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The influence of organic matter on sorption and fate of glyphosate in soil - Comparing different soils and humic substances Texto completo
2009
Albers, Christian N. | Banta, Gary T. | Hansen, Poul Erik | Jacobsen, Ole S.
Soil organic matter (SOM) is generally believed not to influence the sorption of glyphosate in soil. To get a closer look on the dynamics between glyphosate and SOM, we used three approaches: I. Sorption studies with seven purified soil humic fractions showed that these could sorb glyphosate and that the aromatic content, possibly phenolic groups, seems to aid the sorption. II. Sorption studies with six whole soils and with SOM removed showed that several soil parameters including SOM are responsible for the strong sorption of glyphosate in soils. III. After an 80 day fate experiment, ~40% of the added glyphosate was associated with the humic and fulvic acid fractions in the sandy soils, while this was the case for only ~10% of the added glyphosate in the clayey soils. Glyphosate sorbed to humic substances in the natural soils seemed to be easier desorbed than glyphosate sorbed to amorphous Fe/Al-oxides.
Mostrar más [+] Menos [-]Dissipation of oxytetracycline in soils under different redox conditions Texto completo
2009
Yang, Ji-Feng | Ying, Guang-Guo | Zhou, Li-Jun | Liu, Shan | Zhao, Jian-Liang
This study investigated the dissipation kinetics of oxytetracycline in soils under aerobic and anoxic conditions. Laboratory experiments showed that the dissipation of oxytetracycline in soil followed firstorder reaction kinetics and its dissipation rates decreased with increasing concentration. Oxytetracycline dissipated faster in soil under aerobic conditions than under anoxic conditions. The half-lives for oxytetracycline in soil under aerobic conditions ranged between 29 and 56 days for non-sterile treatments and 99-120 days for sterile treatments, while under anoxic conditions the half-lives of oxytetracycline ranged between 43 and 62 days in the non-sterile soil and between 69 and 104 days in the sterile soil. This suggests microbes can degrade oxytetracycline in agricultural soil. Abiotic factors such as strong sorption onto soil components also played a role in the dissipation of oxytetracycline in soil.
Mostrar más [+] Menos [-]Influence of earthworm mucus and amino acids on tomato seedling growth and cadmium accumulation Texto completo
2009
Zhang, Shujie | Hu, Feng | Li, Huixin | Li, Xiuqiang
The effects on the growth of tomato seedlings and cadmium accumulation of earthworm mucus and a solution of amino acids matching those in earthworm mucus was studied through a hydroponic experiment. The experiment included four treatments: 5 mg Cd L⁻¹ (CC), 5 mg Cd L⁻¹ þ 100 mL L⁻¹ earthworm mucus (CE), 5 mg Cd L⁻¹ þ 100 mL L⁻¹ amino acids solution (CA) and the control (CK). Results showed that, compared with CC treatment, either earthworm mucus or amino acids significantly increased tomato seedling growth and Cd accumulation but the increase was much higher in the CE treatment compared with the CA treatment. This may be due to earthworm mucus and amino acids significantly increasing the chlorophyll content, antioxidative enzyme activities, and essential microelement uptake and transport in the tomato seedlings. The much greater increase in the effect of earthworm mucus compared with amino acid treatments may be due to IAA-like substances in earthworm mucus.
