澜沧江梯级水坝库区沉积物重金属和营养盐污染特征及评价

为研究梯级水坝运行条件下沉积物中重金属和营养盐的污染状况,于2016年对澜沧江漫湾和大朝山梯级水坝库区表层沉积物中重金属(As、Cd、Cr、Cu、Pb和Zn)和营养盐(总有机碳TOC、总氮TN)的污染特征展开了调查,并采用潜在生态风险指数(RI)、有机指数(OI)、有机氮百分数(ONP)、TOC/TN和Pearson相关分析评价了梯级水坝库区沉积物污染状况及空间分布特征.结果表明,沿着库区河流纵向梯度,重金属和营养盐污染均表现为坝前静水区相对较高的空间分布格局.重金属潜在生态风险指数(RI)评价结果表明,上游漫湾库区重金属生态风险(I～III级)总体高于下游大朝山库区(I～II级);而营养盐污染程度则表现为下游大朝山库区高于上游漫湾库区的分布格局.两库区沉积物有机质主要由水库水体产生,漫湾库区坝前静水区雨季有机质来源主要为陆源.Pearson相关分析表明,沉积物重金属生态风险与营养盐污染的来源具有一定的空间差异性.梯级水坝工程对沉积物的重金属和营养盐污染具有显著的累积和拦截效应.     

南方丘陵区河流表层沉积物重金属污染评价

采样分析南方丘陵山区瓯江、钱塘江、闽江、九龙江沉积物中重金属含量,并对其来源及生态风险进行研究.结果显示,沉积物中Mn、Zn、As、Cd、Pb、V在九龙江有较高浓度,Ni、Cu在钱塘江浓度最高,Cr、Sb在瓯江浓度最高,而Al、Co和V的最高浓度分布在闽江.但重金属含量空间差异不显著.SQGs、Igeo和EF评价显示,Cd在研究区沉积物中污染最为严重,呈中度至重度污染,其次是Mn、Zn、Pb,其在研究区部分地区存在轻度污染,其他重金属处于无污染状态.RI评价显示,研究区河流沉积物存在极高重金属潜在生态风险,尤其是Cd.相关分析和PCA分析显示,Zn、As、Cd、Pb来自于自然过程、矿业开采及农业生产过程,Cr、Ni、Sb来自于工业生产过程产生废水,Al、Co和V来自于自然过程,而Cu则来源于混合源.pH值、TP、TN和LOI是影响水体中重金属含量的重要因子.本研究为河流生态系统的健康和保护提供重要依据.     

厦门杏林湾水系表层沉积物中PAHs分析与风险评估

利用ASE-GC-MS(加速溶剂萃取与气相色谱质谱仪联用)方法分析了USEPA(美国环保署)16种优控PAHs在厦门城郊杏林湾水系的19个表层沉积物样点中的含量,并对其组成、来源和风险进行了探讨.结果表明,杏林湾水系表层沉积物中PAHs含量介于413.00~2 748.81 ng·g-1,均值为949.56 ng·g-1;在检测出的13种PAHs中,强致癌性的Bk F和Bghi P检出率高达73.68%,均值分别为69.15 ng·g-1和49.86 ng·g-1;PAHs以2~4环为主,其中2+3环比例均值为61.03%,4环比例均值为23.53%;5和6环均值为15.82%.在所采集的沉积物样品中,中度污染占调查样品数的68.42%,高度污染的占31.58%.利用Ant/(Ant+Phe)和Fla/(Fla+Pyr)比值法和主成分分析方法对杏林湾流域中PAHs其来源进行分析,以及平均沉积物质量基准商(m SQG-Q)法进行生态风险评估,结果表明其PAHs的主要来源为石油源以及石油燃烧源;SQG-Q小于0.50;综合含量、组成特征以及沉积物质量基准商等评价表明,研究区域内靠近杏林工业区一侧的2、3、5和9号采样区以及13号港头采样区表层沉积物中PAHs具有较高的生态安全风险;值得进一步关注.     

物理和摇蚊幼虫组合扰动对内源磷再生和形态转化的协同作用

为探讨物理和摇蚊幼虫组合扰动对内源磷再生和形态转化的协同作用,选取了苏州某富营养化河道为研究对象.利用室内静态培养试验和Rhizon间隙水采样技术,着重对比了单纯的摇蚊幼虫扰动和组合扰动下,上覆水、间隙水、沉积物中磷形态数量分布的变化规律.结果表明,组合扰动下,上覆水中不同形态磷含量(TP、PP、DTP、DIP)均处于较高水平,明显高于摇蚊幼虫扰动.这可归因于微生物活性的显著增加.与摇蚊幼虫扰动相比,组合扰动下,间隙水中DIP和Fe2+浓度的降低幅度和降低范围明显更大.这主要是由于物理扰动和底栖生物扰动产生的叠加效应,导致溶解氧渗透深度增加.另外,0~2 cm沉积物中,NH4Cl-P含量明显降低,Fe/Al-P明显增加,并且,NH4Cl-P和Fe/Al-P的变化幅度均在组合扰动下最大.这暗示了物理扰动和底栖生物扰动对磷再生和迁移产生的叠加效应.     

