The kinetics of reductive dehalogenation of a set of halogenated aliphatic hydrocarbons in anaerobic sediment slurries

Disappearance rate constants are reported for the reductive transformation of 17 halogenated aliphatic hydrocarbons in anaerobic sediment-water samples. Statistical experimental design in combination with multivariate chemical characterization of their chemical properties was used to select the compounds. Degradation followed pseudo first-order kinetics through at least two half-lives for 15 of the 17 compounds. Of all the compounds investigated, 1,2,3-trichloropropane and dichloromethane were unique in that they were dehalogenated according to zero-order kinetics. Reductive dehalogenation was the sole transformation reaction taking place.     

白洋淀沉积物耗氧速率及氧亏效应研究

沉积物耗氧是影响水体溶解氧平衡的重要因素,受到沉积物有机质矿化的影响.本文采用柱培养法测定了白洋淀不同水文地貌分区和生境类型的表层沉积物耗氧速率(sediment oxygen demand,SOD),并基于地表水质量标准评估了白洋淀沉积物耗氧对水体产生的氧亏效应,探讨了白洋淀SOD与有机质(OM)的关系.结果表明,白...     

“R1-R4” AND “BOISED” SEDIMENT PREDICTION MODEL TESTS USING FOREST ROADS IN GRANITICS1

ABSTRACT: Erosion and sedimentation data from research watersheds in the Silver Creek Study Area in central Idaho were used to test the prediction of logging road erosion using the R1-R4 sediment yield model, and sediment delivery using the “BOISED” sediment yield prediction model. Three small watersheds were instrumented and monitored such that erosion from newly constructed roads and sediment delivery to the mouths of the watersheds could be measured for four years following road construction. The errors for annual surface erosion predictions for the two standard road tests ranged from +31.2 t/ha/yr (+15 percent) to -30.3 t/ha/yr (-63 percent) with an average of zero t/ha/yr and a standard deviation of the differences of 18.7 t/ha/yr. The annual prediction errors for the three watershed scale tests had a greater range from -40.8 t/ha/yr (-70 percent) to +65.3 t/ha/yr (+38 percent) with a mean of -1.9 t/ha/yr and a standard deviation of the differences of 25.2 t/ha/yr. Sediment yields predicted by BOISED (watershed scale tests) were consistently greater (average of 2.5 times) than measured sediment yields. Hillslope sediment delivery coefficients in BOISED appear to be overly conservative to account for average site conditions and road locations, and thus over-predict sediment delivery. Mass erosion predictions from BOISED appear to predict volume well (465 tonnes actual versus 710 tonnes predicted, or a 35 percent difference) over 15 to 20 years, however mass wasting is more episodic than the model predicts.     

泥沙对双酚A的吸附及其影响因素研究

以黄河泥沙为例,用SPE HPLC MS MS的方法分析了双酚A在泥沙上的吸附规律及其影响因素.结果表明,由于黄河泥沙碳酸盐含量较高,双酚A的等温吸附规律不能用线性吸附方程和Freundlich吸附方程来描述;去除泥沙中碳酸盐后,泥沙对双酚A的吸附量增加,且其吸附规律可用线性吸附方程和Freundlich吸附方程来描述.泥沙总有机质含量和可溶态有机质含量都会影响双酚A的吸附,沉积物和悬浮物对双酚A的吸附量分别与其可溶态有机质含量负相关;由于价态不同,钙离子和钾离子对双酚A的吸附影响规律相反,随着钙离子浓度的增加双酚A吸附量亦增加,而随着钾离子浓度的增加双酚A吸附量却减少.     

紫外可见分光光度法测定湖泊沉积物中的色素

对新疆博斯腾湖沉积物柱样中叶绿素、胡萝卜素、颤藻黄素和蓝藻黄素等几种色素进行了提取并用紫外可见分光光度法进行测定 ,计算了沉积物中几种色素的含量。沉积物中色素指标的分析 ,可以帮助揭示博斯腾湖的环境、历史气候变化等特征     

滇池水体和沉积物中营养盐的分布特征

在滇池外海不同方位选取6个采样点,研究了水质现状,沉积物Eh,pH,总氮,总磷以及间隙水重金属的剖面分布特征。结果表明,滇池水体仍属富营养化状态。在氧化表层下,Eh随沉积深度的增加迅速降低,沉积物深层为还原状态。pH在沉积物剖面变化不大,为7 0～8 5。滇池沉积物含有丰富的营养物质,总氮和总磷最高质量分数分别为8 67和3 46g kg。剖面分布表明,沉积物表层总氮和总磷含量远高于底层,在表层0～10cm含量随深度增加而迅速降低。重金属元素在水-土界面的浓度梯度为沉积物向水体的扩散提供了条件。不同采样点相比,位于昆明市附近的S6点沉积物内负荷较大。在外源减少的情况下,沉积物内负荷可能在一定时间内成为控制滇池水质的主导因子。      

底栖穴居动物对潮滩N迁移转化的影响

以软体动物河蚬(Corbiculafluminea)为例,运用实验模拟的方法,通过对上覆水、孔隙水和沉积物的对比分析,研究了底栖动物对潮滩N迁移转化的影响。实验结果发现,河蚬主要通过排泄和生物扰动影响N在沉积物-水界面间的迁移转化。在富氧的环境下,底栖动物的活动结果使NO3 N在上覆水中有明显的持续累积效应,NH4 N在较深层孔隙水中积累,而NO2 N易在沉积物中累积。     

陕北多沙粗沙区乡村聚落土壤侵蚀的典型流域调查与估算——以碾庄沟流域为例

随着乡村聚落的发展,陕北多沙粗沙区乡村聚落土壤侵蚀的严重性已经凸显。以碾庄沟流域为例,研究了乡村聚落土壤侵蚀方式,并对侵蚀总量进行了估算。结果显示:从乡村聚落土壤侵蚀的主要方式来看,以新建窑洞的弃土侵蚀最大,窑洞坍塌侵蚀次之,聚落水蚀侵蚀量最小,其中塌窑侵蚀和建窑侵蚀两项合计占到乡村聚落土壤侵蚀总量的94.6%;从乡村聚落的侵蚀总量来看,面积占1.08%的乡村聚落产生的侵蚀量却占到全流域侵蚀总量的6.83%,人居侵蚀模数达6.3万t/(km2.a)或8.18 t/(人.a)。因此,对乡村聚落土壤侵蚀应加以重视,而土壤侵蚀的防治工作应该以新建窑洞的管理和废弃窑洞坍塌的治理为重点。     

Kinetics study of aqueous sorption of phenanthrene to humic acids and sediments

IntroductionThesorptionofhydrophobicorganiccontaminants(HOCs)onnaturalgeosorbentsplaysasignificantroleintheirtransport,degradationandultimatefateintheaquaticenvironment (Alexander,1995 ;Luthy ,1997;Weber,2 0 0 1) .Sincethelate 1970s,theorganicmatter(OM)ha…     

镉"加标"沉积物对泥鳅(Misgurnus anguillicaudatus)生物毒性研究

选择泥鳅(Misgurnus anguillicaudaus)作为受试生物,以泥鳅死亡率、血液红细胞数量、红细胞体积、红细胞微核率和核异常率作为测试指标,考察了沉积物中"加标"金属镉(Cd)的毒性状况,探讨了水体沉积物中重金属的生物毒性影响.结果表明:高有机质的粘土粉砂性沉积物能够有效吸附重金属镉;镉加标暴露组泥鳅的死...