中文关键词三峡水库沉积物磷形态有机质粒径 英文关键词Three Gorges Reservoirsedimentphosphorus fractionsorganic mattergrain size

作者	单位	E-mail
潘婵娟	三峡大学土木与建筑学院, 宜昌 443002 长江科学院流域水环境研究所, 武汉 430010 长江科学院流域水资源与生态环境科学湖北省重点实验室, 武汉 430010	576975038@qq.com
黎睿	长江科学院流域水环境研究所, 武汉 430010 长江科学院流域水资源与生态环境科学湖北省重点实验室, 武汉 430010
汤显强	长江科学院流域水环境研究所, 武汉 430010 长江科学院流域水资源与生态环境科学湖北省重点实验室, 武汉 430010 三峡地区地质灾害与生态环境湖北省协同创新中心, 宜昌 443002	ckyshj@126.com
夏振尧	三峡大学土木与建筑学院, 宜昌 443002 三峡地区地质灾害与生态环境湖北省协同创新中心, 宜昌 443002
李青云	长江科学院流域水环境研究所, 武汉 430010 长江科学院流域水资源与生态环境科学湖北省重点实验室, 武汉 430010
杨文俊	长江科学院流域水环境研究所, 武汉 430010 长江科学院流域水资源与生态环境科学湖北省重点实验室, 武汉 430010 三峡地区地质灾害与生态环境湖北省协同创新中心, 宜昌 443002
许文年	三峡大学土木与建筑学院, 宜昌 443002 三峡地区地质灾害与生态环境湖北省协同创新中心, 宜昌 443002

中文摘要 为研究三峡水库蓄水至175 m后干流沉积物总磷（TP）及各形态磷的分布状况，2010年10月采集了乌江、茅坪等13个断面表层沉积物样品，分析了有机质、矿物成分、粒径等理化参数，测定了沉积物总磷、可交换态磷（Ex-P）、铝结合态磷（Al-P）、铁结合态磷（Fe-P）、闭蓄态磷（Oc-P）和钙结合态磷（Ca-P）的含量，探讨了磷形态赋存与沉积物理化性质间的相关性，评估了蓄水对沉积物磷的蓄积及生物可利用性的影响.结果表明，三峡水库干流沉积物有机质含量为7.79~55.63g·kg^-1，主要矿物成分为绿泥石、伊利石和石英.沉积物的主要组成为黏土质粉砂，中值粒径（d₅₀）范围为3.84~23.65 μm.沉积物总磷含量为557.06~837.92 mg·kg^-1，各采样点总磷富集指数均大于1，存在潜在的磷污染风险.沉积物磷形态以Ca-P和Oc-P为主，Ex-P、Fe-P和Al-P含量相对较低，生物可利用性磷仅占总磷含量的2%~8%.与历史资料相比，蓄水后三峡水库沉积物的粒径有细化变小的趋势，易风化矿物组分含量略有增加，蓄水水位的增加并未导致沉积物总磷含量出现明显升高趋势.未来，随着三峡水库来沙进一步减少和泥沙颗粒的逐渐细化，磷在三峡水库部分宽谷河段沉积物有可能逐步蓄积；蓄水运行过程引起的大面积消落带干湿交替以及近坝段浮泥再悬浮都将影响沉积物中磷的生物可利用性水平. 英文摘要 In order to understand the characteristics of the distribution of sediment total phosphorus (TP) and phosphorus fractions in the mainstream sediments in the Three Gorges Reservoir (TGR) after impounding the water level to 175 m, 13 surface sediment samples were collected from the Wujiang to Maoping sections in October 2010. The physico-chemical properties, including organic matter content, particle grain size distribution, and major mineral analysis, as well as total phosphorus and its fractions in the sediment, were determined. Moreover, the relationships among phosphorus fractions, organic matter contents, and particle grain size were discussed, and the effect of the impoundment on sediment phosphorus accumulation and bioavailability was also evaluated. Results indicated that the sediment organic matter content of the TGR was between 7.79 g·kg^-1 and 55.63 g·kg^-1, and the main mineral components were chlorite, illite, and quartz. The sediments were dominated with clayey silt with a median diameter (d₅₀) ranging from 3.84 μm to 23.65 μm. The measured total phosphorus content of the sediments were between 557.06 g·kg^-1 and 837.92 g·kg^-1, and the total phosphorus enrichment index of each sampling site is greater than 1, demonstrating a potential risk for phosphorus pollution. The calcium bound phosphorus (Ca-P) and the reductant soluble phosphorus (Oc-P) were the dominant sediment phosphorus fractions, while the exchangeable phosphorus (Ex-P), the iron bound phosphorus (Fe-P), and aluminum bound phosphorus (Al-P) content were relatively low. Bioavailable P only accounts for 2%-8% of the total phosphorus content. When referring to previous studies, the sediment particle size tended to be smaller and the content of comparatively easy-to-weather minerals slightly increased with the increase of the impoundment water level. However, the increase in the impoundment water level did not result in a significant increase tendency in sediment TP content. In the future, a reduction in sediment input and a decline in sediment particle size may facilitate the accumulation of phosphorus in the sediments in the broad valley section of the TGR. Moreover, large scale dry-wet alternation in the water level fluctuation zone and resuspension of floating mud near the dam both potentially impact the bioavailability of phosphorus in the sediments.

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