细化搜索
结果 261-270 的 753
Eco-restoration: Simultaneous nutrient removal from soil and water in a complex residential–cropland area 全文
2010
Wu, Yonghong | Kerr, Philip G. | Hu, Zhengyi | Yang, Linzhang
An eco-restoration system to remove excess nutrients and restore the agricultural ecosystem balance was proposed and applied from August 2006 to August 2008 in a residential-cropland complex area (1.4 × 105 m2) in Kunming, western China, where the self-purifying capacity of the agricultural ecosystem had been lost. The proposed eco-restoration system examined includes three main foci: farming management, bioremediation, and wastewater treatment. The results showed that the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) from the complex wastewater were 83% and 88%, respectively. The Simpson’s diversity indices of macrophytes and zoobenthos indicated that the system had increased macrophyte and zoobenthic diversity as well as improved growth conditions of the plankton habitats. The results demonstrated that the proposed eco-restoration system is a promising approach for decreasing the output of nutrients from soil, improving agricultural ecosystem health, and minimizing the downstream eutrophication risk for surface waters.
显示更多 [+] 显示较少 [-]Micropollutant removal during biological wastewater treatment and a subsequent ozonation step 全文
2010
Schaar, Heidemarie | Clara, Manfred | Gans, Oliver | Kreuzinger, Norbert
The design criteria for wastewater treatment plants (WWTP) and the sludge retention time, respectively, have a significant impact on micropollutant removal. The upgrade of an Austrian municipal WWTP to nitrogen removal (best available technology, BAT) resulted in increased elimination of most of the analyzed micropollutants. Substances, such as bisphenol-A, 17α-ethinylestradiol and the antibiotics erythromycin and roxithromycin were only removed after the upgrade of the WWTP. Nevertheless, the BAT was not sufficient to completely eliminate these compounds. Thus, a pilot scale ozonation plant was installed for additional treatment of the effluent. The application of 0.6 g O3 g DOC−1 increased the removal of most of the micropollutants, especially for compounds that were not degraded in the previous biological process, as for example carbamazepine and diclofenac. These results indicated that the ozonation of WWTP effluent is a promising technology to further decrease emissions of micropollutants from the treatment process.
显示更多 [+] 显示较少 [-]Factors affecting the concentration in seven-spotted ladybirds (Coccinella septempunctata L.) of Cd and Zn transferred through the food chain 全文
2010
Green, I.D. | Díaz, Ángela | Tibbett, M.
Factors affecting the concentration in seven-spotted ladybirds (Coccinella septempunctata L.) of Cd and Zn transferred through the food chain 全文
2010
Green, I.D. | Díaz, Ángela | Tibbett, M.
The transfer of Cd and Zn from soils amended with sewage sludge was followed through a food chain consisting of wheat, aphids and the predator Coccinella septempunctata. Multiple regression models were generated to predict the concentrations of Cd and Zn in C. septempunctata. No significant model could be generated for Cd, indicting that the concentration of this metal was maintained within relatively narrow limits. A model predicting 64% of the variability in the Zn concentration of C. septempunctata was generated from of the concentration of Zn in the diet, time and rate of Zn consumption. The results suggest that decreasing the rate of food consumption is an effective mechanism to prevent the accumulation of Zn and that the availability of Zn in the aphid prey increased with the concentration in the aphids. The results emphasise the importance of using ecologically relevant food chains and exposure pathways during ecotoxicological studies. Arthropod predators can regulate trace metal body burden through physiological and behavioural mechanisms.
显示更多 [+] 显示较少 [-]Factors affecting the concentration in seven-spotted ladybirds (Coccinella septempunctata L.) of Cd and Zn transferred through the food chain 全文
2010
Green, I.D. | Diaz, A. | Tibbett, Mark
The transfer of Cd and Zn from soils amended with sewage sludge was followed through a food chain consisting of wheat, aphids and the predator Coccinella septempunctata. Multiple regression models were generated to predict the concentrations of Cd and Zn in C. septempunctata. No significant model could be generated for Cd, indicting that the concentration of this metal was maintained within relatively narrow limits. A model predicting 64% of the variability in the Zn concentration of C. septempunctata was generated from of the concentration of Zn in the diet, time and rate of Zn consumption. The results suggest that decreasing the rate of food consumption is an effective mechanism to prevent the accumulation of Zn and that the availability of Zn in the aphid prey increased with the concentration in the aphids. The results emphasise the importance of using ecologically relevant food chains and exposure pathways during ecotoxicological studies.
