Lake Water Environment Research Articles

Fuzzy mathematic assessment model of lake water environment and its application to lake eutrophication rank

本文根据模糊水文学关于水体清洁与污染之间无明确界面,在识别过程中具有模糊性的论点,提出湖泊水环境评价的模糊数学模型。应用此模型对我国12个湖泊富营养化污染状况进行排序,结果与实际相符,文中提出的评价模型,原则上也适用于其他环境领域的评价工作。;According to the thesis of fuzzy hydrology that there exists no definite limits between clean and polluted waters but fuzzy characteristics in the process of the recognition, the authors present the following fuzzy mathematic model of lake water environmental assessment and rank:??? The model is applied to the rank of the eutrophication situations for J2 lakes in China* and the results are in agreement with the facts.Moreover,the model is suitable to the assessments in other environmental fields.

Microcosm for assessing survival of genetically engineered microorganisms in aquatic environments

Laboratory-contained microcosms are important for studying the fate and survival of genetically engineered microorganisms. In this study, we describe a simple aquatic microcosm that utilizes survival chambers in a flowthrough or static renewal system. The model was used to study the survival of genetically engineered and wild-type strains of Escherichia coli and Pseudomonas putida in the lake water environment. Temperature-dependent studies indicated that the genetically engineered microorganisms survived better or at least as well as their wild-type counterparts at 15, 25, and 30 degrees C. The genetic determinants of the genetically engineered microorganisms also remained fairly stable within the host cell under the tested conditions. In the presence of organisms indigenous to lake water, E. coli was eliminated after 20 days, whereas P. putida showed an initial decline but was able to stabilize its population after 5 days. A herbicide, Hydrothol-191, caused a significant decline in numbers of P. putida, but no significant difference was observed between the genetically engineered microorganisms and the wild-type strain. The microcosm described is simple, can be easily adapted to study a variety of environmental variables, and has the advantage that the organisms tested are constantly exposed to test waters that are continuously renewed.

Pitting Corrosion Behavior of Alloy 800 in Chloride-Sulfate Media

Abstract Potentiodynamic polarization techniques were used to determine characteristic pitting potentials for Alloy 800 in chloride and chloride-sulfate media. The effect of chloride concentration in the range of 0.001 to 1 M was investigated. Decreasing chloride concentrations resulted in noble shifts of the critical nucleation potential. Immunity to pitting corrosion was evident at chloride levels below 0.01 M. Increasing sulfate concentrations resulted in improved chloride pitting resistance, although detrimental effects associated with pitting at transpassive potentials were evident with low-level sulfate additions to dilute chloride media. Potentiodynamic and potentiostatic polarization results for Alloy 800 in a lake water environment were found to be consistent with that predicted on the basis of lake water chloride and sulfate contents.