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651.
The concentrations of heavy metals (Cr, Cd, Hg, Cu, Zn, Pb and As) in the water, sediment, and fish were investigated in the middle and lower reaches of the Yangtze River, China. Potential ecological risk analysis of sediment heavy metal concentrations indicated that six sites in the middle reach, half of the sites in the lower reach, and two sites in lakes, posed moderate or considerable ecological risk. Health risk analysis of individual heavy metals in fish tissue indicated safe levels for the general population and for fisherman but, in combination, there was a possible risk in terms of total target hazard quotients. Correlation analysis and PCA found that heavy metals (Hg, Cd, Pb, Cr, Cu, and Zn) may be mainly derived from metal processing, electroplating industries, industrial wastewater, and domestic sewage. Hg may also originate from coal combustion. Significant positive correlations between TN and As were observed. 相似文献
652.
Evaluation of alternative PCB clean-up strategies using an individual-based population model of mink
Salice CJ Sample BE Miller Neilan R Rose KA Sable S 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3334-3343
Population models can be used to place observed toxic effects into an assessment of the impacts on population-level endpoints, which are generally considered to provide greater ecological insight and relevance. We used an individual-based model of mink to evaluate the population-level effects of exposure to polychlorinated biphenyls (PCBs) and the impact that different remediation strategies had on mink population endpoints (population size and extinction risk). Our simulations indicated that the initial population size had a strong impact on mink population dynamics. In addition, mink populations were extremely responsive to clean-up scenarios that were initiated soon after the contamination event. In fact, the rate of PCB clean-up did not have as strong a positive effect on mink as did the initiation of clean-up (start time). We show that population-level approaches can be used to understand adverse effects of contamination and to also explore the potential benefits of various remediation strategies. 相似文献
653.
654.
Megan Bailey Alice M.M. Miller Simon R. Bush Paul A.M. van Zwieten Budy Wiryawan 《Journal of Environmental Policy & Planning》2016,18(2):141-160
Indonesia is one of the world's largest tuna producing countries, yet regulatory oversight remains weak and management is poor. Incentive-based approaches are a way to improve state-based resource management, but they often require strong government regulation. In this paper, we use principal–agent theory and the notion of the ‘incentive gap’ to explore how incentives could be brought to bear in Indonesia through a combination of private and public actors. With a shared fish stock like tuna, we argue that a double principal–agent problem emerges, where information, asymmetries between various players complicate management. We focus on the problems of adverse selection and moral hazard in three different tuna fisheries in Indonesia to identify the nature of the incentive gap, and comment on the mix of public and private actors currently engaged in tuna fishery governance towards reducing the gap. The double principal–agent problem is a useful yet underutilized framework to understand the dynamics of shared stocks management. In this first application to a developing country fishery, we conclude that information asymmetries cannot be overcome without the involvement of private actors, who are increasingly becoming important in aligning regional and global objectives with those of fishers themselves. 相似文献
655.
生态清洁小流域建设对于维护重要水源区水生态安全具有极其重要的意义。以汉江上游的陕西省石泉县饶峰河小流域为研究对象,在对该小流域自然因素和社会经济因素进行调查的基础上,采用GIS空间分析方法,对该小流域治理区域进行精细划分。研究表明饶峰河小流域可划分7个不同的治理区域,分别为:生态修复区、坡耕地修复区、坡面治理区、坡耕地治理区、农田治理区、村镇综合治理区及河(沟)道周边整治区。根据各区域的污染产生特点,针对性地提出各区域治理方向,并进行治理措施配置。该研究可为生态清洁小流域精准治理提供一种新的建设思路。 相似文献
656.
Xiaoyun Bing Marlies de Keizer Jacqueline M. Bloemhof-Ruwaard Jack G.A.J. van der Vorst 《Waste management (New York, N.Y.)》2014,34(4):719-729
Plastic waste is a special category of municipal solid waste. Plastic waste collection is featured with various alternatives of collection methods (curbside/drop-off) and separation methods (source-/post-separation). In the Netherlands, the collection routes of plastic waste are the same as those of other waste, although plastic is different than other waste in terms of volume to weight ratio. This paper aims for redesigning the collection routes and compares the collection options of plastic waste using eco-efficiency as performance indicator. Eco-efficiency concerns the trade-off between environmental impacts, social issues and costs. The collection problem is modeled as a vehicle routing problem. A tabu search heuristic is used to improve the routes. Collection alternatives are compared by a scenario study approach. Real distances between locations are calculated with MapPoint. The scenario study is conducted based on real case data of the Dutch municipality Wageningen. Scenarios are designed according to the collection alternatives with different assumptions in collection method, vehicle type, collection frequency and collection points, etc. Results show that the current collection routes can be improved in terms of eco-efficiency performance by using our method. The source-separation drop-off collection scenario has the best performance for plastic collection assuming householders take the waste to the drop-off points in a sustainable manner. The model also shows to be an efficient decision support tool to investigate the impacts of future changes such as alternative vehicle type and different response rates. 相似文献
657.
Claudia Pittiglio Andrew K. Skidmore Hein A. M. J. van Gils Michael K. McCall Herbert H. T. Prins 《Ambio》2014,43(2):149-161
Crop-raiding elephants affect local livelihoods, undermining conservation efforts. Yet, crop-raiding patterns are poorly understood, making prediction and protection difficult. We hypothesized that raiding elephants use corridors between daytime refuges and farmland. Elephant counts, crop-raiding records, household surveys, Bayesian expert system, and least-cost path simulation were used to predict four alternative categories of daily corridors: (1) footpaths, (2) dry river beds, (3) stepping stones along scattered small farms, and (4) trajectories of shortest distance to refuges. The corridor alignments were compared in terms of their minimum cumulative resistance to elephant movement and related to crop-raiding zones quantified by a kernel density function. The “stepping stone” corridors predicted the crop-raiding patterns. Elephant presence was confirmed along these corridors, demonstrating that small farms located between refuges and contiguous farmland increase habitat connectivity for elephant. Our analysis successfully predicted elephant occurrence in farmland where daytime counts failed to detect nocturnal presence. These results have conservation management implications. 相似文献
658.
在近年来国内休闲农业快速发展的背景下,由于缺乏对其非使用价值的正确认识和判断,出现了高速增长与效果欠佳的矛盾,如何科学评价休闲农场开发的非使用价值,对于该产业发展具有重要意义。条件价值评估方法(CVM)是国内外评估非使用价值和支付意愿较为成熟的方法,但尚未用于对具有"三产融合"和"三生一体"特性的休闲农场的评估,本研究以福建开发较为成熟的长泰福友休闲农场为研究取样点,采用该方法探究游客对休闲农场生态景观质量的感知水平及支付意愿。结果表明:游客对福友休闲农场生态保护价值支付意愿的下限为18.26元,支付上限为23.10元,游客对福友休闲农场生态景观保护的支付意愿为96.45万元/年;提供便捷的支付渠道和公开资金的使用途径能有效提升游客购买生态景观保护价值的支付意愿;农场空气的好坏、农场的生态体验设计、农场的田园功能分区在主题设计、耕作体验形式、内容等方面的创新程度对游客生态保护的支付意愿影响较大;对于大部分拥有一定农场阅历但对农业多功能性认识不足的游客,在便捷的支付手段和珍稀植物品种的吸引下,更倾向于形成较低水平的生态保护价值支付意愿,而那些文化素质较高,特别是拥有农场、生态相关领域研究背景,对于农场生态功能性、体验养生内容拥有一定认知的游客,则愿意在更高的价格水平支付农场的生态保护价值。 相似文献
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660.