced by both soil properties (available P and the P retention potential) and crop characteristics (maximum uptake). Until 1950, P fertilizer application had a negligible influence on crop uptake, but recently it has become a driving factor for food production in industrialized countries and a number of transition countries like Brazil, Korea, and China. This comprehensive and spatially explicit model can be used to assess how long surplus P fertilization is needed or how long depletions of built-up surplus P can continue without affecting crop yield.

Relationship of Cell Sap pH to Organic Acid Change During Ion Uptake 1

PubMed Central

Hiatt, A. J.

1967-01-01

Excised roots of barley (Hordeum vulgare, var. Campana) were incubated in KCl, K2SO4, CaCl2, and NaCl solutions at concentrations of 10−5 to 10−2 n. Changes in substrate solution pH, cell sap pH, and organic acid content of the roots were related to differences in cation and anion absorption. The pH of expressed sap of roots increased when cations were absorbed in excess of anions and decreased when anions were absorbed in excess of cations. The pH of the cell sap shifted in response to imbalances in cation and anion uptake in salt solutions as dilute as 10−5 n. Changes in cell sap pH were detectable within 15 minutes after the roots were placed in 10−3 n K2SO4. Organic acid changes in the roots were proportional to expressed sap pH changes induced by unbalanced ion uptake. Changes in organic acid content in response to differential cation and anion uptake appear to be associated with the low-salt component of ion uptake. PMID:16656506

Long-Term Uptake of Phenol-Water Vapor Follows Similar Sigmoid Kinetics on Prehydrated Organic Matter- and Clay-Rich Soil Sorbents.

PubMed

Borisover, Mikhail; Bukhanovsky, Nadezhda; Lado, Marcos

2017-09-19

Typical experimental time frames allowed for equilibrating water-organic vapors with soil sorbents might lead to overlooking slow chemical reactions finally controlling a thermodynamically stable state. In this work, long-term gravimetric examination of kinetics covering about 4000 h was performed for phenol-water vapor interacting with four materials pre-equilibrated at three levels of air relative humidity (RHs 52, 73, and 92%). The four contrasting sorbents included an organic matter (OM)-rich peat soil, an OM-poor clay soil, a hydrophilic Aldrich humic acid salt, and water-insoluble leonardite. Monitoring phenol-water vapor interactions with the prehydrated sorbents, as compared with the sorbent samples in phenol-free atmosphere at the same RH, showed, for the first time, a sigmoid kinetics of phenol-induced mass uptake typical for second-order autocatalytic reactions. The apparent rate constants were similar for all the sorbents, RHs and phenol activities studied. A significant part of sorbed phenol resisted extraction, which was attributed to its abiotic oxidative coupling. Phenol uptake by peat and clay soils was also associated with a significant enhancement of water retention. The delayed development of the sigmoidal kinetics in phenol-water uptake demonstrates that long-run abiotic interactions of water-organic vapor with soil may be overlooked, based on short-term examination.

Genome Data Mining and Soil Survey for the Novel Group 5 [NiFe]-Hydrogenase To Explore the Diversity and Ecological Importance of Presumptive High-Affinity H2-Oxidizing Bacteria ▿†

PubMed Central

Constant, Philippe; Chowdhury, Soumitra Paul; Hesse, Laura; Pratscher, Jennifer; Conrad, Ralf

2011-01-01

Streptomyces soil isolates exhibiting the unique ability to oxidize atmospheric H2 possess genes specifying a putative high-affinity [NiFe]-hydrogenase. This study was undertaken to explore the taxonomic diversity and the ecological importance of this novel functional group. We propose to designate the genes encoding the small and large subunits of the putative high-affinity hydrogenase hhyS and hhyL, respectively. Genome data mining revealed that the hhyL gene is unevenly distributed in the phyla Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. The hhyL gene sequences comprised a phylogenetically distinct group, namely, the group 5 [NiFe]-hydrogenase genes. The presumptive high-affinity H2-oxidizing bacteria constituting group 5 were shown to possess a hydrogenase gene cluster, including the genes encoding auxiliary and structural components of the enzyme and four additional open reading frames (ORFs) of unknown function. A soil survey confirmed that both high-affinity H2 oxidation activity and the hhyL gene are ubiquitous. A quantitative PCR assay revealed that soil contained 106 to 108 hhyL gene copies g (dry weight)−1. Assuming one hhyL gene copy per genome, the abundance of presumptive high-affinity H2-oxidizing bacteria was higher than the maximal population size for which maintenance energy requirements would be fully supplied through the H2 oxidation activity measured in soil. Our data indicate that the abundance of the hhyL gene should not be taken as a reliable proxy for the uptake of atmospheric H2 by soil, because high-affinity H2 oxidation is a facultatively mixotrophic metabolism, and microorganisms harboring a nonfunctional group 5 [NiFe]-hydrogenase may occur. PMID:21742924

Quantification of root water uptake in soil using X-ray computed tomography and image-based modelling.

PubMed

Daly, Keith R; Tracy, Saoirse R; Crout, Neil M J; Mairhofer, Stefan; Pridmore, Tony P; Mooney, Sacha J; Roose, Tiina

2018-01-01

Spatially averaged models of root-soil interactions are often used to calculate plant water uptake. Using a combination of X-ray computed tomography (CT) and image-based modelling, we tested the accuracy of this spatial averaging by directly calculating plant water uptake for young wheat plants in two soil types. The root system was imaged using X-ray CT at 2, 4, 6, 8 and 12 d after transplanting. The roots were segmented using semi-automated root tracking for speed and reproducibility. The segmented geometries were converted to a mesh suitable for the numerical solution of Richards' equation. Richards' equation was parameterized using existing pore scale studies of soil hydraulic properties in the rhizosphere of wheat plants. Image-based modelling allows the spatial distribution of water around the root to be visualized and the fluxes into the root to be calculated. By comparing the results obtained through image-based modelling to spatially averaged models, the impact of root architecture and geometry in water uptake was quantified. We observed that the spatially averaged models performed well in comparison to the image-based models with <2% difference in uptake. However, the spatial averaging loses important information regarding the spatial distribution of water near the root system. © 2017 John Wiley & Sons Ltd.

Uptake of gaseous formaldehyde by soil surfaces: a combination of adsorption/desorption equilibrium and chemical reactions

NASA Astrophysics Data System (ADS)

Li, Guo; Su, Hang; Li, Xin; Kuhn, Uwe; Meusel, Hannah; Hoffmann, Thorsten; Ammann, Markus; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

2016-08-01

Gaseous formaldehyde (HCHO) is an important precursor of OH radicals and a key intermediate molecule in the oxidation of atmospheric volatile organic compounds (VOCs). Budget analyses reveal large discrepancies between modeled and observed HCHO concentrations in the atmosphere. Here, we investigate the interactions of gaseous HCHO with soil surfaces through coated-wall flow tube experiments applying atmospherically relevant HCHO concentrations of ˜ 10 to 40 ppbv. For the determination of uptake coefficients (γ), we provide a Matlab code to account for the diffusion correction under laminar flow conditions. Under dry conditions (relative humidity = 0 %), an initial γ of (1.1 ± 0.05) × 10-4 is determined, which gradually drops to (5.5 ± 0.4) × 10-5 after 8 h experiments. Experiments under wet conditions show a smaller γ that drops faster over time until reaching a plateau. The drop of γ with increasing relative humidity as well as the drop over time can be explained by the adsorption theory in which high surface coverage leads to a reduced uptake rate. The fact that γ stabilizes at a non-zero plateau suggests the involvement of irreversible chemical reactions. Further back-flushing experiments show that two-thirds of the adsorbed HCHO can be re-emitted into the gas phase while the residual is retained by the soil. This partial reversibility confirms that HCHO uptake by soil is a complex process involving both adsorption/desorption and chemical reactions which must be considered in trace gas exchange (emission or deposition) at the atmosphere-soil interface. Our results suggest that soil and soil-derived airborne particles can either act as a source or a sink for HCHO, depending on ambient conditions and HCHO concentrations.

A hydrological tracer study of water uptake depth in a Scots pine forest under two different water regimes.

PubMed

Plamboeck, A H; Grip, H; Nygren, U

1999-05-01

Little is known about the vertical distribution of water uptake by trees under different water supply regimes, the subject of this study, conducted in a Scots pine stand on sandy loam in northern Sweden. The objective was to determine the water uptake distribution in pines under two different water regimes, desiccation (no precipitation) and irrigation (2 mm day -1 in July and 1 mm day -1 in August), and to relate the uptake to water content, root and soil texture distributions. The natural 18 O gradient in soil water was exploited, in combination with two added tracers, 2 H at 10 cm and 3 H at 20 cm depth. Extraction of xylem sap and water from the soil profile then enabled evaluation of relative water uptake from four different soil depths (humus layer, 0-10, 10-25 and 25-55 cm) in each of two 50-m 2 plots per treatment. In addition, water content, root biomass and soil texture were determined. There were differences in vertical water uptake distribution between treatments. In July, the pines at the irrigated and desiccated plots took up 50% and 30%, respectively, of their water from the upper layers, down to 25 cm depth. In August, the pines on the irrigated plots took up a greater proportion of their water from layers below 25 cm deep than they did in July. In a linear regression, the mean hydraulic conductivity for each mineral soil horizon explained a large part of the variation in relative water uptake. No systematic variation in the residual water uptake correlated to the root distribution. It was therefore concluded that the distribution of water uptake by the pines at Åheden was not a function of root density in the mineral soil, but was largely determined by the unsaturated hydraulic conductivity.

Fungal inoculation and elevated CO2 mediate growth of Lolium mutiforum and Phytolacca americana, metal uptake, and metal bioavailability in metal-contaminated soil: evidence from DGT measurement.

PubMed

Song, Ningning; Wang, Fangli; Zhang, Changbo; Tang, Shirong; Guo, Junkang; Ju, Xuehai; Smith, Donald L

2013-01-01

Fungal inoculation and elevated CO2 may mediate plant growth and uptake of heavy metals, but little evidence from Diffusive Gradients in Thin-films (DGT) measurement has been obtained to characterize the process. Lolium mutiforum and Phytolacca americana were grown at ambient and elevated CO2 on naturally Cd and Pb contaminated soils inoculated with and without Trichoderma asperellum strain C3 or Penicillium chrysogenum strain D4, to investigate plant growth, metal uptake, and metal bioavailability responses. Fungal inoculation increased plant biomass and shoot/root Cd and Pb concentrations. Elevated CO2 significantly increased plants biomass, but decreased Cd and Pb concentrations in shoot/root to various extents, leading to a metal dilution phenomenon. Total Cd and Pb uptake by plants, and DGT-measured Cd and Pb concentrations in rhizosphere soils, were higher in all fungal inoculation and elevated CO2 treatments than control treatments, with the combined treatments having more influence than either treatment alone. Metal dilution phenomenon occurred because the increase in DGT-measured bioavailable metal pools in plant rhizosphere due to elevated CO2 was unable to match the increase in requirement for plant uptake of metals due to plant biomass increase.

Influence of different acid and alkaline cleaning agents on the effects of irrigation of synthetic dairy factory effluent on soil quality, ryegrass growth and nutrient uptake.

PubMed

Liu, Y-Y; Haynes, R J

2013-01-01

The aim of this study was to examine the effects of replacement of phosphoric acid with nitric or acetic acid, and replacement of NaOH with KOH, as cleaning agents in dairy factories, on the effects that irrigation of dairy factory effluent (DFE) has on the soil-plant system. A 16-week greenhouse study was carried out in which the effects of addition of synthetic dairy factory effluent containing (a) milk residues alone or milk residues plus (b) H(3)PO(4)/NaOH, (c) H(3)PO(4)/HNO(3)/NaOH or (d) CH(3)COOH/KOH, on soil's chemical, physical and microbial properties and perennial ryegrass growth and nutrient uptake were investigated. The cumulative effect of DFE addition was to increase exchangeable Na, K, Ca, Mg, exchangeable sodium percentage, microbial biomass C and N and basal respiration in the soil. Dry matter yields of ryegrass were increased by additions of DFE other than that containing CH(3)COOH. Plant uptake of P, Ca and Mg was in the same order as their inputs in DFE but for Na; inputs were an order of magnitude greater than plant uptake. Replacement of NaOH by KOH resulted in increased accumulation of exchangeable K. The effects of added NaOH and KOH on promoting breakdown of soil aggregates during wet sieving (and formation of a < 0.25 mm size class) were similar. Replacement of H(2)PO(4) by HNO(3) is a viable but CH(3)COOH appears to have detrimental effects on plant growth. Replacement of NaOH by KOH lowers the likelihood of phytotoxic effects of Na, but K and Na have similar effects on disaggregation.

Distribution of 3H-GABA uptake sites in the nematode Ascaris

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

Guastella, J.; Stretton, A.O.

1991-05-22

The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, locatedmore » at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.« less

Impact of FGD gypsum on soil fertility and plant nutrient uptake

USDA-ARS?s Scientific Manuscript database

Use of FGD gypsum is thought to improve soil productivity and increase plant production. Thus, a study was conducted to evaluate the effects of FGD gypsum on yield, plant nutrient uptake and soil productivity. The study was conducted on an established bermudagrass pasture. Poultry litter was applied...

Biological Oxygen Demand in Soils and Litters

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Smagina, M. V.; Sadovnikova, N. B.

2018-03-01

Biological oxygen demand (BOD) in mineral and organic horizons of soddy-podzolic soils in the forest-park belt of Moscow as an indicator of their microbial respiration and potential biodestruction function has been studied. The BOD of soil samples has been estimated with a portable electrochemical analyzer after incubation in closed flasks under optimum hydrothermal conditions. A universal gradation scale of this parameter from very low (<2 g O2/(m3 h)) to extremely high (>140 g O2/(m3 h)) has been proposed for mineral and organic horizons of soil. A physically substantiated model has been developed for the vertical distribution of BOD in the soil, which combines the diffusion transport of oxygen from the atmosphere and its biogenic uptake in the soil by the first-order reaction. An analytical solution of the model in the stationary state has been obtained; from it, the soil oxygen diffusivity and the kinetic constants of O2 uptake have been estimated, and the profile-integrated total BOD value has been calculated (0.4-1.8 g O2/(m2 h)), which is theoretically identical to the potential oxygen flux from the soil surface due to soil respiration. All model parameters reflect the recreation load on the soil cover by the decrease in their values against the control.

LIQUID CHROMATOGRAPHIC DETERMINATION OF 5-(METHYLAMINO)-2-PHENYL-4-[3-(TRIFLUROMETHYL) PHENYL]-3-(2H)-FURANONE IN SOIL

EPA Science Inventory

A rapid, sensitive method is described for the determination of 5-(methylamino)-2-phenyl-4-[3-(trifluromethyl)phenyl]-3-(2H)-furanone RE-40885) concentrations in three soil types. he method consists of extraction of soil samples with methanol, filtration, liquid chromatographic s...

[Influence of sulfur on the bioavailability of arsenic uptake by rice (Oryza. sativa L. ) and its speciation in soil ].

PubMed

Yang, Shi-jie; Tang, Bing-pei; Wang, Dai-chang; Rao, Wei; Zhang, Ya-nan; Wang, Dan; Zhu, Yun-ji

2014-09-01

Pot experiments using exogenous arsenic-polluted paddy soils were carried out to investigate the influence of different forms of sulfur fertilizers (sulfur and gypsum) on As uptake by rice and its chemical speciation. Soil solution pH value ranged 7. 38-7. 45 in different growth period of rice, and the pH value of AsS0 and AsS1 treatments was higher than that of AsS2 treatment. Variation of Eh value in soil solution was about 200 mV and the Eh of AsS0 was higher than those of AsS1 and AsS2 treatments. From dry matter weight of root and stem and grain of rice, S-fertilizer applied by sulfur and gypsum could improve the amounts of dry matter in rice, while the effects of sulfur treatments and gypsum treatments were not significant. Concentrations of Fe and Mn in iron-manganese plaque on rice roots were 10-30 g.kg-1 and 0.1-1.3 g.kg-1, respectively. Contents of Fe-Mn plaque were mainly different in the tiller stage. Elemental S treatment could more greatly promote the formation of Fe-Mn plaque of rice root than gypsum treatment. Concentrations of As adsorbed by rice roots surface plaque were 583-719 mg.kg-' in tiller stage, 466-621 mg.kg-1 in boot stage, and 310-384 mg kg-1 in flower and matur stage. And it was consistent with the thickness of Fe-Mn plaque on rice root surface. Concentrations of As uptake in roots and stem and leaf and grain were significantly reduced by the application of S fertilizer, and it may be related to the amount of As adsorbed by Fe-Mn plaque at boot stage. According to chemical speciation of soil arsenic, As of non-specific and specific adsorption was most active, and their amounts of As adsorbed in AsS, treatment were significantly lower by 2.85 mg kg-~' than that in AsS2 treatment in tiller stage, and was 0.77 mg.kg- higher than that in AsS2 treatment in the flower stage. Perhaps soil arsenic was easily dissolved in the soil solution and the bioavailability of AsS, treatment was better than that of AsS, treatment.

Can we predict uranium bioavailability based on soil parameters? Part 2: soil solution uranium concentration is not a good bioavailability index.

PubMed

Vandenhove, H; Van Hees, M; Wannijn, J; Wouters, K; Wang, L

2007-01-01

The present study aimed to quantify the influence of soil parameters on uranium uptake by ryegrass. Ryegrass was established on eighteen distinct soils, spiked with (238)U. Uranium soil-to-plant transfer factors (TF) ranged from 0.0003 to 0.0340kgkg(-1). There was no significant relation between the U soil-to-plant transfer (or total U uptake or flux) and the uranium concentration in the soil solution or any other soil factor measured, nor with the U recovered following selective soil extractions. Multiple linear regression analysis resulted in a significant though complex model explaining up to 99% of variation in TF. The influence of uranium speciation on uranium uptake observed was featured: UO(2)(+2), uranyl carbonate complexes and UO(2)PO(4)(-) seem the U species being preferentially taken up by the roots and transferred to the shoots. Improved correlations were obtained when relating the uranium TF with the summed soil solution concentrations of mentioned uranium species.

Usefulness of NIR spectroscopy for the estimation of the mineral composition and texture of soils and heavy metal uptake

NASA Astrophysics Data System (ADS)

Soriano-Disla, J. M.; Gómez, I.; Jordán, M. M.; Guerrero, C.; Navarro-Pedreño, J.; Meseguer, S.; Sanfeliu, T.

2009-04-01

The accumulation of heavy metals in soils from different sources (atmospheric deposition, agricultural practices, urban-industrial activities, etc.) is of a great environmental concern. In this sense, there is a consensus in the literature that the total heavy metals in soil are not a suitable tool for risk assessment regarding heavy metal mobility and bioavailability. Several approaches have been proposed to estimate this bioavailability but controversy exists to define an universal method. The bioavailability is influenced, apart from other properties like pH, organic matter, etc., by the mineral fraction and texture of a soil. However, the determination of these parameters, especially the mineral composition, is laborious, expensive, and time consuming. Thus, the objectives of this work are the estimation of the texture and mineral components of contrasting soils and the heavy metal uptake (Cu, Zn, Pb, Ni, Cr, Cd) by barley after sewage sludge application using NIR spectroscopy. A set of 70 contrasting soils from different parts of Spain were used for the analysis of the texture and mineral composition. The mineralogical characterization of soil samples was carried out by X-ray diffraction (XRD) using whole soil random powder, oriented clay on ceramic plates, and clay random powder. Chung method was used for semi-quantitative interpretation of X-ray diffraction patterns of soils, obtaining the percentage of Calcite (Ca), Quartz (Q), Albite (Ab), Potassium Feldspar (FK), phyllosilicates (PS). For the prediction of heavy metal uptake, the 70 soils were divided in two separate sets of 36 (experiment 1) and 34 (experiment 2) soils. The methodology for both experiments, separated in time, was the same. The soils were amended with the same dose of sewage sludge (15.71 g dry weight kg-1) and placed in pots. In these pots, a bioassay with barley, under greenhouse conditions, was carried out. Eight weeks after sowing, the plants were harvested. Roots were dried in an

Evaluation of soil pH and moisture content on in-situ ozonation of pyrene in soils.

PubMed

Luster-Teasley, S; Ubaka-Blackmoore, N; Masten, S J

2009-08-15

In this study, pyrene spiked soil (300 ppm) was ozonated at pH levels of 2, 6, and 8 and three moisture contents. It was found that soil pH and moisture content impacted the effectiveness of PAH oxidation in unsaturated soils. In air-dried soils, as pH increased, removal increased, such that pyrene removal efficiencies at pH 6 and pH 8 reached 95-97% at a dose of 2.22 mg O(3)/mg pyrene. Ozonation at 16.2+/-0.45 mg O(3)/ppm pyrene in soil resulted in 81-98% removal of pyrene at all pH levels tested. Saturated soils were tested at dry, 5% or 10% moisture conditions. The removal of pyrene was slower in moisturized soils, with the efficiency decreasing as the moisture content increased. Increasing the pH of the soil having a moisture content of 5% resulted in improved pyrene removals. On the contrary, in the soil having a moisture content of 10%, as the pH increased, pyrene removal decreased. Contaminated PAH soils were stored for 6 months to compare the efficiency of PAH removal in freshly contaminated soil and aged soils. PAH adsorption to soil was found to increase with longer exposure times; thus requiring much higher doses of ozone to effectively oxidize pyrene.

Accumulation of phenanthrene by roots of intact wheat (Triticum acstivnm L.) seedlings: passive or active uptake?

PubMed Central

2010-01-01

Background Polycyclic aromatic hydrocarbons (PAHs) are of particular concern due to their hydrophobic, recalcitrant, persistent, potentially carcinogenic, mutagenic and toxic properties, and their ubiquitous occurrence in the environment. Most of the PAHs in the environment are present in surface soil. Plants grown in PAH-contaminated soils or water can become contaminated with PAHs because of their uptake. Therefore, they may threaten human and animal health. However, the mechanism for PAHs uptake by crop roots is little understood. It is important to understand exactly how PAHs are transported into the plant root system and into the human food chain, since it is beneficial in governing crop contamination by PAHs, remedying soils or waters polluted by PAHs with plants, and modeling potential uptake for risk assessment. Results The possibility that plant roots may take up phenanthrene (PHE), a representative of PAHs, via active process was investigated using intact wheat (Triticum acstivnm L.) seedlings in a series of hydroponic experiments. The time course for PHE uptake into wheat roots grown in Hoagland solution containing 5.62 μM PHE for 36 h could be separated into two periods: a fast uptake process during the initial 2 h and a slow uptake component thereafter. Concentration-dependent PHE uptake was characterized by a smooth, saturable curve with an apparent Km of 23.7 μM and a Vmax of 208 nmol g-1 fresh weight h-1, suggesting a carrier-mediated uptake system. Competition between PHE and naphthalene for their uptake by the roots further supported the carrier-mediated uptake system. Low temperature and 2,4-dinitrophenol (DNP) could inhibit PHE uptake equally, indicating that metabolism plays a role in PHE uptake. The inhibitions by low temperature and DNP were strengthened with increasing concentration of PHE in external solution within PHE water solubility (7.3 μM). The contribution of active uptake to total absorption was almost 40% within PHE water

Liming effects on cadmium stabilization in upland soil affected by gold mining activity.

PubMed

Hong, Chang Oh; Lee, Do Kyoung; Chung, Doug Young; Kim, Pil Joo

2007-05-01

To reduce cadmium (Cd) uptake of plants cultivated in heavy metal-contaminated soil, the best liming material was selected in the incubation test. The effect of the selected material was evaluated in the field. In the incubation experimentation, CaCO(3), Ca(OH)(2), CaSO(4).2H(2)O, and oyster shell meal were mixed with soil at rates corresponding to 0, 400, 800, 1600, 3200 mg Ca kg(-1). The limed soil was moistened to 70% of field moisture capacity, and incubated at 25 degrees C for 4 weeks. Ca(OH)(2) was found to be more efficient on reducing soil NH(4)OAc extractable Cd concentration, due to pH increase induced net negative charge. The selected Ca(OH)(2) was applied at rates 0, 2, 4, 8 Mg ha(-1) and then cultivated radish (Raphanus sativa L.) in the field. NH(4)OAc extractable Cd concentration of soil and plant Cd concentration decreased significantly with increasing Ca(OH)(2) rate, since alkaline-liming material markedly increased net negative charge of soil induced by pH increase, and decreased bioavailable Cd fractions (exchangeable + acidic and reducible Cd fraction) during radish cultivation. Cadmium uptake of radish could be reduced by about 50% by amending with about 5 Mg ha(-1) Ca(OH)(2) without adverse effect on radish yield and growth. The increase of net negative charge of soil by Ca(OH)(2) application may suppress Cd uptake and the competition between Ca(2+) and Cd(2+) may additionally affect the suppression of Cd uptake.

Considerable methane uptake by alpine grasslands despite the cold climate: in situ measurements on the central Tibetan Plateau, 2008-2013.

PubMed

Wei, Da; Xu-Ri; Tenzin-Tarchen; Wang, Yuesi; Wang, Yinghong

2015-02-01

The uptake of CH4 by aerate soil plays a secondary role in the removal of tropospheric CH4 , but it is still highly uncertain in terms of its magnitude, spatial, and temporal variation. In an attempt to quantify the sink of the vast alpine grasslands (1,400,000 km(2)) of the Tibetan Plateau, we conducted in situ measurements in an alpine steppe (4730 m) and alpine meadow (4900 m) using the static chamber and gas chromatograph method. For the alpine steppe, measurements (2008-2013) suggested that there is large interannual variability in CH4 uptake, ranging from -48.8 to -95.8 μg CH4 m(-2) h(-1) (averaged of -71.5 ± 2.5 μg CH4 m(-2) h(-1)), due to the variability in precipitation seasonality. The seasonal pattern of CH4 uptakes in the form of stronger uptake in the early growing season and weaker uptake in the rainy season closely matched the precipitation seasonality and subsequent soil moisture variation. The relationships between alpine steppe CH4 uptake and soil moisture/temperature are best depicted by a quadratic function and an exponential function (Q10 = 1.67) respectively. Our measurements also showed that the alpine meadow soil (average of -59.2 ± 3.7 μg CH4 m(-2) h(-1)) uptake less CH4 than the alpine steppe and produces a similar seasonal pattern, which is negatively regulated by soil moisture. Our measurements quantified--at values far higher than those estimated by process-based models--that both the alpine steppe and alpine meadow are considerable CH4 sinks, despite the cold weather of this high-altitude area. The consecutive measurements gathered in this study also highlight that precipitation seasonality tends to drive the interannual variation in CH4 uptake, indicating that future study should be done to better characterize how CH4 cycling might feedback to the more extreme climate. © 2014 John Wiley & Sons Ltd.