显示更多 [+] 显示较少 [-]Effects of soil properties on food web accumulation of heavy metals to the wood mouse (Apodemus sylvaticus) 全文
2010
Brink, Nico W. van den | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | Hout, Annemariet van der
Effects of soil properties on food web accumulation of heavy metals to the wood mouse (Apodemus sylvaticus) 全文
2010
Brink, Nico W. van den | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | Hout, Annemariet van der
Effects of soil properties on the accumulation of metals to wood mice (Apodemus sylvaticus) were evaluated at two sites with different pH and organic matter content of the soil. pH and organic matter content significantly affected accumulation of Cd, Cu, Pb and Zn in earthworms and vegetation. For Cd, Cu and Zn these effects propagated through the food web to the wood mouse. Soil-to-kidney ratios differed between sites: Cd: 0.15 versus 3.52, Cu: 0.37 versus 1.30 and Zn: 0.33–0.83. This was confirmed in model calculations for Cd and Zn. Results indicate that total soil concentrations may be unsuitable indicators for risks that metals pose to wildlife. Furthermore, environmental managers may, unintentionally, change soil properties while taking specific environmental measures. In this way they may affect risks of metals to wildlife, even without changes in total soil concentrations. Soil properties significantly affect accumulation of heavy metals to wood mice so; risks cannot be based on total concentrations.
显示更多 [+] 显示较少 [-](Table 4) Soil properties and heavy metal concentration in samples from Heteren and Plateaux, The Netherlands 全文
2010
Van Den Brink, Nico W | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | van der Hout, Annemariet
Heavy metal concentrations in soils, vegetation, earthworms and wood mice from Heteren and Plateaux, The Netherlands 全文
2010
Van Den Brink, Nico W | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | van der Hout, Annemariet
Effects of soil properties on the accumulation of metals to wood mice (Apodemus sylvaticus) were evaluated at two sites with different pH and organic matter content of the soil. pH and organic matter content significantly affected accumulation of Cd, Cu, Pb and Zn in earthworms and vegetation. For Cd, Cu and Zn these effects propagated through the food web to the wood mouse. Soil-to-kidney ratios differed between sites: Cd: 0.15 versus 3.52, Cu: 0.37 versus 1.30 and Zn: 0.33-0.83. This was confirmed in model calculations for Cd and Zn. Results indicate that total soil concentrations may be unsuitable indicators for risks that metals pose to wildlife. Furthermore, environmental managers may, unintentionally, change soil properties while taking specific environmental measures. In this way they may affect risks of metals to wildlife, even without changes in total soil concentrations.
显示更多 [+] 显示较少 [-](Tables 9-10) Ratios of heavy metal concentrations between vegetation and soil, and between wood mouse, grass and earthworms from Heteren and Plateaux, The Netherlands 全文
2010
Van Den Brink, Nico W | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | van der Hout, Annemariet
(Tables 5-8) Concentrations of heavy metals in earthworms, in vegetation and in wood mice kidneys obtained from Heteren and Plateaux, The Netherlands 全文
2010
Van Den Brink, Nico W | Lammertsma, Dennis | Dimmers, Wim | Boerwinkel, Marie-Claire | van der Hout, Annemariet
Investigating roles of organic and inorganic soil components in sorption of polar and nonpolar aromatic compounds 全文
2010
Shi, Xin | Ji, Liangliang | Zhu, Dongqiang
The main objective of the present study was to assess the roles of various soil components in sorption of organic compounds differing in polarity. Removal of the whole soil organic matter decreased sorption by approximately 86% for nonpolar 1,3,5-trichlorobenzene (TCB), but only 34–54% for highly polar 1,3,5-trinitrobenzene (TNB); however, removal of the extractable humic/fulvic acids did not much affect sorption of the two sorbates. With normalization of solute hydrophobicity, TNB exhibits several orders of magnitude stronger sorption compared with TCB to maize burn residue (black carbon), extracted humic acid and Na+-saturated montmorillonite clay, suggesting specific sorptive interactions for TNB with the individual model soil components. It was proposed that sorption of TCB to the bulk soil was dominated by hydrophobic partition to the condensed, non-extractable fraction of organic matters (humin/kerogen and black carbon), while interactions with soil clay minerals were an important additional factor for sorption of TNB. Soil humin and black carbon play a predominant role in sorption of 1,3,5-trichlorobenzene, while polar interactions with soil clay minerals are an important additional factor for sorption of 1,3,5-trinitrobenzene.
