【作者】 姚庆祯；

【导师】 张经；

【作者基本信息】 华东师范大学 ， 自然地理学， 2006， 博士

【摘要】 本文在实验室建立了天然水中溶解态砷、硒的氢化物发生原子吸收光谱法（HG—AAS）的测定体系。并在此基础上，研究了长江主流、主要支流、长江口海域及崇明东滩湿地砷、硒的生物地球化学行为。 于2003年4—5月对长江流域各主要的支流及主流沿程采样，对河水中常量离子、溶解和颗粒态砷、硒进行了分析。长江阳离子以钙为主，而阴离子主要为HCO₃^-，阴阳离子含量顺序为HCO₃^-＞SO₄^2-＞Cl^-，Ca²⁺＞Na⁺＞Mg²⁺＞K⁺。长江主流的Na⁺、Mg²⁺、Ca²⁺、HCO₃^-和Cl^-主要来自于上游；主流及主要支流河水的常量离子主要来自于岩石的风化，而大气沉降的影响很小，只有SO₄^2-受大气沉降影响较大。 长江主流各站溶解态无机砷、硒的浓度变化幅度不大，下游浓度略高于上游；主流溶解态砷、硒的浓度分别在12.28—35.6nmol／L、2.20—5.58nmol／L范围内波动；溶解态砷中以As（Ⅴ）为主，As（Ⅲ）／As比值变化范围为0.17—0.43。颗粒态砷、硒的变化范围为6.87—17.8、0.34—1.19mg／kg。长江支流溶解态砷、硒的浓度明显高于主流，且跨度较大，北方支流中砷、硒的浓度明显高于南方支流，支流溶解砷的变化范围分别为6.95—56.7nmol／L。赤水河砷的含量最低，而沱江和湘江的含量最高；溶解态砷中在赤水、岷江和牛栏江以As（Ⅴ）为主，其它支流则以As（Ⅲ）为主。支流溶解硒的变化范围分别为1.47—9.92nmol／L，最高浓度出现在沱江。长江流域河水中砷、硒含量主要受两方面因素影响：一、流域盆地不同的岩石、土壤类型是造成不同支流砷、硒含量差异的初步原因；二、人为活动对长江河水砷、硒含量有重大影响；部分支流如沱江、岷江、嘉陵江及湘江则主要来自人为活动的输入；而上游地区砷、硒含量受酸沉降影响较大。主流溶解态砷、硒的通量从上游到下游呈逐渐增加的趋势，上游对溶解砷、硒的入海通量贡献较小，而洞庭湖水系的贡献较大，约占长江入海通量的80％。三峡工程对颗粒态砷、硒的入海通量影响较大。 分别于2004年9月和2005年8月利用“海监47号”和“海监49号”科学调查船在长江口海域采集不同层次的水样，测定水样及底沉积物中砷、硒以了解痕量元素砷、硒。长江口海域溶解砷、As（Ⅲ）含量的变化范围分别为13.5—25.2、未检出—5.22nmol／L，平均值分别为17.9、1.76nmol／L；无机砷以As（Ⅴ）为主，As（Ⅲ）占总无机砷的比例为0—39.7％，平均比例为9.8％。溶解硒的变化范围分别为1.50—5.70nmol／L，平均含量为3.35nmol／L。底沉积物砷、硒含量变化范围较大，分别为3.87—13.1、0.067—0.23mg／kg，最高含量出现在长江口附近，而最低含量则在台湾暖流影响的区域。生物作用对溶解态硒的分布影响较大，而对溶解态更多还原

【Abstract】 A method for the determination of dissolved selenium and arsenic by Hydride Generate Atomic Absorbed spectrometry （HG-AAS） are established in this study. The method is applied to the study of selenium and arsenic in the Changjiang, Changjiang Estuary and Chongming wetland.The chemistry of major elements, dissolved arsenic and selenium, suspend arsenic and selenium in the river water of the Changjiang （Yangtze River） and its tributaries were studied in April-May 2003. HCO₃^- is the most abundant anion of the changjiang, concentrations of anions follows the order HCO₃^->SO₄^2->Cl^-; Among the cations, Ca²⁺ is predominant, Concentrations of cations vary in the order Ca²⁺>Na⁺>Mg²⁺>K⁺. The result show that the dissolved load of the Changjiang relative to water discharge and in absoulate terms is very high compared with other major waters. Atmosphere input of major elements to the Changjiang is very limited. Weathering and erosion are primary importance in affecting river chemistry, which accelerated by anthropogenic activities （e.g. farming）. Comparison of major element fluxes reveals high chemical loads of Changjiang, which are disproportionate to its limited water discharges.The chemistry of trace element （arsenic and selenium） in the river water of Changjiang （Yangtze River） was studied, based on continuously monitored data at Nantong station, the main Changjiang channel and major tributaries. The results show that the dissolved inorganic arsenic （DIAs） and dissolved inorganic selenium （DISe） concentrations of the Changjiang varies over an order of magnitude throughout the basin （6.95-68.9 nmol/L for DIAs, 1.16-9.92 nmol/L for DISe）. Source rock composition is the primary control on the concentrations of DIAs and DISe in the Changjiang water. Several tributaries （e.g. Xiangjiang, Minjiang and Tuojiang） are contaminated human activities. Flux calculations at Datong （the most downstream main-channel station without tidal influence） indicate that the Changjiang transports 17.6×10⁶mol/a of DIAs and 3.27×10⁶mol/a of DISe to the East China Sea.Two cruises of "Hiajian 47" and "Hiajian 47" were carried out in September 2004 and August 2005, respectively, to understand the behaviors of selenium and arsenic in the Changjiang Estuary. Selenium and Arsenic concentrations display short-term variability and seasonal change in the Changjiang Estuary, with higher更多还原