Uptake of 2, 4-Dichlorophenoxyacetic acid by Pseudomonas fluorescens

USGS Publications Warehouse

Wedemeyer, G.A.

1966-01-01

Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “nonmetabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carriermediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranylion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens

USGS Publications Warehouse

Wedemeyer, Gary

1966-01-01

Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “non-metabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carrier-mediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranyl ion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

Cleanup Verification Package for the 118-H-6:2, 105-H Reactor Ancillary Support Areas, Below-Grade Structures, and Underlying Soils; the 118-H-6:3, 105-H Reactor Fuel Storage Basin and Underlying Soils; The 118-H-6:3 Fuel Storage Basin Deep Zone Side Slope Soils; the 100-H-9, 100-H-10, and 100-H-13 French Drains; the 100-H-11 and 100-H-12 Expansion Box French Drains; and the 100-H-14 and 100-H-31 Surface Contamination Zones

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

M. J. Appel

2006-06-29

This cleanup verification package documents completion of removal actions for the 105-H Reactor Ancillary Support Areas, Below-Grade Structures, and Underlying Soils (subsite 118-H-6:2); 105-H Reactor Fuel Storage Basin and Underlying Soils (118-H-6:3); and Fuel Storage Basin Deep Zone Side Slope Soils. This CVP also documents remedial actions for the following seven additional waste sties: French Drain C (100-H-9), French Drain D (100-H-10), Expansion Box French Drain E (100-H-11), Expansion Box French Drain F (100-H-12), French Drain G (100-H-13), Surface Contamination Zone H (100-H-14), and the Polychlorinated Biphenyl Surface Contamination Zone (100-H-31).

Through form to function: root hair development and nutrient uptake

NASA Technical Reports Server (NTRS)

Gilroy, S.; Jones, D. L.

2000-01-01

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

Effects of combined amendments on crop yield and cadmium uptake in two cadmium contaminated soils under rice-wheat rotation.

PubMed

Guo, Fuyu; Ding, Changfeng; Zhou, Zhigao; Huang, Gaoxiang; Wang, Xingxiang

2018-02-01

Soil cadmium (Cd) contamination in China has become a serious concern due to its high toxicity to human health through food chains. A pot experiment was conducted to investigate the effects of hydrated lime (L), hydroxyapatite (H) and organic fertilizer (F) alone or in combination to remedy a mild (DY) and a moderate (YX) Cd contaminated agricultural soil under rice-wheat rotation. Results showed that crops grain yield and Cd concentration, soil pH, CaCl 2 extractable Cd and Cd speciation were markedly affected by the amendments. In both cropping seasons, hydrated lime and hydroxyapatite significantly immobilized soil Cd, and hydroxyapatite, organic fertilizer significantly increased grain yield. Hydrated lime mainly increased soil carbonates bound Cd fractions resulted from 16.7% to 36.2% and from 16.8% to 28.3%, and hydroxyapatite increased Fe/Mn oxides Cd fractions from 19.3% to 33.4% and from 31.4% to 42.1% in the DY and YX soils, respectively; while organic fertilizer slightly increased soil exchangeable and organic matter bound Cd fractions. Besides, combined amendments contain alkaline materials and organic materials have the potential to decrease grain Cd and increase grain yield simultaneously. Therefore, in view of the effects of amendments on grain yield and Cd concentration, the cost as well as the potential benefits expected, combined amendments like hydrated lime + organic fertilizer, hydrated lime + hydroxyapatite + organic fertilizer are recommended in practical application. Mechanisms of Cd immobilization affected by amendments are mainly attributed to the changes in soil Cd availability and crops root uptake rather than internal translocation in plants. Copyright © 2017 Elsevier Inc. All rights reserved.

Uptake of explosives from contaminated soil by existing vegetation at the Joliet Army Ammunition Plant

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

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D.

1994-01-01

This study examines the uptake of explosives by existing vegetation growing in TNT-contaminated soils on Group 61 at the Joliet Army Ammunition Plant (JAAP). The soils in this group were contaminated more than 40 years ago. In this study, existing plant materials and soil from the root zone were sampled from 15 locations and analyzed to determine TNT uptake by plants under natural field conditions. Plant materials were separated by species if more than one species was present at a sampling location. Standard methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. Plantmore » materials were also analyzed. No. explosives were detected in the aboveground portion of any plant sample. However, the results indicate that TNT, 2-amino DNT, and/or 4-amino DNT were found in some root samples of false boneset (Kuhnia eupatorioides), teasel (Dipsacus sylvestris), and bromegrass (Bromus inermis). It is possible that slight soil contamination remained on the roots, especially in the case of the very fine roots for species like bromegrass, where washing was difficult. The presence of 2-amino DNT and 4-amino DNT, which could be plant metabolites of TNT, increases the likelihood that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.« less

Soil pH effects on the comparative toxicity of dissolved zinc, non-nano and nano ZnO to the earthworm Eisenia fetida.

PubMed

Heggelund, Laura R; Diez-Ortiz, Maria; Lofts, Stephen; Lahive, Elma; Jurkschat, Kerstin; Wojnarowicz, Jacek; Cedergreen, Nina; Spurgeon, David; Svendsen, Claus

2014-08-01

To determine how soil properties influence nanoparticle (NP) fate, bioavailability and toxicity, this study compared the toxicity of nano zinc oxide (ZnO NPs), non-nano ZnO and ionic ZnCl2 to the earthworm Eisenia fetida in a natural soil at three pH levels. NP characterisation indicated that reaction with the soil media greatly controls ZnO properties. Three main conclusions were drawn. First that Zn toxicity, especially for reproduction, was influenced by pH for all Zn forms. This can be linked to the influence of pH on Zn dissolution. Secondly, that ZnO fate, toxicity and bioaccumulation were similar (including relationships with pH) for both ZnO forms, indicating the absence of NP-specific effects. Finally, earthworm Zn concentrations were higher in worms exposed to ZnO compared to ZnCl2, despite the greater toxicity of the ionic form. This observation suggests the importance of considering the relationship between uptake and toxicity in nanotoxicology studies.

Soil respiration and photosynthetic uptake of carbon dioxide by ground-cover plants in four ages of jack pine forest

USGS Publications Warehouse

Striegl, Robert G.; Wickland, K.P.

2001-01-01

Soil carbon dioxide (CO2) emission (soil respiration), net CO2 exchange after photosynthetic uptake by ground-cover plants, and soil CO2 concentration versus depth below land surface were measured at four ages of jack pine (Pinus banksiana Lamb.) forest in central Saskatchewan. Soil respiration was smallest at a clear-cut site, largest in an 8-year-old stand, and decreased with stand age in 20-year-old and mature (60-75 years old) stands during May-September 1994 (12.1, 34.6, 31.5, and 24.9 mol C??m-2, respectively). Simulations of soil respiration at each stand based on continuously recorded soil temperature were within one standard deviation of measured flux for 48 of 52 measurement periods, but were 10%-30% less than linear interpolations of measured flux for the season. This was probably due to decreased soil respiration at night modeled by the temperature-flux relationships, but not documented by daytime chamber measurements. CO2 uptake by ground-cover plants ranged from 0 at the clear-cut site to 29, 25, and 9% of total growing season soil respiration at the 8-year, 20-year, and mature stands. CO2 concentrations were as great as 7150 ppmv in the upper 1 m of unsaturated zone and were proportional to measured soil respiration.

UNSAT-H Version 2. 0: Unsaturated soil water and heat flow model

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

Fayer, M.J.; Jones, T.L.

1990-04-01

This report documents UNSAT-H Version 2.0, a model for calculating water and heat flow in unsaturated media. The documentation includes the bases for the conceptual model and its numerical implementation, benchmark test cases, example simulations involving layered soils and plant transpiration, and the code listing. Waste management practices at the Hanford Site have included disposal of low-level wastes by near-surface burial. Predicting the future long-term performance of any such burial site in terms of migration of contaminants requires a model capable of simulating water flow in the unsaturated soils above the buried waste. The model currently used to meet thismore » need is UNSAT-H. This model was developed at Pacific Northwest Laboratory to assess water dynamics of near-surface, waste-disposal sites at the Hanford Site. The code is primarily used to predict deep drainage as a function of such environmental conditions as climate, soil type, and vegetation. UNSAT-H is also used to simulate the effects of various practices to enhance isolation of wastes. 66 refs., 29 figs., 7 tabs.« less

Role of microbial inoculation and industrial by-product phosphogypsum in growth and nutrient uptake of maize (Zea mays L.) grown in calcareous soil.

PubMed

Al-Enazy, Abdul-Aziz R; Al-Oud, Saud S; Al-Barakah, Fahad N; Usman, Adel Ra

2017-08-01

Alkaline soils with high calcium carbonate and low organic matter are deficient in plant nutrient availability. Use of organic and bio-fertilizers has been suggested to improve their properties. Therefore, a greenhouse experiment was conducted to evaluate the integrative role of phosphogypsum (PG; added at 0.0, 10, 30, and 50 g PG kg -1 ), cow manure (CM; added at 50 g kg -1 ) and mixed microbial inoculation (Incl.; Azotobacter chroococcum, and phosphate-solubilizing bacteria Bacillus megaterium var. phosphaticum and Pseudomonas fluorescens) on growth and nutrients (N, P, K, Fe, Mn, Zn and Cu) uptake of maize (Zea mays L.) in calcareous soil. Treatment effects on soil chemical and biological properties and the Cd and Pb availability to maize plants were also investigated. Applying PG decreased soil pH. The soil available P increased when soil was inoculated and/or treated with CM, especially with PG. The total microbial count and dehydrogenase activity were enhanced with PG+CM+Incl. Inoculated soils treated with PG showed significant increases in NPK uptake and maize plant growth. However, the most investigated treatments showed significant decreases in shoot micronutrients. Cd and Pb were not detected in maize shoots. Applying PG with microbial inoculation improved macronutrient uptake and plant growth. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Depth of soil water uptake by tropical rainforest trees during dry periods: does tree dimension matter?

PubMed

Stahl, Clément; Hérault, Bruno; Rossi, Vivien; Burban, Benoit; Bréchet, Claude; Bonal, Damien

2013-12-01

Though the root biomass of tropical rainforest trees is concentrated in the upper soil layers, soil water uptake by deep roots has been shown to contribute to tree transpiration. A precise evaluation of the relationship between tree dimensions and depth of water uptake would be useful in tree-based modelling approaches designed to anticipate the response of tropical rainforest ecosystems to future changes in environmental conditions. We used an innovative dual-isotope labelling approach (deuterium in surface soil and oxygen at 120-cm depth) coupled with a modelling approach to investigate the role of tree dimensions in soil water uptake in a tropical rainforest exposed to seasonal drought. We studied 65 trees of varying diameter and height and with a wide range of predawn leaf water potential (Ψpd) values. We confirmed that about half of the studied trees relied on soil water below 100-cm depth during dry periods. Ψpd was negatively correlated with depth of water extraction and can be taken as a rough proxy of this depth. Some trees showed considerable plasticity in their depth of water uptake, exhibiting an efficient adaptive strategy for water and nutrient resource acquisition. We did not find a strong relationship between tree dimensions and depth of water uptake. While tall trees preferentially extract water from layers below 100-cm depth, shorter trees show broad variations in mean depth of water uptake. This precludes the use of tree dimensions to parameterize functional models.

Dried gamma-irradiated sewage solids use on calcareous soils: crop yeilds and heavy metals uptake

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

McCaslin, B.D.; Sivinski, J.S.

1979-01-01

Experiments designed to examine gamma-radiation effects on extractable and plant-available sludge elements and to examine the response of crops to sludge applications on two typical, calcareous soils in New Mexico are summarized. Information has been given indicating that the radiation process of reducing pathogens in sewage products being developed by Sandia Laboratories, does not significantly increase the chemical extractability and plant uptake of a broad range of nutrients and heavy metals. However, radiation treatment greatly facilitates handling sewage for experimentation, because pathogen contamination precautions are eliminated and weed seeds killed. Studies on the effects of sludge irradiation on plant nutrientmore » uptake revealed no concentration increases, agreeing with results presented herein. Sewage products may have special potential for use on calcareous soils, such as in New Mexico. For instance, in New Mexico the lack of potassium in sewage products is not a problem and the naturally high pH of New Mexico soil greatly reduces plant availability of many problem heavy metals. Dramatic increases in yield are typified by the greenhouse and field results presented herein, especially for the known micronutrient deficient soils of New Mexico. Results indicate that sewage sludge is an excellent Zn and Fe fertilizer. More research needs to be done before the economics of sludge application can be calculated and more field information is needed before irradiated sewage products are used indiscriminately. (ERB)« less

Muscle contraction increases carnitine uptake via translocation of OCTN2

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

Furuichi, Yasuro; Sugiura, Tomoko; Kato, Yukio

Highlights: Black-Right-Pointing-Pointer Muscle contraction augmented carnitine uptake into rat hindlimb muscles. Black-Right-Pointing-Pointer An increase in carnitine uptake was due to an intrinsic clearance, not blood flow. Black-Right-Pointing-Pointer Histochemical analysis showed sarcolemmal OCTN2 was emphasized after contraction. Black-Right-Pointing-Pointer OCTN2 protein in sarcolemmal fraction was increased in contracting muscles. -- Abstract: Since carnitine plays an important role in fat oxidation, influx of carnitine could be crucial for muscle metabolism. OCTN2 (SLC22A5), a sodium-dependent solute carrier, is assumed to transport carnitine into skeletal muscle cells. Acute regulation of OCTN2 activity in rat hindlimb muscles was investigated in response to electrically induced contractile activity.more » The tissue uptake clearance (CL{sub uptake}) of L-[{sup 3}H]carnitine during muscle contraction was examined in vivo using integration plot analysis. The CL{sub uptake} of [{sup 14}C]iodoantipyrine (IAP) was also determined as an index of tissue blood flow. To test the hypothesis that increased carnitine uptake involves the translocation of OCTN2, contraction-induced alteration in the subcellular localization of OCTN2 was examined. The CL{sub uptake} of L-[{sup 3}H]carnitine in the contracting muscles increased 1.4-1.7-fold as compared to that in the contralateral resting muscles (p < 0.05). The CL{sub uptake} of [{sup 14}C]IAP was much higher than that of L-[{sup 3}H]carnitine, but no association between the increase in carnitine uptake and blood flow was obtained. Co-immunostaining of OCTN2 and dystrophin (a muscle plasma membrane marker) showed an increase in OCTN2 signal in the plasma membrane after muscle contraction. Western blotting showed that the level of sarcolemmal OCTN2 was greater in contracting muscles than in resting muscles (p < 0.05). The present study showed that muscle contraction facilitated carnitine uptake in skeletal muscles

Application of the diffusive gradients in thin films technique for available potassium measurement in agricultural soils: effects of competing cations on potassium uptake by the resin gel.

PubMed

Zhang, Yulin; Mason, Sean; McNeill, Ann; McLaughlin, Michael J

2014-09-09

The utilization of Amberlite (IRP-69 ion-exchange resin, 100-500 wet mesh) as the binding phase in the diffusive gradients in thin films (DGT) technique has shown potential to improve the assessment of plant-available K in soils. The binding phase has recently been optimized by using a mixed Amberlite and ferrihydrite (MAF) gel which results in linear K uptake over extended deployment periods and in solutions with higher K concentrations. As restriction of K uptake by Ca on the Amberlite based resin gel has been previously proposed, potential competing effects of Ca(2+), Mg(2+) and NH(4+) on K uptake by the MAF gel were investigated. These cations had no effect on K elution efficiency which was 85%. However, K uptake by the MAF gel was restricted in the presence of competing cations in solution. Consequently, the diffusion coefficient of K decreased in the presence of cations compared to previous studies but was stable at 1.12×10(-5)cm(2)s(-1) at 25°C regardless of cation concentrations. Uptake of K by the DGT device was affected by the presence of excessive Ca in more than 30% of twenty typical Australian agricultural soils. However, this problem could be circumvented by using a shorter deployment time than the normal 24 h. Moderate correlation of concentrations of K extracted by DGT with Colwell K (extracted by NaHCO(3), R(2)=0.69) and NH4OAc K (R(2)=0.61) indicates that DGT measures a different pool of K in soils than that measured by the standard extractants used. In addition, the MAF gel has the ability to measure Ca and Mg simultaneously. Copyright © 2014 Elsevier B.V. All rights reserved.

Heavy Metal Uptake by Novel Miscanthus Seed-Based Hybrids Cultivated in Heavy Metal Contaminated Soil

NASA Astrophysics Data System (ADS)

Krzyżak, Jacek; Pogrzeba, Marta; Rusinowski, Szymon; Clifton-Brown, John; McCalmont, Jon Paul; Kiesel, Andreas; Mangold, Anja; Mos, Michal

2017-09-01

When heavy metal contaminated soils are excluded from food production, biomass crops offer an alternative commercial opportunity. Perennial crops have potential for phytoremediation. Whilst the conditions at heavy metal contaminated sites are challenging, successful phytoremediation would bring significant economic and social benefits. Seed-based Miscanthus hybrids were tested alongside the commercial clone Miscanthus × giganteus on arable land, contaminated with Pb, Cd and Zn near Katowice. Before the randomized experimental plots were established (25m2 plots with plant density 2/m2) `time-zero' soil samples were taken to determine initial levels of total (aqua regia) and bioavailable (CaCl2 extraction) concentration of Pb, Cd and Zn. After the growing season plant material was sampled during autumn (October, green harvest) and winter (March, brown harvest) to determine differences in heavy metal uptake. Results after the first growing season are presented, including the plot establishment success, biomass yield and heavy metal uptake.

Drivers of atmospheric methane uptake by montane forest soils in the southern Peruvian Andes

NASA Astrophysics Data System (ADS)

Jones, Sam P.; Diem, Torsten; Huaraca Quispe, Lidia P.; Cahuana, Adan J.; Reay, Dave S.; Meir, Patrick; Arn Teh, Yit

2016-07-01

The soils of tropical montane forests can act as sources or sinks of atmospheric methane (CH4). Understanding this activity is important in regional atmospheric CH4 budgets given that these ecosystems account for substantial portions of the landscape in mountainous areas like the Andes. We investigated the drivers of net CH4 fluxes from premontane, lower and upper montane forests, experiencing a seasonal climate, in south-eastern Peru. Between February 2011 and June 2013, these soils all functioned as net sinks for atmospheric CH4. Mean (standard error) net CH4 fluxes for the dry and wet season were -1.6 (0.1) and -1.1 (0.1) mg CH4-C m-2 d-1 in the upper montane forest, -1.1 (0.1) and -1.0 (0.1) mg CH4-C m-2 d-1 in the lower montane forest, and -0.2 (0.1) and -0.1 (0.1) mg CH4-C m-2 d-1 in the premontane forest. Seasonality in CH4 exchange varied among forest types with increased dry season CH4 uptake only apparent in the upper montane forest. Variation across these forests was best explained by available nitrate and water-filled pore space indicating that nitrate inhibition of oxidation or diffusional constraints imposed by changes in water-filled pore space on methanotrophic communities may represent important controls on soil-atmosphere CH4 exchange. Net CH4 flux was inversely related to elevation; a pattern that differs to that observed in Ecuador, the only other extant study site of soil-atmosphere CH4 exchange in the tropical Andes. This may result from differences in rainfall patterns between the regions, suggesting that attention should be paid to the role of rainfall and soil moisture dynamics in modulating CH4 uptake by the organic-rich soils typical of high-elevation tropical forests.

Mapping Soil pH Buffering Capacity of Selected Fields

NASA Technical Reports Server (NTRS)

Weaver, A. R.; Kissel, D. E.; Chen, F.; West, L. T.; Adkins, W.; Rickman, D.; Luvall, J. C.

2003-01-01

Soil pH buffering capacity, since it varies spatially within crop production fields, may be used to define sampling zones to assess lime requirement, or for modeling changes in soil pH when acid forming fertilizers or manures are added to a field. Our objective was to develop a procedure to map this soil property. One hundred thirty six soil samples (0 to 15 cm depth) from three Georgia Coastal Plain fields were titrated with calcium hydroxide to characterize differences in pH buffering capacity of the soils. Since the relationship between soil pH and added calcium hydroxide was approximately linear for all samples up to pH 6.5, the slope values of these linear relationships for all soils were regressed on the organic C and clay contents of the 136 soil samples using multiple linear regression. The equation that fit the data best was b (slope of pH vs. lime added) = 0.00029 - 0.00003 * % clay + 0.00135 * % O/C, r(exp 2) = 0.68. This equation was applied within geographic information system (GIS) software to create maps of soil pH buffering capacity for the three fields. When the mapped values of the pH buffering capacity were compared with measured values for a total of 18 locations in the three fields, there was good general agreement. A regression of directly measured pH buffering capacities on mapped pH buffering capacities at the field locations for these samples gave an r(exp 2) of 0.88 with a slope of 1.04 for a group of soils that varied approximately tenfold in their pH buffering capacities.

Uptake of explosives from contaminated soil by existing vegetation at the Iowa Army Ammunition Plant

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

Schneider, J.F.; Zellmer, S.D.; Tomczyk, N.A.

This study examines the uptake of explosives by existing vegetation growing in soils contaminated with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-3,5-triazine (RDX) in three areas at the Iowa Army Ammunition Plant (IAAP). To determine explosives uptake under natural environmental conditions, existing plant materials and soil from the root zone were sampled at different locations in each area, and plant materials were separated by species. Standard methods were used to determine the concentrations of explosives, their derivatives, and metabolites in the soil samples. Plant materials were also analyzed. The compound TNT was not detected in the aboveground portion of plants, and vegetation growingmore » on TNT-contaminated soils is not considered a health hazard. However, soil and plant roots may contain TNT degradation products that may be toxic; hence, their consumption is not advised. The compound RDX was found in the tops and roots of plants growing on RDX-contaminated soils at all surveyed sites. Although RDX is not a listed carcinogen, several of its potentially present degradation products are carcinogens. Therefore, the consumption of any plant tissues growing on RDX-contaminated sites should be considered a potential health hazard.« less

Preferential uptake of soil nitrogen forms by grassland plant species.

PubMed

Weigelt, Alexandra; Bol, Roland; Bardgett, Richard D

2005-02-01

In this study, we assessed whether a range of temperate grassland species showed preferential uptake for different chemical forms of N, including inorganic N and a range of amino acids that commonly occur in temperate grassland soil. Preferential uptake of dual-labelled (13C and 15N) glycine, serine, arginine and phenylalanine, as compared to inorganic N, was tested using plants growing in pots with natural field soil. We selected five grass species representing a gradient from fertilised, productive pastures to extensive, low productivity pastures (Lolium perenne, Holcus lanatus, Anthoxanthum odoratum, Deschampsia flexuosa, and Nardus stricta). Our data show that all grass species were able to take up directly a diversity of soil amino acids of varying complexity. Moreover, we present evidence of marked inter-species differences in preferential use of chemical forms of N of varying complexity. L. perenne was relatively more effective at using inorganic N and glycine compared to the most complex amino acid phenylalanine, whereas N. stricta showed a significant preference for serine over inorganic N. Total plant N acquisition, measured as root and shoot concentration of labelled compounds, also revealed pronounced inter-species differences which were related to plant growth rate: plants with higher biomass production were found to take up more inorganic N. Our findings indicate that species-specific differences in direct uptake of different N forms combined with total N acquisition could explain changes in competitive dominance of grass species in grasslands of differing fertility.

Do Reductions in Dry Season Transpiration Allow Shallow Soil Water Uptake to Persist in a Tropical Lower Montane Cloud Forest?

NASA Astrophysics Data System (ADS)

Munoz Villers, L. E.; Holwerda, F.; Alvarado-Barrientos, M. S.; Goldsmith, G. R.; Geissert Kientz, D. R.; González Martínez, T. M.; Dawson, T. E.

2016-12-01

Tropical montane cloud forests (TMCF) are ecosystems particularly sensitive to climate change; however, the effects of warmer and drier conditions on TMCF water cycling remain poorly understood. To investigate the plant functional response to reduced water availability, we conducted a study during the mid to late dry season (2014) in the lower limit (1,325 m asl) of the TMCF belt (1200-2500 m asl) in central Veracruz, Mexico. The temporal variation of transpiration rates of dominant upper canopy and mid-story tree species, depth of water uptake, as well as tree water sources were examined using micrometeorological, sapflow and soil moisture measurements, in combination with data on stable isotope (δ18O and δ2H) composition of rain, tree xylem, soil (bulk and low suction-lysimeter) and stream water. The sapflow data suggest that crown conductances decreased as temperature and vapor pressure deficit increased, and soil moisture decreased from the mid to late dry season. Across all samplings (January 21, April 12 and 26), upper canopy species (Quercus spp.) showed more depleted (negative) isotope values compared to mid-story trees (Carpinus tropicalis). Overall, we found that the evaporated soil water pool was the main source for the trees. Furthermore, our MixSIAR Bayesian mixing model results showed that the depth of tree water uptake changed over the course of the dry season. Unexpectedly, a shift in water uptake from deeper (60-120 cm depth) to shallower soil water (0-30 cm) sources was observed, coinciding with the decreases in transpiration rates towards the end of the dry season. A larger reduction in deep soil water contributions was observed for upper canopy trees (from 70±14 to 22±15%) than for mid-story species (from 10±13 to 7±10%). The use of shallow soil water by trees during the dry season seems consistent with the greater root biomass and higher macronutrient concentrations found in the first 10 cm of the soil profiles. These findings are an

Sorption, plant uptake and metabolism of benzodiazepines.

