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321.
Effects of major nutrient additions on metal uptake in phytoplankton 总被引:14,自引:0,他引:14
We examined the influences of major nutrients (N, P, Si) on the accumulation of three trace metals [Cd, Se(IV), and Zn] in four species of marine phytoplankton (diatom, green alga, dinoflagellate, prasinophyte). Relative metal uptake was quantified by the kinetic measurements of metal concentration factor over a short exposure period. Our study demonstrated that nutrient addition significantly influenced the metal uptake rate and the cell growth rate in all four phytoplankton species. An increase in ambient N concentration considerably enhanced metal uptake by the cells. The dry weight concentration factor increased by 2.4-14.9 times for Cd, 1.1-4.0 times for Se, and 1.1-5.4 times for Zn in all four phytoplankton species with an addition of 176.4 microM N. The effects of P or Si addition on metal uptake and cell growth were less pronounced than the effects of N addition. Under most circumstances the rate of metal uptake increased exponentially with increasing cell growth rate constant. Only Se(IV) uptake in the diatom Phaeodactylum tricornutum was not correlated with cell growth rate. Se(IV) was not accumulated by the green algae Chlorella autotrophica at a high P concentration (7.2 microM), but appreciable accumulation was documented in cells inoculated without P addition. Our study therefore demonstrated that nutrient enrichments in many coastal waters can considerably affect trace metal uptake in phytoplankton and presumably metal trophic transfer in marine food chains. 相似文献
322.
Effect of surfactants at low concentrations on the sorption of atrazine by natural sediment. 总被引:1,自引:0,他引:1
A series of experiments were carried out to determine the effect of surfactants at low concentrations on the sorption of atrazine by natural sediments. With surfactant concentrations ranging from 0 to 20 mg/ L, anionic and cationic surfactants appreciably reduce the adsorption of atrazine, while nonionic surfactant decreases the adsorption of atrazine at concentrations equal to or less than 1 mg/L and increases adsorption at higher concentrations. Desorption of atrazine in the presence of different sodium dodecylbenzene sulfonate (SDBS) concentrations shows that a portion of the bound pesticide resists desorption in the SDBS free system. However, the addition of SDBS accelerates the desorption of atrazine. Furthermore, the nature of sediment and the contacting sequence of SDBS, at 10 mg/L, with the sediment, also influence the adsorption of atrazine. The conclusions in this study could be explained partially by the effect of the type and concentration of surfactants and the characteristics of sediments. 相似文献
323.
Ambrose RB Tsiros IX Wool TA 《Journal of the Air & Waste Management Association (1995)》2005,55(5):547-558
This paper presents a modeling analysis of airborne mercury (Hg) deposited on the Ochlockonee River watershed located in Georgia. Atmospheric deposition monitoring and source attribution data were used along with simulation models to calculate Hg buildup in the subwatershed soils, its subsequent runoff loading and delivery through the tributaries, and its ultimate fate in the mainstem river. The terrestrial model calculated annual watershed yields for total Hg ranging from 0.7 to 1.1 microg/m2. Results suggest that approximately two-thirds of the atmospherically deposited Hg to the watershed is returned to the atmosphere, 10% is delivered to the river, and the rest is retained in the watershed. A check of the aquatic model results against survey data showed a reasonable agreement. Comparing observed and simulated total and methylmercury concentrations gave root mean square error values of 0.26 and 0.10 ng/L, respectively, in the water column, and 5.9 and 1 ng/g, respectively, in the upper sediment layer. Sensitivity analysis results imply that mercury in the Ochlockonee River is dominated by watershed runoff inputs and not by direct atmospheric deposition, and that methylmercury concentrations in the river are determined mainly by net methylation rates in the watershed, presumably in wetted soils and in the wetlands feeding the river. 相似文献
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326.
曾光 《安全.健康和环境》2010,10(8):41-42
1员工援助计划员
工援助计划(Employee Assistance Program,EAP),即企业员工心理服务,最早起源于20世纪30年代的美国。当时企业开始注意到员工的酗酒、吸毒和其他一些药物滥用问题会影响到员工的工作绩效。到了20世纪60、70年代,由于美国社会的变动,这些问题变得更加突出。工作压力、家庭暴力、离婚、纠纷等众多个人问题接踵而来,于是一些企业开始聘请专家帮助员工解决这些问题,这就是最初的员工援助计划。随着EAP的不断发展,越来越多的国际大企业都引入了EAP项目。 相似文献
327.
疾病预防控制机构废水具有重金属种类繁多、含病原体数量大、间断性排放等特点,通过运用混凝沉淀+曝气生物滤池(BIOFOR)+ClO2消毒工艺对其废水进行处理,处理后废水达到《医疗机构水污染物排放标准(》GB18466-2005)排放标准。 相似文献
328.
福建省城市生活饮用水源地水质状况及保护措施 总被引:1,自引:0,他引:1
以2003年-2008年饮用水源地水质监测数据为基础,对福建省城市生活饮用水源地水质进行评价及趋势分析。评价结果表明:福建省城市生活饮用水源地水质总体较好,水质逐年改善,冬半年水质优于夏半年,湖库型水源地未出现水质富营养化现象;不同水体类型水源地中,地下水型水源地水质最好,河流型水源地次之,湖库型水源地水质较差。本文针对福建省城市生活饮用水源地水质状况及存在的安全问题,提出了相应的饮用水源地保护措施,为领导决策部门提供一定的理论依据。 相似文献
329.
地方政府要做好自然灾害应对工作必须统筹兼顾两个方面的工作:一是在自然灾害应对的法规、组织等层面上切实发挥政府的主导作用;二是充分发挥多元主体参与的作用,集聚社会力量共同参与自然灾害应对。努力形成组织规范、运转协调的政府主导下的多元主体参与的自然灾害应对模式,切实提高地方政府自然灾害应急管理的能力和水平。 相似文献
330.
正The Journal of Environmental Sciences(JES)is honored to welcome Professors/Drs William A.Mitch,Jiuhui Qu,Susan D.Richardson,Jerald L.Schnoor,Hongxiao Tang,Shu Tao,and Hugh A.Tilson to serve on the Editorial Advisory Board(EAB).Their tremendous experience in scientific publications,leading expertise in topic areas pertinent to JES,diverse international networks/perspectives,and exemplary dedication to scientific excellence will guide and help the continuing healthy growth of JES. 相似文献