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931.
Soil acidification has been of concern in the oil sands region in Alberta due to increased acid deposition. Using the canopy budget model, and accounting for H+ canopy leaching by organic acids, we determined sources and sinks of H+ in throughfall in jack pine (Pinus banksiana) and trembling aspen (Populus tremuloides) stands in two watersheds from 2006 to 2009. In pine stands, H+ deposition was greater in throughfall than in bulk precipitation while the opposite was true in aspen stands. The annual H+ interception deposition was 148.8-193.8 and 49.7-70.0 molc ha−1 in pine and aspen stands, respectively; while the annual H+ canopy leaching was 127.1-128.7 and 0.0-6.0 molc ha−1, respectively. The greater H+ supply in pine stands was caused by greater interception deposition of SO42− and organic acids released from the pine canopy. Such findings have significant implications for establishing critical loads for various ecosystems in the oil sands region. 相似文献
932.
中国癌症与土壤环境中铊元素的关系 总被引:4,自引:0,他引:4
利用土壤环境中铊元素资料769个数据,癌死亡调查资料787080例,研究了胃癌,食管癌,肝癌,宫颈癌,肺癌、大肠癌、白血病、鼻咽癌、乳腺癌死亡率与人群生存区土壤环境中铊元素的关系。 相似文献
933.
Terrestrial carbon storage is influenced by a number of environmental factors, among which topographic and geomorphological
features are of special significance. This study was designed to examine the relationships of soil organic carbon (SOC) density
to various terrain parameters and watershed characteristics across Louisiana, USA. A polygon data set of 484 watersheds and
12 river drainage basins for Louisiana was used to form the landscape units. SOC densities were calculated for each soil map
unit using the State Soil Geographic (STATSGO) database. Average drainage densities and average slopes at watershed and basin
scales were quantified with the 1:24 K Digital Elevation Models (DEM) data, and the Louisiana hydrographic water features.
Correlation and regression analyses were performed to determine relationships among drainage density, slope, elevation, and
SOC. The study found an average watershed drainage density of 1.6 km/km2 and an average watershed slope of 2.9 degrees in Louisiana. The results revealed that SOC density at both watershed and basin
scales was closely related to drainage density, slope, and elevation. SOC density was positively correlated with watershed
drainage density, but negatively correlated with watershed slope gradient and elevation. Regression models were developed
for predicting SOC density at watershed and basin scales, obtaining regression coefficients (r
2) ranging from 0.43 to 0.83. The study showed that estimation of SOC at watershed and drainage basin scales combining DEM
data can be a feasible approach to improve the understanding of the relationships among SOC, topographic, and geomorphological
features. 相似文献
934.
935.
A high-throughput screening method using selective pressurized liquid extraction (SPLE) and enzyme-linked immunosorbent assay (ELISA) for monitoring dioxins in sediment and soil is described. SPLE conditions were developed by extracting sediment or soil together with alumina, 10% AgNO3 in silica, and sulfuric acid impregnated silica (acid silica) using dichloromethane (DCM) as the solvent at 100 °C and 2000 psi. Post-extraction cleanups were not required for ELISA. Two reference sediments (National Institute of Standards and Technology SRM 1944 and Wellington Laboratories WMS01) were analyzed by the SPLE–ELISA method. The ELISA utilized a polyclonal antibody and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as the calibrant. Recoveries of ELISA-derived TCDD equivalents (EQ) relative to the expected gas chromatography/high resolution mass spectrometry (GC/HRMS) derived dioxin toxic equivalent (TEQ) values were 116 ± 11% for SRM 1944 and 102 ± 13% for WMS01. ELISA TCDD EQs were consistent with the dioxin TEQs as measured by GC/HRMS for 25 soil/sediment samples from seven different contaminated sites. The ELISA had an approximate method detection limit of 10 pg g−1 with a precision of 2.6–29% based on the relative percentage difference (%RPD) for duplicate samples. Estimated sample throughput for the SPLE–ELISA was three times or more than that of the GC/HRMS method employing PLE with a multi-column cleanup. 相似文献
936.
Stability of titania nanoparticles in soil suspensions and transport in saturated homogeneous soil columns 总被引:2,自引:0,他引:2
Jing Fang Bei Wen Jin-ming Lin 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1101-1109
The stability of TiO2 nanoparticles in soil suspensions and their transport behavior through saturated homogeneous soil columns were studied. The results showed that TiO2 could remain suspended in soil suspensions even after settling for 10 days. The suspended TiO2 contents in soil suspensions after 24 h were positively correlated with the dissolved organic carbon and clay content of the soils, but were negatively correlated with ionic strength, pH and zeta potential. In soils containing soil particles of relatively large diameters and lower solution ionic strengths, a significant portion of the TiO2 (18.8-83.0%) readily passed through the soils columns, while TiO2 was significantly retained by soils with higher clay contents and salinity. TiO2 aggregate sizes in the column outflow significantly increased after passing through the soil columns. The estimated transport distances of TiO2 in some soils ranged from 41.3 to 370 cm, indicating potential environmental risk of TiO2 nanoparticles to deep soil layers. 相似文献
937.
