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胶东半岛滨海沉积物中硫的迁移转化及其与铁的耦合机制
姜明
Subtype博士
Thesis Advisor盛彦清
2022-05-12
Training institution中国科学院烟台海岸带研究所
Degree Grantor中国科学院烟大学
Place of Conferral中国科学院烟台海岸带研究所
Degree Name工学博士
Degree Discipline环境工程
Keyword海岸带 沉积物 耦合机制
Abstract硫与铁的相互作用是滨海水体黑臭形成的主要原因,而滨海沉积物中硫的迁移转化与不同形态铁的耦合过程会直接或间接影响水体与沉积物的质量演变。海岸带作为海陆相互作用最为剧烈的区域,其具有水质水文条件复杂、咸淡水混杂交替、高负荷污染汇集、高悬浮物聚集沉积等显著特征,该区域沉积物中不同形态硫的迁移转化及其与铁的耦合机制一直是同领域的研究热点之一。胶东半岛滨海河流众多,绝大部分河流的外源污染已经得到了有效控制,但部分河流及近岸海域依然黑臭,这可能与沉积物中硫、铁耦合密切相关,而当前对于滨海沉积物硫、铁循环及其耦合作用机制的认识尚不明朗,无法对滨海水质演变过程进行深度解析和精准防控。因此,本论文以上述问题为导向,聚焦“流域-河口-近海”体系沉积物中的硫循环,探究滨海沉积物中硫的迁移转化及其与铁的耦合机制,以期为滨海河流及河口海岸带环境质量演变过程识别提供科学依据,并为海岸带水体与沉积物污染防治提供技术支撑。主要研究内容和结果如下: (1)近海柱状沉积物中硫铁纵向分布特征及其成岩机制研究:采用改进的冷扩散法,系统地研究了近海区域深层柱状沉积物(深约 4 m)中无机硫和活性铁的纵向分布特征和成岩作用机理。结果表明,沉积物的粒径组成以粉砂(73.6 %)为主,无机硫以铬还原性硫(CRS)为主(65 %),酸可挥发硫(AVS)含量随深度变化保持稳定,但CRS和元素硫(ES)呈现表层和底层高的趋势;活性铁(RFe)以RFe(II)为主(约 80 %),且随深度增加而升高;浅表层沉积物(0 至 -30 cm)以有机质微生物降解为主,该过程有利于AVS向CRS转化,但随着深度增加(-30 至 -160 cm),硫酸盐还原作用增强,此时AVS累积速率大于转化速率;对于深层沉积物(-160 至 -370 cm),铁的还原以化学还原为主,同时生成ES,并促进AVS向CRS的转化;低黄铁矿化度(DOP,0.01 - 0.24)和硫化度(DOS,0.03 - 0.25)值表明,沉积物硫的矿化和硫化几乎不受RFe限制,而主要受活性有机质含量的限制。 (2)滨海河流不同沉积环境下硫铁的横向迁移转化机制研究:综合运用冷扩散提取法、化学提取法、X射线能谱等技术(XPS),以胶东半岛不同沉积类型滨海河流为研究区域,分别对存在潜在工业污染的胶莱河、作为饮用水水源地的夹河以及实施河床硬化的逛荡河表层沉积物中硫和铁的空间分布、赋存形态、迁移转化特征等进行了深入研究。结果表明,三条河流表层沉积物中硫和铁赋存形态分别以有机硫(89 %、85 %和77 %)和高活性Fe(II)(88 %、71 %和84 %)为主。胶莱河、夹河中下游和逛荡河沉积物中低DOP(< 0.52)和高AVS/CRS(> 0.3)值表明,沉积物的黄铁矿化度低,AVS大量积累,活性有机质的含量限制了CRS的形成;夹河中上游站位高DOP(高达0.73)和低AVS/CRS(< 0.3)值表明,CRS大量积累,高活性Fe(III) 的含量是CRS形成的主要限制因素。基于C/N比值和XPS分析表明,外源有机质输入促进了硫酸盐异化还原,有利于胶莱河和逛荡河沉积物中富里酸硫(76 % 和75 %)和AVS(65 % 和 70 %)的富集;而内源性生物输入促进了同化性硫酸盐还原作用,有利于夹河沉积物中腐殖酸硫(74 %)和CRS(70 %)富集。 (3)高磷酸盐和盐度胁迫下滨海流域表层沉积物中硫铁耦合机制研究:以胶东半岛 “流域-河口-近海”体系下两条富含磷酸盐及一定盐度的滨海河流为研究区域,探究了表层沉积物中硫铁磷的耦合作用机制。结果表明,高盐度胁迫会促进CRS的积累(56 %)和钙结合态磷(HCl-P)的固定(71 %),并可诱导沉积物中铁铝结合态磷(NaOH-P)的活化,增加水体富营养化的风险;相关性分析表明,高盐度胁迫沉积物中的活性有机质的含量是 CRS生成的主要限制因素,而ES可以指示高盐度胁迫下沉积物中无机硫和总有机碳的储存损失。高磷酸盐胁迫促进了铁氧化物的异化还原,增加了NaOH-P的固定(58 %),抑制了无机硫富集;当沉积物受人为扰动时,沉积物中AVS的氧化生成铁的氢氧化物和ES,可作为NaOH-P和CRS形成的潜在来源;相关性分析表明, ES的含量是沉积物中AVS向CRS的转化的限制因素。 (4)盐度对河口湾沉积物硫铁纵向迁移与生物作用的影响机制研究:以胶东半岛五龙河河口-丁字湾-黄海为研究区域,探究了盐度梯度下硫铁生物地球化学特征。结果表明,盐度和腐殖酸共同作用增加了细颗粒沉积物的絮凝沉降,致使表层沉积物粒径由河口向海洋方向逐渐变细(50.44 - 76.54 %),对总有机碳的吸附作用增强(0.32 - 0.67 %);基于微生物群落和三维荧光平行因子分析,盐度还会促进溶解性有机质(DOM)构象变化或间接光降解,使其更具有生物降解性,提升沉积物细菌群落的丰富度和多样性,增加表层沉积物类腐殖质的降解,抑制了表层沉积物有机硫的富集;无机硫和有机硫的含量沿盐度升高而增加,其中无机硫含量随深度增加而升高,CRS占主导(51 - 69 %),有机硫含量呈现表层(0至 -14 cm)低,中间层(-14 至 -22 cm)高的趋势,FAS占主导(63 - 82 %);相关性分析表明,CRS和FAS的形成分别受活性有机质和ES的含量的限制;沉积物中RFe(III)占主导(94 %),其含量随深度增加而降低。盐度升高,增加了微生物活性,促进了次表层和底层沉积物硫酸盐异化还原和铁的化学还原,从而有利于无机硫和有机硫的积累。 (5)潮汐过程对沉积物硫铁耦合环境效应模拟研究: 选取典型滨海黑臭沉积物设置室外潮汐模拟实验,探究了潮汐作用下干湿交替过程对高(长期干/湿)、中(短期干/湿)、低(淹水)潮滩沉积物中硫铁生物地球化学耦合过程的响应机制。结果表明,干湿交替过程降低了中高潮滩沉积物中微生物的丰度和多样性,抑制了总有机碳的矿化(增加了7.86 % 和10.13 %),有利于沉积物中RFe(III)的富集(增加了85 %和77 %)。沉积物含水率与AVS存在显著正相关,表明淹水条件有利于硫酸盐还原产生AVS。沉积物无机硫含量排序为:低潮滩 > 中潮滩 > 高潮滩,分别降低了46.82 μmol/g, 63.05 μmol/g,156.56 μmol/g;高潮滩沉积物中无机硫和铁分别以CRS为主(48 %)和RFe(III)(55 %)为主;相关性分析表明,ES是高潮滩沉积物中CRS形成的重要驱动因素;中低潮滩沉积物中无机硫和铁分别以AVS为主(69 % 和71 %)和RFe(II)(54 % 和55 %)为主,相关性分析表明,硫化物的可给性抑制了中低潮滩沉积物中AVS向CRS的转化。