PubMed

Carter, Laura J; Williams, Mike; Martin, Sheridan; Kamaludeen, Sara P B; Kookana, Rai S

2018-07-01

Reuse of treated wastewater for irrigation of crops is growing in arid and semi-arid regions, whilst increasing amounts of biosolids are being applied to fields to improve agricultural outputs. Due to incomplete removal in the wastewater treatment processes, pharmaceuticals present in treated wastewater and biosolids can contaminate soil systems. Benzodiazepines are a widely used class of pharmaceuticals that are released following wastewater treatment. Benzodiazepines are represented by a class of compounds with a range of physicochemical properties and this study was therefore designed to evaluate the influence of soil properties on the sorption behaviour and subsequent uptake of seven benzodiazepines (chlordiazepoxide, clonazepam, diazepam, flurazepam, oxazepam, temazepam and triazolam) in two plant species. The sorption and desorption behaviour of benzodiazepines was strongly influenced by soil type and hydrophobicity of the chemical. The partitioning behaviour of these chemicals in soil was a key controller of the uptake and accumulation of benzodiazepines by radish (Raphanus sativus) and silverbeet (Beta vulgaris). Benzodiazepines such as oxazepam that were neutral, had low sorption coefficients (K d ) or had pH-adjusted log octanol-water partition coefficients (log D ow , pH6.3) values close to 2 had the greatest extent of uptake. Conversely, benzodiazepines such as flurazepam that had an ionised functional groups and greater K d values had comparatively limited accumulation in the selected plant species. Results also revealed active in-plant metabolism of benzodiazepines, potentially analogous to the known metabolic transformation pathway of benzodiazepines in humans. Along with this observed biological transformation of benzodiazepines in exposed plants, previously work has established the widespread presence of the plant signalling molecule γ-amino butyric acid (GABA), which is specifically modulated by benzodiazepines in humans. This highlights the need

Climatic sensitivity of dryland soil CO2 fluxes differs dramatically with biological soil crust successional state

USGS Publications Warehouse

Tucker, Colin; Ferrenberg, Scott; Reed, Sasha C.

2018-01-01

Arid and semiarid ecosystems make up approximately 41% of Earth’s terrestrial surface and are suggested to regulate the trend and interannual variability of the global terrestrial carbon (C) sink. Biological soil crusts (biocrusts) are common dryland soil surface communities of bryophytes, lichens, and/or cyanobacteria that bind the soil surface together and that may play an important role in regulating the climatic sensitivity of the dryland C cycle. Major uncertainties exist in our understanding of the interacting effects of changing temperature and moisture on CO2 uptake (photosynthesis) and loss (respiration) from biocrust and sub-crust soil, particularly as related to biocrust successional state. Here, we used a mesocosm approach to assess how biocrust successional states related to climate treatments. We subjected bare soil (Bare), early successional lightly pigmented cyanobacterial biocrust (Early), and late successional darkly pigmented moss-lichen biocrust (Late) to either ambient or + 5°C above ambient soil temperature for 84 days. Under ambient temperatures, Late biocrust mesocosms showed frequent net uptake of CO2, whereas Bare soil, Early biocrust, and warmed Late biocrust mesocosms mostly lost CO2 to the atmosphere. The inhibiting effect of warming on CO2 exchange was a result of accelerated drying of biocrust and soil. We used these data to parameterize, via Bayesian methods, a model of ecosystem CO2 fluxes, and evaluated the model with data from an autochamber CO2 system at our field site on the Colorado Plateau in SE Utah. In the context of the field experiment, the data underscore the negative effect of warming on fluxes both biocrust CO2 uptake and loss—which, because biocrusts are a dominant land cover type in this ecosystem, may extend to ecosystem-scale C cycling.

Uptake of polybrominated diphenyl ethers by carrot and lettuce crops grown in compost-amended soils.

PubMed

Bizkarguenaga, E; Iparraguirre, A; Oliva, E; Quintana, J B; Rodil, R; Fernández, L A; Zuloaga, O; Prieto, A

2016-02-01

The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed.

Polynuclear aromatic hydrocarbon uptake by carrots grown in sludge-amended soil

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

Wild, S.R.; Jones, K.C.

The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge-amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg [summation]PAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominate dindividual componentsmore » of the [summation]PAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core [summation]PAH concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 [mu]g/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.« less

EphB4-targeted imaging with antibody h131, h131-F(ab′)2 and h131-Fab

PubMed Central

Li, Dan; Liu, Shuanglong; Liu, Ren; Zhou, Yue; Park, Ryan; Naga, Kranthi; Krasnoperov, Valery; Gill, Parkash S.; Li, Zibo; Shan, Hong; Conti, Peter S.

2013-01-01

Accumulating evidence suggests that overexpression of the tyrosine kinase receptor EphB4, a mediator of vascular development, is a novel target for tumor diagnosis, prognosis and therapy. Noninvasive imaging of EphB4 expression could therefore be valuable for evaluating disease course and therapeutic efficacy at the earliest stages of anti-EphB4 treatment. In this study, we systematically investigated the use of anti-EphB4 antibody h131 (150 kD) and its fragments (h131-F(ab′)2, 110 kD; h131-Fab, 50 kD) for near-infrared fluorescence (NIRF) imaging of EphB4 expression in vivo. h131-F(ab′)2 and h131-Fab were produced through pepsin and papain digestion of h131 respectively, whose purity was confirmed by FPLC and SDS-PAGE. After conjugation with Cy5.5, in vivo characteristics of h131, h131-F(ab′)2 and h131-Fab were evaluated in EphB4-positive HT29 tumor model. Although h131-Cy5.5 demonstrated highest tumor uptake among these probes, its optimal tumor uptake level was obtained at 2 d post injection (p.i.). For h131-Fab-Cy5.5, maximum tumor uptake was achieved at 4 h p.i.. However, no significant difference was observed between h131-Fab-Cy5.5 and hIgG-Fab-Cy5.5, indicating the tumor accumulation was mainly caused by passive targeting. In contrast, h131-F(ab′)2-Cy5.5 demonstrated prominent tumor uptake at 6 h p.i. The target specificity was confirmed by hIgG-F(ab′)2-Cy5.5 control and immunofluorescent staining. Collectively, h131-F(ab′)2 exhibited prominent and specific tumor uptake at early time points, which suggests it is a promising agent for EphB4-targeted imaging. PMID:24147882

Converging patterns of uptake and hydraulic redistribution of soil water in contrasting woody vegetation types.

Treesearch

F.C. Meinzer; J.R. Brooks; S. Bucci; G. Goldstein; F.G. Scholz; J.M. Arren

2004-01-01

We used concurrent measurements of soil water content and soil water potential (Ψsoil) to assess the effects of Ψsoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles at six sites characterized by differences in the types and amounts of woody vegetations and...

Characterization and regulation of (/sup 3/H)-serotonin uptake and release in rodent spinal

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

Stauderman, K.A.

1986-01-01

The uptake and release of (/sup 3/H)-serotonin were investigated in rat spinal cord synaptosomes. In the uptake experiments, sodium-dependent and sodium-independent (/sup 3/H)-serotonin accumulation processes were found. Sodium-dependent (/sup 3/H)-serotonin accumulation was: linear with sodium concentrations up to 180 mM; decreased by disruption of membrane integrity or ionic gradients; associated with purified synaptosomal fractions; and reduced after description of descending serotonergic neurons in the spinal cord. Of the uptake inhibitors tested, the most potent was fluoxetine (IC/sub 50/ 75 nM), followed by desipramine (IC/sub 50/ 430 nM) and nomifensine (IC/sub 50/ 950 nM). The sodium-independent (/sup 3/H)-serotonin accumulation process wasmore » insensitive to most treatments and probably represents nonspecific membrane binding. Thus, only sodium-dependent (/sup 3/H)-serotonin uptake represents the uptake process of serotonergic nerve terminals in rat spinal cord homogenates. In the release experiments, K/sup +/-induced release of previously accumulated (/sup 3/H)-serotonin was Ca/sup 2 +/-dependent, and originated from serotonergic synaptosomes. Exogenous serotonin and 5-methyoxy-N,N-dimethyltryptamine inhibited (/sup 3/H)-serotonin release in a concentration-dependent way. Of the antagonists tested, only methiothepin effectively blocked the effect of serotonin. These data support the existence of presynaptic serotonin autoreceptors on serotonergic nerve terminals in the rat spinal cord that act to inhibit a voltage and Ca/sup 2 +/-sensitive process linked to serotonin release. Alteration of spinai cord serotonergic function may therefore be possible by drugs acting on presynaptic serotonin autoreceptors in the spinal cord.« less

Uptake of cesium-137 by crops from contaminated soils

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

Demirel, H.; Oezer, I.; Celenk, I.

1994-11-01

The Turkish tea crop was contaminated following the Chernobyl nuclear accident. Finding ways to dispose of the contaminated tea (Camellia sinensis L.) without damaging the environment was the goal of this research conducted at the Turkish Atomic Energy Authority (TAEA). In this study, an investigation was made of {sup 137}Cs activities of the plants and the ratios of transfer of {sup 137}Cs activity to plants when the contaminated tea was applied to the soil. Experiments were conducted in the field and in pots under greenhouse conditions. The activities of the tea applied in the field ranged from 12 500 tomore » 72 800 Bq/m{sup 2}, whereas this activity was constant at 8000 Bq/pot in the greenhouse experiment. The transfer of {sup 137}Cs from soil to the plants was between 0.037 and 1.057% for wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), corn (Zea mays indentata Sturt), bean (Phaseolus vulgaris L.), lettuce (Lactuca sativa L.), and grass (Lolium perenne L.). The ratio of the transfer of {sup 137}Cs activity to plants increased as the activity {sup 137}Cs in tea applied to soil was increased. The activity in the plants increased due to increased uptake of {sup 137}Cs by plants. 12 refs., 2 figs., 2 tabs.« less

Forest Soil Phosphorus Resources and Fertilization Affect Ectomycorrhizal Community Composition, Beech P Uptake Efficiency, and Photosynthesis

PubMed Central

Zavišić, Aljosa; Yang, Nan; Marhan, Sven; Kandeler, Ellen; Polle, Andrea

2018-01-01

Phosphorus (P) is an important nutrient, whose plant-available form phosphate is often low in natural forest ecosystems. Mycorrhizal fungi mine the soil for P and supply their host with this resource. It is unknown how ectomycorrhizal communities respond to changes in P availability. Here, we used young beech (Fagus sylvatica L.) trees in natural forest soil from a P-rich and P-poor site to investigate the impact of P amendment on soil microbes, mycorrhizas, beech P nutrition, and photosynthesis. We hypothesized that addition of P to forest soil increased P availability, thereby, leading to enhanced microbial biomass and mycorrhizal diversity in P-poor but not in P-rich soil. We expected that P amendment resulted in increased plant P uptake and enhanced photosynthesis in both soil types. Young beech trees with intact soil cores from a P-rich and a P-poor forest were kept in a common garden experiment and supplied once in fall with triple superphosphate. In the following summer, labile P in the organic layer, but not in the mineral top soil, was significantly increased in response to fertilizer treatment. P-rich soil contained higher microbial biomass than P-poor soil. P treatment had no effect on microbial biomass but influenced the mycorrhizal communities in P-poor soil and shifted their composition toward higher similarities to those in P-rich soil. Plant uptake efficiency was negatively correlated with the diversity of mycorrhizal communities and highest for trees in P-poor soil and lowest for fertilized trees. In both soil types, radioactive P tracing (H333PO4) revealed preferential aboveground allocation of new P in fertilized trees, resulting in increased bound P in xylem tissue and enhanced soluble P in bark, indicating increased storage and transport. Fertilized beeches from P-poor soil showed a strong increase in leaf P concentrations from deficient to luxurious conditions along with increased photosynthesis. Based on the divergent behavior of beech in P

Treatment Of Polychlorinated Biphenyls In Two Surface Soils Using Catalyzed H2O2 Propagations

EPA Science Inventory

Two surface soils contaminated with polychlorinated biphenyls (PCBs) collected from Superfund sites in the New England region of the United States, Fletcher Paints and Merrimack Industrial Metals, were evaluated for field treatment at the bench level using catalyzed H₂...

Can increased nitrogen uptake at elevated CO2 be explained by an hypothesis of optimal root function?

NASA Astrophysics Data System (ADS)

McMurtrie, R. E.; Norby, R. J.; Näsholm, T.; Iversen, C.; Dewar, R. C.; Medlyn, B. E.

2011-12-01

Forest free-air CO2 enrichment (FACE) experiments have shown that annual nitrogen (N) uptake increases when trees are grown at elevated CO2 (eCO2) and that increased N uptake is critical for a sustained growth response to eCO2. Processes contributing to increased N uptake at eCO2 may include: accelerated decomposition of soil organic matter due to enhanced root carbon (C) exudation (so-called rhizosphere priming); increased C allocation to fine roots and increased root production at depth, both of which enhance N acquisition; differences in soil N availability with depth; changes in the abundance of N in chemical forms with differing mobility in soil; and reduced N concentrations, reduced maintenance respiration rates, and increased longevities of deeper roots. These processes have been synthesised in a model of annual N uptake in relation to the spatial distribution of roots. We hypothesise that fine roots are distributed spatially in order to maximise annual N uptake. The optimisation hypothesis leads to equations for the optimal vertical distribution of root biomass in relation to the distribution of available soil N and for maximum annual N uptake. We show how maximum N uptake and rooting depth are related to total root mass, and compare the optimal solution with an empirical function that has been fitted to root-distribution data from all terrestrial biomes. Finally, the model is used to explore the consequences of rhizosphere priming at eCO2 as observed at the Duke forest FACE experiment (Drake et al. 2011, Ecology Letters 14: 349-357) and of increasing N limitation over time as observed at the Oak Ridge FACE experiment (Norby et al. 2010, Proc. Nat. Acad. Sci. USA 107: 19368-19373).

Phytoremediation of arsenic contaminated soil by Pteris vittata L. II. Effect on arsenic uptake and rice yield.

PubMed

Mandal, Asit; Purakayastha, T J; Patra, A K; Sanyal, S K

2012-07-01

A greenhouse experiment evaluated the effect of phytoextraction of arsenic from a contaminated soil by Chinese Brake Fern (Pteris vittata L.) and its subsequent effects on growth and uptake of arsenic by rice (Oryza sativa L.) crop. Pteris vittata was grown for one or two growing cycles of four months each with two phosphate sources, using single super phosphate (SSP) and di-ammonium phosphate (DAP). Rice was grown on phytoextracted soils followed by measurements of biomass yield (grain, straw, and root), arsenic concentration and, uptake by individual plant parts. The biomass yield (grain, straw and rice) of rice was highest in soil phytoextracted with Pteris vittata grown for two cycles and fertilized with diammonium phosphate (DAP). Total arsenic uptake in contaminated soil ranged from 8.2 to 16.9 mg pot(-1) in first growing cycle and 5.5 to 12.0 mg pot(-1) in second growing cycle of Pteris vittata. There was thus a mean reduction of 52% in arsenic content of rice grain after two growing cycle of Pteris vittata and 29% after the one growing cycle. The phytoextraction of arsenic contaminated soil by Pteris vittata was beneficial for growing rice resulted in decreased arsenic content in rice grain of <1 ppm. There was a mean improvement in rice grain yield 14% after two growing cycle and 8% after the one growing cycle of brake fern.

Soil moisture--a regulator of arbuscular mycorrhizal fungal community assembly and symbiotic phosphorus uptake.

PubMed

Deepika, Sharma; Kothamasi, David

2015-01-01

Multiple species of arbuscular mycorrhizal fungi (AMF) can colonize roots of an individual plant species but factors which determine the selection of a particular AMF species in a plant root are largely unknown. The present work analysed the effects of drought, flooding and optimal soil moisture (15-20 %) on AMF community composition and structure in Sorghum vulgare roots, using PCR-RFLP. Rhizophagus irregularis (isolate BEG 21), and rhizosphere soil (mixed inoculum) of Heteropogon contortus, a perennial C4 grass, collected from the semi-arid Delhi ridge, were used as AMF inocula. Soil moisture functioned as an abiotic filter and affected AMF community assembly inside plant roots by regulating AMF colonization and phylotype diversity. Roots of plants in flooded soils had lowest AMF diversity whilst root AMF diversity was highest under the soil moisture regime of 15-20 %. Although plant biomass was not affected, root P uptake was significantly influenced by soil moisture. Plants colonized with R. irregularis or mixed AMF inoculum showed higher root P uptake than non-mycorrhizal plants in drought and control treatments. No differences in root P levels were found in the flooded treatment between plants colonized with R. irregularis and non-mycorrhizal plants, whilst under the same treatment, root P uptake was lower in plants colonized with mixed AMF inoculum than in non-mycorrhizal plants.

Growth and Cd uptake by rice (Oryza sativa) in acidic and Cd-contaminated paddy soils amended with steel slag.

PubMed

He, Huaidong; Tam, Nora F Y; Yao, Aijun; Qiu, Rongliang; Li, Wai Chin; Ye, Zhihong

2017-12-01

Contamination of rice (Oryza sativa) by Cd is of great concern. Steel slag could be used to amend Cd-contaminated soils and make them safe for cereal production. This work was conducted to study the effects of steel slag on Cd uptake and growth of rice plants in acidic and Cd-contaminated paddy soils and to determine the possible mechanisms behind these effects. Pot (rhizobag) experiments were conducted using rice plants grown on two acidic and Cd-contaminated paddy soils with or without steel slag amendment. Steel slag amendment significantly increased grain yield by 36-45% and root catalase activity, and decreased Cd concentrations in brown rice by 66-77% compared with the control, in both soils. Steel slag amendment also markedly decreased extractable soil Cd, Cd concentrations in pore-water and Cd translocation from roots to above-ground parts. It also significantly increased soil pH, extractable Si and Ca in soils and Ca concentrations in roots. Significant positive correlations were found between extractable soil Cd and Cd concentrations in rice tissues, but it was negatively correlated with soil pH and extractable Si. Calcium in root tissues significantly and negatively correlated with Cd translocation factors from roots to straw. Overall, steel slag amendment not only significantly promoted rice growth but decreased Cd accumulation in brown rice. These benefits appear to be related to improvements in soil conditions (e.g. increasing pH, extractable Si and Ca), a reduction in extractable soil Cd, and suppression of Cd translocation from roots to above-ground parts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

NASA Astrophysics Data System (ADS)

Inselsbacher, Erich; Schmidt, Susanne; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Brackin, Richard

2016-04-01

Nitrogen (N) uptake by agricultural crops is a key constituent of the global N cycle, as N captured by roots has a markedly different fate than N remaining in the soil. Global evidence indicates that only approximately 50% of applied N fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. This inefficiency is of global concern, and requires innovation based on improved understanding of which N forms are available for and ultimately taken up by crops. However, current soil analysis methods based on destructive soil sampling provide little insight into delivery and acquisition of N forms by roots. Here, we present the results of a study in sugarcane fields receiving different fertilizer regimes comparing soil N supply rates with potential root N uptake rates. We applied microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure flux rates of inorganic N and amino acid N, and analyzed N uptake capacities of sugarcane roots using 15N labelled tracers. We found that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots' uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and organic N may contribute more to crop N supply than is currently assumed. Overall, we show a new approach for examining in situ N relations in soil in context of crop N physiology, which provides a new avenue towards tailoring N fertilizer supply to match the specific uptake abilities and N demand of crops over the growth

Soil zinc and cadmium availability and uptake by wheat (Triticum aestivum L.) as affected by long-term organic matter management

NASA Astrophysics Data System (ADS)

Grüter, Roman; Costerousse, Benjamin; Mayer, Jochen; Mäder, Paul; Thonar, Cécile; Frossard, Emmanuel; Schulin, Rainer; Tandy, Susan

2017-04-01

Zinc (Zn) deficiency is a widespread problem in human mineral nutrition. It is mainly caused by imbalanced diets with low contents of bioavailable Zn. This is in particular a problem in populations depending on cereals such as wheat (Triticum aestivum L.) as a major source of this essential micronutrient element. Increasing Zn concentrations in wheat grains (biofortification) is therefore an important challenge. At the same time, increased uptake of the toxic heavy metal cadmium (Cd) must be prevented. Agronomic practises influence soil properties such as pH and soil organic carbon and thus also have an indirect effect on phytoavailable soil Zn and Cd concentrations and the uptake of these metals by wheat in addition to direct inputs with fertilizers and other amendments. This study investigated the effects of long-term organic matter management on the phytoavailability of soil Zn and Cd and their uptake by wheat on plots of two Swiss long-term field trials. In one trial (DOK), a farming system comparison trial established in 1978, we compared plots under conventional management with mineral fertilization either in combination or not with farmyard manure application to plots under biodynamic organic management and control plots with no fertilizer application. In the second trial (ZOFE), established in 1949, we compared different fertilizer regimes on conventionally managed plots, including plots with application of mineral fertilizers only, farmyard manure, or compost and control plots with no fertilizer application. Soil physico-chemical and biological properties were determined at the beginning of the growing season. Soil Zn and Cd availabilities were assessed by the Diffusive Gradients in Thin Films (DGT) method and by DTPA extraction before and after wheat cultivation. Additionally, various wheat yield components and element concentrations in shoots and grains were measured at harvest. In the ZOFE trial, soil Zn and Cd concentrations were lowest in the mineral

Measurements of water uptake of maize roots: insights for traits that influence water transport from the soil

NASA Astrophysics Data System (ADS)

Ahmed, Mutez A.; Zarebanadkouki, Mohsen; Kroener, Eva; Carminati, Andrea

2015-04-01

Water availability is a primary constraint to the global crop production. Although maize (Zea mays L.) is one of the most important crops worldwide, there is limited information on the function of different root segments and types in extracting water from soils. Aim of this study was to investigate the location of water uptake in maize roots. We used neutron radiography to: 1) image the spatial distribution of maize roots in soil and 2) trace the transport of injected deuterated water (D2O) in soil and roots. Maize plants were grown in aluminum containers (40×38×1 cm) filled with sandy soil. The soil was partitioned into different compartments using 1-cm-thick layers of coarse sand. When the plants were two weeks-old we injected D2O into selected soil compartments. The experiments were performed during the day (transpiring plants) and night (non transpiring plants). The transport of D2O into roots was simulated using a convection-diffusion numerical model of D2O transport into roots. By fitting the observed D2O transport we quantified the diffusion coefficient and the water uptake of the different root segments. The maize root architecture consisted of a primary root, 4-5 seminal roots and many lateral roots connected to the primary and seminal roots. Laterals emerged from the proximal 15 cm of the primary and seminal roots. Both during day and night measurements, D2O entered more quickly into lateral roots than into primary and seminal roots. The quick transport of D2O into laterals was caused by the small radius of lateral roots. The diffusion coefficient of lateral roots (4.68×10-7cm2s-1)was similar to that of the distal segments of seminal roots (4.72×10-7cm2s-1) and higher than of the proximal segments (1.42×10-7cm2s-1). Water uptake of lateral roots (1.64×10-5cms-1)was much higher than that of the distal segments of seminal roots (1.18×10-12cms-1). Water uptake of the proximal seminal segments was negligible. We conclude that the function of lateral

Organic N cycling in Arctic ecosystems: Quantifying root uptake kinetics and temporal variability of soil amino acids.

NASA Astrophysics Data System (ADS)

Homyak, P. M.; Iverson, S. L.; Slessarev, E.; Marchus, K.; Schimel, J.

2017-12-01

Arctic ecosystems are undergoing shifts in plant community composition with increased warming. How these changes may alter ecosystem function is not well constrained, owing in part to uncertainties on how plant-soil feedbacks influence nutrient cycling. For nitrogen (N), in particular, understanding how these feedbacks may alter cycling rates is challenging because i) Arctic plants take up organic N (i.e., amino acids; AA) when inorganic N is limiting, yet ii) it has never been quantified, for any plant species growing in the wild, how much of its N demand is actually met by taking up AA. To advance fundamental understanding of plant-soil feedbacks as the Arctic warms, we are integrating field measurements of AA availability in N-limited tussock tundra (E. vaginatum) and a comparably less N-limited birch shrub tundra (Betula nana and Salix spp.) with a root uptake model. We used soil microdialysis to determine available AA concentrations in the soil solution and potential rates of AA diffusion and mass flow to roots at the Toolik Field Station in Alaska. These measurements are being combined with AA root uptake kinetic experiments using E. vaginatum to establish actual AA root uptake rates. We found that in the early growing season (June), total AA concentrations in the soil solution averaged 104 µg N L-1 and were similar to NH4+ across sites. In the late growing season (August), AA were the dominant form of N averaging 75 µg N L-1 while NH4+ decreased to 13 µg N L-1. In the early growing season AA diffusion rates in the soil averaged 200 ng N cm-2 s-1 and declined to 150 ng N cm-2 s-1 in the late growing season. Lysine, serine, and arginine were the most abundant AA and differences in the N status of sites did not affect total AA concentrations. Amino acids made up at least half of the N diffusing through the soil solution, suggesting they can subsidize the N demand of arctic plants. Ongoing field experiments at Toolik will be used to constrain actual AA root

Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

PubMed Central

Brackin, Richard; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Schmidt, Susanne; Inselsbacher, Erich

2015-01-01

Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots’ uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed. PMID:26496834

An invisible soil acidification: Critical role of soil carbonate and its impact on heavy metal bioavailability

PubMed Central

Wang, Cheng; Li, Wei; Yang, Zhongfang; Chen, Yang; Shao, Wenjing; Ji, Junfeng

2015-01-01

It is well known that carbonates inhibit heavy metals transferring from soil to plants, yet the mechanism is poorly understood. Based on the Yangtze River delta area, we investigated bioaccumulation of Ni and Cd in winter wheat as affected by the presence of carbonates in soil. This study aimed to determine the mechanism through which soil carbonates restrict transport and plant uptake of heavy metals in the wheat cropping system. The results indicate that soil carbonates critically influenced heavy metal transfer from soil to plants and presented a tipping point. Wheat grains harvested from carbonates-depleted (due to severe leaching) soils showed Ni and Cd concentrations 2–3 times higher than those of the wheat grains from carbonates-containing soils. Correspondingly, the incidence of Ni or Cd contamination in the wheat grain samples increased by about three times. With the carbonate concentration >1% in soil, uptake and bioaccumulation of Ni and Cd by winter wheat was independent with the soil pH and carbonate content. The findings suggest that soil carbonates play a critical role in heavy metal transfer from soil to plants, implying that monitoring soil carbonate may be necessary in addition to soil pH for the evaluating soil quality and food safety. PMID:26227091

Strong shift from HCO3 (-) to CO 2 uptake in Emiliania huxleyi with acidification: new approach unravels acclimation versus short-term pH effects.

