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991.
内分泌干扰物(EDCs)在环境和饮用水中的存在已经引起相关机构越来越大的关注.这些化合物通常在很低的浓度就对人类和野生动物产生生理影响.  相似文献   
992.
Thermodynamics is a powerful tool for the study of system development and has the potential to be applied to studies of ecological complexity. Here, we develop a set of thermodynamic indicators including energy capture and energy dissipation to quantify plant community self-organization. The study ecosystems included a tropical seasonal rainforest, an artificial tropical rainforest, a rubber plantation, and two Chromolaena odorata (L.) R.M. King & H. Robinson communities aged 13 years and 1 year. The communities represent a complexity transect from primary vegetation, to transitional community, economic plantation, and fallows and are typical for Xishuangbanna, southwestern China. The indicators of ecosystem self-organization are sensitive to plant community type and seasonality, and demonstrate that the tropical seasonal rainforest is highly self-organized and plays an important role in local environmental stability via the land surface thermal regulation. The rubber plantation is at a very low level of self-organization as quantified by the thermodynamic indicators, especially during the dry season. The expansion of the area of rubber plantation and shrinkage of tropical seasonal rainforest would likely induce local surface warming and a larger daily temperature range.  相似文献   
993.
994.
The use of functionalised metal sulphide nanoparticles (NPs) for nanoremediation and biomedical application is rapidly increasing, which could lead to significant inputs into the marine environment. The potential impact of some NPs on marine organisms is still poorly understood. In the present paper the genotoxic potential of Ag2S and CdS NPs on Mytilus edulis haemocytes was assessed. MPEG-SH (thiol-terminated methyl polyethylene glycol), was used as capping agent to avoid NPs agglomeration. TEM analysis showed that the Ag2S NPs size was 13±7 nm, whereas CdS quantum dots had an average diameter of 4±1 nm. DNA integrity was evaluated by Comet assay following exposure to increasing concentration series (0.01–10 mg/L). Both silver and cadmium NPs showed genotoxic effects at the highest dose. MPEG-SH was also found to exert a weak genotoxic activity, suggesting that at least part of the genotoxic potential of functionalised NPs on mussel cells might be attributable to the capping agent. These results confirm the genotoxic potential of Ag2S NPs for mussel cells and demonstrated, for the first time, that CdS NPs is genotoxic in a marine organism.  相似文献   
995.
Industrial discharges of Al are increasingly common. In this study, the activities of three antioxidases, malondialdehyde (MDA) content and changes in coelomocytes were investigated in earthworms (Eisenia andrei) exposed to different concentrations of aluminium chloride (range 0–200 mg Al kg?1 dry soil) in artificial soils for 32 days. Within the first 16 days of Al exposure, catalase activity was elevated in most treatments, while the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were inhibited in all treatments. After 16 days exposure, SOD and GSH-Px activities returned to normal at lower Al concentrations, but were still inhibited at higher concentrations, hence the inhibition of SOD and GSH-Px showed some exposure-level dependence during the late exposure phase. MDA content was significantly elevated from 16 days after initial exposure. Neutral Red retention time of coelomocytes decreased at the highest exposure concentrations after 32 days, and an increased proportion of cells showing membrane damage was also observed at this time using flow cytometry. We conclude that excessive Al in soils can cause oxidative stress and cell damage in earthworms. Hence, Al accumulation in the environment may present an ecological hazard through suppression of the important functions of earthworms in soil ecosystems.  相似文献   
996.
Understanding the spatial–temporal distribution of vector mosquitoes is essential in designing an efficient mosquito control strategy to reduce the risk of the mosquito-borne disease. In this paper, we apply a non-parametric clustering method, CLUES, to the surveillance data of West Nile virus vector mosquitoes collected by light traps in Peel Region, Ontario, during the mosquito seasons in 2004–2010. In order to obtain robust and reliable results, a statistical smoothing procedure LOWESS is applied to the original time series data. It was found that the mosquito trap sites can be clustered into three groups. The weather impact on the mosquito abundance of each clustered group are similar, while the interannual variability and the highest abundance and peak time in each mosquito season are different. The impact of weather factors on this clustering is investigated.  相似文献   
997.