Other AbstractThe interaction between sulfur and iron is the main reason for the formation of black and odorous in coastal water. The coupling process of sulfur and different forms of iron in coastal sediments can directly or indirectly affect the quality evolution of water and sediments. Coastal zone as the most intense interaction between land and sea, is characterized by complex water quality and hydrological conditions, mixed alternation of salty and freshwater, high pollution level, and accumulation and deposition of a large amount of suspended particulate matters. The migration and transformation of different sulfur forms and and its coupling mechanism with iron have been one of the research highlights in the same field. There are numerous coastal rivers in Jiaodong Peninsula. The exogenous pollution of most rivers has been effectively controlled, but some rivers and coastal water are still suffered from black and odorous, which may be closely related to the coupling of sulfur and iron in sediments. However, the understanding of sulfur and iron cycle and their coupling mechanisms in coatal sediments have been still unclear, causing that the evolution of coastal water quality cannot be deeply analyzed and accurately controlled. Therefore, guided by the above problems, this paper focused on the sulfur cycle in sediments of " river basins - estuarine - offshore" system, and explored the migration and transformation of sulfur and its coupling mechanism with iron in coastal sediments, which aiming to provide a scientific basis for the identification of the environmental quality evolution process of coastal zones, and also to supply technical supports for the prevention and control of coastal water and sediment pollution. The major findings were as follows: (1) Vertical distribution and diagenesis mechanism of sulfur and iron in a sediment core from coastal areas: The vertical sedimentation characteristics and diagenesis mechanism of reduced inorganic sulfur and ractive iron in an offshore sediment core (about 4 m) were systematically studied using the improved cold diffusion method. Results showed that the grain-size was predominantly composed of silt (73.6 %) in sediments, and reduced inorganic sulfur was primarily occupied by CRS (65 %) in sediments. The AVS content presented a narrow range with depth increase, whereas the contents of CRS and ES were higher at the top and bottom layer than that at the middle layer. RFe was dominated by RFe(II) (80 %), and its concent increased with sediment depth. Microbial decomposition of organic matter mainly occured on the shallow surface sediments (0 to -30 cm), which facilitated the conversion of AVS into CRS. With the depth increase (-160 to -370 cm), the enhaced sulfate reduction resulted in a greater accumulation rate of AVS overing the conversion rate. For the deep sediments (-160 to -370 cm), the chemical reduction of iron was the main process, which generated ES and promoted the transformation of AVS to CRS. The low values of DOP (0.01 - 0.24) and DOS (0.03 - 0.25) indicated that pyritization and sulfidation were not limited by the RFe, but by the reactive organic matter contents. (2) Mechanism of the lateral migration and transformation of sulfur and iron in different sedimentary environments of coastal rivers: The spatial distribution, occurrence