PubMed

Kottmeier, Dorothee M; Rokitta, Sebastian D; Tortell, Philippe D; Rost, Björn

2014-09-01

Effects of ocean acidification on Emiliania huxleyi strain RCC 1216 (calcifying, diploid life-cycle stage) and RCC 1217 (non-calcifying, haploid life-cycle stage) were investigated by measuring growth, elemental composition, and production rates under different pCO2 levels (380 and 950 μatm). In these differently acclimated cells, the photosynthetic carbon source was assessed by a (14)C disequilibrium assay, conducted over a range of ecologically relevant pH values (7.9-8.7). In agreement with previous studies, we observed decreased calcification and stimulated biomass production in diploid cells under high pCO2, but no CO2-dependent changes in biomass production for haploid cells. In both life-cycle stages, the relative contributions of CO2 and HCO3 (-) uptake depended strongly on the assay pH. At pH values ≤ 8.1, cells preferentially used CO2 (≥ 90 % CO2), whereas at pH values ≥ 8.3, cells progressively increased the fraction of HCO3 (-) uptake (~45 % CO2 at pH 8.7 in diploid cells; ~55 % CO2 at pH 8.5 in haploid cells). In contrast to the short-term effect of the assay pH, the pCO2 acclimation history had no significant effect on the carbon uptake behavior. A numerical sensitivity study confirmed that the pH-modification in the (14)C disequilibrium method yields reliable results, provided that model parameters (e.g., pH, temperature) are kept within typical measurement uncertainties. Our results demonstrate a high plasticity of E. huxleyi to rapidly adjust carbon acquisition to the external carbon supply and/or pH, and provide an explanation for the paradoxical observation of high CO2 sensitivity despite the apparently high HCO3 (-) usage seen in previous studies.

Enhancing soil infiltration reduces gaseous emissions and improves N uptake from applied dairy slurry.

PubMed

Bhandral, R; Bittman, S; Kowalenko, G; Buckley, K; Chantigny, M H; Hunt, D E; Bounaix, F; Friesen, A

2009-01-01

Rapid infiltration of liquid manure into the soil reduces emissions of ammonia (NH(3)) into the atmosphere. This study was undertaken to assess the effects of two low-cost methods of assisting infiltration of applied dairy slurry on emissions of NH(3), nitrous oxide (N(2)O), and on crop N uptake. The two methods were removing of solids by settling-decantation to make the manure less viscous and mechanically aerating the soil. Ammonia emissions were measured with wind tunnels as percentage of applied total ammoniacal nitrogen (TAN) while emissions of N(2)O were measured with vented chambers. Mechanically aerating the soil before manure application significantly reduced emissions of NH(3) relative to the nonaerated soil in spring (38.6 to 20.3% of applied TAN), summer (41.1 to 26.4% of applied TAN) and fall (27.7 to 13.6% of applied TAN) trials. Decantation of manure had no effect on NH(3) emissions in spring, tended to increase emissions in summer and significantly decreased emissions in fall (30.3 to 11.1% of applied TAN). Combining the two abatement techniques reduced NH(3) emission by 82% in fall, under cool weather conditions typical of manure spreading. The two abatement techniques generally did not significantly affect N(2)O emissions. Uptake of applied N by Italian ryegrass (Lolium multiflorum Lam.) was generally significantly greater with decanted than from whole manure but the effect of aeration was generally small and not significant. The study shows that low cost methods that assist manure infiltration into the soil may be used to greatly reduce ammonia loss without increasing N(2)O emissions, but efficacy of abatement methods is affected by weather conditions.

Soil pH and electrical conductivity are key edaphic factors shaping bacterial communities of greenhouse soils in Korea.

PubMed

Kim, Jeong Myeong; Roh, An-Sung; Choi, Seung-Chul; Kim, Eun-Jeong; Choi, Moon-Tae; Ahn, Byung-Koo; Kim, Sun-Kuk; Lee, Young-Han; Joa, Jae-Ho; Kang, Seong-Soo; Lee, Shin Ae; Ahn, Jae-Hyung; Song, Jaekyeong; Weon, Hang-Yeon

2016-12-01

Soil microorganisms play an essential role in soil ecosystem processes such as organic matter decomposition, nutrient cycling, and plant nutrient availability. The land use for greenhouse cultivation has been increasing continuously, which involves an intensive input of agricultural materials to enhance productivity; however, relatively little is known about bacterial communities in greenhouse soils. To assess the effects of environmental factors on the soil bacterial diversity and community composition, a total of 187 greenhouse soil samples collected across Korea were subjected to bacterial 16S rRNA gene pyrosequencing analysis. A total of 11,865 operational taxonomic units at a 97% similarity cutoff level were detected from 847,560 sequences. Among nine soil factors evaluated; pH, electrical conductivity (EC), exchangeable cations (Ca 2+ , Mg 2+ , Na + , and K + ), available P 2 O 5 , organic matter, and NO 3 -N, soil pH was most strongly correlated with bacterial richness (polynomial regression, pH: R 2 = 0.1683, P < 0.001) and diversity (pH: R 2 = 0.1765, P < 0.001). Community dissimilarities (Bray-Curtis distance) were positively correlated with Euclidean distance for pH and EC (Mantel test, pH: r = 0.2672, P < 0.001; EC: r = 0.1473, P < 0.001). Among dominant phyla (> 1%), the relative abundances of Proteobacteria, Gemmatimonadetes, Acidobacteria, Bacteroidetes, Chloroflexi, and Planctomycetes were also more strongly correlated with pH and EC values, compared with other soil cation contents, such as Ca 2+ , Mg 2+ , Na + , and K + . Our results suggest that, despite the heterogeneity of various environmental variables, the bacterial communities of the intensively cultivated greenhouse soils were particularly influenced by soil pH and EC. These findings therefore shed light on the soil microbial ecology of greenhouse cultivation, which should be helpful for devising effective management strategies to enhance soil microbial diversity and improving crop

Soil pH management without lime, a strategy to reduce greenhouse gas emissions from cultivated soils

NASA Astrophysics Data System (ADS)

Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter

2015-04-01

For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply lime, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than lime. Here we report a newly established field trail in Norway, in which we compare the effects of lime and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of lime on soil pH, and slower effects of the mafic rocks. The

Reduction in soil N2O emissions by pH manipulation and enhanced nosZ gene transcription under different water regimes.

PubMed

Shaaban, Muhammad; Wu, Yupeng; Khalid, Muhammad Salman; Peng, Qi-An; Xu, Xiangyu; Wu, Lei; Younas, Aneela; Bashir, Saqib; Mo, Yongliang; Lin, Shan; Zafar-Ul-Hye, Muhammad; Abid, Muhammad; Hu, Ronggui

2018-04-01

Several studies have been carried out to examine nitrous oxide (N 2 O) emissions from agricultural soils in the past. However, the emissions of N 2 O particularly during amelioration of acidic soils have been rarely studied. We carried out the present study using a rice-rapeseed rotation soil (pH 5.44) that was amended with dolomite (0, 1 and 2 g kg -1 soil) under 60% water filled pore space (WFPS) and flooding. N 2 O emissions and several soil properties (pH, NH 4 + N, NO 3 - -N, and nosZ gene transcripts) were measured throughout the study. The increase in soil pH with dolomite application triggered soil N transformation and transcripts of nosZ gene controlling N 2 O emissions under both water regimes (60% WFPS and flooding). The 60% WFPS produced higher soil N 2 O emissions than that of flooding, and dolomite largely reduced N 2 O emissions at higher pH under both water regimes through enhanced transcription of nosZ gene. The results suggest that ameliorating soil acidity with dolomite can substantially mitigate N 2 O emissions through promoting nosZ gene transcription. Copyright © 2017 Elsevier Ltd. All rights reserved.

The uptake of 3H-vincristine by a mouse carcinoma during a course of fractionated radiotherapy.

PubMed

Zanelli, G D; Rota, L; Trovo, M; Grigoletto, E; Roncadin, M

1989-09-01

The variations in uptake of 3H-vincristine sulphate, given as a bolus i.v. injection, by a transplantable murine tumour during a realistic course of fractionated daily gamma-radiation of 25 x 2.0 Gy have been investigated. Maximum levels of 3H in the tumours are found when the tracer is injected 4h after irradiation and the tumours are dissected out 1 h after injection. During the course of daily irradiation the pattern of uptake varies considerably but reproducibly. There are peaks of uptake after 7, 13 and 22 fractions of 2.0 Gy when the amount of 3H in the tumours is as much as three times that found in non-irradiated tumours. After 17-18 fractions, however, the tumour content of 3H is lower than that of non-irradiated tumours. The wave-like pattern of uptake could be due either to capillary occlusion brought about by radiation induced cellular swelling and oedema followed by re-opening of the capillaries during periods of decreased cellularity, or to some mechanism of recovery from radiation damage during the week-end rest period.

The uptake of 3H-vincristine by a mouse carcinoma during a course of fractionated radiotherapy.

PubMed Central

Zanelli, G. D.; Rota, L.; Trovo, M.; Grigoletto, E.; Roncadin, M.

1989-01-01

The variations in uptake of 3H-vincristine sulphate, given as a bolus i.v. injection, by a transplantable murine tumour during a realistic course of fractionated daily gamma-radiation of 25 x 2.0 Gy have been investigated. Maximum levels of 3H in the tumours are found when the tracer is injected 4h after irradiation and the tumours are dissected out 1 h after injection. During the course of daily irradiation the pattern of uptake varies considerably but reproducibly. There are peaks of uptake after 7, 13 and 22 fractions of 2.0 Gy when the amount of 3H in the tumours is as much as three times that found in non-irradiated tumours. After 17-18 fractions, however, the tumour content of 3H is lower than that of non-irradiated tumours. The wave-like pattern of uptake could be due either to capillary occlusion brought about by radiation induced cellular swelling and oedema followed by re-opening of the capillaries during periods of decreased cellularity, or to some mechanism of recovery from radiation damage during the week-end rest period. PMID:2789937

Plutonium-239 and americium-241 uptake by plants from soil. Final report

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

Brown, K.W.

1979-03-01

Alfalfa was grown in soil contaminated with plutonium-239 dioxide (239PuO2) at a concentration of 29.7 nanocuries per gram (nCi/g). In addition to alfalfa, radishes, wheat, rye, and tomatoes were grown in soils contaminated with americium-241 nitrate (241Am(NO3)3) at a concentration of 189 nCi/g. The length of exposure varied from 52 days for the radishes to 237 days for the alfalfa. The magnitude of plutonium incorporation by the alfalfa as indicated by the concentration ratio, 0.0000025, was similar to previously reported data using other chemical forms of plutonium. The results did indicate, however, that differences in the biological availability of plutoniummore » isotopes do exist. All of the species exposed to americium-241 assimilated and translocated this radioisotope to the stem, leaf, and fruiting structures. The magnitude of incorporation as signified by the concentration ratios varied from 0.00001 for the wheat grass to 0.0152 for the radishes. An increase in the uptake of americium also occurred as a function of time for four of the five plant species. Evidence indicates that the predominant factor in plutonium and americium uptake by plants may involve the chelation of these elements in soils by the action of compounds such as citric acid and/or other similar chelating agents released from plant roots.« less

Effect of different amendments on rice (Oryza sativa L.) growth, yield, nutrient uptake and grain quality in Ni-contaminated soil.

PubMed

Ramzani, Pia Muhammad Adnan; Khan, Waqas-Ud-Din; Iqbal, Muhammad; Kausar, Salma; Ali, Shafaqat; Rizwan, Muhammad; Virk, Zaheer Abbas

2016-09-01

Rice ( Oryza sativa L.) is one of the main staple food crops which is inherently low in micronutrients, especially iron (Fe), and can lead to severe Fe deficiency in populations having higher consumption of rice. Soils polluted with nickel (Ni) can cause toxicity to rice and decreased Fe uptake by rice plants. We investigated the potential role of biochar (BC) and gravel sludge (GS), alone and in combination, for in situ immobilization of Ni in an industrially Ni-contaminated soil at original and sulfur-amended altered soil pH. Our further aim was to increase Fe bioavailability to rice plants by the exogenous application of ferrous sulfate to the Ni-immobilized soil. Application of the mixture of both amendments reduced grain Ni concentration, phytate, Phytate/Fe, Phyt/Zn molar ratios, and soil DTPA-extractable Ni. In addition, the amendment mixture increased 70 % Fe and 229 % ferritin concentrations in rice grains grown in the soil at original pH. The Fe and ferritin concentrations in S-treated soil was increased up to 113 and 383 % relative to control respectively. This enhanced Fe concentration and corresponding ferritin in rice grains can be attributed to Ni/Fe antagonism where Ni has been immobilized by GS and BC mixture. This proposed technique can be used to enhance growth, yield, and Fe biofortification in rice by reducing soil pH while in parallel in situ immobilizing Ni in polluted soil.

Ethanol intake and sup 3 H-serotonin uptake II: A study in alcoholic patients using platelets sup 3 H-paroxetine binding

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

Daoust, M.; Boucly, P.; Ernouf, D.

1991-01-01

The kinetic parameters of {sup 3}H-paroxetine binding and {sup 3}H-serotonin uptake were studied in platelets of alcoholic patients. There was no difference between alcoholic and non alcoholic subjects in {sup 3}H-paroxetine binding. When binding and {sup 3}H-serotonin uptake were studied, in the same plasma of the same subjects, the Vmax of serotonin uptake was increased in alcoholics. The data confirm the involvement of serotonin uptake system in alcohol dependance and suggest that serotonin uptake and paroxetine binding sites may be regulated independently in this pathology.

Improving phosphorus uptake and wheat productivity by phosphoric acid application in alkaline calcareous soils.

PubMed

Akhtar, Muhammad; Yaqub, Muhammad; Naeem, Asif; Ashraf, Muhammad; Hernandez, Vicente Espinosa

2016-08-01

Low phosphorus (P) efficiency from existing granular fertilisers necessitates searching for efficient alternatives to improve wheat productivity in calcareous soil. Multi-location trials have shown that phosphoric acid (PA) produced 16% higher wheat grain over commercial P fertilisers, i.e. diammonium phosphate (DAP) and triple superphosphate (TSP). Methods of P application significantly influenced grain yield and the efficiency of methods was observed in the order: PA placement below seed > PA, DAP or TSP fertigation > DAP or TSP broadcast. The sub-surface application of PA produced highest grain yields (mean of all rates), i.e. 4669, 4158 and 3910 kg ha(-1) in Bagh, Bhalwal and Shahpur soil series, respectively. Phosphoric acid at 66 kg P2 O5 ha(-1) was found more effective in increasing gain yield over that of control. Trend in grain P uptake was found similar to that observed for grain yield. Maximum P uptake by grain was recorded at the highest P rate and the lowest at zero P. The significant increase in P uptake with P rates was generally related to the increase in yield rather than its concentration in grain. Phosphorus agronomic efficiency (PAE) and phosphorus recovery efficiency (PRE) were found higher at lower P rate (44 kg P2 O5 ha(-1) ) and decreased with P application. However, PA applied by the either method resulted in higher PAE and PRE compared to DAP and TSP. Phosphoric acid is suggested as an efficient alternative to commercial granular P fertilisers for wheat production in alkaline calcareous soils. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

CONVERGING PATTERNS OF UPTAKE AND HYDRAULIC REDISTRIBUTION OF SOIL WATER IN CONTRASTING WOODY VEGETATION TYPES

EPA Science Inventory

We used concurrent measurements of soil water content and soil water potential (Ysoil) to assess the effects of Ysoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles in six sites characterized by different types and amounts of woo...

Behavior of Engineered Nanomaterials in Unsaturated Soil: Transport, Effects on pH, and Interactions with Phosphorous

NASA Astrophysics Data System (ADS)

Conway, J.; Keller, A. A.

2013-12-01

Recent life cycle assessments have predicted that soils will be the primary non-landfill sink for many engineered nanomaterials (ENMs), and as their production and use increases annually it becomes increasingly relevant to understand their behavior in the unsaturated surface layers of soil. In this series of experiments, the transport and interactions of three common ENMs, TiO2, CeO2, and CuOH, were measured in an unsaturated potting soil with and without humic acid as a stabilizing agent. Transport was measured in loosely packed soil columns at two concentrations (10 and 100 ppm) with three exposure methods: through the application of contaminated biosolids to the top of the column with subsequent irrigation, by watering with an ENM suspension, and by mixing ENMs homogeneously into the soil and irrigating. Transport was also measured in soil containing intact root structures for the latter two exposure methods at 10 ppm ENM concentration. Soil columns were dried and 3 cm segments were acid digested and measured with inductively coupled plasma atomic emission spectroscopy (ICS-AES). The effect of these ENMs on soil pH was tested after mixing ENM suspensions into soil at four concentrations (0, 1, 10, and 100 mg kg-1). The bioavailability of PO4 in the presence of ENMs was measured by quantifying the soluble, bioavailable (i.e., extractable by Bray No. 1 solution), and tightly bound fractions of P in 0, 1, 10, and 100 mg kg-1 spiked soils via ICP-AES. We found that these three ENMs exhibit limited transport in all exposure scenarios and so will likely remain near the source zone in an environmental exposure. Additionally, these ENMs were seen to decrease soil pH by up to 0.5 in the highest concentrations, which has consequences for plant growth and nutrient mobility. TiO2 and CeO2 also decreased the soluble and bioavailable fractions of P, and so could inhibit the uptake of this limiting nutrient by organisms.

Uptake of methanol on mixed HNO3/H2O clusters: An absolute pickup cross section

NASA Astrophysics Data System (ADS)

Pysanenko, A.; Lengyel, J.; Fárník, M.

2018-04-01

The uptake of atmospheric oxidized organics on acid clusters is relevant for atmospheric new particle formation. We investigate the pickup of methanol (CH3OH) on mixed nitric acid-water clusters (HNO3)M(H2O)N by a combination of mass spectrometry and cluster velocity measurements in a molecular beam. The mass spectra of the mixed clusters exhibit (HNO3)m(H2O)nH+ series with m = 0-3 and n = 0-12. In addition, CH3OH.(HNO3)m(H2O)nH+ series with very similar patterns appear in the spectra after the methanol pickup. The velocity measurements prove that the undoped (HNO3)m(H2O)nH+ mass peaks in the pickup spectra originate from the neutral (HNO3)M(H2O)N clusters which have not picked up any CH3OH molecule, i.e., methanol has not evaporated upon the ionization. Thus the fraction of the doped clusters can be determined and the mean pickup cross section can be estimated, yielding σs ¯ ≈ 20 Å2. This is compared to the lower estimate of the mean geometrical cross section σg ¯ ≈ 60 Å2 obtained from the theoretical cluster geometries. Thus the "size" of the cluster corresponding to the methanol pickup is at least 3-times smaller than its geometrical size. We have introduced a method which can yield the absolute pickup cross sections relevant to the generation and growth of atmospheric aerosols, as illustrated in the example of methanol and nitric acid clusters.

Effects of arbuscular mycorrhizal inoculation and biochar amendment on maize growth, cadmium uptake and soil cadmium speciation in Cd-contaminated soil.

PubMed

Liu, Ling; Li, Jiwei; Yue, Feixue; Yan, Xinwei; Wang, Fayuan; Bloszies, Sean; Wang, Yanfang

2018-03-01

Experiments conducted to understand how arbuscular mycorrhizal (AM) inoculation or biochar application affect plant growth and heavy metal uptake have thus far looked at single applications of either soil amendment. There is little evidence of their synergistic effects, in particular for plants grown in cadmium (Cd) contaminated soil. We conducted a mesocosm experiment to investigate the effect of AM inoculation (Glomus intraradices BEG 141) and/or wheat-straw biochar amendment on maize (Zea mays L. cv. Hongdan No. 897) growth, antioxidant enzymatic activities, and Cd uptake, as well as soil Cd speciation under applications of 0, 3, 6 mg Cd per kg soil. Applying either AM inoculant or biochar alone significantly increased maize growth and reduced Cd uptake. Furthermore, solo AM inoculation alleviating Cd stress more fully than biochar, in turn facilitating maize growth and decreasing soil Cd translocation into plant tissue. Still, solo biochar amendment was more effective at inducing soil alkalinization and contributing to Cd immobilization. Adding biochar together with AM inoculant significantly promoted fungal populations compared to a control. Amending soil with AM inoculant and biochar together produced the largest increase in maize growth and decrease in tissue Cd concentrations. This effect was additive, with 79.1% greater biomass, 51.42%, 82.91%, 43.96% higher activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and 50.06%, 67.19%, 58.04% and 76.19% lower Cd concentrations in roots, stems, leaves, and ears, respectively, at a 6 mg kg -1 Cd contamination rate. The combined treatment also had a synergistic effect on inducing soil alkalinization and causing Cd immobilization, and decreasing Cd phytoavailability and post-harvest transfer risks. These results suggest that AM inoculation in combination with biochar application may be applicable not only for maize production but also for phytostabilization of Cd-contaminated soil

Detection of phosphate transporter genes from arbuscular mycorrhizal fungi in mature tree roots under experimental soil pH manipulation

DOE PAGES

Carrino-Kyker, Sarah R.; Kluber, Laurel A.; Coyle, Kaitlin P.; ...

2016-10-04

We present the majority of terrestrial plant roots are colonized by arbuscular mycorrhizal (AM) fungi that, in exchange for carbon, provide plants with enhanced nutrient uptake — most notably inorganic phosphate (P i). To mediate the uptake of Pi from the soil, AM fungi possess high affinity inorganic phosphate transporters (PTs). Under laboratory conditions, P i concentrations have been shown to regulate AM fungal-specific PT gene expression. The relationship between PT expression and P i in the field remains unexplored. Here we quantify AM fungal-specific PTs from maple tree roots in situ. In an effort to limit edaphic parameters, rootmore » samples were collected from manipulated forested plots that had elevated soil P i availability, either through direct P i application or elevating pH to lower exchangeable aluminum. The aim of the study was to examine AM fungal-specific PT gene expression both prior to and following soil P i amendment; however, a direct correlation between soil P i concentration and PT gene expression was not observed. PT transcripts were detected to a greater extent under elevated pH and, while our results are confounded by an overall low detection of PT genes (23 % of all samples collected), our findings raise interesting questions regarding the role of soil pH on PT function. In conclusion, our study is a first step in understanding how edaphic properties influence PT expression and plant P acquisition in mature tree roots.« less

Detection of phosphate transporter genes from arbuscular mycorrhizal fungi in mature tree roots under experimental soil pH manipulation

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

Carrino-Kyker, Sarah R.; Kluber, Laurel A.; Coyle, Kaitlin P.

We present the majority of terrestrial plant roots are colonized by arbuscular mycorrhizal (AM) fungi that, in exchange for carbon, provide plants with enhanced nutrient uptake — most notably inorganic phosphate (P i). To mediate the uptake of Pi from the soil, AM fungi possess high affinity inorganic phosphate transporters (PTs). Under laboratory conditions, P i concentrations have been shown to regulate AM fungal-specific PT gene expression. The relationship between PT expression and P i in the field remains unexplored. Here we quantify AM fungal-specific PTs from maple tree roots in situ. In an effort to limit edaphic parameters, rootmore » samples were collected from manipulated forested plots that had elevated soil P i availability, either through direct P i application or elevating pH to lower exchangeable aluminum. The aim of the study was to examine AM fungal-specific PT gene expression both prior to and following soil P i amendment; however, a direct correlation between soil P i concentration and PT gene expression was not observed. PT transcripts were detected to a greater extent under elevated pH and, while our results are confounded by an overall low detection of PT genes (23 % of all samples collected), our findings raise interesting questions regarding the role of soil pH on PT function. In conclusion, our study is a first step in understanding how edaphic properties influence PT expression and plant P acquisition in mature tree roots.« less

Impact of interspecific interactions on the soil water uptake depth in a young temperate mixed species plantation

NASA Astrophysics Data System (ADS)

Grossiord, Charlotte; Gessler, Arthur; Granier, André; Berger, Sigrid; Bréchet, Claude; Hentschel, Rainer; Hommel, Robert; Scherer-Lorenzen, Michael; Bonal, Damien

2014-11-01

Interactions between tree species in forests can be beneficial to ecosystem functions and services related to the carbon and water cycles by improving for example transpiration and productivity. However, little is known on below- and above-ground processes leading to these positive effects. We tested whether stratification in soil water uptake depth occurred between four tree species in a 10-year-old temperate mixed species plantation during a dry summer. We selected dominant and co-dominant trees of European beech, Sessile oak, Douglas fir and Norway spruce in areas with varying species diversity, competition intensity, and where different plant functional types (broadleaf vs. conifer) were present. We applied a deuterium labelling approach that consisted of spraying labelled water to the soil surface to create a strong vertical gradient of the deuterium isotope composition in the soil water. The deuterium isotope composition of both the xylem sap and the soil water was measured before labelling, and then again three days after labelling, to estimate the soil water uptake depth using a simple modelling approach. We also sampled leaves and needles from selected trees to measure their carbon isotope composition (a proxy for water use efficiency) and total nitrogen content. At the end of the summer, we found differences in the soil water uptake depth between plant functional types but not within types: on average, coniferous species extracted water from deeper layers than did broadleaved species. Neither species diversity nor competition intensity had a detectable influence on soil water uptake depth, foliar water use efficiency or foliar nitrogen concentration in the species studied. However, when coexisting with an increasing proportion of conifers, beech extracted water from progressively deeper soil layers. We conclude that complementarity for water uptake could occur in this 10-year-old plantation because of inherent differences among functional groups (conifers

Plant uptake of explosives from contaminated soil at the Joliet Army Ammunition Plant

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

Zellmer, S.D.; Schneider, J.F.; Tomczyk, N.A.

1995-04-01

Explosives and their degradation products may enter the animal and human food chains through plants grown on soils contaminated with explosives. Soil and plant samples were collected from the Group 61 area at the Joliet Army Ammunition Plant and analyzed to determine the extent to which 2,4,6-trinitrotoluene (TNT) and its degradation products are taken up by existing vegetation and crops growing on contaminated soils. Neither TNT nor its degradation products was detected in any of the aboveground plant organs of existing vegetation. Oat (Avena sativa L.) and perennial ryegrass (Lolium perenne L.) were planted on TNT-contaminated soils amended with threemore » levels of chopped grass hay. Extractable TNT concentrations in hay-amended soils were monitored for almost 1 year. Crop establishment and growth improved with increased levels of hay amendment, but TNT uptake was not affected or detected in any aboveground crop organs. Evidence was found to indicate that soil manipulation and hay addition may reduce extractable TNT concentration in soils, but the wide variations in TNT concentrations in these soils prevented development of conclusive evidence regarding reduction of extractable TNT concentrations. Results from this study suggest that vegetation grown on TNT-contaminated soils is not a major health concern because TNT and its degradation products were not detected in aboveground plant organs. However, low concentrations of TNT, 4-amino-2,6-dinitrotoluene, and 2-amino-4,6-dinitrotoluene were detected in or on some existing vegetation and crop roots. 21 refs., 10 figs., 26 tabs.« less

Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures.

