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191.
Role of organic acids in enhancing the desorption and uptake of weathered p,p'-DDE by Cucurbita pepo 总被引:5,自引:0,他引:5
White JC Mattina MI Lee WY Eitzer BD Iannucci-Berger W 《Environmental pollution (Barking, Essex : 1987)》2003,124(1):71-80
Experiments were conducted to assess the effect of seven organic acids [succinic, tartaric, malic, malonic, oxalic, citric, ethylene-diaminetetraacetic (EDTA)] over a concentration range of two orders of magnitude (0.001-0.10 M) on the abiotic desorption of weathered p,p'-DDE and the extraction of polyvalent inorganic ions from soil. At 0.05 M all organic acids significantly increased contaminant desorption by 19-80%. Organic acids also increased the aqueous concentration of eight inorganic constituents extracted from soil, with at least a six-fold increase in the release of Al, Fe, Mn, and P at 0.001 M. Zucchini seedlings grown for 28 d in soil containing weathered p,p'-DDE (300 ng/g, dry weight) were periodically amended with distilled water, citric or oxalic acids (0.01 M). Plants receiving water removed 1.7% of the p,p'-DDE from the soil. Seedlings amended with citric or oxalic acids removed 2.1 and 1.9% of the contaminant, respectively, and contained up to 66% more contaminant in the shoot system than unamended vegetation. A second crop of untreated (distilled water) zucchini in the same soil removed more contaminant than the first crop (2.5%), although the addition of organic acids did not further enhance contaminant uptake. The data indicate that the addition of low molecular weight organic acids causes the partial dissolution of the soil structure through the chelation of inorganic structural ions, potentially enhancing bioavailability and having implications for the phytoremediation of persistent organic pollutants in soil. 相似文献
192.
193.
A metallothionein-like protein (MLP) was isolated from naturally cadmium-contaminated lobster hepatopancreas, gills, and green glands. Between 76–99% of the total cadmium was associated with this protein (molecular weight 9,500 daltons) while the remainder was associated with both high (68,000 daltons) and low (<6,000 daltons) molecular weight proteins. MLP was not present in uncontaminated lobster hepatopancreas and only 1% of the total cadmium was associated with the gel filtration fraction corresponding to the protein. 相似文献
194.
There is a need to explore, in an integrated and statistical manner, how the number of species, relative abundance, species composition and life-cycle stages of elasmobranchs in nearshore waters vary among habitat types and during the year. Therefore, four sites in a large marine embayment, each representing a different habitat type, were sampled at regular intervals. These sites were: (1) unvegetated, with no vegetation within at least 200 m; (2) unvegetated, immediately adjacent to sparse mangroves; (3) unvegetated, immediately adjacent to dense mangroves; and (4) vegetated, with seagrass (Posidonia australis) throughout and in the vicinity. Gill netting caught 10 shark species (5 families), 5 ray species (4 families) and 12 teleost species (10 families). Carcharhinus cautus, which contributed approximately 60% to the numbers of elasmobranchs caught, completed its life cycle in nearshore, shallow waters. Negaprion acutidens, Carcharhinus brevipinna, Carcharhinus limbatus and Rhizoprionodon acutus used these waters as a nursery area. C. cautus was caught mainly in the unvegetated sites, particularly in those near mangroves. N. acutidens was caught entirely in unvegetated sites, while R. acutus, C. brevipinna and Chiloscyllium punctatum were caught predominantly or exclusively in seagrass. The mean number of species and mean catch rate of elasmobranchs were greatest for the seagrass site and least for the unvegetated site with no vegetation within at least 200 m and were significantly less for the latter site than for the unvegetated site immediately adjacent to dense mangroves (P<0.05). The numbers of species and catch rates of elasmobranchs were significantly greater in summer and autumn than in winter (P<0.05) and, in the case of number of species, also than in spring (P<0.05). We conclude that the spatial and food resources in the nearshore, shallow waters of Shark Bay are partitioned among elasmobranch species, thus reducing the potential for competition among these species for the resources in those waters.Communicated by G.F. Humphrey, Sydney 相似文献
195.
This paper describes the finite difference algorithm that has been developed for the flow sub-model of the University of Southampton landfill degradation and transport model LDAT. The liquid and gas phase flow components are first decoupled from the solid phase of the full multi-phase, multi-component landfill process constitutive equations and are then rearranged into a format that can be applied as a calculation procedure within the framework of a three dimensional array of finite difference rectangular elements.The algorithm contains a source term which accommodates the non-flow landfill processes of degradation, gas solubility, and leachate chemical equilibrium, sub-models that have been described in White and Beaven (2013).The paper includes an illustration of the application of the flow sub-model in the context of the leachate recirculation tests carried out at the Beddington landfill project. This illustration demonstrates the ability of the sub-model to track movement in the gas phase as well as the liquid phase, and to simulate multi-directional flow patterns that are different in each of the phases. 相似文献
196.
This exploratory study uses model-based cluster analysis to group sixty-one countries based on statistical similarities in terms of happiness, development, income, and carbon emissions. Model-based cluster analysis is appropriate for an initial identification of a pattern that is worthy of further investigation. A key finding is that there may be a Kuznets curve for happiness. The Kuznets curve graphs the proposition that, as an economy develops, economic inequality first increases and then decreases. Similarly, the authors find that clusters of countries at the extremes of the lowest and highest average levels of development and income have the highest self-reported levels of happiness. Clusters of countries in the middle of the development and income spectrum have the comparatively lowest average levels of happiness. Further, carbon emissions are not perfectly associated with happiness. For example, between two clusters with the highest average levels of development, income, and happiness there is a 43 % difference in carbon emissions. A highly developed cluster has roughly the same mean carbon emissions as a cluster with 83 % less income, and the least developed cluster has 93 % of the happiness as the most developed cluster yet 86 % less carbon emissions. Despite limitations of both data and methodology, the overall pattern—that there may be a happiness Kuznets curve and that development, income, and carbon emissions are not associated lockstep with happiness—contributes to the literature on decoupling development from growth in emissions. 相似文献
197.
