岷江上游水电开发特点及其空间格局分析

研究流域的水电开发类型与空间格局,可为水库群的累积环境影响评价、流域水电优化布局等提供科学参考。在流域分割的基础上,对岷江上游水电站的基本类型、水电站的空间分布格局进行了全面分析,并构建水电开发率、水电开发密度和水电开发强度3个指标对流域水电开发程度作出综合评价。结果表明岷江上游流域水电站类型以高水头低闸坝的引水式小水电为主,高坝大库相对较少。梯级水电开发已拓展至岷江三级支流,汶川—都江堰河段是干流水电开发程度最高的河段,杂谷脑河是水电开发程度最高的一级支流流域。岷江上游流域的水电开发率远高于全国平均水平,梯级水电开发密度大于国内主要河流。农村小水电占水电站总数的82%,梯级农村小水电对生态环境的累积影响是将来值得深入探讨的问题。     

中国环境基准研究重点方向探讨

环境基准是环境标准的科学依据,在国家环境质量评价和风险管理体系中处于基础地位。它主要是依据特定对象在环境介质中的暴露数据,以及与环境要素的剂量效应关系数据,通过科学判断得出的,涉及环境化学、毒理学、生态学、流行病学、生物学和风险评估等前沿学科领域。国家环境基准研究是一个长期的系统工程,本文基于环境基准研究的学科特点和国际前沿,结合国家科技需求和相关领域的研究现状,综合分析并提出了未来中国环境基准研究的重点研究方向:1)环境基准的理论与方法学;2)环境基准基础数据库;3)基准目标污染物的筛选甄别和优先排序技术;4)水体营养物基准;5)生物测试与毒性评价技术;6)人体暴露评价理论与相关技术;7)环境基准的审核和校对;8)环境基准与标准转化理论及其对环境管理支撑技术。本文从环境基准学科发展的角度,阐述了与环境基准研究紧密相关的8个重点研究方面的国内外研究进展、关键科学问题以及未来重点研究内容。同时指出,这些重要的研究方向是环境基准研究的根本,未来环境基准的长期战略发展必将是建立在各个重要方向长足发展的基础之上,环境基准研究也必带动这些方向的共同蓬勃发展,为环境地球化学、毒理学、生态学等学科领域发展注入活力。     

澜沧江梯级水库对汞输运的影响

拦河筑坝对河流中汞的输运产生重要影响,但有关高海拔落差河流中汞的来源及输运特征的认识较为匮乏.以澜沧江为研究对象,监测了筑坝河段水体中汞浓度的年时空变化过程（2017—2018）,量化了梯级水库对汞沿程输运的影响.结果表明,澜沧江水体中汞浓度总体与径流的季节分配呈同步变化趋势,但在上下游因土地利用类型的差异而呈现相反的季节性变化特征.因水库的拦截,溶解态汞与总汞的比值沿程呈上升趋势,加之水库泄水量的沿程增加,共同导致了河流汞通量自上游至下游呈非连续累积的趋势,从144 kg·a^-1增加至788 kg·a^-1.相应地,梯级水库对汞的拦截率自上游至下游由88%逐渐降低至65%.该项研究丰富了对梯级水库中汞的补给和输运的认识.     

乌江流域梯级水库入出库河流中总汞和甲基汞的时空分布

2006年1~12月，每月采集乌江流域梯级水库入出库河流水样，用两次金汞齐-冷原子荧光光谱法和蒸馏-乙基化结合GC CVAFS法测定了水中总汞和甲基汞的浓度。结果表明：（1）入出库河流中总汞年均加权浓度分别为317和 2.34 ng/L，甲基汞为014和 0.18 ng/L。（2）不同水库入出库河流中总汞和甲基汞的时空分布特征不同，位于上游第一级的普定和洪家渡水库入库河流中总汞有明显的季节变化趋势，且显著低于出库河流；而甲基汞的季节变化在出库河流中较为明显，而且库龄大的普定、东风、乌江渡水库出库河流中甲基汞浓度显著高于入库河流。（3）相关分析发现水库入库河流中总汞、甲基汞浓度主要受悬浮颗粒物的影响，而与水量间的相关性因水库所处位置的不同而有差异，上游的普定和洪家渡水库中呈显著正相关，其它水库中呈负相关。     

Managing a forgotten greenhouse gas under existing U.S. law: An interdisciplinary analysis

The United States’ legal strategy for addressing climate change in recent years has relied on authority from existing legislation. This has led to measures on a number of different greenhouse gases, notably carbon dioxide, methane and hydrofluorocarbons. However, one greenhouse gas has been largely forgotten: nitrous oxide. Nitrous oxide is the third most abundantly emitted greenhouse gas in the U.S. and worldwide, as well as the largest remaining threat to the stratospheric ozone layer. In addition, the nitrogen atoms in nitrous oxide are part of the highly fluid nitrogen cycle where nitrogen atoms transform readily among different chemical forms, each with a unique environmental and human health impact – a process known as the nitrogen cascade. While the science of the nitrogen cascade has been explored for over a decade, there has been little work on the legal implications of this phenomenon. And yet the nitrogen cascade expands the legal options available for controlling nitrous oxide. This paper studies these options in a U.S. context and explores the environmental and economic impacts of enacting them. We determine that the Clean Air Act, and in particular its broad authority for controlling ozone depleting substances, is the most promising legal pathway for regulating nitrous oxide across all major sources. Invoking such authority could generate significant climate and stratospheric ozone benefits over 2015–2030, equivalent to taking 12 million cars permanently off the road, and 100 million chlorofluorocarbon-laden refrigerators out of service. The economic benefits could sum to over $700 billion over 2015–2030, with every $1.00 spent on abating emissions leading to $4.10 in societal benefits. The bulk of these benefits would come from reductions in other forms of nitrogen pollution such as ammonia and nitrate, highlighting the important and multiple co-benefits that could be achieved by abating nitrous oxide emissions. With the Paris Climate Agreement calling for limiting global temperature increases to “well below” two degrees Celsius, all mitigation opportunities across all sectors need to be considered. This paper suggests that nitrous oxide warrants more attention from policy-makers in the U.S. and around the world.