Mostrar más [+] Menos [-]BVOC emissions, photosynthetic characteristics and changes in chloroplast ultrastructure of Platanus orientalis L. exposed to elevated CO2 and high temperature Texto completo
2009
Velikova, Violeta | Tsonev, Tsonko | Barta, Csengele | Centritto, Mauro | Koleva, Dimitrina | Stefanova, Miroslava | Busheva, Mira | Loreto, Francesco
To investigate the interactive effects of increasing [CO₂] and heat wave occurrence on isoprene (IE) and methanol (ME) emissions, Platanus orientalis was grown for one month in ambient (380 mmol mol 1) or elevated (800 mmol mol 1) [CO₂] and exposed to high temperature (HT) (38 C/4 h). In pre-existing leaves, IE emissions were always higher but ME emissions lower as compared to newly-emerged leaves. They were both stimulated by HT. Elevated [CO₂] significantly reduced IE in both leaf types, whereas it increased ME in newly-emerged leaves only. In newly-emerged leaves, elevated [CO₂] decreased photosynthesis and altered the chloroplast ultrastructure and membrane integrity. These harmful effects were amplified by HT. HT did not cause any unfavorable effects in pre-existing leaves, which were characterized by inherently higher IE rates. We conclude that: (1) these results further prove the isoprene's putative thermo-protective role of membranes; (2) HT may likely outweigh the inhibitory effects of elevated [CO₂] on IE in the future.
Mostrar más [+] Menos [-]Risk assessment of potentially toxic element pollution in soils and rice (Oryza sativa) in a typical area of the Yangtze River Delta Texto completo
2009
Hang, Xiaoshuai | Wang, Huoyan | Zhou, Jianmin | Ma, Chengling | Du, Changwen | Chen, Xiaoqin
Soil pollution with potentially toxic elements (PTEs) resulting from rapid industrial development has caused major concerns. Selected PTEs and their accumulation and distribution in soils and rice (Oryza sativa) collected from Changshu, east China, were analyzed to evaluate the potential health risk to the local population. The soils were primarily contaminated with Hg, followed by Cu, Cd, Pb, and Zn. The concentrations of Pb, Hg, and Cd of 46, 32, and 1 rice samples exceeded their national maximum allowable levels in foods, respectively. Spatial distributions of total Cr, Cu, Pb, Zn, and Cd in soils shared similar geographical trends. The risk assessment of PTEs through rice consumption suggests that the concentrations of Cu, Pb, and Cd in some rice samples exceed their reference oral dose for adults and children. In general, there was no target hazard quotient value of any individual element that was greater than 1, but hazard index values for adults and children were 1.726 and 1.523, respectively. Industrial development has led to increased risk from potentially toxic elements in soils and rice.
Mostrar más [+] Menos [-]Particle-size distribution and gas/particle partitioning of atmospheric polybrominated diphenyl ethers in urban areas of Greece Texto completo
2009
Mandalakis, Manolis | Besis, Athanasios | Stephanou, Euripides G.
Ambient concentrations, gas/particle partitioning and particle-size distribution of polybrominated diphenyl ethers (PBDEs) were investigated in two urban areas (Athens and Heraklion) of Greece. Atmospheric (gas + particle) concentrations of Sigma PBDE varied from 21 to 30 pg m-3 in the center of Athens and from 4 to 44 pg m-3 in the suburbs of Heraklion. A predominance of particulate PBDEs was observed in Athens (71-76% in particles), whereas the opposite was evident in Heraklion (69-92% in gas phase). In both urban areas, PBDE particle-size distribution featured a distinct enrichment in smaller particles. A similar trend was also observed in aerosols of a background marine site. For all sampling sites, more than 46% of Sigma PBDE was associated with particles of <0.57 μm in diameter. Our results imply that particulate PBDEs may have long atmospheric residence time and they may be capable of reaching the deeper parts of the human respiratory system. Analysis of size-segregated aerosol samples indicates a predominance of polybrominated diphenyl ethers in the small particle-size fraction.
Mostrar más [+] Menos [-]Polycyclic aromatic hydrocarbon (PAH) contamination of surface sediments and oysters from the inter-tidal areas of Dar es Salaam, Tanzania Texto completo
2009
Gaspare, Lydia | Machiwa, John F. | Mdachi, S.J.M. | Streck, Georg | Brack, Werner
Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low. PAH contamination may pose hazards to benthos but limited risks to humans
Mostrar más [+] Menos [-]Glutathione transferase (GST) as a candidate molecular-based biomarker for soil toxin exposure in the earthworm Lumbricus rubellus Texto completo
2009
LaCourse, E James | Hernandez-Viadel, Mariluz | Jefferies, James R. | Svendsen, Claus | Spurgeon, David J. | Barrett, John | Morgan, A John | Kille, Peter | Brophy, Peter M.
