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571.
Effects of land use on concentrations of metals in surface soils and ecological risk around Guanting Reservoir,China 总被引:7,自引:0,他引:7
Luo W Lu Y Giesy JP Wang T Shi Y Wang G Xing Y 《Environmental geochemistry and health》2007,29(6):459-471
It is accepted that the historical routine use of agrochemicals may have resulted in undesirable concentrations of metals
in the environment. To investigate and assess the effects of land use on concentrations of heavy metals around the Guanting
Reservoir in China, 52 surface soil samples (depth of 2–10 cm) were taken from areas where four types of land use were practiced
(including arable land, woodland, bare land, orchard land). The metals and metalloids (As, Cr, Ni, Cu, Zn, Cd, and Pb) were
analyzed using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Significant accumulation of As, Cd, and
Cr was found in soils of arable land. Based on correlation and cluster analysis, it can be concluded that Cd and Zn originate
mainly from phosphate fertilizer, Pb from the use of insecticides, fertilizers, and sewage sludge as well as air deposition,
and Cu from copper-based fungicides, while As, Ni and Cr might come from parent soil material. According to an ecological
risk analysis of metals based on the ecological index suggested by Hakanson, the four types of land can be ranked by severity
of ecological risk as follows: arable land > woodland > bare land > orchard land, with a high ecological risk of Cd for all
four types. Management measures for land use planners for avoiding water, soil, and sediment pollution caused by metals around
the Guanting Reservoir are presented. 相似文献
572.
河流生态基流量整合计算模型 总被引:19,自引:2,他引:17
针对北方地区流域水域生态系统人工化明显和河流断流的现状,提出了河流生态基流量的概念,并分析了其内涵.河流生态基流量包括河道生态基流量、河口生态基流量和湿地生态基流量.河流生态基流量计算应考虑流域内不同水系、不同河段生态环境的差异性和时空变化规律.通过改进生态环境需水量的计算方法,分析河流的空间结构特征、各河段的相互关系以及流域的水特征,提出了整合计算模型.整合计算模型分为2类:不同水系和同一水系的整合.同一水系整合计算模型又分为:河流生态基流量整合模型、河流与湿地生态基流量的整合以及河道生态基流量的整合模型.其中最为复杂的河道生态基流量的整合模型共分为6种形式:简单式、汇流式、分流式、组合式、交叉式和河口式.研究结果表明:各子系统的生态基流量是河流生态基流量整合计算的基础;河流生态基流量保证系数是计算的重要参数,其值在确定基数的基础上,通过恢复模式和空间优化配置这2个影响因子进行调整而得到,取值范围为[0,1];整合计算模型需要明确消耗性生态基流量和非消耗性生态基流量,消耗性生态基流量不受保证系数的影响,非消耗性生态基流量因保证系数取值的不同而变化. 相似文献
573.
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575.
Qiang Liu Jin Chen Richard T. Corlett XuLi Fan DongLI Yu HongPei Yang JiangYun Gao 《Conservation biology》2015,29(6):1563-1572
Xishuangbanna is on the northern margins of tropical Asia in southwestern China and has the largest area of tropical forest remaining in the country. It is in the Indo‐Burma hotspot and contains 16% of China's vascular flora in <0.2% of the country's total area (19,690 km2). Rapid expansion of monoculture crops in the last 20 years, particularly rubber, threatens this region's exceptional biodiversity. To understand the effects of land‐use change and collection on orchid species diversity and determine protection priorities, we conducted systematic field surveys, observed markets, interviewed orchid collectors, and then determined the conservation status of all orchids. We identified 426 orchid species in 115 genera in Xishuangbanna: 31% of all orchid species that occur in China. Species richness was highest at 1000–1200 m elevation. Three orchid species were assessed as possibly extinct in the wild, 15 as critically endangered, 82 as endangered, 124 as vulnerable, 186 as least concern, and 16 as data deficient. Declines over 20 years in harvested species suggested over‐collection was the major threat, and utility value (i.e., medicinal or ornamental value) was significantly related to endangerment. Expansion of rubber tree plantations was less of a threat to orchids than to other taxa because only 75 orchid species (17.6%) occurred below the 1000‐m‐elevation ceiling for rubber cultivation, and most of these (46) occurred in nature reserves. However, climate change is projected to lift this ceiling to around 1300 m by 2050, and the limited area at higher elevations reduces the potential for upslope range expansion. The Xishuangbanna Tropical Botanical Garden is committed to achieving zero plant extinctions in Xishuangbanna, and orchids are a high priority. Appropriate in and ex situ conservation strategies, including new protected areas and seed banking, have been developed for every threatened orchid species and are being implemented. 相似文献
576.
