Mobilization potential of heavy metals: A comparison between river and lake sediments

Toxic metals introduced into aquatic environments by human activities accumulation in sediments. A common notion is that the association of metals with acid volatile sulfides (AVS) affords a mechanism for partitioning metals from water to solid phase, thereby reducing biological availability. However, variation in environmental conditions can mobilize the sediment-bound metal and result in adverse environmental impacts. The AVS levels and the effect of AVS on the fate of Cu, Cd, Zn, Ni in sediments in the the Changjiang River, a suboxic river with sandy bottom sediment and the Donghu Lake, a anoxic lake with muddy sediment in China, were compared through aeration, static adsorption and release experiments in laboratory. Sips isotherm equation, kinetic equation and grade ion exchange theory were used to describe the heavy metal adsorb and release process. The results showed that AVS level in the lake sediment are higher than that of the river. Heavy metals in the overlying water can transfer to sediments incessantly as long as the sediment remains undisturbed. The metal release process is mainly related to AVS oxidation in lake sediment while also related to Org-C and Fe-Mn oxyhydroxide oxidation in river sediment. The effect of sulfides on Zn and Ni is high, followed by Cd, and Cu is easy bound to Org-C. AVS plays a major role in controlling metals activity in lake sediment and its presence increase the adsorption capacity both of the lake and river sediments.

Discharges and sediments as sources of extracellular alkaline phosphatase in a shallow Chinese eutrophic lake

Total alkaline phosphatase activity (APA) and soluble reactive phosphorus (SRP) concentrations were measured in municipal wastewater, and a shallow Chinese freshwater lake receiving it. Activities of Dissolved alkaline phosphatase ( ADAP) in overlying and interstitial water were also analyzed monthly at three sites for several years. The lake was enriched with SRP and alkaline phosphatase by discharge of the wastewater, indicating that the inclusion of APA for estimating water pollution was reasonable. Annual data showed that APA in coarser fraction was significantly higher at the site receiving more wastewaters, both in surface and overlying water, suggesting that resuspension of enzyme most likely occurred in the basin heavily discharged. ADAP was an order of magnitude higher in the wastewater than those in lake waters, and was generally higher in interstitial water, a feature more striking at the site receiving more discharges. Besides, it was irrespectively inhibited by Na2WO4, L-cysteine and EDTA-Na, but stimulated by Cu2+, Zn2+, CTAB and Triton X-100 in interstitial, overlying and surface waters. This similarity of responding patterns to the stressors indicated an analogy between dissolved alkaline phosphatase in water column and that in interstitial water, supporting the hypothesis that the polluted sediments act as source of dissolved alkaline phosphatase in eutrophic lakes.

原油在扰动土壤中入渗的实验研究

随着国家发展对能源的迫切需求,石油作为我国能源的主要构成之一,其开采和冶炼也在不断地增加。然而由于某些相关管理环节的不完善引发的污染事故日趋增多,其中原油的土壤污染问题尤为严重。为研究原油在土壤中的入渗过程,通过室内土柱模拟实验,测定了原油在土壤中入渗的湿润距离、湿润推进速率与时间的关系以及被原油污染的土壤中残留物的含量。结果表明:对于同一质地土壤,随着容重的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均降低;容重相同而质地不同的土壤,随着粉粒含量的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均表现为降低趋势;原油在土壤中入渗的湿润距离随时间的变化可以用对数函数拟合,湿润推进速率与时间的关系可以用幂函数拟合,均达到显著水平。研究原油在土壤中的入渗对于了解原油在土壤中的迁移有着重要的意义。

黄土沟壑区小流域土壤pH值的空间分布及条件模拟

土壤pH值是影响土壤养分有效性和化学物质在土壤中行为的主要因素,研究土壤pH值的空间分布特征对于土壤养分管理和土壤污染预测具有重要意义。该文用地统计学方法研究了环境因素复杂的黄土高原小流域土壤pH值空间分布特征。结果表明,黄土沟壑区小流域土壤pH值具有球形—指数套合模型的空间结构特征,其空间异质性主要来源于流域内土地利用和土壤侵蚀等随机因素。与有机质协同的Kriging法能较好地对土壤pH值进行估值,其估值范围小于实测数据,估值误差来源于复杂的环境因素。序贯高斯条件模拟的土壤pH值范围与实测数据接近,模拟的平均值低于实测数据,模拟误差来源于模拟过程中独特的Kriging算法及高斯特性。

植物激素对土壤污染早期诊断研究

通过菲污染诱导动态响应预实验确定了小麦为供试植物，赤霉素(GA3)、细胞分裂素的玉米素和玉米素核苷总含量(Z&ZR)以及脱落酸(ABA)为植物激素供试指标，并且确定试验终点为小麦生长14d。在预实验的基础上，以草甸棕壤为供试土壤，采用室内培养箱盆栽方法，进行多环芳烃菲、芘、荧蒽和苯并(a)芘单一，两-两复合以及三-三复合与3种植物激素的剂量-效应关系研究；3种植物激素对土壤重金属镉、铅、铜和锌单一污染诱导的响应关系研究。并以多环芳烃类的菲和重金属类的镉为代表污染物，进行小麦芽期生长指标及植物激素测定，研究植物激素与生长指标对污染物的响应及敏感性比较。 多环芳烃单一及复合污染诱导实验结果表明：ABA对菲、芘、荧蒽、苯并(a)芘单一及复合污染诱导的响应趋势一致，即随着污染诱导浓度增加，ABA含量显著增加；GA3与四种多环芳烃单一及复合污染诱导存在一定的响应关系，但响应趋势呈多样性变化；对于多环芳烃单一及复合污染诱导，随着污染物浓度增加，Z&ZR含量出现了先增加后减少的趋势，表现为显著的污染诱导抑制效应。ABA和Z&ZR对多环芳烃污染诱导响应敏感，这为其成为土壤污染诊断指标提供了可能性。 在不同的镉、铅、铜、锌污染处理中，小麦体内ABA含量均出现明显增加趋势，与多环芳烃污染胁迫响应一致；GA3含量对镉、铅、铜、锌四种重金属污染胁迫响应趋势相同，均为先增加后减少。对于土壤镉和铅污染胁迫Z&ZR表现为先增加后减少的响应趋势，而对于铜和锌污染胁迫，Z&ZR含量变化与镉、铅胁迫时不同。 植物激素与生长指标对污染胁迫的响应及敏感性比较研究表明，对多环芳烃菲污染诱导，植物激素含量同生长指标相比具有显著的敏感性。对重金属镉污染诱导，内源激素含量和生长指标敏感性都显著，小麦根和芽中ABA含量显著增加，进一步证明了其在植物污染抗逆中的作用机理。

