溴氯海因在水环境中的降解及其对4种水生生物的急性毒性

研究了新型消毒剂溴氯海因(BCDMH)在水环境中的降解规律及其影响因素以及BCDMH对4种不同生态位水生生物(发光菌、小球藻、大型溞和斑马鱼)的急性毒性.结果表明:1)BCDMH的正辛醇/水分配系数(Kow)为3.74(25℃),在水环境中的降解符合一级动力学方程C=C0×e-k·t,其一级反应速率常数k随温度升高而增大,25℃时k值为0.3577,半衰期为1.72d.2)pH6～9时,pH值越低BCDMH降解越快,碱性条件对其降解有显著抑制;自然光照和曝气有利于BCDMH的降解.3)BCDMH对斑马鱼的96hLC50=3.68mg·L-1,属高毒;对大型溞的24hLC50=1.44mg·L-1,属高毒;对小球藻的96hEC50=4.15mg·L-1,属高毒;对发光菌的1hEC50=0.62mg·L-1,属极高毒.     

TIMBER HARVEST IMPACTS ON SMALL HEADWATER STREAM CHANNELS IN THE COAST RANGES OF WASHINGTON1

ABSTRACT: We evaluated changes in channel habitat distributions, particle‐size distributions of bed material, and stream temperatures in a total of 15 first‐or second‐order streams within and nearby four planned commercial timber harvest units prior to and following timber harvest. Four of the 15 stream basins were not harvested, and these streams served as references. Three streams were cut with unthinned riparian buffers; one was cut with a partial buffer; one was cut with a buffer of non‐merchantable trees; and the remaining six basins were clearcut to the channel edge. In the clearcut streams, logging debris covered or buried 98 percent of the channel length to an average depth of 0.94 meters. The slash trapped fine sediment in the channel by inhibiting fluvial transport, and the average percentage of fines increased from 12 percent to 44 percent. The trees along buffered streams served as a fence to keep out logging debris during the first summer following timber harvest. Particle size distributions and habitat distributions in the buffered and reference streams were largely unchanged from the pre‐harvest to post‐harvest surveys. The debris that buried the clearcut streams effectively shaded most of these streams and protected them from temperature increases. These surveys have documented immediate channel changes due to timber harvest, but channel conditions will evolve over time as the slash decays and becomes redistributed and as new vegetation develops on the channel margins.     

EFFECT OF A POINT SOURCE INPUT ON STREAM NUTRIENT RETENTION1

ABSTRACT: We examined the effect of a point source (PS) input on water chemistry and nutrient retention in Spavinaw Creek, Arkansas, during summer baseflows in 1998 and 1999. The nutrient uptake length (S_w) concept was used to quantify the impact of nutrient inputs in the receiving stream. We used an artificial injection upstream of the PS inputs to estimate background S and used the natural decline in nutrient concentrations below the PS to estimate the net nutrient uptake length (S_net). S_w for soluble reactive phosphorus (SRP) in the upstream reference section was O.75 km, but S_net ranged from 9.0 to 31 km for SRP and 3.1 to 12 km for NO₃‐N in the reach below the PS. S_net‐SRP was significantly correlated with discharge whereas S_net‐NO₃‐N was correlated with the amount of NO₃‐N enrichment from the PS. In order to examine specific mechanisms of P retention, loosely exchangeable P and P Sorption Index (PSI) of stream sediments were measured. Sediments exhibited little natural P buffering capacity (low PSI) above the PS, but P loading from the PS further reduced PSI. Loosely exchangeable P in the sediments also increased three fold below the PS, indicating sediments removed some water column P. The physical process of flow and sediment sorption apparently regulated P retention in Spavinaw Creek, whereas the level of N enrichment and possibly biotic uptake and denitrification influenced N retention. Regardless of the mechanism, Spavinaw Creek demonstrated little ability to retain PS‐added nutrients because net nutrient uptake lengths were in the km range.     

