长江中游典型湖泊沉积物重金属分布特征、生态风险评估及溯源

集中采集洞庭湖、洪湖和赤湖表层沉积物样品并检测其中10种重金属含量,使用地理信息系统表征空间分布,利用地累积污染指数法（I_geo）、富集因子法（EF）和潜在生态风险指数法（RI）协同评估重金属积累的潜在风险,并利用相关性分析（Pearson）和主成分分析（PCA）溯源.结果表明,Cd元素的污染状况和潜在生态风险最为严重,东洞庭湖、洪湖和赤湖中ω（Cd）的平均值分别为2.85、1.59和3.57 mg·kg^-1,分别是对应省份土壤背景值的25.87、11.36和37.58倍,均超出风险筛选值（0.6 mg·kg^-1）,其中赤湖超出风险管制值（3.0 mg·kg^-1）.除Cd外,洪湖中的As值得关注,赤湖中的Cu、As、Zn和Pb都不容忽视.三湖的潜在生态风险排序为：赤湖（RI=1 127）>东洞庭湖（RI=831）>洪湖（RI=421）.重金属来源主要是工矿业冶采、农业生产和水产养殖等,部分重金属（Mn和Cu）为自然源.研究对长江中游典型湖泊沉积物重金属防控具有重要意义.     

下蜀土边坡地震稳定性的大型振动台试验研究(Ⅰ)——模型试验设计

为研究下蜀土边坡的地震稳定性,选用天然下蜀土,按照Meymand的相似法则,对一坡高为0.5m、宽度为1.05m、坡角为45°的模型边坡进行了几何相似常数为20的1g大型振动台模型试验详细设计。首先,运用数值模拟的方法确定了模型边坡尺寸适当的边界范围,模型边坡地基厚度、坡脚前缘和坡肩后缘长度均取为0.5m;其次,按照确定的模型几何尺寸设计了符合试验要求的模型箱,其内壁净尺寸(长×宽×高)为1500mm×1050mm×1100mm,属刚性模型箱,且不会与模型边坡发生共振;最后,制定了包括加速度和位移在内的数据量测策略,运用拟静力法求得下蜀土边坡平均屈服加速度为0.561g,综合确定了地震动峰值(PGA)按0.1g、0.3g、0.6g和0.9g的顺序逐级加载的原则,并制定了详细的试验步骤,从而可保障试验得到可靠的结果。     

淡水沉积物中Cd和Cu对河蚬的毒性效应研究

以淡水底栖动物河蚬(Corbicula fluminea)为受试生物,研究了淡水沉积物中重金属Cd和Cu对河蚬的12h挖洞行为和10d存活率的影响.结果表明,河蚬对加标Cd和Cu的淡水沉积物均产生了明显的规避行为.在12h挖洞行为试验中,河蚬对沉积物中Cd的污染反应比Cu更加灵敏,暴露于Cd和Cu的10mg/kg的沉积物中时,河蚬的挖洞比率分别为0.39和0.43.在10d存活率试验中,河蚬的存活率随沉积物中Cd和Cu浓度的升高而降低.在Cd加标浓度为10mg/kg的沉积物中,河蚬的存活率为93.3%,当Cd加标浓度达到300mg/kg时,河蚬存活率降为43.3%;在Cu加标浓度为10mg/kg的沉积物中,河蚬存活率为96.3%;而当Cu加标浓度达到500mg/kg时,河蚬存活率降为34.3%.加标Cd和Cu的两种淡水沉积物对河蚬的LC₅₀分别为285、690mg/kg,表明河蚬对Cd的毒性反应更加灵敏.比较河蚬的挖洞行为和存活率对重金属Cd和Cu的指示作用,挖洞行为比存活率更加快捷,对沉积物中Cd和Cu的指示作用更加明显,故在沉积物重金属污染监测中应优先考虑挖洞行为.     

