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131.
The accelerated eutrophication of freshwaters and to a lesser extent some coastal waters is primarily driven by phosphorus （P） inputs. While efforts to identify and limit point source inputs of P to surface waters have seen some success, nonpoint sources remain difficult to identify, target, and remediate. As further improvements in wastewater treatment technologies becomes increasingly costly, attention has focused more on nonpoint source reduction, particularly the role of agriculture. This attention was heightened over the last 10 to 20 years by a number of highly visible cases of nutrient-related water quality degradation; including the Lake Taihu, Baltic Sea, Chesapeake Bay, and Gulf of Mexico. Thus, there has been a shift to targeted management of critical sources of P loss. In both the U.S. and China, there has been an intensification of agricultural production systems in certain areas concentrate large amounts of nutrients in excess of local crop and forage needs, which has increased the potential for P loss from these areas. To address this, innovative technologies are emerging that recycle water P back to land as fertilizer. For example, in the watershed of Lake Taihu, China one of the largest surface fresh waters for drinking water supply in China, local governments have encouraged innovation and various technical trials to harvest harmful algal blooms and use them for bio-gas, agricultural fertilizers, and biofuel production. In any country, however, the economics of remediation will remain a key limitation to substantial changes in agricultural production. 相似文献
132.
扎兰屯市十分重视环境保护事业的发展,特别是"十一五"期间,环境质量有了突破性改善。环保局以科学发展观为指导思想,认真梳理工作中的经验做法,存在问题。重点在污染减排、环境监管、环保投资、环保意识提高、建设项目管理、维护群众的合法权益等方面与各基层环保交流经验,寻求在突破,积极探索美丽与发展双赢的新道路。 相似文献
133.
We report on the effects of forest management practices of understory removal and N-fixing species (Cassia alata) addition on soilCO2 fluxes in an Eucalyptus urophylla plantation (EUp), Acacia crassicarpa plantation (ACp), 10-species-mixed plantation (Tp), and30-species-mixed plantation (THp) using the static chamber method in southern China. Four forest management treatments, including(1) understory removal (UR); (2) C. alata addition (CA); (3) understory removal and replacement with C. alata (UR+CA); and (4)control without any disturbances (CK), were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season (from April to September), followed bya rapid decrease after October reaching a minimum in February. Soil CO2 fluxes were significantly higher (P < 0.01) in EUp (132.6mg/(m2·hr)) and ACp (139.8 mg/(m2·hr)) than in Tp (94.0 mg/(m2·hr)) and THp (102.9 mg/(m2·hr)). Soil CO2 fluxes in UR and CAwere significantly higher (P < 0.01) among the four treatments, with values of 105.7, 120.4, 133.6 and 112.2 mg/(m2·hr) for UR+CA,UR, CA and CK, respectively. Soil CO2 fluxes were positively correlated with soil temperature (P < 0.01), soil moisture (P < 0.01),NO3?-N (P < 0.05), and litterfall (P < 0.01), indicating that all these factors might be important controlling variables for soil CO2fluxes. This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various managementpractices. 相似文献
134.
采用傅立叶变换红外光谱(FTIR)对典型稻田生态系统长期定位试验的土壤有机质(SOM)结构进行分析,探讨不同施肥处理下表层与深层土壤有机质的分布差异及其稳定性机制.结果表明,长期不同施肥措施下稻田表层土壤有机碳(SOC)含量以有机-无机肥配施处理最高,其中高量有机肥(HOM)、低量有机肥(LOM)和秸秆还田(STW)处理较对照(CK)处理分别增加了18.5%、12.9%和18.4%.土壤有机质的化学结构也存在一定的差异性,与CK相比,施肥处理均增加了土壤中化学抗性化合物(脂族性、芳香族)、碳水化合物以及有机硅化合物的官能团吸收强度,其中HOM、LOM和STW处理最为明显.以烷烃类化合物为例,HOM、LOM和STW处理下其吸收强度为0.30、0.25和0.29,较CK分别增加了87%、56%和81%.表层土壤有机质各官能团的吸收峰强度皆高于深层土壤,同样以HOM、LOM和STW处理的差异最显著.本研究结果揭示了长期有机-无机肥配施下对亚热带稻田土壤有机质较丰富的化学抗性官能团结构的影响,贡献于其较高的有机质含量,这也从一方面揭示了稻田土壤有机质积累的化学稳定机制. 相似文献
135.
针对流域非点源污染的关键源区,配置最佳管理措施（BMPs,Best Management Practices）是非点源污染控制的有效途径.然而,受限于研究成本和不同地区自然地理条件的差异性,通过实地监测对BMPs削减效率进行评估的研究案例还不多见.多数相关研究仅关注单一类型BMPs的效率评估,使得研究成果仅仅适用于某些特定区域.对BMPs的潜在效益进行评估,可通过收集不同区域内BMPs的削减效率信息来实现.本文采用基于文献的BMPs效率评估方法,通过整理国内154篇关于BMPs研究的文献信息,建立适用于农业流域非点源污染控制的BMPs数据库.在此基础上,采用VBA（Visual Basic for Applications）和SQL（Structured Query Language）程序语言构建BMPs削减效率评估工具箱.该工具箱适用于非点源污染控制措施削减效率的评估,能够根据不同研究区特征,给出目标BMPs的污染负荷削减量,从而为BMPs的优选提供定量依据.以密云水库上游蛇鱼川小流域为案例研究区,根据该流域的非点源污染特征,对拟采用的BMPs进行评估,结果表明：草型植物篱、25 m河岸缓冲带、河岸带畜禽活动护栏以及集中放牧等措施控制效率最高. 相似文献
136.