显示更多 [+] 显示较少 [-]Spatial and seasonal variations of the contamination within water body of the Grand Canal, China 全文
2010
Wang, Xiaolong | Han, Jingyi | Xu, Ligang | Zhang, Qi
To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal.
显示更多 [+] 显示较少 [-]Assessment of nematode community structure as a bioindicator in river monitoring 全文
2010
Wu, H.C. | Chen, P.C. | Tsay, T.T.
Nematode communities from river water and sediments were assessed for the abundance, feeding types, maturity indices and nematode channel ratio (NCR). The sampling sites studied included different levels of pollution and contamination from agricultural, industrial and sewage sources. The nematode abundance found in the sediment samples was more than that in the water samples. The lowest nematode abundance in sediment samples and the lowest NCR in water samples were both found at the industrial pollution site. Water samples showed positive correlation between the NCR and river pollution index (RPI). Mean maturity indices in sediment samples were inversely correlated with RPI. The pollutant source determined the relationship between NCR and pollution level, while maturity index always showed negative correlation with pollutant level regardless of the pollutant sources. The nematode abundance and its community structure were both reliable bioindicators for monitoring long-term river pollution in both qualitative and quantitative aspects.
显示更多 [+] 显示较少 [-]Isolating the impact of sediment toxicity in urban streams 全文
2010
Marshall, Stephen | Pettigrove, Vincent | Carew, Melissa | Hoffmann, Ary
Several factors can contribute to the ecological degradation of stream catchments following urbanization, but it is often difficult to separate their relative importance. We isolated the impact of polluted sediment on the condition of an urban stream in Melbourne, Australia, using two complementary approaches. Using a rapid bioassessment approach, indices of stream condition were calculated based on macroinvertebrate field surveys. Urban stream reaches supported impoverished macroinvertebrate communities, and contained potentially toxic concentrations of heavy metals and hydrocarbons. Using a field microcosm approach, a bioassay was carried out to assess sediment pollution effects on native macroinvertebrates. Sediment from urban sites substantially altered the microcosm macroinvertebrate community, most likely due to elevated heavy metal and hydrocarbon concentrations. Macroinvertebrate surveys combined with a bioassay approach based on field microcosms can help isolate the effect of stream pollutants in degraded ecosystems.
显示更多 [+] 显示较少 [-]Impact of climate fluctuations on deposition of DDT and hexachlorocyclohexane in mountain glaciers: Evidence from ice core records 全文
2010
Wang, Xiaoping | Gong, Ping | Zhang, Qianggong | Yao, Tandong
How do climate fluctuations affect DDT and hexachlorocyclohexane (HCH) distribution in the global scale? In this study, the interactions between climate variations and depositions of DDT and HCH in ice cores from Mt. Everest (the Tibetan Plateau), Mt. Muztagata (the eastern Pamirs) and the Rocky Mountains were investigated. All data regarding DDT/HCH deposition were obtained from the published results. Concentrations of DDT and HCH in an ice core from Mt. Everest were associated with the El Nino-Southern Oscillation. Concentrations of DDT in an ice core from Mt. Muztagata were significantly correlated with the Siberia High pattern. Concentrations of HCH in an ice core from Snow Dome of the Rocky Mountains responded to the North Atlantic Oscillation. These associations suggested that there are some linkages between climate variations and the global distribution of persistent organic pollutants. Our study approves the potential contribution of ice core records of POPs to transport mechanisms of POPs.
显示更多 [+] 显示较少 [-]Lichens as an integrating tool for monitoring PAH atmospheric deposition: A comparison with soil, air and pine needles 全文
2010
Augusto, Sofia | Máguas, Cristina | Matos, João Luís de | Pereira, Maria João | Branquinho, Cristina
The aim of this study was to validate lichens as biomonitors of PAH atmospheric deposition; for that, an inter-comparison between the PAH profile and concentrations intercepted in lichens with those of air, soil and pine needles was performed. The study was conducted in a petro-industrial area and the results showed that PAH profiles in lichens were similar to those of the air and pine needles, but completely different from those of soils. Lichens accumulated higher PAH concentrations when compared to the other environmental compartments and its concentrations were significantly and linearly correlated with concentrations of PAHs in soil; we showed that a translation of the lichen PAHs concentrations into regulatory standards is possible, fulfilling one of the most important requirements of using lichens as biomonitors. With lichens we were then able to characterize the air PAHs profile of urban, petro-industrial and background areas. Lichen PAH concentrations can identify geographic areas that may be out of compliance with regulatory standards.
显示更多 [+] 显示较少 [-]