三氯生在水生生态系统中的污染现状及其生物毒性效应

三氯生(triclosan, TCS)是一种合成型广谱类抗菌剂,广泛应用于人类的生产生活,使用中伴随生活污水进入环境并已广泛分布,其中水生生态系统是TCS的主要污染区域之一。通过汇总分析国内外不同类型水生生态系统中TCS的调查研究结果,发现TCS已经普遍存在于淡水和近海水生生态系统中,生活污染处理厂出水是河流中TCS的主要污染源,区域污染水平与人口密度和工业发展程度密切相关;水体中的浓度受降雨、河口区潮汐作用以及季节影响; TCS对水生生物存在显著毒性效应,其效应浓度因物种而异,与生物的发育阶段也有关系。     

3种有机磷农药对水生生物的乙酰胆碱酯酶抑制效应的物种敏感度分析初探

通过筛选敌敌畏、马拉硫磷和对硫磷3种有机磷农药对水生生物的急性毒性数据和乙酰胆碱酯酶抑制效应数据,构建物种敏感度分布曲线进行了比较分析。结果表明,敌敌畏对水生生物的急性毒性和乙酰胆碱酯酶抑制效应的大小顺序为:酶体内抑制效应酶体外抑制效应急性毒性;马拉硫磷和对硫磷的乙酰胆碱酯酶抑制效应数据不足但趋势相似,顺序为:酶体内抑制效应急性毒性酶体外抑制效应。敌敌畏的急性毒性和酶体外抑制效应的5%危害浓度(HC5)分别为2.07μg·L~(-1)和1.53μg·L~(-1),两者相差1.4倍。在水质基准推导中,乙酰胆碱酯酶抑制效应数据对有机磷农药的水生生物基准具有重要的参考价值。     

杀虫剂三唑磷在室内淡水微宇宙中的生态效应

作为一种中等毒性的有机磷杀虫剂,三唑磷在稻区的使用十分普遍。为弄清其对淡水生态系统的影响,选择5组浓度(0、0.35、1.75、17.5、52.5μg·L~(-1)),在以藻类作为营养源的室内微宇宙系统内进行研究,采用多变量分析软件CANOCO 5对数据进行分析。非限制性排序和多重比较的结果表明,给药后0~6 d,三唑磷对于浮游动物群落的最高无作用浓度(NOEC_(community))和最低有效浓度(LOEC_(community))分别为17.5μg·L~(-1)和52.5μg·L~(-1)。给药后第9天,最高浓度组(52.5μg·L~(-1))的群落结构开始恢复,此刻三唑磷在水中的实测浓度平均值为4.35μg·L~(-1)。对于单个物种种群密度做差异显著性分析和多重比较,结果显示浮游动物当中受影响最大的是绿色湖湾介Strandesia viridis。给药30 d后,该物种在52.5μg·L~(-1)处理组的种群密度明显下降,历时57 d的试验结束时,种群密度仍未恢复到对照水平。对于藻类,非限制性排序和多重比较的结果显示三唑磷在群落层次的影响未达到能够明显区分NOEC_(community)和LOEC_(community)的程度。在单物种层面,在给药后9~12 d,三唑磷对单细胞的羊角月牙藻Selenastrum capricornutum种群有刺激作用。其NOECspecies和LOECspecies分别为1.75μg·L~(-1)和17.5μg·L~(-1)。没有迹象表明三唑磷的引入能够明显改变水体pH、电导、浊度和水体C循环状况。结合暴露评估软件GNEEC(Version 2.0)输出的环境浓度(峰值为2.44μg·L~(-1)),本研究结果显示三唑磷在正常使用剂量下有可能对稻田周边浮游动物群落的内部结构造成扰动,但是它不会对整个系统造成不可恢复的影响。     

洱海湖滨带挺水植物残体腐解特征及其环境效应初探

采用试验模拟的方法,研究洱海4种主要挺水植物茭草(Zizania caduciflora)、香蒲(Typha latifolia)、水葱(Scirpus validus)和芦苇(Phragnites australis)在水体中的腐解特征. 结果表明:在21 d的腐解试验中,水葱腐解速率最快,茭草和香蒲其次,芦苇最慢; 挺水植物单位干物质TN释放量表现为水葱>茭草≈香蒲>芦苇,TP释放量表现为水葱>茭草>香蒲>芦苇; 4种植物TP释放率均高于TN,腐解出的TP进入水体的比例也明显高于TN. 水体中ρ(TN),ρ(TP)及ρ(COD_Cr)均在腐解初期(1～3 d)快速上升,pH和ρ(DO)快速下降; 随后,ρ(TN),ρ(TP)及ρ(COD_Cr)均缓慢下降,pH和ρ(DO)则缓慢回升. 结合洱海湖滨带挺水植物空间分布的调查结果,估算全湖湖滨带4种挺水植物中TN和TP的总质量分别为17.622和2.870 t,其中茭草和香蒲中的TN和TP分别占91%和95%,对茭草和香蒲进行适时、适宜的收割对改善湖滨带的水质具有重要的意义.      

