Assessing the Potential Impacts to Riparian Ecosystems Resulting from Hemlock Mortality in Great Smoky Mountains National Park

Hemlock Woolly Adelgid (Adelges tsugae) is spreading across forests in eastern North America, causing mortality of eastern hemlock (Tsuga canadensis [L.] Carr.) and Carolina hemlock (Tsuga caroliniana Engelm.). The loss of hemlock from riparian forests in Great Smoky Mountains National Park (GSMNP) may result in significant physical, chemical, and biological alterations to stream environments. To assess the influence of riparian hemlock stands on stream conditions and estimate possible impacts from hemlock loss in GSMNP, we paired hardwood- and hemlock-dominated streams to examine differences in water temperature, nitrate concentrations, pH, discharge, and available photosynthetic light. We used a Geographic Information System (GIS) to identify stream pairs that were similar in topography, geology, land use, and disturbance history in order to isolate forest type as a variable. Differences between hemlock- and hardwood-dominated streams could not be explained by dominant forest type alone as forest type yields no consistent signal on measured conditions of headwater streams in GSMNP. The variability in the results indicate that other landscape variables, such as the influence of understory Rhododendron species, may exert more control on stream conditions than canopy composition. The results of this study suggest that the replacement of hemlock overstory with hardwood species will have minimal impact on long-term stream conditions, however disturbance during the transition is likely to have significant impacts. Management of riparian forests undergoing hemlock decline should, therefore, focus on facilitating a faster transition to hardwood-dominated stands to minimize long-term effects on water quality.     

柴外光催化氧化-分光光度法测定水体中的总磷

光催化氧化技术是一种新兴的样品预处理技术,探究新型的光催化氧化消解方法对样品前处理有着显著的优势。本文拟采用二氧化钛为催化剂,通过使用光催化氧化消解方法对水体样品进行前处理,再用分光光度法测定水中的总磷,并与常用消解方法进行对比,确定本方法的准确度与精密度。     

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。     

China＇s Total Emission Control Policy： a Critical Review

As part of a comprehensive environmental management system, many countries establish emission control targets for mass emissions of a pollutant. Such targets are often the key objective of an environmental policy, such as an emission trading program. In China, however, it is more than just an objective of one particular policy; it has become a concept that has influenced many national environmental policies and activities. The objective of this article is to review the implementation of the total emission control policy in the past 10 years and explore emerging issues in its implementation. The article has three sections： a summary of the implementation experience, issues with the design and implementation of the policy, and policy recommendations.     

原核小球藻USTB-01去除化肥厂废水中总氮的研究

采用1株异养原核小球藻USTB-01对化肥厂废水中总氮的去除进行了研究。结果表明,添加一定量的磷酸盐和碳酸钠特别是葡萄糖分别作为磷、无机碳和有机碳源,不仅可以明显促进原核小球藻USTB-01的生长,而且可以大幅度提高废水的总氮去除效率。在4 d时间内原核小球藻USTB-01的生长从OD680 nm0.5增加到3.6,提高到7倍,而废水中总氮的浓度从125 mg/L降低到10.3 mg/L,去除率达到了93.1%,处理后的废水可以达标排放。不仅在高含氮废水的处理,而且在利用废水中的氮培养原核小球藻USTB-01的废水资源化利用方面均具有重要的意义。     

全要素能源效率与环境污染关系研究

能源与环境问题已成为世界焦点,回顾文献发现,已有研究大多单独从能源或环境问题进行分析,对能源与环境特别是能源效率与环境污染之间关系的研究较少。能源效率与环境污染之间存在着密切的联系,对两者关系进行更为深入、全面的研究显得十分必要。本文首先利用DEA方法和环境污染治理成本法分别测算了我国1989-2007年的全要素能源效率和环境污染经济损失;在初步评判两者关系的基础上,进一步通过协整和ECM模型得到本文的结论:我国的全要素能源效率与环境污染经济损失之间存在长期均衡关系,前者是后者的Granger原因;同时,全要素能源效率的短期波动对于降低环境污染经济损失具有明显的作用,这种作用大于长期波动的影响。这意味着全要素能源效率的提高对减少环境污染具有重要作用,节能减排目标的实现离不开能源效率的作用。     

农业生产污染对经济增长绩效的影响程度研究——基于环境全要素生产率的分析

本文在使用单元调查评估法对中国农业污染物排放量进行核算的基础上,结合SBM模型、方向性距离函数和GML指数,对1995-2013年中国农业生产效率和全要素生产率进行测算,考察农业生产污染对农业经济增长绩效的影响。结果表明:1不考虑污染因素的农业经济增长核算方法忽略了农业生产污染造成的损失,导致农业全要素生产率被高估近一倍;2投入冗余和污染过度是农业生产无效率的主要来源,且后者对其影响更为明显;3中国农业生产率增长主要来自技术进步,技术效率对其促进作用有限;4考虑污染成本与否会对各地经济增长绩效评价产生较大影响,忽略污染因素可能导致政策偏误。     

Nitrate Dynamics in Two Streams Impacted by Wastewater Treatment Plant Discharge: Point Sources or Sinks?

