渤海辽东湾表层沉积物中金属元素分布特征

利用X射线荧光光谱(XRF)、等离子质谱仪(ICP-MS)和原子荧光光度计(AFS)分别测定了辽东湾表层沉积物中的金属元素含量,探讨了它们的分布特征、来源及污染程度.结果表明,沉积物中Cu、Zn、Pb、Cd、Ni、Cr、Co、Hg、As和Ag等元素含量在空间分布上存在明显梯度,其空间分布模式(4种)受到沉积物细粒组分、有机质含量及与河口间距离等因素的制约.通过与沉积物质量标准及其他海区的比较,评价了研究区沉积物中几种重要金属元素(Cu、Zn、Pb、Cd、Cr、Ni、Ag、Hg和As)的污染情况.富集系数显示, Fe、Ti、Mn、P、Cu、Zn、Ni、Cr、Co、Sc和V为无富集;As为轻度富集;Pb、Cd、Ag和Hg为中度富集. Fe、Ti、Cu、Zn、Cr、Ni、Co、Mn、P、V和Sc主要来源于陆地岩石和土壤风化产物;Pb和As既有岩石和土壤风化产物等自然源的贡献,又受到了人为活动的影响;Hg、Cd和Ag主要来自人为源;Ba和Sr主要与海洋生物活动有关.依据沉积物质量综合评价,将辽东湾沉积物划分为4类.     

城市小型人工湖围隔中生源要素和藻类的时空分布

利用浅水湖泊围隔研究了水华形成过程中生源要素和藻类的分布．结果显示,在围隔内添加磷能促进藻类快速增殖并形成水华．随时间推移,围隔内藻的生物量先升高然后逐渐降低;表层水氮和磷的浓度逐渐下降,其中磷的下降趋势较为明显．在垂直分布上,叶绿素a、总磷、总氮、硝态氮浓度随深度增加而降低;溶解性总磷、氨氮浓度随深度增加而升高．水华期藻类多样性指数下降,优势种主要为蓝藻、绿藻和甲藻,外源磷的添加会使藻类多样性指数提高,但二者并非线性关系．水华期并不是1种藻占绝对优势,有时是2种以上的藻同时爆发．     

铊在河流沉积物上的吸附解吸行为研究

水体环境条件的改变直接影响铊在水体沉积物的吸附解吸行为,进而影响到铊在水环境中的迁移、转化途径.本实验采用北京市凉水河(L8)及其沿岸的藕田(L6)沉积物作为研究对象,研究了Tl(Ⅰ)在沉积物上的吸附特征及pH对其吸附过程的影响,并考察了以沉积物浸出液和背景电解质作为解吸体系时,Tl(Ⅰ)自沉积物上解吸的变化情况.研究结果表明:①两种沉积物对铊的吸附速度较快,初始的5 min内,沉积物对铊的吸附量达到最大吸附量的90％ (L6)和80％(L8)以上,12h基本达到吸附平衡.②沉积物L6和L8对Tl(I)吸附量均随着初始浓度的升高而增大,但是L6的吸附量明显高于L8.两种沉积物对铊的吸附等温线用Freundlich方程和Langmuir方程拟合均得到较好的拟合结果,在分析吸附解吸机理时,Langmuir方程更能说明其物理化学意义.③pH对铊在沉积物上的吸附影响较大,随着体系pH的增大,吸附量逐渐增大.④沉积物浸出液的高效体积排阻色谱和三维荧光表征结果表明沉积物浸出液中主要以类蛋白和腐殖酸类物质为主,荧光强度集中在1100 ～1550之间.用沉积物浸出液代替背景电解质作为解吸体系时,解吸量增加了2.232 mg·kg-1(L6)和1.494 mg·kg-1(L8)(C0 =0.33 mg·L-1),铊更易从沉积物浸出液的环境下解吸下来,进入水体.     