太湖生物区系研究及与北美五大湖的比较

研究太湖水生生物区系特征,分析各类生物区系的变化及其原因,并与北美五大湖相应的水生生物区系进行了比较. 结果表明:太湖共有水生生物146科442种,其中鱼类25科107种,占24.2%; 底栖动物21科66种,占14.9%; 浮游动物37科103种,占23.3%; 浮游植物29科81种,占18.3%; 水生植物34科85种,占19.2%. 总体上太湖各类水生生物的种数和科数差别都不大,鱼类和浮游动物稍多. 北美五大湖各类水生生物的种数分别为鱼类134种、底栖动物165种、浮游动物132种以及浮游植物1 456种,除浮游植物种类较多外,其他3类水生生物的种数与太湖大致相当. 五大湖鱼类以鲑科和鲤科鱼类为主体,分别占鱼类总数的18.7%和20.1%,其中除伊利湖外其他4个湖都是鲑科占优势; 太湖鱼类以鲤科为主体,占鱼类总数的56.1%,这是太湖鱼类区系的主要特征,也是我国淡水鱼类的主要特征,所以鲤科是我国水质基准推导的优先选择物种. 太湖和五大湖中鱼类、底栖动物和浮游动物3类生物所占比例差别不大.      

淮河蚌埠段采样点鱼虾贝类重金属的富集

应用WFX-110型原子吸收分光光度法测定淮河蚌埠段污染较重采样点鱼虾贝类不同组织中重金属(Cu,Mn,Zn,Fe,Ni,Cd和Pb)的含量.结果表明:在同一组织中w(Fe),w(Zn),w(Cu),w(Mn)和w(Ni)高于w(Cd)和w(Pb),变化趋势为日本沼虾>河蚌>鱼;鱼虾贝类不同组织重金属含量变化趋势为w(Fe)>w(Mn)>w(Zn)>w(Ni)>w(Cu)>w(Pb)>w(Cd).w(Cu),w(Mn),w(Zn)和w(Fe)在肠、鳃、肝胰脏等组织中较高,在精巢、肌肉等组织中较低;w(Ni),w(Cd)和w(Pb)在肝胰脏、鳃等组织中较高,在肌肉、脑等组织中较低.其中,日本沼虾和河蚌对重金属元素的富集能力明显强于淡水鱼类;而肝胰脏和鳃是鱼虾贝类体内重金属富集的主要部位;其食用部分w(Cd)和w(Pb)均超过无公害食品水产品中有害物质限量(NY 5073—2006)和人体卫生消费标准,因此不宜食用,表明淮河蚌埠段采样点附近生物受重金属影响明显.      

水生植物重建工程对小柘皋河富营养化水质的净化效果

利用筛选出来的芦苇(Phragmites australis Trin)、茭草〔Zizania latifolia (Griseb.) Stapf〕、香蒲(Typha orientalis Presl.)、菱角(Trapa natans Linn.)、莲(Nelumbo nucifera Gaertn)和菹草(Potamogeton crispus Linn.)6个工具物种,在小柘皋河道内进行水生植物群落重建恢复试验工程,并对该河道工程区内的水质进行1 a检测. 结果表明:恢复后小柘皋河植被面积占整个河道的65%～75%,河道水生植物年生产量约1.42×106 kg(以湿质量计),相当于1.98×1012 J(能量);河道内的水生植物都具有一定的抗水力冲击负荷能力,能适应河道污水水质和水量均不稳定的动态变化特征,并对污水中COD_Cr,TN,NO₃--N,TP和NH₄+-N等均有去除作用,去除率平均值分别为23.61%,25.00%,26.37%,32.93%和33.55%.