Guoxiong Hua Brett Lyons Ian Singleton 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):916-921
In this study, three different soils with contrasting features, spiked with 300 mg benzo[a]pyrene (BaP)/kg dry soil, were incubated at 20 °C and 60% water holding capacity for 540 days. At different time points, BaP and DNA were extracted and quantified, and DNA adducts were quantified by 32P-postlabelling. After 540 days incubation, 69.3, 81.6 and 83.2% of initial BaP added remained in Cruden Bay, Boyndie and Insch soils, respectively. Meanwhile, a significantly different amount of DNA-BaP adducts were found in the three soils exposed to BaP over time. The work demonstrates the concept that DNA adducts can be detected on DNA extracted from soil. Results suggest the technique is not able to directly reflect bioavailability of BaP transformation products. However, this new method provides a potential way to detect mutagenic compounds in contaminated soil and to assess the outcomes of soil remediation. 相似文献
938.
Hansen M Krogh KA Brandt A Christensen JH Halling-Sørensen B 《Environmental pollution (Barking, Essex : 1987)》2009,157(2):474-480
The antibacterial potency of eight anticoccidial drugs was tested in a soil bacteria bioassay (pour plate method), EC50-values between 2.4 and 19.6 μM were obtained; however, one compound, nicarbazin exhibited an EC50-value above the maximum tested concentration (21 μM, 9.1 mg L−1). The potency of mixtures of two of the compounds, narasin and nicarbazin, was synergistic (more than additive) with 10-fold greater antibacterial potency of the mixture than can be explained by their individual EC50-values. The influence of pH, temperature, oxygen concentration and light on the transformation of robenidine and salinomycin was investigated. Robenidine was transformed by photolysis (DT50 of 4.1 days) and was unstable at low pH (DT50 of approximately 4 days); salinomycin was merely transformed at low pH, the latter into an unknown number of products. The antibacterial potency of the mixtures of transformation products of robenidine after photolysis and at low pH was comparable with that of the parent compound. Finally five photo-transformation products of robenidine were structural elucidated by accurate mass measurements, i-FIT values (isotopic pattern fit) and MS/MS fragmentation patterns. 相似文献
939.
Potential for microbially mediated redox transformations and mobilization of arsenic in uncontaminated soils 总被引:1,自引:0,他引:1
Shigeki Yamamura Mirai Watanabe Norio Yamamoto Kazunari Sei Michihiko Ike 《Chemosphere》2009,77(2):169-174
Surface soil samples, which had no significant As contamination, were examined for As(V) reduction, As(III) oxidation and As mobilization capability. All five soil samples tested exhibited microbial As(V)-reducing activities both in aerobic and anaerobic conditions. Under aerobic conditions when As(V) reduction had almost ceased, oxidation of As(III) to As(V) occurred, whereas only As(V) reduction was observed under anaerobic conditions. In cultures incubated with As(III), As(III) was oxidized by indigenous soil microbes only under aerobic conditions. These results indicate that microbial redox transformations of As are ubiquitous in the natural environment regardless of background As levels. Mobilization through microbially mediated As(V) and Fe(III) reduction occurred both in the presence and absence of oxygen. Significant variation in dissolved As occurred depending on the Fe contents of soils, and re-immobilization of As arose in the presence of oxygen, presumably as a consequence of dissolved As(III) and Fe(II) oxidation. There was no apparent correlation between dissolved Fe(II) and As, suggesting that reductive dissolution of Fe(III) minerals does not necessarily determine the extent of As release from soils. 相似文献
940.
A two-stage process using electrokinetic remediation and electrochemical degradation for treating benzo[a]pyrene spiked kaolin 总被引:1,自引:0,他引:1
An innovative process that combines soil electrokinetic remediation and liquid electrochemical oxidation for the degradation of organic compounds present in a polluted soil was developed and evaluated by using benzo[a]pyrene spiked kaolin. In order to increase benzo[a]pyrene solubility during electrokinetic treatment, the addition of a co-solvent or surfactant, such as ethanol or Brij 35, as flushing solution was tested. The research carried out demonstrated the influence of the desorption agent employed on benzo[a]pyrene remediation from the kaolin matrix. Thus, if the flushing solution was ethanol at 40%, there was no presence of contaminant in either chamber. On the contrary, when a solution of surfactant Brij 35 was used, benzo[a]pyrene was transported towards the cathode chamber, where it was collected. Moreover, the extent of this recovery depends on the pH profile on the soil. When no pH control was used, around 17% of initial contaminant was detected in the cathode chamber; however, when pH control was applied, the recovery of benzo[a]pyrene could be higher than 76%, when the pH control in the anode chamber was set at 7.0.In order to obtain the total degradation of mobilised benzo[a]pyrene from the contaminated soil, the liquid collected by electrokinetic remediation was oxidised by electrochemical treatment. This oxidation was accomplished via an electrochemical cell with a working volume of 0.4 L, and graphite as electrode material. The benzo[a]pyrene was almost totally degraded in 1 d, reaching a degradation of about 73% in 16 h. 相似文献