东海海域表层沉积物中硫酸盐还原菌分布特征研究

利用2011年4、7、8和10月对东海海域4个航次的调查资料,以表层沉积物中硫酸盐还原菌（SRB）为研究对象,针对于SRB所共有的异化型亚硫酸盐还原酶（DSR）中的β亚基基因（dsrB）,通过荧光定量PCR技术对SRB丰度的时空分布特征进行了描述.结果表明,SRB丰度变化范围为1.87×105~4.69×10⁸cells/g,平均值为1.15×10⁸cells/g,且4月SRB丰度最低,7月SRB丰度最高;SRB数量在总细菌中的比例介于0.0039%~1.6176%之间,说明SRB在东海表层沉积物的细菌总量中比例很小;SRB丰度的水平分布特征整体表现为南部海域高于北部海域,长江口及浙闽沿岸泥质区高于非泥质区.此外,SRB丰度与环境因子的相关性分析表明,温度和溶解氧是影响SRB丰度的重要因素.     

Aliphatic and polycyclic aromatic hydrocarbons in the bottom sediments from Klaipėda Harbour,Lithuania (Baltic Sea)

A total of 22 bottom surface sediment samples were collected from Klaip?da Harbour, Lithuania (Baltic Sea). Sediment parameters, such as grain size and concentrations of total organic carbon, aliphatic hydrocarbons (ALHs) and polycyclic aromatic hydrocarbons (PAHs), were determined. Hydrocarbon contamination levels in the sediments were estimated based on classifications provided in the literature, and potential biological effects were assessed based on the effects range low–effects range median values of the Sediment Quality Guidelines and on the total toxic benzo(a)pyrene equivalent. The results demonstrated that concentrations of PAHs and total aliphatic hydrocarbons in the sediments varied between 1.6 and 5456?ng?g^?1 d.w. and 6.9 and 727?μg?g^?1 d.w., respectively. In most cases, the concentrations of ALHs and PAHs in the sediments indicated low to moderate levels of pollution and were not observed to have any significant adverse effects on living biota. To determine possible sources of hydrocarbons, hydrocarbon compositions were analysed, and ALHs’ and PAHs’ specific diagnostic ratios were calculated. According to the results, the Klaip?da Harbour bottom sediments were dominated by PAHs of pyrogenic origin, whereas the origin of ALHs was mixed, that is, anthropogenic with a biogenic (aquatic and terrestrial) input.     

Sequence of the main geochemical controls on the Cu and Zn fractions in the Yangtze River estuarine sediments

Metal speciation can provide sufficient information for environmental and geochemical researches. In this study, based on the speciation determination of Cu and Zn in the Yangtze Estuary sediments, roles of eight geochemical controls (i.e., total organic carbon (TOC), clay, Fe/Mn in five chemical fractions and salinity) are fully investigated and sequenced with correlation analysis (CA) and principal components analysis (PCA). Results show that TOC, clay and Fe/Mn oxides are key geochemical factors affecting the chemical speciation distributions of Cu and Zn in sediments, while the role of salinity appears to be more indirect effect. The influencing sequence generally follows the order: TOC>clay>Mn oxides>Fe oxides>salinity. Among the different fractions of Fe/Mn oxides, residual and total Fe content, and exchangeable and carbonate Mn exert the greatest influences, while exchangeable Fe and residual Mn show the poorest influences.     

沸石覆盖原位控制湖泊内源中等活性有机磷迁移转化

为揭示湖泊内源中等活性有机磷(MLOP)控制与释放发生机制,采用室内模拟试验,研究沸石覆盖原位控制湖泊内源MLOP迁移转化影响因子.结果表明:酸性水体促进内源MLOP迁移,碱性条件下抑制其转化,不同pH值试验水体沉积物中内源MLOP相对浓度为:[MLOP/TP]pH8>[MLOP/TP]pH7>[MLOP/TP]pH6;温度明显提高内源MLOP迁移水平,低温水体相对高温水体沉积物中内源MLOP含量较低,5℃条件下内源MLOP迁移表观量最大,其随时间迁移量呈幂函数关系,可表示为[MLOP/TP]=0.2823T0.657(R2为0.9709);好氧或厌氧条件下,内源MLOP均发生迁移,且迁移特征和影响效能高度一致,迁移平衡后好氧环境内源MLOP和厌氧内源MLOP相对浓度呈线性相关,可表示为[MLOP/TP]好氧环境=1.0884[MLOP/TP]厌氧环境 -0.0271(R2为99895);光照因子促使内源MLOP迁移,而避光和沸石粒径因素对内源MLOP迁移影响较小;底栖生物颤蚓通过爬行、摄食、掘穴、栖所建造及分泌排泄等一系列活动影响内源MLOP迁移.沸石原位控制湖泊内源MLOP迁移转化效能较弱.     