We examined nitrate processing in headwater stream reaches downstream of two wastewater treatment plant outfalls during low streamflow. Our objectives were to quantify nitrate mass flux before and after effluent discharge and to use field and laboratory techniques to assess the mechanism of nitrate uptake. Microcosm experiments were utilized to determine the location of nitrate processing, and molecular biomarkers were used to detect and quantify microbial denitrification. At one site, downstream nitrate mass flux was significantly (p = 0.01) lower than sum of upstream and wastewater effluent fluxes, indicating rapid stream assimilation of incoming nitrate in the vicinity of the point source. Microcosm experiments supported the theory that nitrate processing occurs in sediments. Molecular assays for denitrifcation‐associated functional genes nosZ, nirS, and nirK, provided evidence that effluent contained enriched denitrifying communities relative to ambient stream water. Nitrate loss at the site with greater uptake was correlated with sulfate loss (p < 0.01; r² = 0.86), suggesting a possible link between sulfate reducing bacteria and denitrifying bacterial communities. Results suggest there is an opportunity to better understand nitrate dynamics in cases where point sources may act as point sinks under specific sets of conditions.     

A GIS Framework for Regional Modeling of Riverine Nitrogen Transport: Case Study,San Antonio and Guadalupe Basins

This article presents a framework for integrating a regional geographic information system (GIS)‐based nitrogen dataset (Texas Anthropogenic Nitrogen Dataset, TX‐ANB) and a GIS‐based river routing model (Routing Application for Parallel computation of Discharge) to simulate steady‐state riverine total nitrogen (TN) transport in river networks containing thousands of reaches. A two‐year case study was conducted in the San Antonio and Guadalupe basins during dry and wet years (2008 and 2009, respectively). This article investigates TN export in urbanized (San Antonio) vs. rural (Guadalupe) drainage basins and considers the effect of reservoirs on TN transport. Simulated TN export values are within 10 percent of measured export values for selected stations in 2008 and 2009. Results show that in both years the San Antonio basin contributed a larger quantity than the Guadalupe basin of delivered TN to the coastal ocean. The San Antonio basin is affected by urban activities including point sources, associated with the city of San Antonio, in addition to greater agricultural activities. The Guadalupe basin lacks major metropolitan areas and is dominated by rangeland, rather than fertilized agricultural fields. Both basins delivered more TN to coastal waters in 2009 than in 2008. Furthermore, TN removal in the San Antonio and Guadalupe basins is inversely related to stream orders: the higher the order the more TN delivery (or the less TN removal).     

基于纳污能力控制的省区初始排污权ITSP配置模型

省区初始排污权配置具有多阶段性、复杂性及不确定性特征。面向水功能区限制纳污红线约束,根据省区初始排污权配置的基本假设,引入区间数和随机数来描述不确定性信息,以因省区初始排污权配置产生的经济效益为第1个阶段,以因承担减排责任而可能产生的治污损失为第2个阶段,设计实现流域经济效益最优的目标函数,并以配置结果能够体现社会效益、生态环境效益和社会经济发展连续性为约束条件,构建基于纳污能力控制的省区初始排污权区间两阶段随机规划(ITSP)配置模型,分水污染物类别确定不同减排情形下的省区初始排污权配置方案。在三种减排情形下,2020年太湖流域各省区的初始排污权配置结果表明:1江苏省、浙江省和上海市的COD初始排污权配置区间量没有明显变化,其NH3-N和TP初始排污权配置区间量总体呈上升或递增趋势;2太湖流域各省区因初始排污权的配置产生的总体经济效益最优区间数分别为[335.35,399.75]亿元、[336.63,401.11]亿元和[339.08,402.74]亿元,最优区间数的下限值、上限值及期望值总体呈上升或递增趋势。分类确定不同减排情形下的配置方案,并提出方案实施的政策建议,为排污权配置决策提供更为准确的决策空间。