| 摘要: |
| 人类围垦活动对环境的影响逐渐成为研究热点，但此模式对沉积物中磷形态赋存特征及其释放风险的影响尚不明晰。深入探究这一问题对认识沉积物磷内源释放，加强区域水环境治理具有重要意义。本研究以江汉平原典型沉湖湿地为例，在连续提取湖区（G1）和围垦区（G2）沉积物磷形态的基础上，对比识别影响沉积物磷赋存形态的重要因素，并结合等温吸附热力学实验分析沉积物磷的释放能力。结果表明：（1）人类围垦对沉积物磷形态的影响主要集中在生物有效磷（BAP）上。围垦后沉积物含水率下降，导致G1和G2沉积柱中可交换态磷（Ex-P）存在极显著差异（P < 0.001）；低pH和高氧化还原（Eh）环境使铁氧化物中无定形氧化铁（Feox1）向结晶态氧化铁（Feox2）转化增加，造成沉积物对铁结合态磷（Fe-P）吸附减弱，G2沉积柱中Fe-P空间异质性更强（G1的1.52倍）；围垦后人类活动复杂，有机磷（OP）在表层大量累积（占TP含量的51%），新鲜度指数表明期间存在更剧烈的微生物作用。（2）吸附热力学实验表明，相同沉积环境下，G2钻孔沉积物最大吸附量（PAC）和吸附饱和度（DPS）仅有0.726 mg/g和10.6%，平衡吸附浓度（EPC0）却高达0.378 mg/L，与G1沉积物表现相反。说明围垦后沉积物中磷的释放风险增加，表现出“磷源”的特征，建议在此类区域加强对内源磷的管理。 |
| 关键词: 围垦活动 沉积物 磷形态 内源释放 生物有效磷 释放风险 |
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| Occurrence characteristics and adsorption capacities of phosphorus speciation in sediments from land reclamation and lake areas: A study of Chenhu Wetland in Jianghan Plain, China |
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Jiang Ting, Ma Teng, Peng Ziqi, Zheng Bolin, Jiang Qianqian
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Ma Teng
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| Abstract: |
| Land reclamation from lake is increasingly concerned as a potential risk to surface water eutrophication. However, the characteristics of phosphorous（P）and possibility of its release in sediments remain unclear. Undertaking extensive research on this topic holds substantial significance for elucidating the mechanisms of internal phosphorus release from sediments, and enhancing strategies for the management of regional water environments. In this study, two boreholes（lake area G1 and land reclamation area G2）were selected in Chen Lake, Jianghan Plain. Sediment samples from these boreholes were examined for P species as well as other properties. The risk of sediment phosphorous release was explored by thermodynamic adsorption experiments. The results showed that:（1）The principal emphasis of the impact exerted by land reclamation on phosphorus speciation was centered on bioavailable phosphorus（BAP）. The exchangeable phosphorus（Ex-P）in the G1 and G2 sediment boreholes differed significantly（P<0.001）due to the decreased water content in sediment; and the environment with low pH and high redox （Eh） accelerated the transformation of amorphous iron oxides（Feox1）into crystalline iron oxides（Feox2）, which diminished the sorption capacity of iron-bound phosphorus（Fe-P）and strengthen the spatial heterogeneity of Fe-P in the sediment borehole of G2, being 1.52 times that of G1. After the reclamation of lake areas for agriculture, human activities became more complex, organic phosphorus（OP）accumulated extensively in the surface layers, accounting for 51% of the total phosphorus（TP）content. During this period, there was also intensified microbial activities indicated by freshness index. （2）The values of the maximum adsorption capacity（PAC）were merely 0.726 mg/g and the degree of phosphorous saturation（DPS）were only 10.6% in the sediment borehole of G2. Nevertheless, the equilibrium phosphorous concentration（EPC0）were highly 0.378 mg/L in G2. Therefore, the risk of P release increased following land reclamation, acting as "phosphorous source" for the overlying water. It is recommended that the management of internal phosphorus be strengthened in such areas. |
| Key words: Land reclamation from lake Sediment Phosphorus speciation Internal phosphorus release Bioavailable phosphorus Phosphorus release risk |
