CONTROL OF SUSPENDED SOLIDS AND PHYTOPLANKTON WITH FISHES AND A MUSSEL1

ABSTRACT: Filtering efficiency of the fathead minnow (Pimephales promelas), gizzard shad (Dorosoma cepedianum), carp (Cyprinus carpio), and a freshwater mussel (Elliptio coinpianata) was measured in field and laboratory trials to assess the ability of each species to control phytoplankton and suspended solid densities. All fish species tested were ineffective filterers and generally increased, rather than suppressed, algal and suspended solid concentrations. Filtering efficiencies of fish varied between -354 and 84 percent, depending on the size, shape, abundance, palatability, composition, and resistance to digestion of the particles. Because of poor filtering abilities, unpredictable feeding habits, and sensitivity to stress, the fish species examined are not effective biological controls in waste lagoons. In contrast, the freshwater mussel Elliptio was a highly effective control organism, averaging 66 percent filtering efficiency over a wide size range of algal and suspended particles. Filtration efficiency was positively correlated with mussel density. Elliptio was efficient at filtering small particles, which are particularly difficult to remove. Mean filtration rates ranged from 53 to 134 ml/mussel/h depending on the algal species consumed and algal densities (range 50–180,000 cells/ml) and 3 mg/L/mussel/h on suspended solids (range 14 to 112 mg/L). Water clarification was facilitated by both direct consumption and pseudofeces deposition. Elliptio and probably other mussel species can effectively control algae and suspended solids in wastewater lagoons and eutrophic lakes, if environmental conditions, especially dissolved oxygen levels, are suitable (>5 mg/L) for their survival.     

Establishing the link between ammonia emission control and measurements of reduced nitrogen concentrations and deposition

In the context of international efforts to reduce the impactsof atmospheric NH₃ and NH₄ ⁺ (collectively, NH_x), it is important to establish the link between NH₃emissions and monitoring of NH_x concentrations and deposition. This is equally relevant to situations where NH₃emissions changes are certain (e.g. due to changed source sectoractivity), as to cases where NH₃ abatement technologies havebeen implemented. Correct interpretation of adequate atmosphericmeasurements is essential, since monitoring data provide the onlymeans to evaluate trends in regional NH₃ emissions.These issues have been reviewed using available measurements and modelling from nine countries. In addition to historic datasets,the analysis here considers countries where NH₃ source sector activity changed (both increases and decreases) and countries where NH₃ abatement policies have been implemented.In The Netherlands an `ammonia gap' was identified between the expected reduction and results of monitoring, and was attributedinitially to ineffectiveness of the abatement measures. The analysis here for a range of countries shows that atmospheric interactions complicate the expected changes, particularly sinceSO₂ emissions have decreased at the same time, while at manysites the few years of available data show substantial inter-annual variation. It is concluded that networks need to beestablished that speciate between NH₃ and aerosol NH₄ ⁺, in addition to providing wet deposition, and sample at sufficient sites for robust regional estimates to be established. Such measurements will be essential to monitor compliance of the international agreements on NH₃ emission abatement.     

云南省国际河流水质状况及其保护

介绍了云南省红河，澜沧江，怒江和伊洛瓦底江4大国际河流水系2000年的水质状况，对其1991－2000年的水质变化趋势及其主要污染因素进行了分析。据此提出了“十五”期间和以后较长一段时间内水环境治理的综合对策和措施。     

东营市地下淡水资源及其可持续开发利用

根据新兴城市东营市严重缺乏淡水资源的现实状况和本区内地下淡水资源是由浅层地下淡水、深层地下淡水和淡水透镜体组成的现状,在深入研究本区地下淡水的补给和动态变化的基础上,提出了从补给、开采和利用等各个层次上采取开源节流、循环利用、科学规划等方式,实现本区地下淡水资源的可持续利用.     