Global fallout Pu recorded in lacustrine sediments in Lake Hongfeng, SW China

Studies on the distribution and isotope compositions of fallout Pu are important for source characterization of possible future non-fallout Pu contamination in aquatic environments, and useful for dating of recent sediments to understand the pollution history of environmental contaminants. We present the historical record of atmospheric Pu fallout reconstructed from a sediment core from Lake Hongfeng, China. The Pu activity profile was in agreement with the 137Cs profile. Inventories were 50.7 Bq m(-2) for 239+240Pu and 1586 Bq m(-2) for 137Cs. The average 240Pu/239Pu atom ratio was 0.185+/-0.009, indicating that Pu originated from global stratospheric fallout rather than from direct tropospheric or close-in fallout from the Chinese nuclear testing conducted in the 1970s. Our data suggested that Lake Hongfeng would be an ideal setting for monitoring atmospheric fallout and environmental changes in this region.     

NITROGEN TRANSFORMATIONS IN SEDIMENTS AS AFFECTED BY CHEMICAL AMENDMENTS1

ABSTRACT: A study was conducted to elucidate some of the chemical factors affecting the rate and pathways of N transformations in lake sediments. The main emphasis was placed on modifying a noncalcareous sediment with CaCO₃ to approximate the composition of a calcareous sediment. Additionally, the effects of Ca²⁺, CO₃^2-, Mg2⁺ and OH^- were evaluated by using appropriate chemicals. Further, the effect of aluminum sulfate was evaluated with both sediment types. Sediment pH at 7 days was not affected by CaCO₃, but was decreased by aluminum sulfate. The CaCO₃ treatment increased the rate of ammonification, nitrification, reduction of acetylene to ethylene and methane formation, while with few exceptions the other treatments decreased the rate of the transformations studied. Aluminum sulfate, which has been proposed as a lake restoration treatment, increased ammonification but decreased most of the other transformations.     

Impact of anions on the heavy metals release from marine sediments

Marine sediments from Lianshan Bay in Huludao, China, were studied in laboratory. A series of simulated experiments were carried out to investigate the influences of three kinds of anions CL^-, SO4^2- and HCO3^- on the release ofCd, Pb, Cu and Zn from the sediments. The results showed that the sequences about the impact of the three anions were Cl^-〉HCO3^-〉SO4^2＋. The release potential of heavy metals in the presence of each anions was in the following order： Cd≥Cu 〉Zn≈Pb. The correlations were positive between CI content and the quantity of Cd released from the marine sediment, whereas there was no significant relationship between CI content and amount of Cu and Zn released. For SO4^2- and HCO3^-, the release of the heavy metals from marine sediments was not obvious.     

太湖五里湖底泥污染特性研究

五里湖是太湖污染最严重的水域。为对其治理提供依据,在该湖区设置了4个采样点,对底泥的表层样、柱状样、间隙水样和上覆水体作了重金属和营养盐分布测试,并作了数据统计分析。结果表明：以地积累指数评价,五里湖底泥的重金属污染程度为轻度,总体可达到《土壤环境质量标准》（GB15618-1995）三级标准,根据超出背景值的倍数分析,五里湖重金属含量顺序为Cu>Cd>Pb>Hg>As>Cr。重金属含量表层（0～5 cm）相对较低,第二层（5～10 cm）和第三层（10～20 cm）是主要的污染沉积层,这与底泥沉积特征是相对应的。表层底泥总氮、总磷和有机质含量较高并具有明显的相关性,相关系数介于0.757 6～0.862 2之间,显示了污染物质的同源性。表层底泥和间隙水中营养盐含量明显高于湖水,相对于湖水呈可释放状态,是湖体内源污染之一。     

重点流域水系沉积物中多环芳烃标准样品制备

环境标准样品是监测过程中重要的质量控制手段,中国受天然基体标准样品制备技术的制约,尚未拥有自己的沉积物中多环芳烃标准样品。为制备符合中国重点流域沉积物类型及多环芳烃浓度水平的沉积物标准样品,对中国6个重点流域的沉积物进行了采样,获得了制备多环芳烃标准样品的原料。分析常温及冷冻2种干燥方式对多环芳烃的影响,为制备大批量多环芳烃标准样品提供数据支持。对11个点位样品采用气相色谱质谱法测定16种优控多环芳烃化合物浓度,结果表明,样品均匀性良好,样品中多环芳烃检出率在99%以上,江河沉积物样品中多环芳烃浓度区间为664~2.91×103μg/kg,湖泊样品最高值达到1.25×105μg/kg,其主要污染源是化学燃料的燃烧。为中国制备水系沉积物中多环芳烃标准样品积累了技术基础。     

Simulating the dynamics of sulfur species and zinc in wetland sediments

In situ measurements comparing vertical SO₄²⁻ profiles in vegetated and non-vegetated sediments showed that SO₄²⁻ concentrations in vegetated sediments increased significantly at the beginning of the growing season and then gradually decreased during the rest of the growing season. Throughout the growing season, SO₄²⁻ concentrations remained higher in the vegetated sediments than in the sediments without plants. The higher SO₄²⁻ concentrations in the vegetated sediments indicate that oxygen release from roots and evapotranspiration-induced advection by plants play an important role in the dynamics of sulfur species in sediments. Since the total pool of solid-phase sulfide is relatively large compared to the mass of SO₄²⁻ in the sediments, the gradual decrease of SO₄²⁻ concentrations may result from limitation of the solid-phase sulfide that is in direct contact with or very close to the roots and rhizomes. This would mean that the main pool of solid-phase sulfide and associated trace metals are not affected by the oxygen release from roots, and the associated trace metals will not become bioavailable during the growing season.