forms, migration and transformation characteristics of sulfur and iron in surface sediments of Jiaolai River with potential industrial pollution, Jiahe River as a drinking water source and Guangdang River with river bed hardening were studied by using cold diffusion extraction method, chemical extraction method and XPS. Results showed that the forms of sulfur and iron in surface sediments of the three rivers are predominantly composed of organic sulfur (89 %、85 % and 77 %) and labile Fe(II) (88 %、71 % and 84 %), respectively. The low values of DOP (< 0.52)and high AVS/CRS ( > 0.3) in the Jiaolai River, the middle and lower reaches of the Jiehe River and the Guangdang River indicated a low degree of pyritization and large accumulation of AVS in sediments. The CRS formation was limited by the reactive organic matter contents. The high DOP (up to 0.73) and low AVS/CRS (< 0.3) in the middle and upper reaches of Jiahe River indicated that large accumulation of CRS was limited by CRS formation. Both results of C/N ratios and XPS analysis showed that exogenous organic matter input promoted sulfate dissimilatory reduction and the enrichment of fulvic acid sulfur (FAS, 76 % and 75 %) and AVS in surface sediments of Jiaolai River (FAS, 76 %; AVS, 65 %) and Guangdang River (FAS, 75 %; AVS, 70 %). Neverthless, endogenous biological input promoted assimilative sulfate reduction and the enrichment of humic acid sulfur (HAS) and CRS in sediments of Jiahe River (FAS, 74 %; AVS, 70 %). (3) Coupling mechanism of sulfur and iron in surface sediments of coastal watershed under high phosphate and salinity stress: Taking two coastal rivers with high phosphate and high salinity in the " basins - estuarine - offshore " system of Jiaodong Peninsula as the research area, the coupling mechanism of sulfur, iron and phosphorus in surface sediments was investigated. Results showed that the high salinity promoted the accumulation of the CRS (56 %) and the fixation of HCl-P (71 %), and induced the activation of NaOH-P in surface sediments, thus increasing the risk of water eutrophication. Correlation analysis showed that CRS formation was limited by the TOC. And ES could be used as an indicator of RIS and TOC storage loss in sediments under high salinity stress. High phosphorus stress boosted the dissimilatory reduction of iron oxides and the NaOH-P (58 %) fixation, inhibiting the reduced inorganic sulfur enrichment in sediments. AVS was oxidated to iron hydroxides in sediments, which could serve as potential sources of NaOH-P formation when sediments were anthropogenically disturbed. Correlation analysis showed that the transformation of AVS to CRS was limited by the ES contents in sediments under high salinity stress. (4) Effects of salinity on vertical migration and biological interactions of sulfur and iron in estuarine-bay sediments: Taking “Wulong River Estuary-Dingzi Bay- Yellow Sea” as the study area, the biogeochemical characteristics of sulfur and iron influenced by along an estuarine salinity gradient were investigated. Results showed that the combined effect of salinity and humic acid facilitated the flocculation of fine-grained sediments (50.44 to 76.54 %), resulting in