正确认识绿色贸易壁垒

绿色贸易壁垒能促进广大发展中国家不断提高产品的环境保护水平,保护本国的生态环境,但在环保大潮的冲击下,一些贸易企业会由于产品不符合要求而面临出口困境。本文以绿色贸易壁垒产生的原因及应采取的措施等方面进行论述,指出绿色贸易壁垒既是挑战又是机遇,要正确认识绿色贸易壁垒。     

Greening up: the effects of environmental standards in EU and US trade agreements

Can environmental provisions in preferential trade agreements (PTAs) foster an environmental race to the top? The ways in which different enforcement mechanisms in North–South PTAs affect the implementation of environmental standards in developing countries are examined. It is argued that environmental provisions in European Union (EU) and United States (US) PTAs will be effective in instigating policy change in partner countries, although the timing of the effect will vary significantly. Fines and sanctions in US PTAs incentivize partner countries to reform during the negotiation process. Reform in EU PTA partners is predicted to occur during agreement implementation as a result of the EU’s policy dialogue approach. Illustrative evidence is provided and the hypotheses are tested using statistical estimations of EU and US PTAs with environmental provisions on developing countries’ environmental policy reform.     

States,coalitions, and the legalization of the global climate regime: negotiations on the post-2020 architecture

Why do some states and state coalitions, acting within the United Nations Framework Convention on Climate Change (UNFCCC), support harder legalization of the global climate regime? In order to explain why, the effects of four causal factors are considered: climate vulnerability, the emission intensity of the national economy, a state’s power position, and socialization into climate norms. To identify the legalization positions of UNFCCC actors, an original content analysis is conducted of all the submission and meeting statements made at the Ad Hoc Working Group on the Durban Platform during the years 2012–2015. Subsequently, a qualitative comparative analysis is carried out to find out which combinations of the causal factors offer a sufficient explanation for the analyzed outcome, leading to the identification of two causal pathways that lead states to endorse harder legalization of the climate regime.     

Domestic politics and the formation of international environmental agreements

We investigate the effect of domestic politics on international environmental policy by incorporating into a classic stage game of coalition formation the phenomenon of lobbying by special-interest groups. In doing so, we contribute to the theory of international environmental agreements, which has overwhelmingly assumed that governments make decisions based on a single set of public-interest motivations. Our results suggest that lobbying on emissions may affect the size of the stable coalition in counterintuitive ways. In particular, a powerful business lobby may increase the government's incentives to sign an agreement, by providing it with strong bargaining power with respect to that lobby at the emission stage. This would result in lower total emissions when the number of countries involved is not too large. We also show that things change radically when lobbying bears directly on the membership decisions, suggesting that both the object and timing of lobbying matter for the way in which membership decisions, emissions and welfare are affected.     

Linking Soil Erosion to Instream Dissolved Phosphorus Cycling and Periphyton Growth

Phosphorus (P) is a limiting nutrient in freshwater systems and when present in runoff from agricultural lands or urban centers may contribute to excessive periphyton growth. In this study, we examined the link between soil erosion and delivery of eroded soil to streams during flow events, and the impact of that freshly deposited soil on dissolved reactive P (DRP) concentrations and periphyton growth under baseflow conditions when the risk of stream eutrophication is greatest. A microcosm experiment was designed to simulate the release of P from soil which had been amended with different amounts of P fertilizer to overlying water during baseflow conditions. Unglazed tiles, inoculated for five days in a second order stream, were incubated for seven days in microcosms containing soil with eight levels of soil Mehlich‐3 plant available phosphorus (M3P) ranging from 20 to 679 mg/kg M3P. Microcosm DRP was monitored. Following incubation tiles were scraped and the periphyton analyzed for chlorophyll a. Microcosm DRP concentrations increased with increasing soil M3P and equilibrium phosphorus concentration (EPC₀). Relationships between M3P, EPC₀, and DRP were nonlinear and increases in soil M3P and/or DRP had a greater impact on biomass accumulation when these parameters were above threshold values of 30 mg/kg M3P and 0.125 mg/L DRP. Significantly, this ecological threshold corresponds to the agronomic thresholds above which increased soil M3P does not increase plant response.     

切尔诺贝利核电站事故后果模式估算国际比对

介绍我国参加国际原子能机构（IAEA）组织的“切尔诺贝利核电站事故后果模式估算国际比对”中采用的模式及其估算结果与实测值以及与其地各国估算结果的比较。提出土壤表面沉积量与农作物可食部分核素浓度估算模式（属半动态模式,其余模式采用国内通用的静态模式）。比较结果表明,对事故后当年的浓度预测结果与实测值符合较好,对事故后第２年及更长时间的预测结果明显偏高,有待改进。