PubMed

Liu, Shurong; Berns, Anne E; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

2017-02-01

Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH 2 OH) to nitrous oxide (N 2 O) is a possible mechanism of N 2 O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO 2 ) and organic matter (OM) content of soil as well as soil pH are important control variables of N 2 O formation in the soil. But until now, their combined effect on abiotic N 2 O formation from NH 2 OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO 2 and OM, respectively, and quantified the interactive effects of the three variables on the NH 2 OH-to-N 2 O conversion ratio (R NH2OH-to-N2O ). Furthermore, the effect of OM quality on R NH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO 2 and OM on R NH2OH-to-N2O . In general, increasing MnO 2 and decreasing pH increased R NH2OH-to-N2O , while increasing OM content was associated with a decrease in R NH2OH-to-N2O . Organic matter quality also affected R NH2OH-to-N2O . However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures

NASA Astrophysics Data System (ADS)

Liu, Shurong; Berns, Anne E.; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

2017-02-01

Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH2OH) to nitrous oxide (N2O) is a possible mechanism of N2O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO2) and organic matter (OM) content of soil as well as soil pH are important control variables of N2O formation in the soil. But until now, their combined effect on abiotic N2O formation from NH2OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO2 and OM, respectively, and quantified the interactive effects of the three variables on the NH2OH-to-N2O conversion ratio (RNH2OH-to-N2O). Furthermore, the effect of OM quality on RNH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO2 and OM on RNH2OH-to-N2O. In general, increasing MnO2 and decreasing pH increased RNH2OH-to-N2O, while increasing OM content was associated with a decrease in RNH2OH-to-N2O. Organic matter quality also affected RNH2OH-to-N2O. However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

Hydroponic Uptake of Atrazine and Lambda-cyhalothrin in Aquatic Macrophytes

NASA Astrophysics Data System (ADS)

Bouldin, J. L.; Farris, J. L.; Moore, M. T.; Smith, S.; Cooper, C. M.

2005-05-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to soil geochemical modifications and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48 h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8 d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that the seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Phytoremediation of arsenic contaminated paddy soils with Pteris vittata markedly reduces arsenic uptake by rice.

PubMed

Ye, Wen-Ling; Khan, M Asaduzzaman; McGrath, Steve P; Zhao, Fang-Jie

2011-12-01

Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P. vittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P. vittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. Copyright © 2011 Elsevier Ltd. All rights reserved.

Heavy Metal Concentrations in Soils and Factors Affecting Metal Uptake by Plants in the Vicinity of a Korean Cu-W Mine.

PubMed

Jung, Myung Chae

2008-04-04

Heavy metal concentrations were measured in soils and plants in and around a copper-tungsten mine in southeast Korea to investigate the influence of past base metal mining on the surface environment. The results of chemical analysis indicate that the heavy metals in soils decreased with distance from the source, controlled mainly by water movement and topography. The metal concentrations measured in plant species generally decreased in the order; spring onions > soybean leaves > perilla leaves » red pepper > corn grains » jujube grains, although this pattern varied moderately between different elements. The results agree with other reports that metal concentrations in leaves are usually much higher than those in grain. Factors influencing the bioavailability of metals and their occurrences in crops were found as soil pH, cation exchange capacity, organic matter content, soil texture, and interaction among the target elements. It is concluded that total metal concentrations in soils are the main controls on their contents in plants. Soil pH was also an important factor. A stepwise linear multiple regression analysis was also conducted to identify the dominant factors influencing metal uptake by plants. Metal concentrations in plants were also estimated by computer-aided statistical methods.

Soil fertility controls soil-atmosphere carbon dioxide and methane fluxes in a tropical landscape converted from lowland forest to rubber and oil palm plantations

NASA Astrophysics Data System (ADS)

Hassler, E.; Corre, M. D.; Tjoa, A.; Damris, M.; Utami, S. R.; Veldkamp, E.

2015-10-01

Expansion of palm oil and rubber production, for which global demand is increasing, causes rapid deforestation in Sumatra, Indonesia, and is expected to continue in the next decades. Our study aimed to (1) quantify changes in soil CO2 and CH4 fluxes with land-use change and (2) determine their controlling factors. In Jambi Province, Sumatra, we selected two landscapes on heavily weathered soils that differ mainly in texture: loam and clay Acrisol soils. In each landscape, we investigated the reference land-use types (forest and secondary forest with regenerating rubber) and the converted land-use types (rubber, 7-17 years old, and oil palm plantations, 9-16 years old). We measured soil CO2 and CH4 fluxes monthly from December 2012 to December 2013. Annual soil CO2 fluxes from the reference land-use types were correlated with soil fertility: low extractable phosphorus (P) coincided with high annual CO2 fluxes from the loam Acrisol soil that had lower fertility than the clay Acrisol soil (P < 0.05). Soil CO2 fluxes from the oil palm (107.2 to 115.7 mg C m-2 h-1) decreased compared to the other land-use types (between 178.7 and 195.9 mg C m-2 h-1; P < 0.01). Across land-use types, annual CO2 fluxes were positively correlated with soil organic carbon (C) and negatively correlated with 15N signatures, extractable P and base saturation. This suggests that the reduced soil CO2 fluxes from oil palm were the result of strongly decomposed soil organic matter and reduced soil C stocks due to reduced litter input as well as being due to a possible reduction in C allocation to roots due to improved soil fertility from liming and P fertilization in these plantations. Soil CH4 uptake in the reference land-use types was negatively correlated with net nitrogen (N) mineralization and soil mineral N, suggesting N limitation of CH4 uptake, and positively correlated with exchangeable aluminum (Al), indicating a decrease in methanotrophic activity at high Al saturation. Reduction in

Effect of water management, arsenic and phosphorus levels on rice in a high-arsenic soil-water system: II. Arsenic uptake.

PubMed

Talukder, A S M H M; Meisner, C A; Sarkar, M A R; Islam, M S; Sayre, K D; Duxbury, J M; Lauren, J G

2012-06-01

Rice consumption is one of the major pathways for As intake in populations that depend on a rice diet in several countries of South and South-east Asia. Pot experiments were undertaken to investigate the effects of water management (WM), arsenic (As) contaminated soil-water and Phosphorus (P) rates on As uptake in rice plants. There were 18 treatments comprising of three each of As rates (0, 20 and 40 mg kg(-1) soil) and P rates (0, 12.5 and 25 mg kg(-1) soil) and two WM (aerobic and anaerobic) strategies on winter (boro var. BRRI dhan 29) and monsoon (aman var. BRRI dhan 32) rice at the Wheat Research Center (WRC), Nashipur, Dinajpur, Bangladesh. Arsenic concentrations in rice grain and straw increased significantly (P ≤ 0.01) with the increasing As rates in the soil. Arsenic availability in soil pore-water solution was less (58%) under aerobic WM (redox potential-Eh=+135 to +138 mV; pH-6.50 at 24.3 °C) as compared to anaerobic WM (flooded: Eh=-41 to -76 mV; pH-6.43 at 23 °C). The highest total grain As content 2.23 ± 0.12 mg kg(-1) and 0.623 ± 0.006 mg kg(-1) was found in T(6) (P(12.5)As(40)-anaerobic) and T(9) (P(25)As(40)-anaerobic) in BRRI dhan 29 and BRRI dhan 32, respectively, which was significantly higher (41-45%) than in the same As and P treatments for pots under aerobic WM. The As content in rice straw (up to 24.7 ± 0.49 ppm in BRRI dhan 29, 17.3 ± 0.49 mg kg(-1) in BRRI dhan 32 with the highest As level) suggested that As can more easily be translocated to the shoots under anaerobic conditions than aerobic condition. BRRI dhan 29 was more sensitive to As than BRRI dhan 32. Under aerobic WM, P soil amendments reduced As uptake by rice plants. The study demonstrated that aerobic water management along with optimum P amendment and selection of arsenic inefficient rice varieties are appropriate options that can be applied to minimize As accumulation in rice which can reduce effects on human and cattle health risk as well as soil contamination

Feedbacks between soil penetration resistance, root architecture and water uptake limit water accessibility and crop growth - A vicious circle.

PubMed

Colombi, Tino; Torres, Lorena Chagas; Walter, Achim; Keller, Thomas

2018-06-01

Water is the most limiting resource for global crop production. The projected increase of dry spells due to climate change will further increase the problem of water limited crop yields. Besides low water abundance and availability, water limitations also occur due to restricted water accessibility. Soil penetration resistance, which is largely influenced by soil moisture, is the major soil property regulating root elongation and water accessibility. Until now the interactions between soil penetration resistance, root system properties, water uptake and crop productivity are rarely investigated. In the current study we quantified how interactive effects between soil penetration resistance, root architecture and water uptake affect water accessibility and crop productivity in the field. Maize was grown on compacted and uncompacted soil that was either tilled or remained untilled after compaction, which resulted in four treatments with different topsoil penetration resistance. Higher topsoil penetration resistance caused root systems to be shallower. This resulted in increased water uptake from the topsoil and hence topsoil drying, which further increased the penetration resistance in the uppermost soil layer. As a consequence of this feedback, root growth into deeper soil layers, where water would have been available, was reduced and plant growth decreased. Our results demonstrate that soil penetration resistance, root architecture and water uptake are closely interrelated and thereby determine the potential of plants to access soil water pools. Hence, these interactions and their feedbacks on water accessibility and crop productivity have to be accounted for when developing strategies to alleviate water limitations in cropping systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Accumulation, availability, and uptake of heavy metals in a red soil after 22-year fertilization and cropping.

PubMed

Zhou, Shiwei; Liu, Jing; Xu, Minggang; Lv, Jialong; Sun, Nan

2015-10-01

Fertilization is important to increase crop yields, but long-term application of fertilizers probably aggravated the risk of heavy metals in acidic soils. In this study, the effect of 22-year fertilization and cropping on accumulation, availability, and uptake of heavy metals in red soil was investigated. The results showed that pig manure promoted significantly cadmium (Cd) accumulation (average 1.1 mg kg(-1)), nearly three times higher than national soil standards and, thus, increased metal availability. But the enrichment of heavy metals decreased remarkably by 50.5 % under manure fertilization, compared with CK (control without fertilization). On the contrary, chemical fertilizers increased greatly lead (Pb) availability and Cd activity; in particular, exceeding 85 % of soil Cd became available to plant under N (nitrogen) treatment during 9-16 years of fertilization, which correspondingly increased their enrichment by 29.5 %. Long-term application of chemical fertilizers caused soil acidification and manure fertilization led to the increase in soil pH, soil organic matter (SOM), and available phosphorus (Olsen P), which influenced strongly metal behavior in red soil, and their effect had extended to deeper soil layer (20∼40 cm). It is advisable to increase application of manure alone with low content of heavy metals or in combination with chemical fertilizers to acidic soils in order to reduce toxic metal risk.

Quartz Crystal Microbalance: Aerosol Viscoelastic Measurement Calibration and Subsiquent H2O Uptake

NASA Astrophysics Data System (ADS)

Farland, D. R., Jr.; Gilles, M. K.; Harder, T.; Weis, J.; Mueller, S.

2015-12-01

Aerosol particles exposed to various atmospheric relative humidity (RH) levels exhibit hygroscopic properties which are not fully understood. Water adsorption or diffusion depends on particle viscosity in semi-solid to liquid states. This relationship between particle viscosity as a function of RH and the corresponding hygroscopic behavioral response is the purpose of this study. However, reliable techniques for viscosity quantification have been limited. A Quartz Crystal Microbalance with Dissipation (QCM-D) was used for viscosity measurements and to determine phase changes. Prior to studies on field samples, microscope immersion/viscosity standard oils, salt crystals, sugars and alpha-pinene secondary organic aerosol (SOA) surrogates are used for viscosity, RH calibrations, water uptake and phase change measurements. RH was controlled by flowing N2 gas saturated with H2O for RH's between 0-75% RH. For higher RH values, (75-100% RH range) saturated salt solutions were flowed over a gore membrane to protect the QCM sensor from direct contact with the solutions. The viscosity calibration constructed via QTools fitting software illustrates the limitations as well as the ranges of reliability of the QCM viscosity measurements. Deliquescing salt crystals of differing deliquescence relative humidity's (DRH), sugars and alpha-pinene SOA's provided insight into the detection of various phase change behaviors. Water uptake experiments performed on alpha-pinene SOA and sucrose sugar yielded significantly different frequency and dissipation responses than the deliquescing salts. Future work will apply these experimental methods and analysis on aerosol particles collected during the GoAmazon field campaign.

Phytoextraction: simulating uptake and translocation of arsenic in a soil-plant system.

PubMed

Ouyang, Ying

2005-01-01

The uptake, transport, and accumulation of metals by plants are functions central to successful phytoextraction. This study investigates the uptake and translocation of arsenic from a contaminated sandy soil by a mature Chinese brake fern (Pteris vittata L.). An existing mathematical model for the coupled transport of water, heat, and solutes in the soil-plant-atmosphere continuum (CTSPAC) was modified to examine the flow of water as well as the uptake and translocation of total arsenic in the xylem of the fern. This model was calibrated using greenhouse measurements before its application. Simulation results showed that about 20% of the soil arsenic was removed by the fern in 10 d, of which about 90% of the arsenic was stored in the fronds and 10% in the roots. Although arsenic mass in the plant tissues increased consecutively with time, arsenic concentration in the xylem sap of the root tips has a typical diurnal distribution pattern: increasing during the day and decreasing at night, resulting from daily variations of frond surface water transpiration. The largest difference in simulated arsenic concentration in the root tips between the day and night was about 5%. This study also suggests that the use of transpiration stream concentration factor (TSCF), which is defined as the ratio of chemical concentration in the xylem sap to that in the external solution, to evaluate the translocation efficiency of arsenic for the hyperaccumulator Chinese brake fern (Pteris vittata L.) could be limited.

Theoretical studies on the coupling interactions in H2SO4···HOO˙···(H2O)n (n = 0-2) clusters: toward understanding the role of water molecules in the uptake of HOO˙ radical by sulfuric acid aerosols.

PubMed

Li, Ping; Ma, Zhiying; Wang, Weihua; Zhai, Yazhou; Sun, Haitao; Bi, Siwei; Bu, Yuxiang

2011-01-21

A detailed knowledge of coupling interactions among sulfuric acid (H(2)SO(4)), the hydroperoxyl radical (HOO˙), and water molecules (H(2)O) is crucial for the better understanding of the uptake of HOO˙ radicals by sulfuric acid aerosols at different atmospheric humidities. In the present study, the equilibrium structures, binding energies, equilibrium distributions, and the nature of the coupling interactions in H(2)SO(4)···HOO˙···(H(2)O)(n) (n = 0-2) clusters have been systematically investigated at the B3LYP/6-311++G(3df,3pd) level of theory in combination with the atoms in molecules (AIM) theory, natural bond orbital (NBO) method, energy decomposition analyses, and ab initio molecular dynamics. Two binary, five ternary, and twelve tetramer clusters possessing multiple intermolecular H-bonds have been located on their potential energy surfaces. Two different modes for water molecules have been observed to influence the coupling interactions between H(2)SO(4) and HOO˙ through the formations of intermolecular H-bonds with or without breaking the original intermolecular H-bonds in the binary H(2)SO(4)···HOO˙ cluster. It was found that the introduction of one or two water molecules can efficiently enhance the interactions between H(2)SO(4) and HOO˙, implying the positive role of water molecules in the uptake of the HOO˙ radical by sulfuric acid aerosols. Additionally, the coupling interaction modes of the most stable clusters under study have been verified by the ab initio molecular dynamics.

Different components of /sup 3/H-imipramine binding in rat brain membranes: relation to serotonin uptake sites

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

Gobbi, M.; Taddei, C.; Mennini, T.

1988-01-01

In the present paper, the authors confirm and extend previous studies showing heterogeneous /sup 3/H-imipramine (/sup 3/H-IMI) binding sites. Inhibition curves of various drugs (serotonin, imipramine, desmethyl-imipramine, d-fenfluramine, d-norfenfluramine and indalpine, a potent serotonin uptake inhibitor) obtained using 2 nM /sup 3/H-IMI and in presence of 120 mM NaCl, confirmed the presence of at least three /sup 3/H-IMI binding sites: two of these were serotonin-insensitive while the third one was selectively inhibited by serotonin and indalpine with nanomolar affinities. Moreover this last component was found to be selectively modulated by chronic imipramine treatment thus suggesting a close relation to serontoninmore » uptake mechanism. These data indicate that the use of a more selective inhibitors of the serotonin-sensitive component (like indalpine or serotonin itself) to define non specific /sup 3/H-IMI, may be of help in understanding its relation with serotonin uptake system. 22 references, 2 figures, 2 tables.« less

Effects of warming on uptake and translocation of cadmium (Cd) and copper (Cu) in a contaminated soil-rice system under Free Air Temperature Increase (FATI).

PubMed

Ge, Li-Qiang; Cang, Long; Liu, Hui; Zhou, Dong-Mei

2016-07-01

Global warming has received growing attentions about its potential threats to human in recent, however little is known about its effects on transfer of heavy metals in agro-ecosystem, especially for Cd in rice. Pot experiments were conducted to evaluate Cd/Cu translocation in a contaminated soil-rice system under Free Air Temperature Increase (FATI). The results showed that warming gradually decreased soil porewater pH and increased water-soluble Cd/Cu concentration, reduced formation of iron plaque on root surface, and thus significantly increased total uptake of Cd/Cu by rice. Subsequently, warming significantly promoted Cd translocation from root to shoot, and increased Cd distribution percentage in shoot, while Cu was not significantly affected. Enhanced Cd uptake and translocation synergistically resulted in higher rice grain contamination with increasing concentration from 0.27 to 0.65 and 0.14-0.40 mg kg(-1) for Indica and Japonica rice, respectively. However increase of Cu in brown grain was only attributed to its uptake enhancement under warming. Our study provides a new understanding about the food production insecurity of heavy metal contaminated soil under the future global warming. Copyright © 2016. Published by Elsevier Ltd.

[Effect of Nano Zeolite on Chemical Fractions of Cd in Soil and Its Uptake by Cabbage].

PubMed

Xiong, Shi-juan; Xu, Wei-hong; Xie, Wen-wen; Chen, Rong; Chen, Yong-qin; Chi, Sun-lin; Chen, Xu- gen; Zhang, Jin-zhong; Xiong, Zhi-ting; Wang, Zheng-yin; Xie, De-ti

2015-12-01

Incubation experiments were carried out to investigate the influence of different nano zeolite (NZ) and ordinary zeolite (OZ) levels(0, 5, 10 and 20 g · kg⁻¹) on the change trends in fraction distribution coefficient (FDC) of Cd when exposed to different Cadmium (Cd) levels (1, 5, 10 and 15 mg · kg⁻¹), and pot experiments were carried out to investigate their influence on soil Cd fraction and Cd uptake by cabbage. The results in incubation experiments showed that the application of nano zeolite as well as ordinary zeolite effectively decreased the FDC of exchangeable Cd and increased the FDC of Fe-Mn oxide fraction. The FDC of soil Cd from 0 d to 28 d was deceased at first, then increased and tended to be stable, and finally increased. At the end of incubation, the FDC of soil exchangeable Cd decreased from 72.0%-88.0% to 30.0%-66.4%. Exchangeable fraction Cd was the most dominant Cd fraction in soil during the whole incubation. The results in pot experiment indicated that the application of nano zeolite and ordinary zeolite decreased the concentration and FDC of soil exchangeable Cd, and concurrently the concentration and FDC of Cd in carbonate, Fe-Mn oxide, organic matter and residual fraction were increased. The lowest EX-Cd was observed in the treatment with high dose of nano zeolite (20 g · kg⁻¹). The FDC of exchangeable Cd showed significant negative relationship with the soil pH (P < 0.05), and was concurrently extremely positively correlated with Cd concentration in shoot and root of cabbage (P < 0.01). Soil pH increased by 1.8%-45.5% and 6.1%-54.3% in the presence of zeolite when exposed to 5 mg · kg⁻¹ 1 and Cd, respectively; FDC of exchangeable Cd decreased by 16.3%-47.7% and 16.2%-46.7%; Cd concentration in each tissues of cabbage decreased by 1.0%-75.0% and 3.8%-53.2%, respectively. Moreover, the reduction effect of nano zeolite on soil and plant Cd was better than that of ordinary zeolite. The growth of cabbage was stimulated by low and

Summer cover crops and soil amendments to improve growth and nutrient uptake of okra

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

Wang, Q.R.; Li, Y.C.; Klassen, W.

2006-04-15

A pot experiment with summer cover crops and soil amendments was conducted in two consecutive years to elucidate the effects of these cover crops and soil amendments on 'Clemson Spineless 80' okra (Abelmoschus esculentus) yields and biomass production, and the uptake and distribution of soil nutrients and trace elements. The cover crops were sunn hemp (Crotalaria juncea), cowpea (Vigna unguiculata), velvetbean (Mucuna deeringiana), and sorghum sudan-grass (Sorghum bicolor x S. bicolor var. sudanense) with fallow as the control. The organic soil amendments were biosolids (sediment from wastewater plants), N-Viro Soil (a mixture of biosolids and coal ash), coal ash (amore » combustion by-product from power plants), co-compost (a mixture of 3 biosolids: 7 yard waste), and yard waste compost (mainly from leaves and branches of trees and shrubs, and grass clippings) with a soil-incorporated cover crop as the control. As a subsequent vegetable crop, okra was grown after the cover crops, alone or together with the organic soil amendments, had been incorporated. All of the cover crops, except sorghum sudangrass in 2002-03, significantly improved okra fruit yields and the total biomass production. Both cover crops and soil amendments can substantially improve nutrient uptake and distribution. The results suggest that cover crops and appropriate amounts of soil amendments can be used to improve soil fertility and okra yield without adverse environmental effects or risk of contamination of the fruit. Further field studies will be required to confirm these findings.« less

Plant uptake of elements in soil and pore water: field observations versus model assumptions.

PubMed

Raguž, Veronika; Jarsjö, Jerker; Grolander, Sara; Lindborg, Regina; Avila, Rodolfo

2013-09-15

Contaminant concentrations in various edible plant parts transfer hazardous substances from polluted areas to animals and humans. Thus, the accurate prediction of plant uptake of elements is of significant importance. The processes involved contain many interacting factors and are, as such, complex. In contrast, the most common way to currently quantify element transfer from soils into plants is relatively simple, using an empirical soil-to-plant transfer factor (TF). This practice is based on theoretical assumptions that have been previously shown to not generally be valid. Using field data on concentrations of 61 basic elements in spring barley, soil and pore water at four agricultural sites in mid-eastern Sweden, we quantify element-specific TFs. Our aim is to investigate to which extent observed element-specific uptake is consistent with TF model assumptions and to which extent TF's can be used to predict observed differences in concentrations between different plant parts (root, stem and ear). Results show that for most elements, plant-ear concentrations are not linearly related to bulk soil concentrations, which is congruent with previous studies. This behaviour violates a basic TF model assumption of linearity. However, substantially better linear correlations are found when weighted average element concentrations in whole plants are used for TF estimation. The highest number of linearly-behaving elements was found when relating average plant concentrations to soil pore-water concentrations. In contrast to other elements, essential elements (micronutrients and macronutrients) exhibited relatively small differences in concentration between different plant parts. Generally, the TF model was shown to work reasonably well for micronutrients, whereas it did not for macronutrients. The results also suggest that plant uptake of elements from sources other than the soil compartment (e.g. from air) may be non-negligible. Copyright © 2013 Elsevier Ltd. All rights

Cyclic variations in nitrogen uptake rate of soybean plants: effects of pH and mixed nitrogen sources

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.; Chaillou, S.

1991-01-01

To determine if the daily pattern of NO3- and NH4+ uptake is affected by acidity or NO3- : NH4+ ratio of the nutrient solution, non-nodulated soybean plants (Glycine max) were exposed for 21 days to replenished, complete nutrient solutions at pH 6.0, 5.5, 5.0, and 4.5 which contained either 1.0 mM NH4+, 1.0 mM NO3- [correction of NO3+], 0.67 mM NH4+ plus 0.33 mM NO3- (2:1 NH4+ : NO3-) [correction of (2:1 NH3+ : NO4-)], or 0.33 mM NH4+ plus 0.67 mM NO3- (1:2 NH4+ : NO3-). Net uptake rates of NH4+ and NO3- were measured daily by ion chromatography as depletion from the replenished solutions. When NH4+ and NO3- were supplied together, cumulative uptake of total nitrogen was not affected by pH or solution NH4+ : NO3- ratio. The cumulative proportion of nitrogen absorbed as NH4+ decreased with increasing acidity; however, the proportional uptake of NH4+ and NO3- was not constant, but varied day-to-day. This day-to-day variation in relative proportions of NH4+ and NO3- absorbed when NH4+ : NO3- ratio and pH of solution were constant indicates that the regulatory mechanism is not directly competitive. Regardless of the effect of pH on cumulative uptake of NH4+, the specific nitrogen uptake rates from mixed and from individual NH4+ and NO3- sources oscillated between maxima and minima at each pH with average periodicities similar to the expected interval of leaf emergence.

Uptake of (/sup 3/H)serotonin into plasma membrane vesicles from mouse cerebral cortex

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

O'Reilly, C.A.; Reith, M.E.A.

1988-05-05

Preparations of plasma membrane vesicles were used as a tool to study the properties of the serotonin transporter in the central nervous system. The vesicles were obtained after hypotonic shock of synaptosomes purified from mouse cerebral cortex. Uptake of (/sup 3/H)serotonin had a Na/sup +/-dependent and Na/sup +/-independent component. The Na/sup +/-dependent uptake was inhibited by classical blockers of serotonin uptake and had a K/sub m/ of 63-180 nM, and a V/sub max/ of 0.1-0.3 pmol mg/sup -1/ s/sup -1/ at 77 mM Na/sup +/. The uptake required the presence of external Na/sup +/ and internal K/sup +/. Replacement ofmore » Cl/sup -/ by other anions (NO/sub 2//sup -/, S/sub 2/O/sub 3//sup 2 -/) reduced uptake appreciably. Gramicidin prevented uptake. Although valinomycin increased uptake somewhat, the membrane potential per se could not drive uptake because no uptake was observed when a membrane potential was generated by the SCN/sup -/ ion in the absence of internal K/sup +/ and with equal (Na/sup +/) inside and outside. The increase of uptake as a function of (Na/sup +/) indicated a K/sub m/ for Na/sup +/ of 118 mM and a Hill number of 2.0, suggesting a requirement of two sodium ions for serotonin transport. The present results are accommodated very well by the model developed for porcine platelet serotonin transport except for the number of sodium ions that are required for transport.« less

The effect of pH on metal accumulation in two Alyssum species.