大理河流域微塑料空间分布及其来源

微塑料（直径<5 mm的塑料颗粒）作为一种新型环境污染物,对土壤及水生生态系统构成了严重威胁.本研究基于黄河中游大理河流域采集的21个沉积泥沙和12个农田土壤样品,分析了大理河流域不同介质中微塑料赋存特征和组成差异,揭示了不同介质中微塑料来源及 沉积泥沙中微塑料丰度的影响因素.结果表明,大理河流域沉积泥沙和农田土壤中都受到微塑料的严重污染,其丰度分别为440~1190个·kg^-1和1180~2930个·kg^-1,其中,小粒径微塑料（粒径<500 μm）为主要组成,分别占泥沙和土壤中微塑料颗粒总数的50.12%和72.5%.纤维是泥沙和土壤中微塑料最常见的形状,分别为66.95%和48.3%;薄膜和小球微塑料在农田土壤中较多,比沉积泥沙中高6.51%和13.83%.通过拉曼 光谱仪测试,沉积泥沙中微塑料聚合物组成主要为聚对苯二甲酸乙二醇酯（PET）和聚丙烯（PP）,农田土壤中主要微塑料聚合物组成为聚乙烯（PE）.农用地膜是农田土壤中主要微塑料来源,生活污水和固体废物是泥沙中微塑料的主要来源.此外,沉积泥沙中微塑料丰度的主要影响 因素为速效磷含量和径流流速.本研究结果可为深入了解黄河中游流域微塑料污染状况提供参考.     

Comparison of Pb and Cd adsorption to the surface coatings and surficial sediments collected in Xianghai Wetland

Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of heavy metals in aquatic environments. Pb and Cd adsorption to the surface coatings and surficial sediments were measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0.0.5 mol/L, 25℃ and pH 6.0 for surface coatings: and 0.00.5 mol/L CaCl2 solution, 25℃ and pH 6.0 for surficial sediments). The Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings and surficial sediments, and the component analyses of surface coatings and surficial sediments were also carried out.Correlation analyses between the maximum adsorption of Pb and Cd (Гmax) and the components in the surface coatings and surficial sediments suggested that there was a statistically significant trend for Pb and Cd adsorption(Гmax) to the surface coatings to increase with increasing in contents of Fe and Mn oxides in the surface coatings and surficial sediments. And the metal adsorption abilities of surface coatings were much stronger than those of surficial sediments, highlighting that in the same water, i.e. at the same pH and initial metal concentrations, the metals(such as lead and cadmium) in supernatant were feasible to be adsorbed by surface coatings than surficial sediments. The more importance of surface coatings than surficial sediments for adsorbing and cycling of heavy metals in aquatic environments was evidenced.     

基于无人机多光谱影像的小微水域水质要素反演

总磷(TP)、悬浮物浓度(SS)、浊度(TUB)3种水质参数可以直接通过遥感反演得到,常用于评价区域水环境的污染状况.以浙江农林大学东湖为研究对像,使用无人机携带多光谱传感器(Mica Sense Red Edge)获取多光谱影像,进而提取16个光谱参数,分别构建东湖水域TP、SS、TUB的反演模型.结果表明:光谱参数V5(NIR 0.770～0.890μm)与TP、SS相关性显著(r分别为0.470、-0.537,p0.05),V4(0.670～0.760μm)与TUB相关性显著(r=0.486,p0.05).在建立的TP反演模型中,指数函数模型精度最高,决定系数R~2为0.7829;在建立的SS、TUB反演模型中,多项式函数模型精度最高,决定系数R~2分别为0.7503、0.7334.经检验,TP、SS、TUB模型估测值与实测值线性拟合曲线的决定系数R~2分别为0.7374、0.8978、0.6726,满足水质要素反演的精度要求.最后利用建立的模型,结合多光谱影像数据,建立了东湖水域各参数的空间分布图,实现了水质参数的可视化,可为小微水域的污染防治提供技术支撑.     

基于高山湖泊沉积记录的贵州北部大气重金属污染历史重建

大气重金属污染是全球面临的主要环境问题之一,受监测资料的局限,目前我国在大气重金属污染的历史过程及其对偏远地区地表环境的影响方面的研究还较为薄弱.通过对贵州北部梵净山顶沉积物中金属元素含量和Pb同位素的分析,研究了近400年来Cd、Cr、Cu、Hg、Ni、Pb和Zn等大气污染的历史过程.公元约1800年之前,沉积物中金属元素含量较为稳定; 1800年以来,Cr、Cu、Ni和Zn等含量总体呈先增加后降低的趋势;而Cd、Hg和Pb含量逐渐增加.富集系数与207Pb/206Pb结果表明,Cd、Pb和Hg是典型的大气污染元素; Hg污染开始于公元1880年前后,Cd和Pb污染开始于20世纪50年代,近年来污染程度均逐渐加重.沉积记录反映的贵州北部梵净山地区目前大气Hg污染水平与我国东部其他远离人类活动直接影响的地区相当,但远高于欧美及青藏高原等地区;不同地区间Cd与Pb污染水平具有较大的差异.梵净山地区大气Hg污染可能受到全球和区域污染排放的共同影响,Cd和Pb污染主要来自于区域有色金属冶炼及燃煤等释放.     

