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201.
The U.S. Environmental Protection Agency Environmental Monitoring and Assessment Program (EMAP) uses water clarity as a water quality indicator for integrated assessments of coastal waters. After the publication of the first National Coastal Condition Report (USEPA, 2001c), the national water clarity reference value of 10% of ambient surface light at 1~m depth was reevaluated and modified to reflect expected differences in regional reference light conditions. These regional differences range from naturally turbid estuaries like those found in Mississippi and Louisiana to clear water estuaries expected to support extensive beds of submerged aquatic vegetation in, e.g., Florida and Tampa Bays. For the second National Coastal Condition Report, water clarity was assessed based on regional reference values (USEPA, 2004). Different regional water clarity reference values and data collection methods necessitated the development of a water clarity index based on light attenuation coefficients (k). This index incorporates regional reference conditions and is interchangeable with secchi depth and percent light transmission calculated from light meter measurements. Evaluation of the water clarity index shows that k values based on transmissivity at 1~m can be estimated from secchi depth measurements and successfully used as a surrogate for transmissivity calculated from light meter data. An approach for assessing water clarity in Gulf of Mexico estuaries using light meter data and secchi depth is presented. 相似文献
202.
空气质量自动监测二氧化硫不确定度分析 总被引:1,自引:0,他引:1
不确定度是反映某一测量方法,在一定置信概率条件下测量所产生的不确定量。根据测量原理建立数学模型,分析各种不确定度分量的来源,评定标准不确定度,确定合成不确定度和扩展不确定度,通过不确定影响分量的分析,找出影响测量结果的最大不确定度分量,重点控制其分量,保证测量的准确性和精度,同时也可通过重新评估显著性不确定分量,找出方法存在的不足和问题,提出逐步控制不确定分量的步骤和方法,改善测量方法和手段提高测量准确性和精度,不断减少测量的不确定量。 相似文献
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How is young people's pro-environmental orientation related to their parents' pro-environmental values, attitudes, and behaviours? To answer this question, we examine parent–child similarities of general values as well as specific attitudes and behaviours related to three common household practices: purchasing environmentally friendly products, curtailing electricity use, and handling waste responsibly in a sample of 601 Danish families. Significant and positive, but weak correlations between parents' and children's values are found across all of Schwartz's ten value domains. The parent–child correlations are stronger for specific pro-environmental attitudes and behaviours. The positive correlations suggest that family socialization exert a significant influence on young consumers' pro-environmental orientation. Still, the young generation is, on average, significantly less environmentally concerned than their parents' generation. Implications of these findings are discussed. 相似文献
205.
Marco Iotti Paola Fabbri Massimo Messori Francesco Pilati Patrizia Fava 《Journal of Polymers and the Environment》2009,17(1):10-19
Organic–inorganic hybrid coatings based on poly(ε-caprolactone), poly(ethylene oxide) or poly(lactic acid) as organic phase
and silica from tetraethoxysilane as inorganic phase were prepared by the sol–gel approach. Coatings were applied onto poly(lactic
acid) films for food packaging in order to improve its barrier properties towards oxygen and water vapour. All the prepared
coatings were dense, homogeneous layers characterized by a good adhesion to the substrate. The permeance of the coating layers
resulted one order of magnitude lower than that of the uncoated poly(lactic acid) (PLA) film. The hydrophilic character of
the coating did not permit to gain a significant decrease in the water vapour permeance. The perfect visual transparency of
the coatings allows their application without worsening of the esthetical properties of the substrate PLA film. 相似文献
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207.
Polymer coating of copper oxide nanoparticles increases nanoparticles uptake and toxicity in the green alga Chlamydomonas reinhardtii 总被引:1,自引:0,他引:1
Copper oxide nanoparticles (CuO NPs) are frequently used in a polymer-coated form, to be included in paints or fabrics for antimicrobial properties. Their application in antifouling paints may lead to the contamination of aquatic ecosystems. However, the toxicological risk of NPs in the environment is hard to evaluate due to a lack of knowledge on the mechanisms of NP interaction with biological systems. In this study, we investigated the effect of polymer coating on CuO NP toxicity in the green alga Chlamydomonas reinhardtii by comparing bare and polymer-coated CuO NPs prepared from the same CuO nanopowder. Both CuO NP suspensions were toxic to C. reinhardtii after 6 h treatment to concentrations of 0.005-0.04 g L−1. Bare and polymer-coated CuO NPs induced a decrease of Photosystem II activity and the formation of reactive oxygen species. Polymer-coated CuO NP was found to be more toxic than the uncoated CuO NP. The higher toxicity of CS-CuO NP was mainly associated with the increased capacity of polymer-coated CuO NP to penetrate the cell compared to bare CuO NPs. These results indicates that the high toxicity of polymer-coated CuO NPs in algal cells results of intracellular interactions between NPs and the cellular system. 相似文献
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针对电网通信的智能化监测应用需要,提出了一种用于电力通信的Adhoc自适应预约按需传输多址接入协议,该协议在接入阶段可以根据业务量动态调整接入策略;在传输阶段可以无冲突的发送分组.针对该协议的吞吐量和平均时延性能进行了仿真分析.分析结果表明:协议能提高信道利用率、降低接入时延,可用于现代电力通信网络,以上研究结果对Adhoe在电力通信的工程中应用有较好参考意义. 相似文献