The mechanism of blackening beach in Sanya Bay: the interaction between iron oxides and organic matter
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摘要:
在野外现场调查的基础上，对三亚湾近海沉积物及海滩沉积物进行粒度、有机质、铁形态等地球化学分析及扫描电镜显微观察，结果显示，三亚湾近海表层沉积物以粉砂质为主且由岸向海粒径变细，砂含量减少，粉砂和黏土含量增多，指示湾内水动力较弱，近岸水动力有所增强。三亚湾海滩黑化的有机污染物来源主要有雨污水外溢、三亚河沉积物中的“腐泥”以及三亚湾历史排污口底泥再悬浮和再沉积等。三亚湾海滩缺少细粒沉积物，黏土矿物不是造成有机质富集的主要原因。扫描电镜及能谱分析显示海滩致黑矿物主要为铁氧化物，铁形态分析结果表明氧化铁、游离铁络合度皆与有机碳含量呈明显正相关关系。在弱碱性的氧化环境中，铁氧化物通过配体交换形成的络合作用吸附有机质，金属离子通过阳离子架桥作用促进铁氧化物对有机质的吸附。因此，铁氧化物-有机质-重金属元素三者相互作用可能是导致污染有机质胶结及三亚湾海滩黑化现象的发生的主要作用机制。
Abstract:Recently, Sanya Bay, Hainan Island, South China, suffered from beach blackening, which has become an environmental issue affecting local tourism and ecological health. After the field investigation, we conducted a geochemical analysis on grain size, organic matter content, and different iron forms of offshore and beach sediments in Sanya Bay. Results show that the surface sediments are mainly silty. The grain sizes become finer with less sandy and more silty and clayey contents from nearshore to offshore. This distribution pattern indicates that the hydrodynamic force in the bay is weak and it is enhanced in the nearshore. The main sources of organic matter of beach blackening in surface sediments of the Sanya Bay are the overflow of rainwater and sewage, the "sapropel" from the sediments of Sanya River, and the resuspension and redeposition of sediment loaded from the previously discharge of organic pollutants. Clay minerals are not the main reason for the enrichment of organic matter. SEM-EDS analysis shows that the main blackening minerals are iron oxides. Iron morphology analysis show that the complexities of iron oxides and free iron are positively correlated with organic carbon content. In the weakly alkaline oxidation environment, iron oxides adsorb organic matter via complexation by ligand exchange, and metal ions promote the adsorption of organic matter by cation bridging. Therefore, the interaction of iron oxides, organic matter, and heavy metals shall be responsible for the cementation of polluted organic matter and formation of the beach blackening in Sanya Bay.
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Key words:
- Sanya Bay /
- beach blackening /
- organic matter /
- iron oxide /
- adsorption
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[1] 付博新,刘林. 漳州南太武海滩泥化综合整治[J]. 水运工程,2016(10):50-56. doi: 10.3969/j.issn.1002-4972.2016.10.010
[2] 王俊强, 施浩, 王沛政. 三亚湾沙滩沙子黑化研究分析[J]. 技术与市场, 2016, 23（11）: 31-32.
[3] 胡劲召,赵由之,卢徐节,等. “泥化”沙岸中活性二价铁分布及其环境效应[J]. 齐齐哈尔大学学报(自然科学版),2017,33(4):53-56. doi: 10.3969/j.issn.1007-984X.2017.04.012
[4] 毛龙江,张永战,张振克,等. 海南岛三亚湾现代沉积环境[J]. 海洋地质与第四纪地质,2007,27(4):17-22. doi: 10.16562/j.cnki.0256-1492.2007.04.006
[5] SCHWERTMANN U, MURAD E. Forms and translocation of iron inpodzolized soils[C]//KIMBLE J M, YECK RD （eds） Proceedings of the fifth international soil correlation meeting: characterization, classification, and utilization of spodosols. USDA Soil Conservation Service, Lincoln, NE. 1990: 319-342.
[6] SHEPARD F P. Nomenclature based on sand-silt-clay ratios[J]. Journal of Sedimentary Research,1954,24(3):151-158.
[7] PEJRUP M . The triangular diagram used for classification of estuarine sediments: a new approach[M]. Oxford: Pergamon Press, 1988: 289-299.
[8] 屈童,高岗,徐新德,等. 三角洲—浅海沉积体系陆源有机质分布控制因素[J]. 沉积学报,2020,38(3):648-660. doi: 10.14027/j.issn.1000-0550.2019.057
[9] 刘丛强. 生物地球化学过程与地表物质循环: 西南喀斯特流域侵蚀与生源要素循环[M]. 北京: 科学出版社, 2007.
[10] ADAMS R S,BUSTIN R M. The effects of surface area,grain size and mineralogy on organic matter sedimentation and preservation across the modern Squamish Delta,British Columbia:the potential role of sediment surface area in the formation of petroleum source rocks[J]. International Journal of Coal Geology,2001,46(2):93-112.
[11] LAWRENCE M. Extent of coverage of mineral surfaces by organic matter in marine sediments[J]. Geochimica et Cosmochimica Acta,2005,63:207-215.
[12] LAWRENCE M. Relationships between mineral surfaces and organic carbon concentrations in soils and sediments[J]. Chemical Geology, 1994, 114:347-363.
[13] KEIL R G,TSAMAKIS E,FUH C B et al. Mineralogical and textural controls on the organic composition of coastal marine sediments:hydrodynamic separation using SPLITT-fractionation[J]. Geochimica et Cosmochimica Acta,1994,58(2):879-893. doi: 10.1016/0016-7037(94)90512-6
[14] 陈家坊,何群,邵宗臣. 土壤中氧化铁的活化过程的探讨[J]. 土壤学报,1983(4):387-393.
[15] 胡梦茜, 崔振昂, 吴自军, 等. 三亚湾海滩泥黑化空间差异与形成条件[J]. 海洋地质前沿, 2022, 38（7）: 23-30.
[16] 何群, 陈家坊. 土壤中游离铁和络合态铁的测定[J]. 土壤, 1983, 15（6）: 242-244.
[17] RIEDEL T, ZAK D, BIESTER H, et al. Iron traps terrestrially derived dissolved organic matter at redox interfaces[C]//Proceedings of the National Academy of Sciences, 2013, 110（25）: 10101-10105.
[18] 杨顶田,单秀娟,刘素敏,等. 三亚湾近10年pH的时空变化特征及对珊瑚礁石影响分析[J]. 南方水产科学,2013,9(1):1-7. doi: 10.3969/j.issn.2095-0780.2013.01.001
[19] 刘娟,王津,陈永亨,等. 铊在矿物胶体和天然有机质界面上迁移转化行为的研究进展[J]. 地球与环境,2013,41(3):326-333.
[20] 王龙,马杰,邓迎璇,等. 金属离子在铁(氢)氧化物与腐殖质微界面上的吸附机理和模型研究进展[J]. 农业资源与环境学报,2017,34(5):405-413. doi: 10.13254/j.jare.2017.0125
[21] 王丹丽,王恩德. 针铁矿及腐殖质对水体重金属离子的吸附作用[J]. 安全与环境学报,2001,1(4):1-4. doi: 10.3969/j.issn.1009-6094.2001.04.001
[22] 庞瑜. 腐植酸、水铁矿及其共沉物对土壤Pb形态及生物有效性的影响[D]. 兰州: 兰州大学, 2017.
[23] 谢亚巍. 铁氧化物及其腐殖酸复合物对砷的吸持特性研究[D]. 重庆: 西南大学, 2012.
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