The social license to operate framework considers how society grants or withholds informal permission for resource extractors to exploit publicly owned resources. We developed a modified model, which we refer to as the social license to hunt (SLH). In it we similarly consider hunters as operators, given that wildlife are legally considered public resources in North America and Europe. We applied the SLH model to examine the controversial hunting of large carnivores, which are frequently killed for trophies. Killing for trophies is widespread, but undertaken by a minority of hunters, and can pose threats to the SLH for trophy-seeking carnivore hunters and potentially beyond. Societal opposition to large carnivore hunting relates not only to conservation concerns but also to misalignment between killing for trophies and dominant public values and attitudes concerning the treatment of animals. We summarized cases related to the killing of grizzly bears (Ursus arctos), wolves (Canis lupus), and other large carnivores in Canada, the United States, and Europe to illustrate how opposition to large carnivore hunting, now expressed primarily on social media, can exert rapid and significant pressure on policy makers and politicians. Evidence of the potential for transformative change to wildlife management and conservation includes proposed and realized changes to legislation, business practice, and wildlife policy, including the banning of some large carnivore hunts. Given that policy is ultimately shaped by societal values and attitudes, research gaps include developing increased insight into public support of various hunting policies beyond that derived from monitoring of social media and public polling. Informed by increased evidence, the SLH model can provide a conceptual foundation for predicting the likelihood of transient versus enduring changes to wildlife conservation policy and practice for a wide variety of taxa and contexts.  相似文献   
998.
Knowledge and understanding about how the ecological systems of the Earth support life form the foundation for ecological literacy, which, in turn, is of critical importance for sustainability. There is widespread concern that levels of ecological literacy within many contemporary human societies are too low to enable effective decision-making about how to live sustainably. This paper presents and discusses the findings of an ecological literacy assessment of South Australian adults. The assessment tested for knowledge and understanding of ecological systems and interconnections with human society. Analyses revealed significant relationships between assessment scores and a range of value-based and behavioural characteristics. Such characteristics included the value placed on nature, time spent outdoors and in nature, involvement in nature-based activities, and perceived sources of ecological knowledge and understanding. Higher average scores were correlated with higher values accorded to involvement in outdoor activities, importance of the outdoors to enjoyment of life, importance of nature in the household, volunteer environmental activity and growing food. Higher scores were also correlated with higher education, research activities, outdoor lifestyles, place-based experiences, volunteer activities, mentors and colleagues, and books and magazines. Lower scores were achieved by those who considered media, natural disasters and environmental marketing to be major contributors to their ecological knowledge. These findings contribute to a broader study of the relationships between ecological literacy and a range of both socio-demographic and psychographic characteristics. They invite serious consideration from any society that values the participation of an informed population with the capacity to make sustainable environmental decisions.  相似文献   
999.
The atomised nature of the humanitarian system has led to frequent and repeated attempts to coordinate humanitarian activity. Since 2005, some of the best resourced, and arguably most successful, coordination mechanisms have been the humanitarian Clusters, groups of UN (United Nations) and non‐UN actors that engage in sectoral coordination of humanitarian response (such as the provision of healthcare and water) at the global and country level. Nevertheless, it is not clear exactly what ‘coordination’ means in the context of a Cluster. Formal guidance suggests that they should be aiming to create a single, joint strategy to guide the activities of members. Actual experience of the Clusters, however, indicates that looser forms of coordination are more effective. This finding resonates with organisational theory, and with the experience of emergency management professionals beyond the international humanitarian sector. To capitalise fully on the success of the Clusters, policymakers may need to rethink their attitudes to, and expectations of, coordination.  相似文献   
1000.
为研究三峡水库春季水体营养盐与浮游植物的空间分布状况,于2013年3月对三峡水库22条支流及干流的6个断面进行采样监测. 结果表明:来水、回水、河口和干流4类断面ρ(TN)平均值分别为1.69、1.84、2.01、1.51 mg/L;ρ(TP)平均值分别为0.115、0.191、0.179和0.181 mg/L;不同类型断面间ρ(TN)、ρ(TP)差异不显著;水体中N、P的主要形态分别为NO3--N和PO43--P;N/P〔n(N)/n(P)〕从来水(110.8)至干流(18.9)逐渐降低. 三峡水库总体上为中营养状态,回水和河口区富营养化程度较高,富营养断面比例分别为45.4%和36.4%. 研究期间共检出浮游植物8门98属,其中以绿藻门、硅藻门和蓝藻门为主,分别检出42、26和17属;从组成上看,来水和干流断面以硅藻-绿藻为主,回水、河口断面以绿藻-硅藻为主. 浮游植物丰度由高到低依次为回水、河口、来水和干流断面. 调查期间,22条支流中有15条支流在不同位置发生水华,但主要集中在回水区;拟多甲藻水华为主要类型且集中在库区的下游支流,而库区中上游支流则以隐藻、衣藻、小球藻、小环藻等水华为主. 环境因子排序分析表明,在水华集中的回水-河口区域,影响浮游植物丰度分布的主要环境因子数明显少于其他区域,温度和ρ(DO)为该区域浮游植物丰度分布的主要影响因子,而ρ(TN)、ρ(TP)的影响不明显.   相似文献   
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