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题名: 生物扰动对沉积物中重金属二次释放的影响作用与机制
作者: 何怡
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 王东升
关键词: 铊,重金属,生物扰动,活性炭,修复 ; Thallium, Heavy metals, Bioturbation/bioirrigation, Activited carbon, Remediation
其他题名: Influence and Mechanism of Heavy Metals Secondary Release from Contaminated Sediments by Bioturbation/bioirrigation
学位专业: 环境工程
中文摘要:       沉积物是重金属迁移转化的重要媒介。生物扰动能改变沉积物的物理化学组成,从而影响其中重金属的赋存形态和迁移转化特征,对水环境存在潜在生态风险。研究生物扰动对重金属二次释放的影响机制显得尤为重要。研究选择颤蚓、羽摇蚊幼虫和泥鳅作为生物扰动源,沉积物经铊、镉、铜、锌与铅人为污染,主要考察上覆水与孔隙水中重金属的浓度。
      通过对颤蚓、羽摇蚊幼虫和泥鳅28天的生物扰动作用研究发现,在实验初期,溶解态铊释放 到上覆水中的速度很快,但是14天之后,生物尤其是泥鳅的扰动作用抑制了沉积物中溶解态铊向水中的释放,这可能是因为浮游植物的生长使上覆水的pH值升高,这一过程中产生的铁锰氧化物吸附和共沉淀铊导致的。颗粒态和总量铊的含量与颗粒态铁和锰的浓度以及浊度的相关关系也证明了这一推论。生物扰动能显著促进沉积物中有机质向上覆水迁移,释放至上覆水中的有机物以富里酸类与腐殖酸类有机物为主。
      考察了颤蚓与泥鳅的生物扰动作用对沉积物中铊和其他重金属在三个埋藏深度(1.0-2.0 cm, 4.0-5.0 cm, 8.0-9.0 cm)下的迁移转化过程的影响。沉积物中埋藏在浅层的重金属最易发生迁移 (1.0-2.0 cm > 4.0-5.0 cm > 8.0-9.0 cm)。另外,生物扰动对重金属在沉积物中的分布进行了重新分配,且泥鳅的影响较大,这可能是因为泥鳅埋孔为孔隙水的流通提供了更大的通道。生物的扰动作用对埋藏在深度为4.0-5.0 cm和8.0-9.0 cm的重金属释放到上覆水中的浓度无明显影响,只有埋藏深度为1.0-2.0 cm的处理中,泥鳅组中铊与铜释放至上覆水中的浓度明显高于颤蚓组,且这两组均低于对照组(无生物),这可能是因为生物的向下扰动作用为重金属的扩散提供了通道,使埋藏在表层的污染物向下移动。
       粉末活性炭和颗粒活性炭的加入对重金属污染沉积物都有一定的修复效果,其中对铜污染沉积物的修复效果最好,生物扰动作用降低了上覆水中重金属尤其是镉和锌的浓度,说明生物扰动过程中形成的铁锰氧化物对重金属发生了吸附共沉淀作用。但是活性炭尤其是粉末活性炭的加入促进了生物对重金属的生物富集作用,粉末活性炭的加入使生物体内重金属的累积量(与未添加活性炭的处理进行比较)增加了1.2-3.7倍,这可能是由于受试生物摄入了吸附重金属的活性炭,致使受试生物肠胃乃至体内的重金属含量升高,从而降低了生物的成活率。
英文摘要:        Sediment is an important medium for the heavy metals mobilization and transport in it. Bioturbation can change the physical and chemical properties of the sediment to affect the forms and remobilization of heavy metals buried in the sediment, thus it took potential ecological risks to the aquatic environment. So, bioturbation is particularly important to study the effects on the heavy metals secondary release from contaminated sediments. Tubificid, Chironomid larvae, and Loach were chosen for the bioturbation source, and sediment was spiked with thallium (Tl), cadmium (Cd), copper (Cu), zinc (Zn), and lead (Pb), above all, research primarily studied the concentrations of heavy metals in the overlying water and sediment pore water.
       In this project, we observed the effects of bioturbation/bioirrigation by three different riverine organism types (Tubificid, Chironomid larvae, and Loach) on heavy metals release from contaminated sediment. During the first few days, the leaching of dissolved Tl from sediment into water was fast, and the dissolved Tl under bioturbation/bioirrigation was much higher than in the control group. However, after 14 days, the bioturbation/bioirrigation process seemed to suppress the release of dissolves Tl from the sediment to overlying water, especially for the treatment with Loach. This may partly be due to the sorption or coprecipitation of Tl simultaneous with the formation of iron and manganese hydrous oxides with increased pH values as a consequence of phytoplankton growth. Linear regression analysis confirmed that both the total and particulate Tl concentrations had good correlations with particulate Fe and Mn concentrations as well as turbidity in the overlying water. Bioturbation/bioirrigation can significantly promote the migration of organic matters release from sediment into the overlying water, and dominated in the organic matters were fulvic acids and humic acids.
       In addition, the remobilization of buried Tl, Cu, Zn, and Pb from three different sediment depth layers (1.0-2.0 cm, 4.0-5.0 cm, 8.0-9.0 cm) with Tubificid and Loach was evaluated. The highest remobilization occurred from the most shallow layers (1.0-2.0 cm > 4.0-5.0 cm > 8.0-9.0). In addition, The bioturbation/bioirrigation redistributed the heavy metals along the depths in the sediment pore water, especially in the presence of Loach which may be for that the Loach provided much bigger holes for the circulation of pore water. The contaminants buried in deeper layers of 4.0-5.0 cm and 8.0-9.0 cm displaying no significant remobilization with bioturbation, only remobilization of Tl and Cu was significantly lower in the presence of Tubificid and Loach than controls (without bioturbation), this maybe due to bioturbation provided channel for the heavy metals diffusion down into the sediment.
      Powder activated carbon (PAC) and granular activated carbon (GAC) addition in the absence of Chironomid larvae resulted in reduction of heavy metal concentrations compared to untreated sediment, especially for Cu. In systems with bioturbation, the dissolved Cd and Zn concentration decreased sharply with time in the overlying water, which indicating that the Fe\Mn oxides formed during the bioturbation adsorbed or co-precipitated with heavy metals. In comparison with untreated sediment, the coexistence of AC enhanced the accumulation of heavy metals in Chironomid larvae, especially for PAC, which increase by 1.2-3.7 times, which may be for that the Chiromonid larvae ingested AC adsorbed lots of heavy metals. This increased bioaccumulation may slow the eclosion process and decrease the survival of Chironomid larvae.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36801
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
何怡. 生物扰动对沉积物中重金属二次释放的影响作用与机制[D]. 北京. 中国科学院研究生院. 2016.
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