The earthworm Lumbricus rubellus (Hoffmeister, 1843) is a terrestrial pollution sentinel. Enzyme activity and transcription of phase II detoxification superfamily glutathione transferases (GST) is known to respond in earthworms after soil toxin exposure, suggesting GST as a candidate molecular-based pollution biomarker. This study combined sub-proteomics, bioinformatics and biochemical assay to characterise the L. rubellus GST complement as pre-requisite to initialise assessment of the applicability of GST as a biomarker. L. rubellus possesses a range of GSTs related to known classes, with evidence of tissue-specific synthesis. Two affinity-purified GSTs dominating GST protein synthesis (Sigma and Pi class) were cloned, expressed and characterised for enzyme activity with various substrates. Electrospray ionisation mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) following SDS-PAGE were superior in retaining subunit stability relative to two-dimensional gel electrophoresis (2-DE). This study provides greater understanding of Phase II detoxification GST superfamily status of an important environmental pollution sentinel organism. This study currently provides the most comprehensive view of the Phase II detoxification enzyme superfamily of glutathione transferases within the important environmental pollution sentinel earthworm Lumbricus rubellus.
Mostrar más [+] Menos [-]Fate of linear alkylbenzenes and benzothiazoles of anthropogenic origin and their potential as environmental molecular markers in the Pearl River Delta, South China Texto completo
2009
Ni, Hong-Gang | Shen, Ru-Lang | Zeng, Hui | Zeng, E. Y. (Eddy Y)
The mass emissions of linear alkylbenzenes (LABs), benzothiazole (BT), and 2-[4-morpholinyl]benzothiazole (24MoBT) from anthropogenic activities within one year were estimated according to the population and the number of automobiles in the Pearl River Delta (PRD), South China. Based on the estimation, the distribution of these compounds among various environmental media was simulated with a mass balance box model established in the present study. The results showed that 79% of LABs generated in the PRD was stored in sediment while only 1.3% of LABs was presumably transported to the adjacent South China Sea (SCS). On the contrary, 47% of BT and 77% of 24MoBT generated in the region were carried with riverine runoff to the coastal ocean. The results from the present study suggest that hydrophobic compounds tend to stay in the watershed of the PRD, whereas hydrophilic ones mainly outflow to the coastal ocean. A simple mass balance box model examines the fate of linear alkylbenzenes and benzothiazoles in the Pearl River Delta, South China.
Mostrar más [+] Menos [-]Long-term air monitoring of organochlorine pesticides using Semi Permeable Membrane Devices (SPMDs) in the Alps Texto completo
2009
Levy, W. | Henkelmann, B. | Pfister, G. | Bernhöft, S. | Kirchner, M. | Jakobi, G. | Bassan, R. | Kräuchi, N. | Schramm, K.W.
Atmospheric sampling of organochlorine pesticides (OCPs) was conducted using Semi Permeable Membrane Devices (SPMDs) deployed in the Alps at different altitudinal transects for two consecutive exposure periods of half a year and a third simultaneous year-long period. Along all the altitude profiles, the sequestered amounts of OCPs increased in general with altitude. SPMDs were still working as kinetic samplers after half a year for the majority of the OCPs. However, compounds with the lowest octanol-air partition coefficient (Koa), reached equilibrium within six months. This change in the SPMD uptake was determined for the temperature gradient along the altitude profile influencing Koa, OCPs availability in the gaseous phase, and SPMD performance. In sum, it seems two effects are working in parallel along the altitude profiles: the change in SPMD performance and the different availability of OCPs along the altitudinal transects determined by their compound properties and concentrations in air. SPMDs were in different uptake stages regarding OCPs, as they were influenced by the temperature (season, triolein state, and altitude) and Koa.
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