《组织行为杂志》2017,38(5):692-711
A well‐known downside of organizational mergers is that employees fail to identify with the newly formed organization. We argue that developing an understanding of factors that affect post‐merger identification requires taking the pre‐merger status of the merger partners relative to each other into account. This is because relative pre‐merger status determines employees' susceptibility to different aspects of the merger process. Specifically, for employees of a high status pre‐merger organization, we expected post‐merger identification to be strongly influenced by (i) pre‐merger identification and (ii) the perceived change in the status. In contrast, we expected post‐merger identification of employees of a low status pre‐merger organization to be strongly affected by the perceived justice of the merger event. Longitudinal data were obtained from a merger of two public sector organizations and the results supported our hypotheses. Our study shows that the extent to which pre‐merger identification, status change, and justice are important determinants of post‐merger identification depends on the relative pre‐merger status of the merger partners. Our discussion focuses on theoretical implications and managerial ramifications of these findings. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
577.
根据2002年-2011年同安湾海域水质监测结果,采用单因子污染指数评价法和富营养化水平法对同安湾海域近十年水质状况进行分析与评价。结果表明,该海域主要污染因子为无机氮和活性磷酸盐,各年均值大部分超三类海水水质标准;溶解氧、化学需氧量、重金属(汞、铜、铅、镉)及砷、油类均符合一类海水水质标准。该海域目前处于N高P低的富营养状态,氮磷比趋势不够稳定,但磷限制性富营养化趋势有所下降。 相似文献
578.
随着农村经济的不断发展,农村环境污染日趋严重。虽然吉林省在农村环境污染防治和生态保护方面取得了一些成效,但农村环保工作仍然十分薄弱。农村环境连片整治示范项目以饮用水水源保护和人居环境质量改善为主要目标,重点支持农村饮用水水源地保护、生活污水和生活垃圾污染治理、畜禽养殖污染治理与综合利用等项目。基于吉林省农村环境存在的共性问题和污染成因分析,有关人士提出了“切实保护农村饮用水源地,加强村庄生活污染治理力度,畜禽养殖污染治理,工矿企业污染治理,农业面源污染治理”等五方面治理措施,有利于促进全省农村环境的有效改善。 相似文献
579.
锡林郭勒盟是我国重要的煤炭能源基地,近年来,煤电一体化开发为地区带来经济效益的同时也给环境带来巨大压力,大面积的草原受到破坏和威胁,引发了一系列生态问题,需要在锡盟未来的地区经济发展中引起注意。应该借鉴国际上对煤炭业开征环境保护税的经验,进行我国草原区煤炭业环境保护税费改革的制度设计和政策落实。 相似文献
580.
利用GC-ECD测定了钦州湾沉积物中17种有机氯农药的含量,并对其组分分布和来源进行了分析。结果表明,样品中有机氯农药的总量为1.50~129ng/g,滴滴涕(DDTs)浓度为0.59~126ng/g,六六六(HCHs)的浓度为nd~2.65ng/g。有机氯农药的分布特征为茅尾海>钦州外湾,茅尾海东岸>西岸。组分分布特征分析显示,DDTs主要来自于历史积累,林丹在某些采样区域内有近期输入。与国内外不同地区沉积物中有机氯农药残留相比,钦州湾沉积物中有机氯农药污染处于低到中等水平。以沉积物生态风险评估值为基准的分析表明,研究区内DDT含量存在较大的生态风险。 相似文献