PubMed

Kukier, Urszula; Peters, Carinne A; Chaney, Rufus L; Angle, J Scott; Roseberg, Richard J

2004-01-01

Nickel phytoextraction using hyperaccumulator plants offers a potential for profit while decontaminating soils. Although soil pH is considered a key factor in metal uptake by crops, little is known about soil pH effects on metal uptake by hyperaccumulator plants. Two Ni and Co hyperaccumulators, Alyssum murale and A. corsicum, were grown in Quarry muck (Terric Haplohemist) and Welland (Typic Epiaquoll) soils contaminated by a Ni refinery in Port Colborne, Ontario, Canada, and in the serpentine Brockman soil (Typic Xerochrepts) from Oregon, USA. Soils were acidified and limed to cover pH from strongly acidic to mildly alkaline. Alyssum grown in both industrially contaminated soils exhibited increased Ni concentration in shoots as soil pH increased despite a decrease in water-soluble soil Ni, opposite to that seen with agricultural crop plants. A small decrease in Alyssum shoot Ni concentration as soil pH increased was observed in the serpentine soil. The highest fraction of total soil Ni was phytoextracted from Quarry muck (6.3%), followed by Welland (4.7%), and Brockman (0.84%). Maximum Ni phytoextraction was achieved at pH 7.3, 7.7, and 6.4 in the Quarry, Welland, and Brockman soils, respectively. Cobalt concentrations in shoots increased with soil pH increase in the Quarry muck, but decreased in the Welland soil. Plants extracted 1.71, 0.83, and 0.05% of the total soil Co from Welland, Quarry, and Brockman, respectively. The differences in uptake pattern of Ni and Co by Alyssum from different soils and pH were probably related to the differences in organic matter and iron contents of the soils.

The propagation of a soil H218O labeling through the atmosphere-plant-soil system under drought using H218O and C18OO as two independent proxies

NASA Astrophysics Data System (ADS)

Barthel, Matthias; Sturm, Patrick; Hammerle, Albin; Siegwolf, Rolf; Gentsch, Lydia; Buchmann, Nina; Knohl, Alexander

2013-04-01

Above- and belowground processes in plants are tightly coupled via carbon and water flows through the atmosphere-plant-soil system. While recent studies elucidated the influence of drought on the carbon flow through plant and soil using 13C, much less is known about the propagation of 18O. Therefore, this study aimed to examine the timing and intensity of 18O enrichment in soil and shoot CO2 and H2O vapor fluxes of European beech saplings (Fagus sylvatica L.) after applying 18O-labeled water to the soil. A custom-made chamber system, separating shoot from soil compartments, allowed independent measurements of shoot and soil related processes in a controlled climate chamber environment. Gas-exchange of oxygen stable isotopes in CO2 and H2O-vapor served as the main tool for investigation and was monitored in real-time using laser spectroscopy. This is the first study measuring concurrently and continuously the enrichment of 18O in CO2 and H2O in shoot- and soil gas-exchange after applying 18O-labeled water to the soil. Photosynthesis (A) and stomatal conductance (gs) of drought-stressed plants showed an immediate coinciding small increase to the H218O irrigation event after only ~30 min. This rapid information transfer, however, was not accompanied by the arrival of 18O labeled water molecules within the shoot. The actual label induced 18O enrichment in transpired water and CO2 occurred not until ~4h after labeling. Further, the timing of the enrichment of 18O in the transpirational flux was similar in both treatments, thus pointing to similar transport rates. However, drought reduced the 18O exchange rate between H2O and CO2at the shoot level, likely caused by a smaller leaf CO2retroflux. Moreover, 18O exchange between H2O and CO2 occurred also in the soil. However, the there was no difference observed between the treatments.

Hyperforin inhibits vesicular uptake of monoamines by dissipating pH gradient across synaptic vesicle membrane.

PubMed

Roz, Netta; Rehavi, Moshe

2003-06-13

Extracts of Hypericum perforatum (St. John's wort) have antidepressant properties in depressed patients and exert antidepressant-like action in laboratory animals. The phloroglucinol derivative hyperforin has become a topic of interest, as this Hypericum component is a potent inhibitor of monoamines reuptake. The molecular mechanism by which hyperforin inhibits monoamines uptake is yet unclear. In the present study we try to clarify the mechanism by which hyperforin inhibits the synaptic vesicle transport of monoamines. The pH gradient across the synaptic vesicle membrane, induced by vacuolar type H(+)-ATPase, is the major driving force for vesicular monoamines uptake and storage. We suggest that hyperforin, like the protonophore FCCP, dissipates an existing Delta pH generated by an efflux of inwardly pumped protons. Proton transport was measured by acridine orange fluorescence quenching. Adding Mg-ATP to a medium containing 130 mM KCl and synaptic vesicles caused an immediate decrease in fluorescence of acridine orange and the addition of 1 microM FCCP abolished this effect. H(+)-ATPase dependent proton pumping was inhibited by hyperforin in a dose dependent manner (IC(50) = 1.9 x 10(-7) M). Hyperforin acted similarly to the protonophore FCCP, abolishing the ATP induced fluorescence quenching (IC(50) = 4.3 x 10(-7) M). Hyperforin and FCCP had similar potencies for inhibiting rat brain synaptosomal uptake of [3H]monoamines as well as vesicular monoamine uptake. The efflux of [3H]5HT from synaptic vesicles was sensitive to both drugs, thus 50% of preloaded [3H]5HT was released in the presence of 2.1 x 10(-7) M FCCP and 4 x 10(-7) M hyperforin. The effect of hyperforin on the pH gradient in synaptic vesicle membrane may explain its inhibitory effect on monoamines uptake, but could only partially explain its antidepressant properties.

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.

Mechanism of Aluminum Inhibition of Net 45Ca2+ Uptake by Amaranthus Protoplasts 1

PubMed Central

Rengel, Zdenko; Elliott, Daphne C.

1992-01-01

Calcium ions serve as a second messenger in signal transduction and metabolic regulation. Effects of Al on calcium homeostasis remain to be elucidated. Short-term net 45Ca2+ uptake by Amaranthus tricolor protoplasts was monitored from uptake media prepared to test the influence of pH, Al, and various inhibitors. Accumulation of 45Ca2+ increased during the first 3 to 6 minutes and then leveled off or declined. Al and Ca2+ channel blockers (verapamil and bepridil) decreased net 45Ca2+ uptake. This decrease was more pronounced when Al and bepridil were both present in uptake media, but Al did not aggravate verapamil-induced reduction of net 45Ca2+ uptake. Erythrosin B and calmidazolium each increased net 45Ca2+ uptake, probably by interfering with Ca2+ efflux. This effect was undetectable in the presence of Al. Mycophenolic acid decreased net 45Ca2+ uptake; guanosine alleviated this effect. Al-induced reduction of net 45Ca2+ uptake was not aggravated by mycophenolic acid. Net 45Ca2+ uptake was generally less at pH 4.5 than at 5.5 for all treatments. It is concluded that Al ions affect net 45Ca2+ uptake by binding to the verapamil-specific channel site that is different from the bepridil-specific one, as well as by interfering with the action of guanosine 5′-triphosphate-binding proteins. PMID:16668688

Observations of molecular hydrogen (H2) mixing ratio and stable isotopic composition at the Cabauw tall tower; very depleted source signature suggests microbial H2 production in Dutch pasture soil.

NASA Astrophysics Data System (ADS)

Batenburg, Anneke; Popa, Elena; Vermeulen, Alex; van den Bulk, Pim; Jongejan, Piet; Fisher, Rebecca; Lowry, Dave; Nisbet, Euan; Röckmann, Thomas

2017-04-01

obtain a realistic picture of the uncertainty of the result. This showed a wide distribution with more than 99 % of the values below -400 ‰, suggesting that the H2 cycle at Cabauw is under the influence of a source mix that is much more D-depleted than currently accepted values for fossil fuel combustion. Since microbial production of very D-depleted H2 has been observed previously at Cabauw, we consider it likely that this contributes to the low apparent source signature. A comparison of the samples from different sampling heights shows that there is a significant shift to lower δD(H2) values at the lower sampling levels. This shows that the uptake of H2 by the soil, which preferentially removes "light" H2, is relatively weak at the site. It also points again to local to regional microbial production of H2, and possibly to differences between national vehicle fleets.

Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review.

PubMed

Shahid, Muhammad; Shamshad, Saliha; Rafiq, Marina; Khalid, Sana; Bibi, Irshad; Niazi, Nabeel Khan; Dumat, Camille; Rashid, Muhammad Imtiaz

2017-07-01

Chromium (Cr) is a potentially toxic heavy metal which does not have any essential metabolic function in plants. Various past and recent studies highlight the biogeochemistry of Cr in the soil-plant system. This review traces a plausible link among Cr speciation, bioavailability, phytouptake, phytotoxicity and detoxification based on available data, especially published from 2010 to 2016. Chromium occurs in different chemical forms (primarily as chromite (Cr(III)) and chromate (Cr(VI)) in soil which vary markedly in term of their biogeochemical behavior. Chromium behavior in soil, its soil-plant transfer and accumulation in different plant parts vary with its chemical form, plant type and soil physico-chemical properties. Soil microbial community plays a key role in governing Cr speciation and behavior in soil. Chromium does not have any specific transporter for its uptake by plants and it primarily enters the plants through specific and non-specific channels of essential ions. Chromium accumulates predominantly in plant root tissues with very limited translocation to shoots. Inside plants, Cr provokes numerous deleterious effects to several physiological, morphological, and biochemical processes. Chromium induces phytotoxicity by interfering plant growth, nutrient uptake and photosynthesis, inducing enhanced generation of reactive oxygen species, causing lipid peroxidation and altering the antioxidant activities. Plants tolerate Cr toxicity via various defense mechanisms such as complexation by organic ligands, compartmentation into the vacuole, and scavenging ROS via antioxidative enzymes. Consumption of Cr-contaminated-food can cause human health risks by inducing severe clinical conditions. Therefore, there is a dire need to monitor biogeochemical behavior of Cr in soil-plant system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gravity-driven transport of three engineered nanomaterials in unsaturated soils and their effects on soil pH and nutrient release.

PubMed

Conway, Jon R; Keller, Arturo A

2016-07-01

The gravity-driven transport of TiO2, CeO2, and Cu(OH)2 engineered nanomaterials (ENMs) and their effects on soil pH and nutrient release were measured in three unsaturated soils. ENM transport was found to be highly limited in natural soils collected from farmland and grasslands, with the majority of particles being retained in the upper 0-3 cm of the soil profile, while greater transport depth was seen in a commercial potting soil. Physical straining appeared to be the primary mechanism of retention in natural soils as ENMs immediately formed micron-scale aggregates, which was exacerbated by coating particles with Suwannee River natural organic matter (NOM) which promote steric hindrance. Small changes in soil pH were observed in natural soils contaminated with ENMs that were largely independent of ENM type and concentration, but differed from controls. These changes may have been due to enhanced release of naturally present pH-altering ions (Mg(2+), H(+)) in the soil via substitution processes. These results suggest ENMs introduced into soil will likely be highly retained near the source zone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Uptake and translocation of imidacloprid, clothianidin and flupyradifurone in seed-treated soybeans.

PubMed

Stamm, Mitchell D; Heng-Moss, Tiffany M; Baxendale, Frederick P; Siegfried, Blair D; Blankenship, Erin E; Nauen, Ralf

2016-06-01

Seed treatment insecticides have become a popular management option for early-season insect control. This study investigated the total uptake and translocation of seed-applied [(14) C]imidacloprid, [(14) C]clothianidin and [(14) C]flupyradifurone into different plant parts in three soybean vegetative stages (VC, V1 and V2). The effects of soil moisture stress on insecticide uptake and translocation were also assessed among treatments. We hypothesized that (1) uptake and translocation would be different among the insecticides owing to differences in water solubility, and (2) moisture stress would increase insecticide uptake and translocation. Uptake and translocation did not follow a clear trend in the three vegetative stages. Initially, flupyradifurone uptake was greater than clothianidin uptake in VC soybeans. In V1 soybeans, differences in uptake among the three insecticides were not apparent and unaffected by soil moisture stress. Clothianidin was negatively affected by soil moisture stress in V2 soybeans, while imidacloprid and flupyradifurone were unaffected. Specifically, soil moisture stress had a positive effect on the distribution of flupyradifurone in leaves. This was not observed with the neonicotinoids. This study enhances our understanding of the uptake and distribution of insecticides used as seed treatments in soybean. The uptake and translocation of these insecticides differed in response to soil moisture stress. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

A five-year study of the impact of nitrogen addition on methane uptake in alpine grassland.

PubMed

Yue, Ping; Li, Kaihui; Gong, Yanming; Hu, Yukun; Mohammat, Anwar; Christie, Peter; Liu, Xuejun

2016-08-30

It remains unclear how nitrogen (N) deposition affects soil methane (CH4) uptake in semiarid and arid zones. An in situ field experiment was conducted from 2010 to 2014 to systematically study the effect of various N application rates (0, 10, 30, and 90 kg N ha(-1) yr(-1)) on CH4 flux in alpine grassland in the Tianshan Mountains. No significant influence of N addition on CH4 uptake was found. Initially the CH4 uptake rate increased with increasing N application rate by up to 11.5% in 2011 and then there was gradual inhibition by 2014. However, the between-year variability in CH4 uptake was very highly significant with average uptake ranging from 52.9 to 106.6 μg C m(-2) h(-1) and the rate depended largely on seasonal variability in precipitation and temperature. CH4 uptake was positively correlated with soil temperature, air temperature and to a lesser extent with precipitation, and was negatively correlated with soil moisture and NO3(-)-N content. The results indicate that between-year variability in CH4 uptake was impacted by precipitation and temperature and was not sensitive to elevated N deposition in alpine grassland.

Olivine weathering in soil, and its effects on growth and nutrient uptake in Ryegrass (Lolium perenne L.): a pot experiment.

PubMed

ten Berge, Hein F M; van der Meer, Hugo G; Steenhuizen, Johan W; Goedhart, Paul W; Knops, Pol; Verhagen, Jan

2012-01-01

Mineral carbonation of basic silicate minerals regulates atmospheric CO(2) on geological time scales by locking up carbon. Mining and spreading onto the earth's surface of fast-weathering silicates, such as olivine, has been proposed to speed up this natural CO(2) sequestration ('enhanced weathering'). While agriculture may offer an existing infrastructure, weathering rate and impacts on soil and plant are largely unknown. Our objectives were to assess weathering of olivine in soil, and its effects on plant growth and nutrient uptake. In a pot experiment with perennial ryegrass (Lolium perenne L.), weathering during 32 weeks was inferred from bioavailability of magnesium (Mg) in soil and plant. Olivine doses were equivalent to 1630 (OLIV1), 8150, 40700 and 204000 (OLIV4) kg ha(-1). Alternatively, the soluble Mg salt kieserite was applied for reference. Olivine increased plant growth (+15.6%) and plant K concentration (+16.5%) in OLIV4. At all doses, olivine increased bioavailability of Mg and Ni in soil, as well as uptake of Mg, Si and Ni in plants. Olivine suppressed Ca uptake. Weathering estimated from a Mg balance was equivalent to 240 kg ha(-1) (14.8% of dose, OLIV1) to 2240 kg ha(-1) (1.1%, OLIV4). This corresponds to gross CO(2) sequestration of 290 to 2690 kg ha(-1) (29 10(3) to 269 10(3) kg km(-2).) Alternatively, weathering estimated from similarity with kieserite treatments ranged from 13% to 58% for OLIV1. The Olsen model for olivine carbonation predicted 4.0% to 9.0% weathering for our case, independent of olivine dose. Our % values observed at high doses were smaller than this, suggesting negative feedbacks in soil. Yet, weathering appears fast enough to support the 'enhanced weathering' concept. In agriculture, olivine doses must remain within limits to avoid imbalances in plant nutrition, notably at low Ca availability; and to avoid Ni accumulation in soil and crop.

Olivine Weathering in Soil, and Its Effects on Growth and Nutrient Uptake in Ryegrass (Lolium perenne L.): A Pot Experiment

PubMed Central

ten Berge, Hein F. M.; van der Meer, Hugo G.; Steenhuizen, Johan W.; Goedhart, Paul W.; Knops, Pol; Verhagen, Jan

2012-01-01

Mineral carbonation of basic silicate minerals regulates atmospheric CO2 on geological time scales by locking up carbon. Mining and spreading onto the earth's surface of fast-weathering silicates, such as olivine, has been proposed to speed up this natural CO2 sequestration (‘enhanced weathering’). While agriculture may offer an existing infrastructure, weathering rate and impacts on soil and plant are largely unknown. Our objectives were to assess weathering of olivine in soil, and its effects on plant growth and nutrient uptake. In a pot experiment with perennial ryegrass (Lolium perenne L.), weathering during 32 weeks was inferred from bioavailability of magnesium (Mg) in soil and plant. Olivine doses were equivalent to 1630 (OLIV1), 8150, 40700 and 204000 (OLIV4) kg ha−1. Alternatively, the soluble Mg salt kieserite was applied for reference. Olivine increased plant growth (+15.6%) and plant K concentration (+16.5%) in OLIV4. At all doses, olivine increased bioavailability of Mg and Ni in soil, as well as uptake of Mg, Si and Ni in plants. Olivine suppressed Ca uptake. Weathering estimated from a Mg balance was equivalent to 240 kg ha−1 (14.8% of dose, OLIV1) to 2240 kg ha−1 (1.1%, OLIV4). This corresponds to gross CO2 sequestration of 290 to 2690 kg ha−1 (29 103 to 269 103 kg km−2.) Alternatively, weathering estimated from similarity with kieserite treatments ranged from 13% to 58% for OLIV1. The Olsen model for olivine carbonation predicted 4.0% to 9.0% weathering for our case, independent of olivine dose. Our % values observed at high doses were smaller than this, suggesting negative feedbacks in soil. Yet, weathering appears fast enough to support the ‘enhanced weathering’ concept. In agriculture, olivine doses must remain within limits to avoid imbalances in plant nutrition, notably at low Ca availability; and to avoid Ni accumulation in soil and crop. PMID:22912685

Effect of pH on bacteriophage transport through sandy soils

USGS Publications Warehouse

Kinoshita, Takashi; Bales, Roger C.; Maguire, Kimberley M.; Gerba, Charles P.

1993-01-01

Effects of pH and hydrophobicity on attachment and detachment of PRD-1 and MS-2 in three different sandy soils were investigated in a series of laboratory-column experiments. Concentrations of the lipid-containing phage PRD-1 decreased 3–4 orders of magnitude during passage through the 10–15-cm-long columns. Attachment of the lipid-containing phage PRD-1 was insensitive to pH and was apparently controlled by hydrophobic interactions in soil media. The less-hydrophobic phage MS-2 acted conservatively; it was not removed in the columns at pH's 5.7–8.0. The sticking efficiency (α) in a colloid-filtration model was between 0.1 and 1 for PRD-1, indicating a relatively high removal efficiency. Phage attachment was reversible, but detachment under steady-state conditions was slow. An increase in pH had a moderate effect on enhancing detachment. Still, these soils should continue to release phage to virus-free water for days to weeks following exposure to virus-containing water. In sandy soils with a mass-fraction organic carbon as low as a few hundredths of a percent, pH changes in the range 5.7–8.0 should have little effect on retention of more-hydrophobic virus (e.g., PRD-1), in that retardation will be dominated by hydrophobic effects. Sharp increases in pH should enhance detachment and transport of virus previously deposited on soil grains. A more hydrophilic virus (e.g., MS-2) will transport as a conservative tracer in low-carbon sandy soil.

Uptake of allochthonous dissolved organic matter from soil and salmon in coastal temperate rainforest streams

Treesearch

Jason B. Fellman; Eran Hood; Richard T. Edwards; Jeremy B. Jones

2009-01-01

Dissolved organic matter (DOM) is an important component of aquatic food webs. We compare the uptake kinetics for NH4-N and different fractions of DOM during soil and salmon leachate additions by evaluating the uptake of organic forms of carbon (DOC) and nitrogen (DON), and proteinaceous DOM, as measured by parallel factor (PARAFAC) modeling of...

A comparison of uptake of metformin and phenformin mediated by hOCT1 in human hepatocytes.

PubMed

Sogame, Yoshihisa; Kitamura, Atsushi; Yabuki, Masashi; Komuro, Setsuko

2009-11-01

Metformin, a biguanide that has been used to treat type 2 diabetes mellitus, is reportedly transported into human hepatocytes by human organic cation transporter 1 (hOCT1). The objective of this study was to investigate differences in the hepatic uptake of metformin and phenformin, a biguanide derivative similar to metformin. Special focus was on the role of active transport into cells. Experiments were therefore performed using human cryopreserved hepatocytes and hOCT1 expressing oocytes. Both biguanides proved to be good substrates for hOCT1. However, phenformin exhibited a much higher affinity and transport activity, with a marked difference in uptake kinetics compared with metformin. Both biguanides were transported actively by hOCT1, with the active transport components much greater than passive transport components in both cases, suggesting that functional changes in hOCT1 might affect the transport of both compounds to the same degree. This study for the first time produced detailed comparative findings for uptake profiles of metformin and phenformin in human hepatocytes and hOCT1 expressing oocytes. It is considered that hOCT1 may not be the only key factor that determines the frequency of metformin and phenformin toxicity, considering the major contribution of this transporter to the total hepatic uptake and comparable width of their therapeutic concentrations.

Soil pH effects on the interactions between dissolved zinc, non-nano- and nano-ZnO with soil bacterial communities.

PubMed

Read, Daniel S; Matzke, Marianne; Gweon, Hyun S; Newbold, Lindsay K; Heggelund, Laura; Ortiz, Maria Diez; Lahive, Elma; Spurgeon, David; Svendsen, Claus

2016-03-01

Zinc oxide nanoparticles (ZnO NPs) are used in an array of products and processes, ranging from personal care products to antifouling paints, textiles, food additives, antibacterial agents and environmental remediation processes. Soils are an environment likely to be exposed to manmade nanoparticles due to the practice of applying sewage sludge as a fertiliser or as an organic soil improver. However, understanding on the interactions between soil properties, nanoparticles and the organisms that live within soil is lacking, especially with regards to soil bacterial communities. We studied the effects of nanoparticulate, non-nanoparticulate and ionic zinc (in the form of zinc chloride) on the composition of bacterial communities in soil with a modified pH range (from pH 4.5 to pH 7.2). We observed strong pH-dependent effects on the interaction between bacterial communities and all forms of zinc, with the largest changes in bacterial community composition occurring in soils with low and medium pH levels (pH 4.8 and 5.9). The high pH soil (pH 7.2) was less susceptible to the effects of zinc exposure. At the highest doses of zinc (2500 mg/kg dw soil), both nano and non-nano particulate zinc applications elicited a similar response in the soil bacterial community, and this differed significantly to the ionic zinc salt treatment. The results highlight the importance of considering soil pH in nanotoxicology studies, although further work is needed to determine the exact mechanisms controlling the toxicity and fate and interactions of nanoparticles with soil microbial communities.

Effects of soil pH on the Vicia-micronucleus genotoxicity assay.

PubMed

Dhyèvre, Adrien; Foltête, Anne Sophie; Aran, Delphine; Muller, Serge; Cotelle, Sylvie

2014-11-01

In the field of contaminated sites and soil management, chemical analyses only bring typological data about pollution. As far as bioavailability and effects on organisms are concerned, we need ecotoxicology tools. In this domain, among many existing tests, we chose to study genotoxicity because it is a short-term endpoint with long-term consequences. The aim of this study is to assess the effects of soil pH on the results of the Vicia faba root tip micronucleus test for the two following reasons: (i) to define the pH range within which the test can be performed without modifying the soil to be tested, within the framework of the ISO standard of the test and (ii) to provides information about the effects of the pH on the genotoxic potential of soils. In this context, we modified the pH of a standard soil with HCl or NaOH and we spiked the matrix with copper (2, 4 and 8 mmol kg(-1) dry soil) or with maleic hydrazide, an antigerminative chemical (5, 10 and 20 μmol kg(-1) dry soil). We concluded that the pH had no effect on the mitotic index or micronucleus frequency in the root cells of the negative controls: extreme pH values did not induce micronucleus formation in root cells. Moreover, according to our results, the Vicia-micronucleus test can be performed with pH values ranging between 3.2 and 9.0, but in the ISO 29200 "Soil quality--assessment of genotoxic effects on higher plants--V. faba micronucleus test" we recommended to use a control soil with a pH value ranging between 5 and 8 for a more accurate assessment of chemical genotoxicity. We also found that acid pH could increase the genotoxic potential of pollutants, especially heavy metals. With hydrazide maleic spiked soil, plants were placed in a situation of double stress, i.e. toxicity caused by extreme pH values and toxicity induced by the pollutant. Copyright © 2014 Elsevier B.V. All rights reserved.

Temperature and pH effects on plant uptake of benzotriazoles by sunflowers in hydroponic culture.

PubMed

Castro, Sigifredo; Davis, Lawrence C; Erickson, Larry E

2004-01-01

This article describes a systematic approach to understanding the effect of environmental variables on plant uptake (phyto-uptake) of organic contaminants. Uptake (and possibly phytotransformation) of xenobiotics is a complex process that may differ from nutrient uptake. A specific group of xenobiotics (benzotriazoles) were studied using sunflowers grown hydroponically with changes of environmental conditions including solution volume, temperature, pH, and mixing. The response of plants to these stimuli was evaluated and compared using physiological changes (biomass production and water uptake) and estimated uptake rates (influx into plants), which define the uptake characteristics for the xenobiotic. Stirring of the hydroponic solution had a significant impact on plant growth and water uptake. Plants were healthier, probably because of a combination of factors such as improved aeration and increase in temperature. Uptake and possibly phytotransformation of benzotriazoles was increased accordingly. Experiments at different temperatures allowed us to estimate an activation energy for the reaction leading to triazole disappearance from the solution. The estimated activation energy was 43 kJ/mol, which indicates that the uptake process is kinetically limited. Culturing plants in triazole-amended hydroponic solutions at different pH values did not strongly affect the biomass production, water uptake, and benzotriazole uptake characteristics. The sunflowers showed an unexpected capacity to buffer the solution pH.

Nutrient Uptake and Use Efficiency by Tropical Legume Cover Crops at varying pH of an Oxisol

USDA-ARS?s Scientific Manuscript database

Oxisols comprise large soil group in tropical America. These soils are acidic and having low fertility. Use of tropical legume cover crops in cropping systems is an important strategy to improve fertility of these soils for sustainable crop production. Data are limited on nutrient uptake and use ef...

Effect of H(2)SO(4) and HCl in the anode purging solution for the electrokinetic-Fenton remediation of soil contaminated with phenanthrene.

