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Результаты 171-180 из 2,459
Impacts of simulated drought on pore water chemistry of peatlands
2014
Juckers, Myra | Watmough, Shaun A.
Northern peatlands are increasingly threatened by climate change and industrial activities. This study examined the impact of simulated droughts on pore water chemistry at six peatlands in Sudbury, Ontario, that differ in copper (Cu), nickel (Ni) and cobalt (Co) contamination, including a site that had been previously limed. All sites responded similarly to simulated drought: pore water pH declined significantly following the 30 day drought and the decline was greater following the 60 day drought treatment. The decline in pore water pH was due to increasing sulphate concentrations, whereas nitrate increased more in the 60 day drought treatment. Decreases in pH were accompanied by large increases in Ni and Co that greatly exceeded provincial water quality guidelines. In contrast, dissolved organic carbon (DOC) concentrations decreased significantly following drought, along with concentrations of Cu and Al, which are strongly complexed by organic acids.
Показать больше [+] Меньше [-]Are persistent organic pollutants and metals in eel muscle predictive for the ecological water quality?
2014
Van Ael, Evy | Belpaire, Claude | Breine, Jan | Geeraerts, Caroline | Van Thuyne, Gerlinde | Eulaers, Igor | Blust, Ronny | Bervoets, Lieven
Relationships between the presence of PCBs, OCPs and metals in aquatic ecosystems and the ecological water quality were investigated by combining datasets of long-term monitoring of chemicals in European eel (Anguilla anguilla, N = 1156) in Flanders (Belgium) and the Ecological Quality Ratio (EQR), based on the assessment of fish assemblages at 185 locations. For most pollutants, EQR scores were lower when pollutant levels were higher. Threshold concentrations for a good quality could be formulated for PCB's, most metals and OCPs. Mixed models suggested that the ecological water quality was significantly correlated with the presence of PCBs. However, the low R2 indicates that other environmental pressures may significantly influence the biotic integrity of fish communities. Empirical data and their analyses are essential to enable defining threshold values of bioaccumulated levels to allow better protection of the aquatic environment and its biota through associated food webs as demanded by the Water Framework Directive.
Показать больше [+] Меньше [-]Effects of storage temperature and duration on release of antimony and bisphenol A from polyethylene terephthalate drinking water bottles of China
2014
Fan, Ying-Ying | Zheng, Jian-Lun | Ren, Jing-Hua | Luo, Jun | Cui, Xin-Yi | Ma, Lena Q.
We investigated effects of storage temperature and duration on release of antimony (Sb) and bisphenol A (BPA) from 16 brands of polyethylene terephthalate (PET) drinking water bottles in China. After 1-week storage, Sb release increased from 1.88–8.32 ng/L at 4 °C, to 2.10–18.4 ng/L at 25 °C and to 20.3–2604 ng/L at 70 °C. The corresponding releases for BPA were less at 0.26–18.7, 0.62–22.6, and 2.89–38.9 ng/L. Both Sb and BPA release increased with storage duration up to 4-week, but their releasing rates decreased with storage time, indicating that Sb and BPA release from PET bottles may become stable under long term storage. Human health risk was evaluated based on the worst case, i.e., storage at 70 °C for 4-week. Chronic daily intake (CDI) caused by BPA release was below USEPA regulation, Sb release in one brand exceeded USEPA regulated CDI (400 ng/kg bw/d) with values of 409 and 1430 ng/kg bw/d for adult and children.
Показать больше [+] Меньше [-]Trends in atmospheric deposition fluxes of sulphur and nitrogen in Czech forests
2014
Hůnová, Iva | Maznová, Jana | Kurfürst, Pavel
We present the temporal trends and spatial changes of deposition of sulphur and nitrogen in Czech forests based on records from long-term monitoring. A statistically significant trend for sulphur was detected at most of the sites measuring for wet, dry, and total deposition fluxes and at many of these the trend was also present for the period after 2000. The spatial pattern of the changes in sulphur deposition flux between 1995 and 2011 shows the decrease over the entire forested area in a wide range of 18.1–0.2 g m−2 year−1 with the most pronounced improvement in formerly most impacted regions. Nitrogen still represents a considerable stress in many areas. The value of nitrogen deposition flux of 1 g m−2 year−1 is exceeded over a significant portion of the country. On an equivalent basis, the ion ratios of NO3−/SO42− and NH4+/SO42− in precipitation show significantly increasing trends in time similarly to those of pH.
Показать больше [+] Меньше [-]Components from wheat roots modify the bioactivity of ZnO and CuO nanoparticles in a soil bacterium
2014
Martineau, Nicole | McLean, Joan E. | Dimkpa, Christian O. | Britt, David W. | Anderson, Anne J.
ZnO and CuO nanoparticles (NPs) have widespread commercial uses and their impact on agricultural systems is unresolved. This study examined whether the metabolites washed from wheat (Triticum aestivum L.) roots modulated the metabolic response to the NPs of a biosensor generated in the root colonizer, Pseudomonas putida KT2440. The root wash components boosted light output of the biosensor consistent with their catabolism. Dose-dependent and rapid inhibition of cell metabolism occurred with both ZnO and CuO NPs in water suspensions but high light output was maintained in root wash. Root wash also protected biosensor output in challenges with Zn ions. However the root wash components did not protect culturability or biosensor light output upon exposure to Cu ions. Imaging by atomic force microscopy suggested that root wash materials coated the NPs. We deduced that the response of a microbe to these metal oxide NPs could be negated by components released from roots.