decreasing the particle size from the estuary to the ocean, thereby enhacing the adsorption of TOC (0.32 to 0.67 %). The results of microbiome and three-dimensional fluorescence parallel factor analysis showed that salinity directly promoted conformational change of DOM or indirect photodegradation, which made DOM more biodegradable. Furthermore, salinity increased the richness and diversity of sediment bacterial community, and then enhanced the degradation of humic-like in surface sediments, which was not conducive to the enrichment of organic sulfur in surface sediments (0 to -14 cm). Reduced inorganic sulfur and organic sulfur contents increased with the increase of the salinity gradient, among which reduced inorganic sulfur increased with depth. Organic sulfur content at the middle layer (-14 to -22 cm) was higher than that of the top layer. Reduced inorganic sulfur and organic sulfur were dominated by CRS (51 - 69 %) and FAS (63 - 82 %), respectively. Correlation analysis showed that the formation of CRS and FAS was restricted by reactive organic matter and ES contents, respectively. The RFe in sediments was manily occupied by RFe(III) (94 %), which was decreased with depth. Salinity improved the microbial activity and promoted the dissimilatory reduction of sulfate and chemical reduction of iron, thereby enhancing the enrichment of reduced inorganic sulfur and organic sulfur in subsurface and bottom sediments. (5) Simulation of environmental effects of tidal processes on the coupling mechanism of sulfur and iron in sediments: Typical malodorous sediments were selected and used to carry out outdoor tidal simulation experiment. The response mechanism of dry-wet alternation to the biogeochmical coupling of sulfur and iron in high (long-term dry-wet), medium (short-term dry-wet) and low (flooded) tidal flat sediments was investigated. Results showed that the dry-wet alternation inhibited microbial activity and TOC mineralization, and promoted RFe(III) enrichment in high (TOC, 7.86 %; RFe(III), 85 %) and middle tide flats (TOC, 10.13 %; RFe(III), 77 %). There was a positive correlation between moisture and AVS, indicating that the flooding condition was favorable for AVS formation through sulfate reduction. Reduced inorganic sulfur content was ordered as follows: low tide beach > mid tide beach > high tide beach, decreasing by 46.82 μmol/g, 63.05 μmol/g, 156.56 μmol/g, respectively. CRS and RFe(III) were the main species of reduced inorganic sulfur and RFe (CRS, 48 %; RFe(III), 55 %), respectively, and ES was an important driving factor for CRS formation in high tidal flat based on correlation analysis. Reduced inorganic sulfur and RFe in middle tidal flat and low tidal flat were composed mainly of AVS (69 % and 71 %) and RFe(II) (54 % and 55 %), respectively. Correlation analysis showed that the conversion from AVS to CRS was restricted to the availability of sulfide in both middle tidal flat and low tidal flat.
Pages162
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/30529
Collection中科院烟台海岸带研究所知识产出
Recommended Citation
GB/T 7714
姜明. 胶东半岛滨海沉积物中硫的迁移转化及其与铁的耦合机制[D]. 中国科学院烟台海岸带研究所. 中国科学院烟大学,2022.
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