PubMed

Kim, Jung-Hwan; Kim, Jong Yun; Kim, Soo-Sam

2009-09-01

The Electrokinetic-Fenton (EK-Fenton) process is a powerful technology to remediate organic-contaminated soil. The behavior of salts and acids introduced for the pH control has significant influence on the H(2)O(2) stabilization and destruction of organic contaminants. In this study, the effects of the type and concentration of acids, which were introduced at the anode, were investigated for the treatment of clayey soil contaminated with phenanthrene. In experiments with H(2)SO(4) as the anode solution, H(2)O(2) concentration in the anode reservoir decreased due to reaction between reduced species of sulfate and H(2)O(2), as time elapsed. By contrast, HCl as an electrolyte in the anode reservoir did not decrease the H(2)O(2) concentration in the anode reservoir. The reaction between the reduced species of sulfate and H(2)O(2) hindered the stabilization of H(2)O(2) in the soil and anode reservoir. In experiments with HCl for pH control, Cl(.), and Cl(2)(. -), which could be generated with mineral catalyzed Fenton-like reaction, did not significantly hinder H(2)O(2) stabilization. H(2)O(2) transportation with electro-osmotic flow and mineral catalyzed Fenton-like reaction on the soil surface resulted in the simultaneous transport and degradation of phenanthrene, which are dependent of the advancement rate of the acid front and electro-osmotic flow toward the cathode according to HCl and H(2)SO(4) concentrations in the anode purging solution.

Species turnover (β-diversity) in ectomycorrhizal fungi linked to NH4+ uptake capacity.

PubMed

Kranabetter, J M; Hawkins, B J; Jones, M D; Robbins, S; Dyer, T; Li, T

2015-12-01

Ectomycorrhizal (EcM) fungal communities may be shaped by both deterministic and stochastic processes, potentially influencing ecosystem development and function. We evaluated community assembly processes for EcM fungi of Pseudotsuga menziesii among 12 sites up to 400 km apart in southwest British Columbia (Canada) by investigating species turnover (β-diversity) in relation to soil nitrogen (N) availability and physical distance. We then examined functional traits for an N-related niche by quantifying net fluxes of NH4+, NO3- and protons on excised root tips from three contrasting sites using a microelectrode ion flux measurement system. EcM fungal communities were well aligned with soil N availability and pH, with no effect of site proximity (distance-decay curve) on species assemblages. Species turnover was significant (β(1/2) = 1.48) along soil N gradients, with many more Tomentella species on high N than low N soils, in contrast to Cortinarius species. Ammonium uptake was greatest in the spring on the medium and rich sites and averaged over 190 nmol/m(2)/s for Tomentella species. The lowest uptake rates of NH4+ were by nonmycorrhizal roots of axenically grown seedlings (10 nmol/m(2)/s), followed by Cortinarius species (60 nmol/m(2)/s). EcM roots from all sites displayed only marginal uptake of nitrate (8.3 nmol/m(2)/s). These results suggest NH4+ uptake capacity is an important functional trait influencing the assembly of EcM fungal communities. The diversity of EcM fungal species across the region arguably provides critical belowground adaptations to organic and inorganic N supply that are integral to temperate rainforest ecology. © 2015 John Wiley & Sons Ltd.

Functional analysis of [methyl-(3)H]choline uptake in glioblastoma cells: Influence of anti-cancer and central nervous system drugs.

PubMed

Taguchi, Chiaki; Inazu, Masato; Saiki, Iwao; Yara, Miki; Hara, Naomi; Yamanaka, Tsuyoshi; Uchino, Hiroyuki

2014-04-01

Positron emission tomography (PET) and PET/computed tomography (PET-CT) studies with (11)C- or (18)F-labeled choline derivatives are used for PET imaging in glioblastoma patients. However, the nature of the choline transport system in glioblastoma is poorly understood. In this study, we performed a functional characterization of [methyl-(3)H]choline uptake and sought to identify the transporters that mediate choline uptake in the human glioblastoma cell lines A-172 and U-251MG. In addition, we examined the influence of anti-cancer drugs and central nervous system drugs on the transport of [methyl-(3)H]choline. High- and low-affinity choline transport systems were present in A-172 cells, U-251MG cells and astrocytes, and these were Na(+)-independent and pH-dependent. Cell viability in A-172 cells was not affected by choline deficiency. However, cell viability in U-251MG cells was significantly inhibited by choline deficiency. Both A-172 and U-251MG cells have two different choline transporters, choline transporter-like protein 1 (CTL1) and CTL2. In A-172 cells, CTL1 is predominantly expressed, whereas in U-251MG cells, CTL2 is predominantly expressed. Treatment with anti-cancer drugs such as cisplatin, etoposide and vincristine influenced [methyl-(3)H]choline uptake in U-251MG cells, but not A-172 cells. Central nervous system drugs such as imipramine, fluvoxamine, paroxetine, reboxetine, citalopram and donepezil did not affect cell viability or [methyl-(3)H]choline uptake. The data presented here suggest that CTL1 and CTL2 are functionally expressed in A-172 and U-251MG cells and are responsible for [methyl-(3)H]choline uptake that relies on a directed H(+) gradient as a driving force. Furthermore, while anti-cancer drugs altered [methyl-(3)H]choline uptake, central nervous system drugs did not affect [methyl-(3)H]choline uptake. Copyright © 2014 Elsevier Inc. All rights reserved.

Carbon uptake in granular basalt is mitigated by added organic carbon.

NASA Astrophysics Data System (ADS)

Howard, E. L.; Van Haren, J. L. M.; Dontsova, K.

2017-12-01

Soils represent a large, and potentially long-term, storage component of the global carbon budget. Accurate projections of the response of soil respiration -the release of CO2 from soils generated either through root respiration or microbial respiration- to rainfall events remains one of the largest uncertainties in global carbon cycling models. Similarly poorly represented in models is the uptake of CO2 by basalt soils. In an attempt to address these unknowns, we have investigated how the addition of carbon influences the negative CO2 flux observed after wetting basalt. At Biosphere 2 we have constructed a large scale environmentally controlled experiment known as the Landscape Evolution Observatory (LEO). The objective of LEO is to observe the interactions between water, microbes, and climate in the formation of soil and landscapes utilizing granular basalt as a young soil. Previous studies show that water addition to the LEO soil leads to considerable CO2 uptake and that the addition of plants does not alter this response. In this study, we conducted soil incubations to investigate the effect of varying soil carbon content on CO2 fluxes. During incubations we measured CO2 emissions from two types of soil (granular basalt and sand soil) mixed with seven (0, 5, 10, 25, 50, 75, 100%) different proportions of Kalso prairie. The carbon content varied from nearly zero in the basalt to 6.5% in the Kalso Prarie soil. Other parameters that influence soil CO2 fluxes such as pH were taken into account. In conclusion, our experiments confirm that unweathered basalt will consume CO2 when wetted, whereas added carbon will cause a strong pulse of CO2 following water addition. This supports our hypotheses that the carbon content is a large contributor and that maturation of basalt flows will lead to a shift in the carbon dynamics from inorganic to organic dominated. Likewise, these transitions would be expected to be present during soil formation after primary succession and

Revisiting Mt. Kilimanjaro: Do n-alkane biomarkers in soils reflect the δ2H isotopic composition of precipitation?

NASA Astrophysics Data System (ADS)

Zech, M.; Zech, R.; Rozanski, K.; Hemp, A.; Gleixner, G.; Zech, W.

2014-06-01

During the last decade compound-specific deuterium (δ2H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ2H of precipitation (δ2Hprec). Recently, several authors suggested that δ2H of n-alkanes (δ2H,sub>n-alkanes) can also be used as proxy in paleoaltimetry studies. Here we present results from a δ2H transect study (~1500 to 4000 m a.s.l.) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ2Hprec is present above ~2000 m a.s.l., i.e. δ2Hprec values become more negative with increasing altitude. The compound-specific δ2H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ2Hn-alkane results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro (Peterse et al., 2009, BG, 6, 2799-2807), a major re-interpretation is required given that the δ2Hn-alkane results do not reflect the δ2Hprec results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% at ~ 2000 m a.s.l. to 51% at 4000 m a.s.l.), strongly controls δ2Hleaf water. The modelled δ2H leaf water enrichment along the altitudinal transect matches well the measured 2H leaf water enrichment as assessed by using the δ2Hprec and δ2Hn-alkane results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ2Hprec but rather δ2

Influence of iron plaque on uptake and accumulation of Cd by rice (Oryza sativa L.) seedlings grown in soil.

PubMed

Liu, Houjun; Zhang, Junling; Christie, Peter; Zhang, Fusuo

2008-05-15

Iron plaque is ubiquitously formed on the root surfaces of rice. However, little is known about the role of iron plaque in Cd movement from soil to the plant aboveground parts. A pot experiment was conducted to investigate the influence of iron plaque in Cd uptake and accumulation by rice seedlings in soil. Rice seedlings were pre-cultivated in solution culture for 16 days. Two seedlings were transplanted in a nylon bag containing no substrate but surrounded by soil amended with Fe and Cd combined at rates of 0, 1, or 2 g Fe kg(-1) and 0, 2.0, or 10 mg Cd kg(-1) soil. Fe was added to induce different amounts of iron plaque, and Cd to simulate Cd-polluted soils. Plants were grown for a further 43 days and then harvested. The length of the longest leaf and SPAD values of the newly mature leaves were measured during plant growth. Fe and Cd concentrations were determined in dithionite-citrate-bicarbonate (DCB) soil extracts and in plant roots and shoots. Shoot and root dry weights were significantly affected by Fe supply level but not by added Cd. Root dry weight declined with increasing Fe supply but shoot dry weight decreased at 2 g Fe kg(-1) and increased at 1 g Fe kg(-1) (except at 2 mg Cd kg(-1)). The length of the longest leaf and SPAD values of the newly mature leaves were significantly affected by plant growth stage and added Fe and Cd. Fe tended to diminish the negative effect of Cd on these two parameters. Cd concentrations in DCB extracts increased with increasing Cd and Fe supply. In contrast, external Fe supply markedly reduced shoot and root Cd concentrations and there was generally no significant difference between the two Fe supply levels. Shoot and root Cd concentrations increased with increasing Cd addition. Root Cd concentrations were negatively correlated with root Fe concentrations. The proportion of Cd in DCB extracts was significantly lower than in roots or shoots. The results indicate that enhanced Fe uptake by plants can diminish the negative

The effect of folate status on the uptake of physiologically relevant compounds by Caco-2 cells.

PubMed

Tavares, Sandra; Sousa, Joana; Gonçalves, Pedro; Araújo, João R; Martel, Fátima

2010-08-25

The aim of this work was to investigate the effect of folate status on the uptake of several physiologically relevant substances by Caco-2 cells. For this, Caco-2 cells cultured in high-folate conditions (HF) and low-folate conditions (LF) were compared. Growth rates of HF and LF Caco-2 cells were similar. However, proliferation rate of LF cells was greater than that of HF cells during the first 2days of culture and slightly smaller thereafter, viability of LF cells was greater than that of HF cells, and apoptosis index was similar in both cell cultures. We verified that in LF cells, comparatively to HF cells: (1) uptake of [3H]folic acid is upregulated, via an increase in the Vmax of uptake; (2) uptake of [3H]deoxy-glucose, [3H]O-methyl-glucose and [3H]1-methyl-4-phenylpyridinium (MPP+) is downregulated, via a decrease in the Vmax of uptake; additionally, a reduction in Km was observed for [3H]O-methyl-glucose; (3) uptake of [3H]5-hydroxytryptamine and [14C]butyrate is not changed; and (4) the steady-state mRNA levels of the folic acid transporters RFC (reduced folate carrier), PCFT (proton-coupled folate transporter) and FRalpha (folate receptor alpha), of the organic cation transporter OCT1 (organic cation transporter type 1), of the glucose transporter GLUT2 (facilitative glucose transporter type 2) and of the butyrate transporter MCT1 (monocarboxylate transporter type 1) were decreased. In conclusion, folate deficiency produces substrate-specific changes in the uptake of bioactive compounds by Caco-2 cells. Moreover, these changes are associated with alterations in the mRNA levels of specific transporters for these compounds. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Uptake and transformation of soil [14C]-trinitrotoluene by cool-season grasses

USDA-ARS?s Scientific Manuscript database

This study investigated the fate and uptake of [14C]-TNT from soil into orchardgrass (Dactylis glomerata), perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) over a one year period in a greenhouse-controlled environment. Pots (n=4 for each grass, containing 10 mg cold TNT/kg s...

Role of Root Hairs and Lateral Roots in Silicon Uptake by Rice

PubMed Central

Ma, Jian Feng; Goto, Shoko; Tamai, Kazunori; Ichii, Masahiko

2001-01-01

The rice plant (Oryza sativa L. cv Oochikara) is known to be a Si accumulator, but the mechanism responsible for the high uptake of Si by the roots is not well understood. We investigated the role of root hairs and lateral roots in the Si uptake using two mutants of rice, one defective in the formation of root hairs (RH2) and another in that of lateral roots (RM109). Uptake experiments with nutrient solution during both a short term (up to 12 h) and relatively long term (26 d) showed that there was no significant difference in Si uptake between RH2 and the wild type (WT), whereas the Si uptake of RM109 was much less than that of WT. The number of silica bodies formed on the third leaf in RH2 was similar to that in WT, but the number of silica bodies in RM109 was only 40% of that in WT, when grown in soil amended with Si under flooded conditions. There was also no difference in the shoot Si concentration between WT and RH2 when grown in soil under upland conditions. Using a multi-compartment transport box, the Si uptake at the root tip (0–1 cm, without lateral roots and root hairs) was found to be similar in WT, RH2, and RM109. However, the Si uptake in the mature zone (1–4 cm from root tip) was significantly lower in RM109 than in WT, whereas no difference was found in Si uptake between WT and RH2. All these results clearly indicate that lateral roots contribute to the Si uptake in rice plant, whereas root hairs do not. Analysis of F2 populations between RM109 and WT showed that Si uptake was correlated with the presence of lateral roots and that the gene controlling formation of lateral roots and Si uptake is a dominant gene. PMID:11743120

Enhanced biodegradation of asphalt in the presence of Tween surfactants, Mn(2+) and H2O2 by Pestalotiopsis sp. in liquid medium and soil.

PubMed

Yanto, Dede Heri Yuli; Tachibana, Sanro

2014-05-01

Asphalt and fractions thereof can contaminate water and soil environments. Forming as residues in distillation products in crude oil refineries, asphalts consist mostly of asphaltene instead of aliphatics, aromatics, and resins. The high asphaltene content might be responsible for the decrease in bioavailability to microorganisms and therefore reduce the biodegradability of asphalt in the environment. In this study, the effect on asphalt biodegradation by Pestalotiopsis sp. in liquid medium and soil of nonionic Tween surfactants in the presence of Mn2+ and H2O2 was examined. The degradation was enhanced by Tween 40 or Tween 80 (0.1%) in the presence of Mn2+ (1 mM) and H2O2 (0.05 mM). A Tween surfactant, Mn2+, and H2O2 can overcome bioavailability-mediated constraints and increase ligninolytic activities, particularly manganese peroxidase and laccase activities. The study is significant for the bioremediation of asphalt and/or viscous-crude oil-contaminated environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

Soil tension mediates isotope fractionation during soil water evaporation

NASA Astrophysics Data System (ADS)

Gaj, Marcel; McDonnell, Jeffrey

2017-04-01

Isotope tracing of the water cycle is increasing in its use and usefulness. Many new studies are extracting soil waters and relating these to streamflow, groundwater recharge and plant transpiration. Nevertheless, unlike isotope fractionation factors from open water bodies, soil water fractionation factors are poorly understood and until now, only empirically derived. In contrast to open water evaporation where temperature, humidity and vapor pressure gradient define fractionation (as codified in the well-known Craig and Gordon model), soil water evaporation includes additionally, fractionation by matrix effects. There is yet no physical explanation of kinetic and equilibrium fraction from soil water within the soil profile. Here we present a simple laboratory experiment with four admixtures of soil grain size (from sand to silt to clay). Oven-dried samples were spiked with water of known isotopic composition at different soil water contents. Soils were then stored in sealed bags and the headspace filled with dry air and allowed to equilibrate for 24hours. Isotopic analysis of the headspace vapor was done with a Los Gatos Inc. water vapor isotope analyzer. Soil water potential of subsamples were measured with a water potential meter. We show for the first time that soil tension controls isotope fractionation in the resident soil water. Below a Pf 3.5 the δ-values of 18O and 2H of the headspace vapor is more positive and increases with increasing soil water potential. Surprisingly, we find that the relationship between soil tension and equilibrium fractionation is independent of soil type. However, δ-values of each soil type plot along a distinct evaporation line. These results indicate that equilibrium fractionation is affected by soil tension in addition to temperature. Therefore, at high soil water tension (under dry conditions) equilibrium fractionation is not consistent with current empirical formulations that ignore these effects. These findings may have

Bioaccumulation of metals by lichens: Uptake of aqueous uranium by Peltigera membranacea as a function of time and pH

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

Haas, J.R.; Bailey, E.H.; Purvis, O.W.

1998-11-01

Uranium sorption experiments were carried out at {approximately}25 C using natural samples of the lichen Peltigera membranacea. Thalli were incubated in solutions containing 100 ppm U for up to 24 h at pH values from 2 to 10. Equilibrium sorption was not observed at less than {approximately}6 h under any pH condition. U sorption was strongest in the pH range 4--5, with maximum sorption occurring at a pH of 4.5 and an incubation time of 24 h. Maximum U uptake by P. membranacea averaged {approximately}42,000 ppm, or {approximately}4.2 wt% U. This appears to represent the highest concentration of biosorbed U,more » relative to solution U activity, of any lichen reported to date. Investigation of post-experimental lichen tissues using electron probe microanalysis (EPM) reveals that U uptake is spatially heterogeneous within the lichen body, and that U attains very high local concentrations on scattered areas of the upper cortex. Energy dispersive spectroscopic (EDS) analysis reveals that strong U uptake correlates with P signal intensity, suggesting involvement of biomass-derived phosphate ligands or surface functional groups in the uptake process.« less

Ethanol intake and sup 3 H-serotonin uptake I: A study in Fawn-Hooded rats

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

Daoust, M.; Compagnon, P.; Legrand, E.

1991-01-01

Ethanol intake and synaptosomal {sup 3}H-serotonin uptake were studied in male Fawn-Hooded and Sprague-Dawley rats. Fawn-Hooded rats consumed more alcohol and more water than Sprague-Dawley rats. Plasma alcohol levels of Sprague-Dawley rats were not detectable but were about 5 mg/dl in Fawn-Hooded rats. Ethanol intake increased the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex, but not in thalamus. In Fawn-Hooded rats, serotonin uptake (Vmax) was higher than in Sprague-Dawley rats cortex. Ethanol intake reduced the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex. In cortex, the carrier affinity for serotonin was increased inmore » alcoholized Fawn-Hooded rats. These results indicate that synaptosomal {sup 3}H-serotonin uptake is affected by ethanol intake. In Fawn-Hooded rats, high ethanol consumption is associated with high serotonin uptake. In rats presenting high serotonin uptake, alcoholization reduces {sup 3}H-serotonin internalization in synaptosomes, indicating a specific sensitivity to alcohol intake of serotonin uptake system.« less

Comparison of uptake, translocation and accumulation of several neonicotinoids in komatsuna (Brassica rapa var. perviridis) from contaminated soils.

PubMed

Li, Yong; Long, Ling; Yan, Huangqian; Ge, Jing; Cheng, Jinjin; Ren, Liyun; Yu, Xiangyang

2018-06-01

The accumulation of pesticides in vegetables may have serious effects on human health and ecosystems via food chains; therefore, it is of great importance to investigate the uptake and accumulation behaviours of pesticides in vegetable tissues. In the present study, the uptake, translocation and accumulation of five neonicotinoids, thiamethoxam (THIM), clothianidin (CLO), thiacloprid (THID), acetamiprid (ACE) and dinotefuran (DIN), in komatsuna (Brassica rapa var. perviridis, a vegetable) were investigated. The concentrations of neonicotinoids in vegetable tissues ranged from 0.068 ± 0.002 to 29.6 ± 2.5 mg/kg. During the cultivation (except for the first day), the concentration of each neonicotinoid in shoots was the highest, followed by roots and the soil. The concentrating of neonicotinoids from the soil to roots followed the order of THIM > CLO > THID > DIN > ACE, while the order of the ability of translocation neonicotinoids from roots to shoots was the just opposite. The difference in uptake and translocation behaviours of the test neonicotinoids seems to be not correlated with the octanol/water partition coefficient (logK ow ), water solubility or dissociation constant (pK a ), but significantly correlated with molecular weight. In addition, a greater concentration of the THIM-metabolite clothianidin (M-CLO) was detected in vegetable shoots than in roots and the soil. Copyright © 2018 Elsevier Ltd. All rights reserved.

Plant uptake/bioavailability of heavy metals from the contaminated soil after treatment with humus soil and hydroxyapatite.

PubMed

Misra, Virendra; Chaturvedi, Pranav Kumar

2007-10-01

Uptake /bioavailability study using the Indian mustard plant (Brassica juncea) was undertaken at the interval of 7, 14 and 21 days to test the immobilization of heavy metals from contaminated soil that were amended with humus soil and/or hydroxyapatite. For this, four sets consisting of non-humus soil + metals (Cd, Cr, Ni and Pb), humus soil + metals, non-humus and humus soil in the ratio of 1:3 + metals and non-humus soil: humus soil in the ratio of 1:3 + metals + 1% hydroxyapatite were prepared. The bioavailability of Pb, Cd, Cr and Ni in non-humus soil system was 58%, 67%, 65% and 63%, respectively in 7 days, more than 80% in 14 days and more than 90% in 21 days. Use of non-humus, humus soil in the ratio of 1:3 and addition of 1% hydroxyapatite decreased the bioavailability of lead around 21 to 22.5%, Cd 35 to 36%, Cr 25.5 to 26.9%, Ni 34 to 39% in 7, 14 and 21 days. Apart from this increase in the fresh weight of the plant was also noticed during the experiment. The data showed that addition of 1% hydroxyapatite in the non-humus-humus soil system caused the increase in the fresh weight around 90% in 7, 14 and 21 days as compared to plant grown in non-humus and metal soil system.

pH as a Driver for Ammonia-Oxidizing Archaea in Forest Soils.

PubMed

Stempfhuber, Barbara; Engel, Marion; Fischer, Doreen; Neskovic-Prit, Ganna; Wubet, Tesfaye; Schöning, Ingo; Gubry-Rangin, Cécile; Kublik, Susanne; Schloter-Hai, Brigitte; Rattei, Thomas; Welzl, Gerhard; Nicol, Graeme W; Schrumpf, Marion; Buscot, Francois; Prosser, James I; Schloter, Michael

2015-05-01

In this study, we investigated the impact of soil pH on the diversity and abundance of archaeal ammonia oxidizers in 27 different forest soils across Germany. DNA was extracted from topsoil samples, the amoA gene, encoding ammonia monooxygenase, was amplified; and the amplicons were sequenced using a 454-based pyrosequencing approach. As expected, the ratio of archaeal (AOA) to bacterial (AOB) ammonia oxidizers' amoA genes increased sharply with decreasing soil pH. The diversity of AOA differed significantly between sites with ultra-acidic soil pH (<3.5) and sites with higher pH values. The major OTUs from soil samples with low pH could be detected at each site with a soil pH <3.5 but not at sites with pH >4.5, regardless of geographic position and vegetation. These OTUs could be related to the Nitrosotalea group 1.1 and the Nitrososphaera subcluster 7.2, respectively, and showed significant similarities to OTUs described from other acidic environments. Conversely, none of the major OTUs typical of sites with a soil pH >4.6 could be found in the ultra- and extreme acidic soils. Based on a comparison with the amoA gene sequence data from a previous study performed on agricultural soils, we could clearly show that the development of AOA communities in soils with ultra-acidic pH (<3.5) is mainly triggered by soil pH and is not influenced significantly by the type of land use, the soil type, or the geographic position of the site, which was observed for sites with acido-neutral soil pH.

Can liming reduce cadmium (Cd) accumulation in rice (Oryza sativa) in slightly acidic soils? A contradictory dynamic equilibrium between Cd uptake capacity of roots and Cd immobilisation in soils.

PubMed

Yang, Yongjie; Chen, Jiangmin; Huang, Qina; Tang, Shaoqing; Wang, Jianlong; Hu, Peisong; Shao, Guosheng

2018-02-01

Cadmium (Cd) accumulation in rice is strongly controlled by liming, but information on the use of liming to control Cd accumulation in rice grown in slightly acidic soils is inconsistent. Here, pot experiments were carried out to investigate the mechanisms of liming on Cd accumulation in two rice varieties focusing on two aspects: available/exchangeable Cd content in soils that were highly responsive to liming, and Cd uptake and transport capacity in the roots of rice in terms of Cd accumulation-relative gene expression. The results showed that soil availability and exchangeable iron, manganese, zinc and Cd contents decreased with increased liming, and that genes related to Cd uptake (OsNramp5 and OsIRT1) were sharply up-regulated in the roots of the two rice varieties. Thus, iron, manganese, zinc and Cd contents in rice plants increased under low liming applications but decreased in response to high liming applications. However, yield and rice quantities were only slightly affected. These results indicated that Cd accumulation in rice grown in slightly acidic soils presents a contradictory dynamic equilibrium between Cd uptake capacity by roots and soil Cd immobilisation in response to liming. The enhanced Cd uptake capacity under low liming dosages increases risks to human health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effectiveness of urea in enhancing the extractability of 2,4,6-trinitrotoluene from chemically variant soils.

PubMed

Das, Padmini; Sarkar, Dibyendu; Makris, Konstantinos C; Punamiya, Pravin; Datta, Rupali

2013-11-01

One of the major challenges in developing an effective phytoremediation technology for 2,4,6-trinitrotoluene (TNT) contaminated soils is limited plant uptake resulting from low solubility of TNT. The effectiveness of urea as a solubilizing agent in increasing plant uptake of TNT in hydroponic systems has been documented. Our preliminary greenhouse experiments using urea were also very promising, but further characterization of the performance of urea in highly-complex soil-solution was necessary. The present study investigated the natural retention capacity of four chemically variant soils and optimized the factors influencing the effectiveness of urea in enhancing TNT solubility in the soil solutions. Results show that the extent of TNT sorption and desorption varies with the soil properties, and is mainly dependent on soil organic matter (SOM) content. Hysteretic desorption of TNT in all tested soils suggests irreversible sorption of TNT and indicates the need of using an extractant to increase the release of TNT in soil solutions. Urea significantly (p<0.0001) enhanced TNT extraction from all soils, by increasing its solubility at the solid/liquid interface. Soil organic matter content and urea application rates showed significant effects, whereas pH did not exert any significant effect on urea catalysis of TNT extraction from soil. The optimum urea application rates (125 or 350 mg kg(-1)) for maximizing TNT extraction were within the limits set by the agronomic fertilizer-N rates used for major agricultural crops. The data obtained from this batch study will facilitate the optimization of a chemically-catalyzed phytoremediation model for cleaning up TNT-contaminated soils. Copyright © 2013 Elsevier Ltd. All rights reserved.