Mercury bioaccumulation in fish in an artificial lake used to carry out cage culture

As a global toxic pollutant,mercury(Hg)bioaccumulation within food chain could be influenced by human disturbance.Ten typical fish species were collected from Changshou Lake,an artificial lake used to carry out cage fish culture,to investigate the C/N isotopic compositions and Hg bioaccumulation in fish.The results showed that the total Hg(THg)and methylmercury(MeHg)levels in fish muscles((56.03±43.96)and(32.35±29.57)ng/g,wet weight),comparable with those in most studies in China,were significantly lower than the international marketing limit(0.5 mg/kg).Past human input for cage culture in this lake led to abnormal~(15)N enrichment in food chain,as the quantitative trophic levels based onδ~(15)N were different with that classified by feeding behaviors.This phenomenon subsequently demonstrated that it should be considered thoughtfully with respect to the application of the traditional method for understanding Hg bioaccumulation power by the slope of log_(10)[Hg]withδ~(15)N regression in specific water body(i.e.,Changshou Lake).In addition,no significant linear correlation between Hg and body weight or length of some fish species was observed,suggesting that the fish growth in the eutrophic environment was disproportionate with Hg bioaccumulation,and fish length or weight was not the main factor affecting Hg transfer with food web.The occurrence of human disturbance in aquatic system presents a challenge to a better understanding of the Hg bioaccumulation and biomagnification within the food chain.     

梁子湖近代沉积物重金属含量研究初探

通过对湖北省梁子湖高分辨率沉积物中重金属元素的研究,得到了梁子湖区近代环境污染的波动记录。对所测数据进行因子分析和聚类分析,得到影响沉积物中重金属含量和组成的物质来源,其中Cd、Ni、Fe主要反映了流域侵蚀作用控制的重金属分布;Zn、Pb、Mn、Co、Cu主要反映了人为污染(尤其是大气干湿沉降)对重金属含量变化规律的影响。据分析结果推测,深35-40cm处元素含量高峰值对应于19世纪末近代工业兴起．环境变化所致;20cm处高峰值对应于上世纪中叶以武汉钢铁公司为代表的现代工业污染留下的物质记录;10cm至表层金属含量逐渐增加,为改革开放以来城市和城镇工业的发展导致的大气污染物中重金属含量的急剧升高,该结果说明利用梁子湖区高分辨率金属沉积记录研究人类活动重大环境污染事件对环境的影响是切实可行的。     

Mechanisms of photochemical release of dissolved organic matter and iron from resuspended sediments

Photochemical reactions can alter the transformation of sedimentary organic matter into dissolved organic matter (DOM) and affect its ultimate fate in water ecosystems. In the present study, the photorelease of DOM and Fe from resuspended lake sediments was investigated under different O₂ and NO₃^? concentration conditions to study the mechanisms of DOM and Fe photorelease. The amount of photoreleased Fe, which ranged from 0.22 to 0.70 μmol/L, was significantly linearly correlated with the amount of photoreleased DOM. O₂ and NO₃^? could promote the photochemical release of DOM and Fe, especially during the initial 4 h irradiation. In general, the order of the photorelease rates of DOM and Fe under different conditions was as follows: NO₃^?/aerobic > aerobic ≈ NO₃^?/anaerobic > anaerobic. The photorelease rates of DOM and Fe were higher for the initial 4 hr irradiation than these for the subsequent 8 hr irradiation. The photorelease of DOM and Fe is thought to proceed via direct photodissolution and indirect processes. The relative contributions of indirect processes (>60%) was much greater than that of direct photodissolution (<40%). The photoproduced H₂O₂ under aerobic and anaerobic conditions indicated that hydroxyl radicals (?OH) are involved in the photorelease of DOM. Using ?OH scavengers, it was found that 38.7%, 53.7%, and 77.6% of photoreleased DOM was attributed to ?OH under anaerobic, aerobic, and NO₃^?/aerobic conditions, respectively. Our findings provide insights for understanding the mechanisms and the important role of ?OH in the DOM and Fe photorelease from resuspended sediments.