二氨基萘分光光度法测定饮用水中硒

为建立测定饮用水中硒的分光光度法 ,研究了硒与二氨基萘反应产物的吸收光谱特性、共存离子干扰、测量范围、检出限、精密度和准确度。结果表明 :Se4+与 2 ,3-二氨基萘反应产物的最大吸收波长为 377nm,摩尔吸光系数 ε377=2 .7× 10 4L/ (mol·cm) ,检出限 0 .0 18μg,线性范围 0 .2～ 10 μg/ ml,回归方程 A=0 .0 77C+0 .0 14,相关系数 r=0 .9999,相对标准偏差小于 5 .47% ,回收率 96 .5 %～ 10 6 %。该方法具有简便、灵敏、准确等特点 ,能满足饮用水中硒的常规监测     

Factors Controlling the Bioaccumulation of Mercury, Methylmercury, Arsenic, Selenium, and Cadmium by Freshwater Invertebrates and Fish

Concentrations of mercury (Hg), methylmercury (MMHg), arsenic (As), selenium (Se), and cadmium (Cd) were measured in atmospheric deposition, stream water, and biota in two streams in western Maryland. Overall, concentrations were slightly higher in the water of the lower pH Herrington Creek tributary (HRCT). Bioaccumulation factors were also higher for HRCT compared to Blacklick Run (BLK). MMHg concentrations in biota increased with trophic level and essentially all the Hg was as MMHg in predatory insects and insectivorous/carnivorous fish. Thus, the overall trophic status of the organism was indicated by the %MMHg in its tissues. Levels of As, Se, Cd, and Hg, however, decreased with increasing trophic level. Adsorption of As to the exoskeleton of invertebrates appears to be an important accumulation mechanism. MMHg was distributed evenly throughout crayfish and fish organs, whereas As, Se, Cd, and Hg were found in higher concentrations in detoxifying organs. Concentrations in biota in this study were somewhat elevated compared to other rural sites, but were less than those of point source–contaminated sites. Overall, as atmospheric inputs to the two watersheds were similar, the results of this study show the importance of water chemistry in determining the bioaccumulation of the metals and metalloids into insects. Subsequent transfer to higher trophic levels is related to both the ability of the organisms to depurate and the mode of accumulation, either directly from water or from food. Received: 19 April 1999/Accepted: 12 October 1999     

Bioaccumulation of Copper, Iron, and Zinc by Pinus halepensis (Miller)

No abstract available.     

荧光分光光度法测定水中硒的改进

用二氨基萘荧光法测定水中硒进行的改进,改进后,其标准系列线性良好,硒含量在０－２．５μｇ／Ｌ范围内符合比尔定律,相关系数ｒ＝０．９９８８,回归方程ｙ＝４１．５１ｘ－４．３０４。最低检出浓度为０．１２５μｇ／Ｌ。本法简化了操作过程,减少了污染机会,得到了较好的精密度和准确度。     

水中砷、硒的双道原子荧光测定法

[目的]探讨水中砷、硒同时测定的方法,提高工作效率。[方法]用湿法消解样品,双道原子荧光法测定,砷灯电流50 mA,硒灯电流80 mA,负高压280 V,介质酸度20%,硼氢化钾浓度1.5%。[结果]砷在0~40μg/L线性良好,相关系数0.9998,检出限0.17μg/L,相对标准偏差1.13%~4.57%,回收率88.5%~98.0%;硒在0~20μg/L线性良好,相关系数0.9993,检出限0.24μg/L,相对标准偏差2.92%~5.49%,回收率87.0%~95.7%。[结论]该法可适用于水中砷和硒的同时测定。     

催化动力学光度法测定植物中的痕量硒(Ⅳ)

在酸性介质和三乙醇胺存在下，硒(Ⅳ)能催化硫化钠氧化亚甲基兰褪色。研究了这一催化反应的动力学条件，建立了利用动力学光度法测定硒(Ⅳ)的新方法。该方法的检测限为3.74×10-7g/L，硒的含量在0～50μg/50ml范围内与褪色反应的A0—A呈线性关系。该方法具有良好的选择性和准确度，用于植物中痕量硒(Ⅳ)的测定，结果满意。     

催化动力学光度法测定植物中的痕量硒(IV)