N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

NASA Astrophysics Data System (ADS)

Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

2014-11-01

Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (<7.0 ± 5.0 μg NO-N m-2 h-1; <0.0 ± 1.4 μg N2O-N m-2 h-1) or in the case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%). N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha-1 yr-1 (N2O), 0.68 kg N ha-1 yr-1 (NO) and 6.65 kg N ha-1 yr-1 (N2). The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events

The yeast H+-ATPase Pma1 promotes Rag/Gtr-dependent TORC1 activation in response to H+-coupled nutrient uptake.

PubMed

Saliba, Elie; Evangelinos, Minoas; Gournas, Christos; Corrillon, Florent; Georis, Isabelle; André, Bruno

2018-03-23

The yeast Target of Rapamycin Complex 1 (TORC1) plays a central role in controlling growth. How amino acids and other nutrients stimulate its activity via the Rag/Gtr GTPases remains poorly understood. We here report that the signal triggering Rag/Gtr-dependent TORC1 activation upon amino-acid uptake is the coupled H + influx catalyzed by amino-acid/H + symporters. H + -dependent uptake of other nutrients, ionophore-mediated H + diffusion, and inhibition of the vacuolar V-ATPase also activate TORC1. As the increase in cytosolic H + elicited by these processes stimulates the compensating H + -export activity of the plasma membrane H + -ATPase (Pma1), we have examined whether this major ATP-consuming enzyme might be involved in TORC1 control. We find that when the endogenous Pma1 is replaced with a plant H + -ATPase, H + influx or increase fails to activate TORC1. Our results show that H + influx coupled to nutrient uptake stimulates TORC1 activity and that Pma1 is a key actor in this mechanism. © 2018, Saliba et al.

Chemically assisted phytoextraction: a review of potential soil amendments for increasing plant uptake of heavy metals.

PubMed

Meers, E; Tack, F M G; Van Slycken, S; Ruttens, A; Du Laing, G; Vangronsveld, J; Verloo, M G

2008-01-01

The contamination of soils by trace metals has been an unfortunate sideeffect of industrialization. Some of these contaminants can interfere with vulnerable enduses of soil, such as agriculture or nature, already at relatively low levels of contamination. Reversely, conventional civil-technical soil-remediation techniques are too expensive to remediate extended areas of moderately contaminated soil. Phytoextraction has been proposed as a more economic complementary approach to deal with this specific niche of soil contamination. However, phytoextraction has been shown to be a slow-working process due to the low amounts of metals that can be annually removed from the soil under normal agronomic conditions. Therefore, extensive research has been conducted on process optimization by means of chemically improving plant availability and the uptake of heavy metals. A wide range of potential amendments has been proposed in the literature, with considerable attention being spent on aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA). However, these compounds have received increasing criticism due to their environmental persistence and associated risks for leaching. This review presents an overview of potential soil amendments that can be employed for enhancing metal uptake by phytoextraction crops, with a distinct focus on more degradable alternatives to persistent compounds such as EDTA.

Hydroponic uptake of atrazine and lambda-cyhalothrin in Juncus effusus and Ludwigia peploides.

PubMed

Bouldin, J L; Farris, J L; Moore, M T; Smith, S; Cooper, C M

2006-11-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to changes in soil geochemistry and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Sorption and pH determine the long-term partitioning of cadmium in natural soils.

PubMed

Ardestani, Masoud M; van Gestel, Cornelis A M

2016-09-01

The bioavailability of metals in soil is a dynamic process. For a proper extrapolation to the field of laboratory studies on fate and effects, it is important to understand the dynamics of metal bioavailability and the way it is influenced by soil properties. The aim of this study was to assess the parallel (concurrent) effect of pH and aging time on the partitioning of cadmium in natural LUFA 2.2 soil. Cadmium nitrate-spiked pH-amended LUFA 2.2 soils were incubated under laboratory conditions for up to 30 weeks. Measured pHpw was lower after 3 weeks and decreased only slightly toward the end of the test. Cadmium concentrations in the pore water increased with time for all soil pH levels, while they decreased with increasing pH. Freundlich kf values ranged between 4.26 and 934 L kg(-1) (n = 0.79 to 1.36) and were highest at the highest pH tested (pH = 6.5). Multiple linear regression analysis, based on a soil ligand modeling approach, resulted in affinity constants of 2.61 for Ca(2+) (log KCa-SL) and 5.05 for H(+) (log KH-SL) for their binding to the active sites on the soil surface. The results showed that pH and aging time are two important factors which together affect cadmium partitioning and mobility in spiked natural soils.

The mycorrhizal type governs root exudation and nitrogen uptake of temperate tree species.

PubMed

Liese, Rebecca; Lübbe, Torben; Albers, Nora W; Meier, Ina C

2018-01-01

Even though the two dominant mycorrhizal associations of temperate tree species differentially couple carbon (C) and nitrogen (N) cycles in temperate forests, systematic differences between the biogeochemical cycles of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species remain poorly described. A classification according to the mycorrhizal type offers the chance, though, to develop a global frame concept for the prediction of temperate ecosystem responses to environmental change. Focusing on the influence of mycorrhizal types on two key plant processes of biogeochemical cycling (root exudation and N acquisition), we investigated four temperate deciduous tree species per mycorrhizal type in a drought experiment in large mesocosms. We hypothesized that (H1) C loss by root exudation is higher in ECM than in AM trees, (H2) drought leads to higher reductions in root exudation of drought-sensitive ECM trees and (H3) inorganic N uptake is higher in AM than in ECM trees. In contradiction to H2, we found no systematic difference in root exudation between the mycorrhizal types at ample soil moisture, but almost twofold higher exudation in ECM trees when exposed to soil drought. In addition, photosynthetic C cost of root exudation strongly increased by ~10-fold in drought-treated ECM trees, while it only doubled in AM trees, which confirms H1. With respect to H3, we corroborated that AM trees had higher absolute and relative inorganic N acquisition rates than ECM trees, while the organic N uptake did not differ between mycorrhizal types. We conclude that ECM trees are less efficient in inorganic N uptake than AM trees, but ECM trees increase root C release as an adaptive response to dry soil to maintain hydraulic conductivity and/or nutrient availability. These systematic differences in key biogeochemical processes support hints on the key role of the mycorrhizal types in coupling C and N cycles in temperate forests. © The Author 2017. Published by Oxford

Spatial P heterogeneity in forest soil: Influence on microbial P uptake and community structure

NASA Astrophysics Data System (ADS)

Zilla, Thomas; Angulo-Schipper, Bridith; Méndez, Juan Carlos; Dippold, Michaela A.; Kuzyakov, Yakov; Spielvogel, Sandra

2017-04-01

Other than nitrogen, phosphorus (P) is the most important growth limiting nutrient in soils. Yet, little information is available concerning the spatial heterogeneity of P content in forest soils. More so, the effects of a homogeneous vs. heterogeneous soil P distribution on microbial P acquisition and community structure have yet to be determined. Thus, a rhizotron experiment based on a P-deficient forest soil was conducted to investigate competitive P uptake strategies of microbes. F. sylvatica-bearing rhizotrons were labeled with Fe33PO4, a relatively immobile P source native to the study soil. Homogeneous and heterogeneous P patterns were created to study the effects of spatial P heterogeneity on plant and microbial P acquisition. P mobilization by microorganisms was tracked by an improved 33P-PLFA method, linking 33P incorporation in microbes with changes in microbial community structure in soils in situ. The microbial P uptake was enhanced in rhizotrons with high P availability and in those with a patchy P distribution. Characteristic PLFAs indicate a congregation of beech-associated ectomycorrhizal fungi in P-rich patches. These ectomycorrhizal fungi are likely to strongly increase P mobilization from the used Fe33PO4 in high P habitats. In contrast, habitats with low P availability require a more complex microbial community structure without a dominant group to mobilize this inaccessible P source. Therefore, hotspots of P are likely to promote the efforts of fungal hyphae for P mobilization - an effect which decreases with lower P content. Additionally, gram positive and negative bacteria exhibit a vastly higher P uptake under increasingly patchy P distributions. However, they form a smaller portion of the microbial community than in homogeneously P enriched rhizotrons, suggesting that filamentous organisms benefit from the patchy P distribution. Thus, only a heterogeneous P distribution promotes P acquisition of forest microbial communities from mineral P

Organic and inorganic nitrogen uptake by 21 dominant tree species in temperate and tropical forests.

PubMed

Liu, Min; Li, Changcheng; Xu, Xingliang; Wanek, Wolfgang; Jiang, Ning; Wang, Huimin; Yang, Xiaodong

2017-11-01

Evidence shows that many tree species can take up organic nitrogen (N) in the form of free amino acids from soils, but few studies have been conducted to compare organic and inorganic N uptake patterns in temperate and tropical tree species in relation to mycorrhizal status and successional state. We labeled intact tree roots by brief 15N exposures using field hydroponic experiments in a temperate forest and a tropical forest in China. A total of 21 dominant tree species were investigated, 8 in the temperate forest and 13 in the tropical forest. All investigated tree species showed highest uptake rates for NH4+ (ammonium), followed by glycine and NO3- (nitrate). Uptake of NH4+ by temperate trees averaged 12.8 μg N g-1 dry weight (d.w.) root h-1, while those by tropical trees averaged 6.8 μg N g-1 d.w. root h-1. Glycine uptake rates averaged 3.1 μg N g-1 d.w. root h-1 for temperate trees and 2.4 μg N g-1 d.w. root h-1 for tropical trees. NO3- uptake was the lowest (averaging 0.8 μg N g-1 d.w. root h-1 for temperate trees and 1.2 μg N g-1 d.w. root h-1 for tropical trees). Uptake of NH4+ accounted for 76% of the total uptake of all three N forms in the temperate forest and 64% in the tropical forest. Temperate tree species had similar glycine uptake rates as tropical trees, with the contribution being slightly lower (20% in the temperate forest and 23% in the tropical forest). All tree species investigated in the temperate forest were ectomycorrhizal and all species but one in the tropical forest were arbuscular mycorrhizal (AM). Ectomycorrhizal trees showed significantly higher NH4+ and lower NO3- uptake rates than AM trees. Mycorrhizal colonization rates significantly affected uptake rates and contributions of NO3- or NH4+, but depended on forest types. We conclude that tree species in both temperate and tropical forests preferred to take up NH4+, with organic N as the second most important N source. These findings suggest that temperate and tropical forests

Temporal variability in trace metal solubility in a paddy soil not reflected in uptake by rice (Oryza sativa L.).

PubMed

Pan, Yunyu; Koopmans, Gerwin F; Bonten, Luc T C; Song, Jing; Luo, Yongming; Temminghoff, Erwin J M; Comans, Rob N J

2016-12-01

Alternating flooding and drainage conditions have a strong influence on redox chemistry and the solubility of trace metals in paddy soils. However, current knowledge of how the effects of water management on trace metal solubility are linked to trace metal uptake by rice plants over time is still limited. Here, a field-contaminated paddy soil was subjected to two flooding and drainage cycles in a pot experiment with two rice plant cultivars, exhibiting either high or low Cd accumulation characteristics. Flooding led to a strong vertical gradient in the redox potential (Eh). The pH and Mn, Fe, and dissolved organic carbon concentrations increased with decreasing Eh and vice versa. During flooding, trace metal solubility decreased markedly, probably due to sulfide mineral precipitation. Despite its low solubility, the Cd content in rice grains exceeded the food quality standards for both cultivars. Trace metal contents in different rice plant tissues (roots, stem, and leaves) increased at a constant rate during the first flooding and drainage cycle but decreased after reaching a maximum during the second cycle. As such, the high temporal variability in trace metal solubility was not reflected in trace metal uptake by rice plants over time. This might be due to the presence of aerobic conditions and a consequent higher trace metal solubility near the root surface, even during flooding. Trace metal solubility in the rhizosphere should be considered when linking water management to trace metal uptake by rice over time.

Biochar alters microbial community and carbon sequestration potential across different soil pH.

PubMed

Sheng, Yaqi; Zhu, Lizhong

2018-05-01

Biochar application to soil has been proposed for soil carbon sequestration and global warming mitigation. While recent studies have demonstrated that soil pH was a main factor affecting soil microbial community and stability of biochar, little information is available for the microbiome across different soil pH and the subsequently CO 2 emission. To investigate soil microbial response and CO 2 emission of biochar across different pH levels, comparative incubation studies on CO 2 emission, degradation of biochar, and microbial communities in a ferralsol (pH5.19) and a phaeozems (pH7.81) with 4 biochar addition rates (0.5%, 1.0%, 2.0%, 5.0%) were conducted. Biochar induced higher CO 2 emission in acidic ferralsol, largely due to the higher biochar degradation, while the more drastic negative priming effect (PE) of SOC resulted in decreased total CO 2 emission in alkaline phaeozems. The higher bacteria diversity, especially the enrichment of copiotrophic bacteria such as Bacteroidetes, Gemmatimonadetes, and decrease of oligotrophic bacteria such as Acidobacteria, were responsible for the increased CO 2 emission and initial positive PE of SOC in ferralsol, whereas biochar did not change the relative abundances of most bacteria at phylum level in phaeozems. The relative abundances of other bacterial taxa (i.e. Actinobacteria, Anaerolineae) known to degrade aromatic compounds were also elevated in both soils. Soil pH was considered to be the dominant factor to affect CO 2 emission by increasing the bioavailability of organic carbon and abundance of copiotrophic bacteria after biochar addition in ferralsol. However, the decreased bioavailability of SOC via adsorption of biochar resulted in higher abundance of oligotrophic bacteria in phaeozems, leading to the decrease in CO 2 emission. Copyright © 2017. Published by Elsevier B.V.

Soluble soil aluminum alters the relative uptake of mineral nitrogen forms by six mature temperate broadleaf tree species: possible implications for watershed nitrate retention.

PubMed

Burnham, Mark B; Cumming, Jonathan R; Adams, Mary Beth; Peterjohn, William T

2017-11-01

Increased availability of monomeric aluminum (Al 3+ ) in forest soils is an important adverse effect of acidic deposition that reduces root growth and inhibits nutrient uptake. There is evidence that Al 3+ exposure interferes with NO 3 - uptake. If true for overstory trees, the reduction in stand demand for NO 3 - could increase NO 3 - discharge in stream water. These effects may also differ between species that tolerate different levels of soil acidity. To examine these ideas, we measured changes in relative uptake of NO 3 - and NH 4 + by six tree species in situ under increased soil Al 3+ using a 15 N-labeling technique, and measured soluble soil Al levels in a separate whole-watershed acidification experiment in the Fernow Experimental Forest (WV). When exposed to added Al 3+ , the proportion of inorganic N acquired as NO 3 - dropped 14% across species, but we did not detect a reduction in overall N uptake, nor did tree species differ in this response. In the long-term acidification experiment, we found that soluble soil Al was mostly in the free Al 3+ form, and the concentration of Al 3+ was ~65 μM higher (~250%) in the mineral soil of the acidified watershed vs. an untreated watershed. Thus, increased levels of soil Al 3+ under acidic deposition cause a reduction in uptake of NO 3 - by mature trees. When our 15 N uptake results were applied to the watershed acidification experiment, they suggest that increased Al 3+ exposure could reduce tree uptake of NO 3 - by 7.73 kg N ha -1  year -1 , and thus increase watershed NO 3 - discharge.

Biochar contribution to soil pH buffer capacity

NASA Astrophysics Data System (ADS)

Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

2014-05-01

Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

Imaging and modelling root water uptake

NASA Astrophysics Data System (ADS)

Zarebanadkouki, M.; Meunier, F.; Javaux, M.; Kaestner, A.; Carminati, A.

2017-12-01

Spatially resolved measurement and modelling of root water uptake is urgently needed to identify root traits that can improve capture of water from the soil. However, measuring water fluxes into roots of transpiring plants growing in soil remains challenging. Here, we describe an in-situ technique to measure local fluxes of water into roots. The technique consists of tracing the transport of deuterated water (D2O) in soil and roots using time series neutron radiography and tomography. A diffusion-convection model was used to model the transport of D2O in roots. The model includes root features such as the endodermis, xylem and the composite flow of water in the apoplastic and symplastic pathways. Diffusion permeability of root cells and of the endodermis were estimated by fitting the experiment during the night, when transpiration was negligible. The water fluxes at different position of the root system were obtained by fitting the experiments at daytime. The results showed that root water uptake was not uniform along root system and varied among different root types. The measured profiles of root water uptake into roots were used to estimate the radial and axial hydraulic of the roots. A three-dimensional model of root water uptake was used to fit the measured water fluxes by adjusting the root radial and axial hydraulic conductivities. We found that the estimated radial conductivities decreased with root age, while the axial conducances increased, and they are different among root types. The significance of this study is the development of a method to estimate 1) water uptake and 2) the radial and axial hydraulic conductivities of roots of transpiring plants growing in the soil.

Sustainable measures for sewage sludge treatment - evaluating the effects on P reaction in soils and plant P uptake

NASA Astrophysics Data System (ADS)

Shenker, Moshe; Einhoren, Hana

2016-04-01

Wastewater treatment, whether for water reusing or for releasing into the environment, results in sewage sludge rich in organic matter and nutrients. If free of pathogens and pollutants, this waste material is a widely used as soil amendment and source of valuable nutrients for agronomic use. Nevertheless, its P/N ratio largely exceeds plant P/N demand. Limiting its application rates according to the P demand of crops will largely limit its application rates and its beneficial effect as a soil amendment and as a source for other nutrients. An alternative approach, in which P is stabilized before application, was evaluated in this study. Anaerobically digested fresh sewage sludge (FSS) was stabilized by aluminum sulfate, ferrous sulfate, and calcium oxide (CaO), as well as by composting with shredded woody yard-waste to produce Al-FSS, Fe-FSS, CaO-FSS, and FSS-compost, respectively. Defined organic-P sources (glucose-1-phosphate and inositol-hexa-phosphate) and a P fertilizer (KH2PO4) were included as well and a control with no P amendments was included as a reference. Each material was applied at a fixed P load of 50 mg kg-1 to each of three soils and P speciation and plants P uptake were tested along 112 days of incubation at moderate (near field capacity) water content. Tomato seedlings were used for the P uptake test. The large set of data was used to evaluate the effect of each treatment on P reactions and mechanisms of retention in the tested soils and to correlate various P indices to P availability for plants. Plant P uptake was highly correlated to Olsen-P as well as to water-soluble inorganic-P, but not to water-soluble organic-P and not to total P or other experimentally-defined stable P fractions. We conclude that the P stabilization in the sludge will allow beneficial and sustainable use of sewage sludge as a soil amendment and source of nutrients, but the stabilization method should be selected in accordance with the target soil properties.

Precipitation of CaCO3 due to the Uptake of CO2 in Aqueous Solutions - Mechanisms and Rates

NASA Astrophysics Data System (ADS)

Dietzel, M.; Purgstaller, B.; Rinder, T.; Niedermayr, A.

2012-12-01

In natural and man-made environments the exchange of CO2 between aqueous solutions and the atmosphere frequently induces precipitation of CaCO3 polymorphs. Liberation of gaseous CO2 is well known to induce carbonate formation and extensively studied. In contrast significant gaps of knowledge exist with respect to the combined CO2 uptake and CaCO3 formation, although it is known to be highly valid for many natural and man-made surroundings causing e.g. travertine and scaling in analogy to CO2 liberation. Recently CO2 uptake is also discussed for biomineralization issues and debated for CO2 sequestration by using alkaline residue materials. In the present study CO2 uptake and CaCO3 precipitation mechanisms and rates were experimentally studied by diffusion of CO2 through a polyethylene membrane from an inner to an outer solution containing carbonic acid and CaCl2 (10 mM), respectively. The pH of the outer solution was kept constant between 8.3 and 11.5 by pH stat. technique (25°C). At a critical Ion Activity Product (IAP) CaCO3 is formed in the outer solution. The NaOH titration curve and Ca2+ concentrations reflect CO2 uptake and CaCO3 precipitation rates. To discover the impact of a drift in pH due to CO2 uptake on CaCO3 precipitation hydrogeochemical modeling was applied. XRD, (micro)Raman pattern and SEM imaging reveal the formation of calcite and vaterite at pH 8.3 and 9, whereas at pH > 10 vaterite is additionally formed. However at a given pH the formation of individual CaCO3 polymorphs strongly depends on the CO2 uptake rate (adjusted by membrane thickness), which controls carbonate accumulation in the solution. At elevated pH of the outer solution the uptake rate of CO2 is significantly higher and less time for nucleation of CaCO3 is required compared to lower pH. Surprisingly at the total experimental time of ≈ 20 h the amount of precipitated CaCO3 is similar for all experiments. This can be explained by significant higher CaCO3 precipitation rates at

Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation.

PubMed

Zhang, Yuping; Sallach, J Brett; Hodges, Laurie; Snow, Daniel D; Bartelt-Hunt, Shannon L; Eskridge, Kent M; Li, Xu

2016-01-01

Treated wastewater is expected to be increasingly used as an alternative source of irrigation water in areas facing fresh water scarcity. Understanding the behaviors of contaminants from wastewater in soil and plants following irrigation is critical to assess and manage the risks associated with wastewater irrigation. The objective of this study was to evaluate the effects of soil texture and drought stress on the uptake of antibiotics and the internalization of human pathogens into lettuce through root uptake following wastewater irrigation. Lettuce grown in three soils with variability in soil texture (loam, sandy loam, and sand) and under different levels of water stress (no drought control, mild drought, and severe drought) were irrigated with synthetic wastewater containing three antibiotics (sulfamethoxazole, lincomycin and oxytetracycline) and one Salmonella strain a single time prior to harvest. Antibiotic uptake in lettuce was compound-specific and generally low. Only sulfamethoxazole was detected in lettuce with increasing uptake corresponding to increasing sand content in soil. Increased drought stress resulted in increased uptake of lincomycin and decreased uptake of oxytetracycline and sulfamethoxazole. The internalization of Salmonella was highly dependent on the concentration of the pathogen in irrigation water. Irrigation water containing 5 Log CFU/mL Salmonella resulted in limited incidence of internalization. When irrigation water contained 8 Log CFU/mL Salmonella, the internalization frequency was significantly higher in lettuce grown in sand than in loam (p = 0.009), and was significantly higher in lettuce exposed to severe drought than in unstressed lettuce (p = 0.049). This work demonstrated how environmental factors affected the risk of contaminant uptake by food crops following wastewater irrigation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Soil methane oxidation in both dry and wet temperate eucalypt forests shows a near-identical relationship with soil air-filled porosity

NASA Astrophysics Data System (ADS)

Fest, Benedikt J.; Hinko-Najera, Nina; Wardlaw, Tim; Griffith, David W. T.; Livesley, Stephen J.; Arndt, Stefan K.

2017-01-01

Well-drained, aerated soils are important sinks for atmospheric methane (CH4) via the process of CH4 oxidation by methane-oxidising bacteria (MOB). This terrestrial CH4 sink may contribute towards climate change mitigation, but the impact of changing soil moisture and temperature regimes on CH4 uptake is not well understood in all ecosystems. Soils in temperate forest ecosystems are the greatest terrestrial CH4 sink globally. Under predicted climate change scenarios, temperate eucalypt forests in south-eastern Australia are predicted to experience rapid and extreme changes in rainfall patterns, temperatures and wild fires. To investigate the influence of environmental drivers on seasonal and inter-annual variation of soil-atmosphere CH4 exchange, we measured soil-atmosphere CH4 exchange at high-temporal resolution (< 2 h) in a dry temperate eucalypt forest in Victoria (Wombat State Forest, precipitation 870 mm yr-1) and in a wet temperature eucalypt forest in Tasmania (Warra Long-Term Ecological Research site, 1700 mm yr-1). Both forest soil systems were continuous CH4 sinks of -1.79 kg CH4 ha-1 yr-1 in Victoria and -3.83 kg CH4 ha-1 yr-1 in Tasmania. Soil CH4 uptake showed substantial temporal variation and was strongly controlled by soil moisture at both forest sites. Soil CH4 uptake increased when soil moisture decreased and this relationship explained up to 90 % of the temporal variability. Furthermore, the relationship between soil moisture and soil CH4 flux was near-identical at both forest sites when soil moisture was expressed as soil air-filled porosity (AFP). Soil temperature only had a minor influence on soil CH4 uptake. Soil nitrogen concentrations were generally low and fluctuations in nitrogen availability did not influence soil CH4 uptake at either forest site. Our data suggest that soil MOB activity in the two forests was similar and that differences in soil CH4 exchange between the two forests were related to differences in soil moisture and

Testosterone enhances C-14 2-deoxyglucose uptake by striated muscle. [sex hormones and muscle

NASA Technical Reports Server (NTRS)

Toop, J.; Max, S. R.

1982-01-01

The effect of testosterone propionate (TP) on C-14 2-deoxyglucose (C-14 2DG) uptake was studied in the rat levator ani muscle in vivo using the autoradiographic technique. Following a delay of 1 to 3 h after injecting TP, the rate of C-14 2DG uptake in experimental animals began to increase and continued to increase for at least 20 h. The label, which corresponds to C-14 2-deoxyglucose 6-phosphate, as demonstrated by chromatographic analysis of muscle extracts, was uniformly distributed over the entire muscle and was predominantly in muscle fibers, although nonmuscular elements were also labeled. The 1 to 3 h time lag suggests that the TP effect may be genomic, acting via androgen receptors, rather than directly on muscle membranes. Acceleration of glucose uptake may be an important early event in the anabolic response of the rat levator ani muscle to androgens.

Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO2 emission.

PubMed

Shaaban, Muhammad; Wu, Lei; Peng, Qi-An; van Zwieten, Lukas; Chhajro, Muhammad Afzal; Wu, Yupeng; Lin, Shan; Ahmed, Muhammad Mahmood; Khalid, Muhammad Salman; Abid, Muhammad; Hu, Ronggui

2017-04-01

Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO 2 emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO 2 emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g -1 soil, herein referred to as CK, L, and H, respectively. The soil pH (H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO 2 emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO 2 emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg -1 in the RR soil and 244 and 481 mg kg -1 in the RF soil by H treatments. The NH 4 - -N and NO 3 - -N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO 2 release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.