蠡湖表层沉积物中磷的形态与赋存特征及其生物有效性

采用连续分级提取法研究了蠡湖表层沉积物中有机磷和无机磷的形态及其赋存特征,同时结合间隙水体中DTP(溶解性总磷)的空间分布特征,讨论了各形态磷的生物有效性及其释放风险. 结果表明,蠡湖沉积物中的磷以IP(无机磷)为主,w(IP)占w(TP)的58.09%. IP中以生物可利用性差的Ca-P_i(Ca结合态无机磷)占优势,w(Ca-P_i)为(207.75±48.56)mg/kg,占w(IP)的48.97%;沉积物OP(有机磷)中以活性最差的NA-P_o(非活性有机磷)占绝对优势,w(NA-P_o)为(195.33±50.73)mg/kg,占w(OP)的67.09%. 间隙水中的磷以DIP(溶解性无机磷)为主,ρ(DIP)占ρ(DTP)的11.86%~86.13%,平均值为59.65%. WA-P_i(弱吸附态无机磷)、PA-P_i(潜在活性无机磷)、Fe/Al-P_i(Fe/Al结合态无机磷)、WA-P_o(弱吸附态有机磷)、PA-P_o(潜在活性有机磷)的质量分数均与间隙水中ρ(DTP)呈极显著正相关(P<0.01),w(Ca-P_i)与间隙水中ρ(DTP)呈正相关(P<0.05),w(NA-P_o)与间隙水中ρ(DTP)无显著的相关性. 因此,即使在外源磷得到有效控制的情况下,沉积物中的IP及高活性有机磷的释放仍有可能导致湖泊富营养化状态维持不变.      

黄土丘陵区不同土地利用类型下生物土壤结皮的入渗效应

为揭示黄土丘陵区BSCs(生物土壤结皮)的入渗特征,以甘肃省定西市安家沟小流域为例,选择荒草地、沙棘灌丛和油松林3种典型土地利用类型进行采样,采用环刀模拟法研究不同土地利用类型下苔藓结皮和地衣结皮对水分入渗的影响. 结果表明:①不同土地利用类型下的2种BSCs均明显减少初渗速率和达到稳渗所需时间,初渗速率降幅最小值、最大值分别出现在油松林、荒草地下地衣结皮;荒草地、沙棘灌丛苔藓结皮稳渗速率相对裸土分别增加2.4%、10.0%,而二者地衣结皮明显降低稳渗速率,降幅分别为45.2%和55.0%,油松林下苔藓结皮和地衣结皮稳渗速率均增幅为18.2%. ②苔藓结皮在3种土地利用类型下均促进土壤水分入渗,其入渗量调控率在荒草地、沙棘灌丛和油松林下分别是1.0%、10.0%和0.7%;而地衣结皮在荒草地和沙棘灌丛下明显阻碍水分入渗,其入渗量调控率的绝对值分别为43.9%和50.0%,在油松林下的入渗量调控率则为16.5%. ③Horton模型对生物土壤结皮入渗过程拟合效果最好,较适于描述本区具有生物结皮覆盖的土壤入渗特征.      

Determination of polychlorinated biphenyl and polycyclic aromatic hydrocarbon marine regional Sediment Quality Guidelines within the European Water Framework Directive

Marine regional Sediment Quality Guidelines (SQG) for polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) from the Basque coast (SE Bay of Biscay) were determined, on the basis of sediment chemistry, toxicity and benthic community disturbance from analysis of 756 estuarine and coastal samples. The SQG were calculated using a percentile approach (based upon effect and non-effect data), using non-normalised and normalised concentration, by total organic carbon. However, normalisation by total organic carbon did not result in any improvement in accuracy compared with non-normalised values. Hence, this study proposes non-normalised SQG values for assessment of the chemical and physicochemical status in marine waters in the Basque Country, within the Water Framework Directive: 24.6–29 μg kg^?1 for total PCBs; 164–285 μg kg^?1 for low molecular weight PAH; 922–1537 μg kg^?1 for high molecular weight PAH; and 1607–2617 μg kg^?1 for total PAH.