A number of studies have examined emotional and belief responses following a disaster, yet there has been limited comparative analysis of responses to disasters in different places. This paper reviews the results of 366 questionnaires that evaluated key emotional and belief concepts in Haiti after the earthquake on 12 January 2010 (n=212) and in Indonesia after the earthquake in Yogyakarta on 27 May 2006 (n=154). The results indicate significant differences between the responses in the two settings, particularly in relation to feelings of impunity, self‐blame for the disaster, regret about pre‐earthquake behaviour, and a sense of justice in the world. Furthermore, the impacts of age, education, and gender on responses also were different in the two case study sites. Overall, the results suggest that understanding the cultural, religious, and social contexts of different disaster locales is important in comprehending the emotions and beliefs that manifest themselves in the wake of a major disaster. 相似文献
198.
Aaron D. Peacock David B. Hedrick Philip E. Long Kelly P. Nevin Charles T. Resch Derek R. Lovley David C. White 《补救:环境净化治理成本、技术与工艺杂志》2011,21(4):85-106
At the Old Rifle uranium mill‐tailing site in eastern Colorado, a test of subsurface amendment with acetate to stimulate the reductive immobilization of uranium was monitored by using lipid biomarker analysis and incorporation of 13C‐labeled acetate into lipid biomarkers. Both sediment and groundwater samples were analyzed. Within 7 days of acetate addition, groundwater microbial biomass increased by a factor of 5, and remained higher than control values in most samples for the 28 days sampled. At 29 days after the beginning of acetate amendment, 4 of 12 sediment samples had microbial biomass greater than the 95 percent confidence interval of controls. The mole percents of the phospholipid fatty acids 16:1ω7c and 16:1ω5c increased over control values upon acetate amendment, and incorporated high levels of 13C from labeled acetate in groundwater and sediment samples. 16:1ω7c is a biomarker for Geobacter, and evidence is provided that 16:1ω5c represents an unidentified iron‐reducing bacterium, probably a member of the Desulfobulbaceae. Biomarkers for organisms other than iron‐reducing bacteria, iso‐ and anteiso‐branched fatty acids and 18:1ω9c, decreased upon acetate amendment, and had their highest stable isotope incorporation at least 4 days after labeled acetate amendment ended, evidence for carbon‐sharing between iron‐reducers and other microorganisms. © 2011 Wiley Periodicals, Inc. 相似文献
199.
Colin Robertson Carson J. Q. Farmer Trisalyn A. Nelson Ian K. Mackenzie Michael A. Wulder Joanne C. White 《Environmental monitoring and assessment》2009,158(1-4):593-608
The current mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak in British Columbia and Alberta is the largest recorded forest pest infestation in Canadian history. We integrate a spatial hierarchy of mountain pine beetle and forest health monitoring data, collected between 1999 and 2006, with provincial forest inventory data, and generate three information products representing 2006 forest conditions in British Columbia: cumulative percentage of pine infested by mountain pine beetle, percentage of pine uninfested, and the change in the percentage of pine on the landscape. All input data were formatted to a standardized spatial representation (1 ha minimum mapping unit), with preference given to the most detailed monitoring data available at a given location for characterizing mountain pine beetle infestation conditions. The presence or absence of mountain pine beetle attack was validated using field data (n?=?2054). The true positive rate for locations of red attack damage over all years was 92%. Classification of attack severity was validated using the Kruskal gamma statistic (γ?=?0.49). Error between the survey data and field data was explored using spatial autoregressive (SAR) models, which indicated that percentage pine and year of infestation were significant predictors of survey error at α?=?0.05. Through the integration of forest inventory and infestation survey data, the total area of pine infested is estimated to be between 2.89 and 4.14 million hectares. The generated outputs add value to existing monitoring data and provide information to support management and modeling applications. 相似文献
200.
Effects of Place Identity,Place Dependence,and Experience-Use History on Perceptions of Recreation Impacts in a Natural Setting 总被引:3,自引:2,他引:1
It is generally accepted that recreation use in natural environments results in some degree of negative social and environmental impact. Environmental managers are tasked with mitigating the impact while providing beneficial recreation opportunities. Research on the factors that influence visitors' perceptions of environmental and social conditions is necessary to inform sound environmental management of protected natural areas. This study examines the effect of prior experience with the setting and two dimensions of place attachment (i.e., place identity and place dependence) on visitors' perceptions of three types of recreation impacts (i.e., depreciative behavior, environmental impacts, and recreation conflict). Principal components analysis, confirmatory factor analysis, and structural equation modeling were used to test the study hypotheses using data collected from 351 visitors through on-site questionnaires (response rate of 93 percent). The results show that prior experience exhibited a moderate and significant direct positive effect on place identity, place dependence, and visitors' perceptions of recreation impacts. Contrary to study hypotheses and prior research, neither place dependence nor place identity exhibited a significant effect on the dependent variables. The results show that prior experience causes visitors to be more sensitive to depreciative behaviors, environmental impacts, and recreation conflict. These findings raise concerns over potential visitor displacement and deterioration of site conditions. Implications for resource managers are discussed, which include education, modifying visitor use patterns, and site design strategies. 相似文献