土壤污染生态毒理诊断指标体系研究

生态毒理试验集合了污染物的整体效应及化学品代谢物质产生的效应.它可提供土壤中所有污染物对土壤质量影响的全部信息.然而，现有生态毒理试验方法大多用于水生生态系统的生态毒性检验，对土壤污染的诊断需要建立新的生态毒理诊断方法.该文选择4类典型土壤（红壤、草甸棕壤、暗棕壤和栗钙土），以（小麦、白菜、萝卜、西红柿、大葱）为供试植物，进行了重金属（Cu、Zn、Pb、Cd）、有机氯、多环芳烃污染的植物种子发芽与根伸长抑制试验;植物早期生长试验研究;以草甸棕壤为供试土壤，进行了重金属（Cu、Zn、Pb、Cd）单一、复合污染条件下的蚯蚓（郝子爱胜）急性毒性实验;以草甸棕壤、污染土壤和生物修复土壤进行蚕豆根尖实验和土壤原生动物（纤毛虫）实验.

花卉植物在污染土壤修复中的资源潜力分析

通过对14种草本花卉在Cd、Cd-Pb、Cd-Pb-柴油、Cd-甲胺磷等单一与复合污染条件下的耐性及重金属积累特性研究，就这些花卉对污染土壤修复的资源潜力有了大致的认识，为污染环境的生态修复及其集成技术的创新与应用提供了科学依据，同时也提供了具有我国自主知识产权的污染土壤修复材料的基本信息。通过盆栽实验，发现黄蜀葵、醉蝶、金盏菊、凤仙、蜀葵和紫茉莉六种植物对Cd单一污染表现出较强的耐性，约占参试花卉种的43％，说明花卉植物较有耐重余属的潜力。金盏菊在实验浓度下，地上部富集系数大于1且地上部的Cd含量大于根部含量，表现出重金属超积累植物的基本特征，但在本试验条件下还没有达到100mgkg-1Cd的超积累植物临界含量特征，因此，有待进一步实验证实。熔液培养条件下，黄蜀葵、紫茉莉、凤仙、万寿菊、串红五种花卉种子发芽对Cd表现为较强的耐性，因为其种子发芽率在Cd污染暴露条件下无明显影响（p＞0.05）。但是，Cd对这五种花卉幼苗期根伸长的影响较为显著（p＜0.05），并且Cd与花卉植物的幼苗期根长抑制之间存在线性相关关系。在复合污染条件下（Cd-Pb，Cd-Pb-柴油），14种参试花卉种，除金鸡菊和观赏向曰葵两种花卉表现出生物量明显（P＜0.05）下降，即对重金属复合污染耐性较弱外，其余12种表现出对复合污染有较强的耐性。黄蜀葵在Cd一甲胺磷联合作用下的耐性研究表明，Cd与甲胺磷对黄蜀葵且对幼苗期根伸长的影响较发芽的影响大。对Cd与甲胺磷的联合效应分析表明Cd和甲胺磷存在拮抗作用，同时这种联合作用则是更多地依赖于Cd而非甲胺磷。

Atmospheric cu and pb deposition and transport in lake sediments in a remote mountain area；northern China

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黄土高原不同土壤中Cd形态分级及其生物有效性研究

研究黄土高原主要农田土壤重金属Cd的形态与生物有效性的关系,为评价本区土壤重金属Cd污染程度及其生物有效性提供一定的理论与数据依据。【方法】以黄土高原自北向南采集的12个0~20 cm耕层土壤为供试土样,通过室内分析和盆栽试验,研究了黄土高原石灰性土壤中不同形态Cd的分布特征及其生物有效性。【结果】黄土高原农田土壤Cd各形态总体分布特征为:有机结合态Cd、铁锰氧化物结合态Cd>碳酸盐结合态Cd>交换态Cd>残渣态Cd,自北向南各形态Cd含量均呈不同程度的增加趋势。各土壤类型间铁锰氧化物结合态Cd及碳酸盐结合态Cd平均含量均表现为:干润砂质新成土<黄土正常新成土<简育干润均腐土<土垫旱耕人为土,自北向南依次增加。碳酸盐结合态Cd和全Cd含量主要受到全氮、有效磷和砂粒含量的影响,且全氮和有效磷含量对其的影响为正效应。铁锰氧化物结合态Cd含量主要受全氮、有效磷、砂粒和粉砂粒含量的影响,且全氮、有效磷和粉砂粒含量对其的影响为正效应。土壤中各形态Cd含量与有机质、C/N、pH、CaCO3、粘粒含量的相关性均不显著,其中与C/N、pH、粘粒含量呈负相关。Cd在小麦茎叶层的含量小于根系;而作物不同部位Cd累积量表现...