在酸性介质和三乙醇胺存在下 ,硒 (IV)能催化硫化钠氧化亚甲基兰褪色。研究了这一催化反应的动力学条件 ,建立了利用动力学光度法测定硒 (IV)的新方法。该方法的检测限为3 .74× 1 0 - 7g/ L,硒的含量在 0～ 5 0 μg/ 5 0 ml范围内与褪色反应的 A0 -A呈线性关系。该方法具有良好的选择性和准确度 ,用于植物中痕量硒 (IV)的测定 ,结果满意     

Selenium (selenate) transport by human placental brush border membrane vesicles

1. Selenate uptake by human placental brush-border-membrane vesicles was studied in order to establish whether this anion shares a pathway with sulphate. 2. Selenate uptake was found to be saturable with respect to medium selenate and was inhibited by the anion exchange inhibitor 4,4'-diisothiocyano-stilbene-2,2'-disulphonate (DIDS). 3. Anions which have a similar tetrahedral shape to selenate, e.g. chromate, molybdate, tungstate and sulphate, were effective inhibitors of selenate uptake when added to the incubation medium. 4. Sulphate inhibited selenate influx in a dose-dependent fashion; moreover sulphate was found to be a competitive inhibitor of selenate uptake. 5. It is concluded that selenate and sulphate share a pathway for transport in the human placental microvillus membrane.     

Mercury and Selenium Bioaccumulation in the Smooth Hammerhead Shark, Sphyrna zygaena Linnaeus, from the Mexican Pacific Ocean

We analyzed total mercury and selenium bioaccumulation in muscle tissue and cartilage fibers (fins) from smooth hammerhead shark, Sphyrna zygaena, caught off Baja California Sur, Mexico. In muscle tissue, the mercury concentration ranged from 0.005 to 1.93 μg g⁻¹ ww (wet weight), which falls within the safety limits for food set by international agencies (Hg > 1.0 μg g⁻¹ ww). Only one specimen showed a mercury value that exceeded this limit. In fins, the mercury bioaccumulation was lower (<0.05). Selenium in muscle ranged from 0.11 to 1.63 μg g⁻¹ ww, while in fins it ranged from 0.13 to 0.56 μg g⁻¹ ww.     

Sexual characteristics are altered by 4-tert-octylphenol and 17beta-estradiol in the adult male guppy (Poecilia reticulata)

Endocrine-disrupting chemicals (EDCs) are believed to interfere with animal reproduction, but only few biomarkers above the cellular level have been developed to assess the adverse effects of these chemicals. Using the guppy (Poecilia reticulata) as a model organism, studies have been undertaken with the object of comparing biomarker responses to EDCs at increasing levels of biological complexity. Short-term exposure to the xenoestrogen 4-tert-octylphenol and the natural estrogen 17beta-estradiol (E2) changed important sexual characteristics in the adult male guppy. Both compounds increased the number of sperm cells in the ejaculates, reduced the area and color intensity of the sexually attractive orange spots, and inhibited testis growth. In the case of E2, the effects on sperm count and coloration were still evident after 3 months of recovery in clean water. Preliminary results on male reproductive capability demonstrated that treated males produced fewer offspring than untreated fish, indicating an impairment of reproduction itself.     

原子荧光光度法同时测定水中砷和硒

目的建立用原子荧光光度法对生活饮用水中砷和硒进行同时分析的方法。方法采用双道原子荧光光度计、砷、硒高性能空心阴极灯等,在含砷10 ng/ml、含硒20 ng/ml的体系中进行。结果砷、硒的检出限分别为0.0088 ng/ml、0.02 ng/ml;回收率砷95.5%～101.4%、硒94.5%～100.6%;相对标准偏差砷在1.7%～4.2%之间、硒在2.7%～7.8%之间。线性范围砷在1.0～10.0 ng/ml浓度范围内,相关系数0.9998;硒在2.0～20.0 ng/ml浓度范围内,相关系数0.9993。测定结果与GB/T5750-2006测定水样中砷和硒的结果比较差异无统计学意义（P〉0.05）。结论此方法简化了测定砷和硒的操作步骤,缩短了检验时间,具有灵敏度高,稳定性强等优点。     

Investigation of acute toxicity of deltamethrin on guppies (Poecilia reticulata)

Deltamethrin, a synthetic pyrethroid pesticide contaminating aquatic ecosystems as a potential toxic pollutant, was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) were selected for the bioassay experiments. The 48-h LC50 was determined for the guppies. The experiments were repeated three times and a total of 210 guppies were used. The static test method of acute toxicity test was used. In addition, behavioral changes at each deltamethrin concentration were determined for the individuals. Data obtained from the deltamethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The 48-h LC50 value for guppy was estimated as 5.13 microg/L.