Показать больше [+] Меньше [-]Relationship between site-specific nitrogen concentrations in mosses and measured wet bulk atmospheric nitrogen deposition across Europe
2014
Harmens, Harry | Schnyder, Elvira | Thöni, Lotti | Cooper, David M. | Mills, Gina | Leblond, Sébastien | Mohr, Karsten | Poikolainen, Jarmo | Santamaria, Jesus | Skudnik, Mitja | Zechmeister, Harald G. | Lindroos, Antti-Jussi | Hanus-Illnar, Andrea
To assess the relationship between nitrogen concentrations in mosses and wet bulk nitrogen deposition or concentrations in precipitation, moss tissue and deposition were sampled within a distance of 1 km of each other in seven European countries. Relationships for various forms of nitrogen appeared to be asymptotic, with data for different countries being positioned at different locations along the asymptotic relationship and saturation occurring at a wet bulk nitrogen deposition of ca. 20 kg N ha−1 yr−1. The asymptotic behaviour was more pronounced for ammonium-N than nitrate-N, with high ammonium deposition at German sites being most influential in providing evidence of the asymptotic behaviour. Within countries, relationships were only significant for Finland and Switzerland and were more or less linear. The results confirm previous relationships described for modelled total deposition. Nitrogen concentration in mosses can be applied to identify areas at risk of high nitrogen deposition at European scale.
Показать больше [+] Меньше [-]Combining measurements and modelling to quantify the contribution of atmospheric fallout, local industry and road traffic to PAH stocks in contrasting catchments
2014
Gateuille, David | Evrard, Olivier | Lefevre, Irène | Moreau-Guigon, Elodie | Alliot, Fabrice | Chevreuil, Marc | Mouchel, J.-M. (Jean-Marie)
Various sources supply PAHs that accumulate in soils. The methodology we developed provided an evaluation of the contribution of local sources (road traffic, local industries) versus remote sources (long range atmospheric transport, fallout and gaseous exchanges) to PAH stocks in two contrasting subcatchments (46–614 km²) of the Seine River basin (France). Soil samples (n = 336) were analysed to investigate the spatial pattern of soil contamination across the catchments and an original combination with radionuclide measurements provided new insights into the evolution of the contamination with depth. Relationships between PAH concentrations and the distance to the potential sources were modelled. Despite both subcatchments are mainly rural, roadside areas appeared to concentrate 20% of the contamination inside the catchment while a local industry was found to be responsible for up to 30% of the stocks. Those results have important implications for understanding and controlling PAH contamination in rural areas of early-industrialized regions.
Показать больше [+] Меньше [-]Incidence of anticancer drugs in an aquatic urban system: From hospital effluents through urban wastewater to natural environment
2014
Ferrando-Climent, L. | Rodriguez-Mozaz, S. | Barceló, D.
The presence of 10 anticancer drugs was studied along the entire urban water cycle -from hospital effluents through urban wastewater treatment plant till surface waters- and their potential environmental risk was assessed. Azathioprine, etoposide, docetaxel, paclitaxel, methotrexate, cyclophosphamide, tamoxifen and ciprofloxacin were detected in hospital effluent and in the urban influent of the sewage treatment plant although most of them were totally eliminated after WWTP. Only cyclophosphamide, tamoxifen and ciprofloxacin were found in both WWTP effluent and in the receiving river at a concentration range between nd-20 ng L−1, 25–38 ng L−1 and 7–103 ng L−1 respectively. Tamoxifen and ciprofloxacin, commonly used for veterinary practices, were also detected in the river upstream the sewage discharge. In addition, they both were considered to pose a potential risk to the environment based on the levels found in the WWTP effluent together with their ecotoxicological impact in selected organisms.
Показать больше [+] Меньше [-]Effects of arsenate, chromate, and sulfate on arsenic and chromium uptake and translocation by arsenic hyperaccumulator Pteris vittata L
2014
de Oliveira, Letúzia Maria | Ma, Lena Q. | Santos, Jorge A.G. | Guilherme, Luiz R.G. | Lessl, Jason T.
We investigated effects of arsenate (AsV), chromate (CrVI) and sulfate on As and Cr uptake and translocation by arsenic hyperaccumulator Pteris vittata (PV), which was exposed to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25 mM for 2-wk in hydroponic system. PV was effective in accumulating large amounts of As (4598 and 1160 mg/kg in the fronds and roots at 0.05 mM AsV) and Cr (234 and 12,630 mg/kg in the fronds and roots at 0.05 mM CrVI). However, when co-present, AsV and CrVI acted as inhibitors, negatively impacting their accumulation in PV. Arsenic accumulation in the fronds was reduced by 92% and Cr by 26%, indicating reduced As and Cr translocation. However, addition of sulfate increased uptake and translocation of As by 26–28% and Cr by 1.63 fold. This experiment demonstrated that As and Cr inhibited each other in uptake and translocation by PV but sulfate enhanced As and Cr uptake and translocation by PV.
Показать больше [+] Меньше [-]Species composition of a soil invertebrate multi-species test system determines the level of ecotoxicity
2014
Sechi, Valentina | D'Annibale, Alessandra | Maraldo, Kristine | Johansen, Anders | Bossi, Rossana | Jensen, John | Krogh, Paul Henning
A soil multi-species, SMS, experimental test system consisting of the natural microbial community, five collembolan species and a predatory mite along with either Enchytraeus crypticus or the earthworm Eisenia fetida were exposed to α-cypermethrin. A comparison of the performance of these two types of SMSs is given to aid the development of a standard test system. E. fetida had a positive effect on the majority of the species, reducing the negative insecticide effect. E. fetida affected the species sensitivity and decreased the degradation of the insecticide due to the organic matter incorporation of earthworm food. After 8 weeks, the EC50 was 0.76 mg kg−1 for enchytraeids and ranged between 2.7 and 18.9 mg kg−1 for collembolans, more sensitive than previously observed with single species. Changes observed in the community structure and function illustrates the strength of a multi-species test system as an ecotoxicological tool compared to single species tests.
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