以2001年在东北典型黑土上进行的保护性耕作长期定位试验下免耕、垄作及常规耕作土壤进行了室内培养实验,按照田间持水量(water-holding capacity,WHC)的30%、60%、90%、120%、150%、180%、210%、240%、270%设定了9个水分梯度,并分别对其二氧化碳(CO_2)排放量进行了22 d的短期观测,以研究不同耕作方式下土壤水分状况对土壤呼吸的初期影响.结果表明:1干土条件下在加水培养初期,3种耕作方式均产生了明显的激发效应,并且土壤呼吸速率与土壤含水量间存在正相关关系.2除干旱(30%WHC)及淹水(240%WHC、270%WHC)条件下,3种耕作方式CO_2排放通量分别为免耕垄作常规耕作.3对不同耕作方式下土壤水分状况及CO_2排放通量进行了方程拟合,在30%~270%WHC条件下,免耕的CO_2排放通量与水分状况拟合为二次回归方程,而垄作与常规耕作则是线性回归方程.在30%~210%WHC条件下,免耕与垄作下土壤CO_2排放通量与水分状况均可拟合为较好的对数方程,可决系数R~2分别为0.966、0.956. 相似文献
137.
Terence J. Centner Nicholas S. Eberhart 《Journal of Environmental Planning and Management》2016,59(4):746-768
The public is concerned that activities accompanying hydraulic fracturing in the development of shale gas resources are unnecessarily adversely affecting them and the environment and is petitioning elected representatives to take actions to reduce risks. The health risks associated with fracturing chemicals and air pollutants are relatively unknown and constitute the impetus for public concern. An evaluation of state legal and regulatory provisions regarding best management practices discloses that states are not adopting timely regulations to protect people and the environment from activities accompanying hydraulic fracturing. Simultaneously, regulatory policy concerning negative externalities suggests that governments underinvest in the protection of human health and environmental quality. Governments have choices in protecting people from dangers that accompany shale gas development. Due to the risks of injuries and unpaid damages from shale gas development, governmental policies need to evolve to accord people greater health protection. 相似文献
138.
Manufacturing firms are striving to improve their sustainable performance in order to satisfy multiple stakeholders. Eco-innovation is a promising approach that decreases environmental impact and helps firms to increase their business value. There are several antecedents which help the firms to innovate and improve their triple bottom line performance. Among the antecedents, management and innovative practices are directly related to eco-innovation. It is not well known what practices and innovations help the firms to eco-innovate as well as to improve sustainable performance. Hence, the research objective of this paper is to identify the suitable combination of management and innovative practices that help firms to eco-innovate as well as to achieve overall sustainable performance. The paper develops an eco-innovation conceptual model which relates the management and innovative practices (antecedents) and overall sustainable performance (consequences) of eco-innovation using institutional theory. Using Indian manufacturing sector’s empirical data and Structural Equation Modelling (SEM) approach, this paper determines the effect of eco-innovation’s antecedents and consequences. In the Indian context, this study suggests that the role of management practice is more significant towards eco-innovation than innovative practices. The results reflect practitioners’ view on how to increase innovation rate and to focus more on social aspects. The finding suggests that training on environmental related practices could tackle innovation and social aspects in the Indian manufacturing sector context. 相似文献
139.
140.
The nutrient and pesticide abatement efficiency of varying mixtures was examined in a vegetated free water surface constructed wetland. Three different agricultural chemical pollutant mixture conditions were assessed: nutrients only (N and P); pesticides only (atrazine, S-metolachlor and permethrin); and a mixture of nutrients and pesticides. With nutrients only, 672 h nutrient mitigation of 77–91% total phosphorous (TP) and 74–98% total nitrogen (TN) was associated with distance from the injection point and rainfall, whereas with nutrient and pesticide mixtures, 672 h nutrient mitigation of 11–71% TP and 84–98% TN were associated with distance and time. With pesticides only, 672 h pesticide mitigation of 50–99% was associated with distance and time, whereas with nutrients and pesticide mixtures, 672 h pesticide mitigation of 48–99% was associated primarily with distance. Dissipation half-lives were 2–10 times greater for P and 1.5–5 times greater for N when pesticides were present. Pesticide dissipation half-lives showed no clear differences with or without nutrients. While vegetated free water surface constructed wetlands can be effective best management practice tools to trap and abate agricultural run-off during rainfall events, efficiencies can be affected by different types of complex pollutant mixtures and wetland design and implementation should accommodate varying efficiencies. 相似文献