仙桃地区关键带生态演化与碳埋藏

仙桃地区湖群不断萎缩，水体富营养化水平和湿地沉积物重金属含量持续升高，江汉湖群生态系统日益脆弱，加强对该地区生态环境演化研究、分析人类活动和富营养化对湖泊生态系统的影响、探究该地区不同沉积环境的碳埋藏规律等显得尤为重要.在对江汉平原重点地区(仙桃彭场镇幅和脉旺咀幅)第四纪地质调查的基础上，选取研究区大型渔场、小型鱼塘、沟滩、湖泊、水稻田、泄洪道、旱地、汉水阶地8种不同沉积环境的16个关键带点位，分别测定了其表层及浅层钻孔沉积物的色素、TOC(total organic carbon，总有机碳)与TN(total nitrogen，总氮).表层沉积物TOC含量反映了研究区南部多湖泊区域有机碳埋藏量较高，而北部冲、洪积成因环境相对较低，与色素、TN所指示的人类活动强度和富营养化水平相吻合.湿地浅层钻孔沉积物碳埋藏速率变化整体表现为升高趋势，与色素所指示的湖泊富营养化的趋势相吻合；不同沉积环境碳埋藏速率差异较大，最高为大型渔场77.71 g·m-2·a-1、最低为汉水阶地3.61 g·m-2·a-1.研究结果表明，受到人类活动影响，湖相沉积物中碳埋藏量相对较高，湖泊碳汇功能不断增强，这对江汉平原关键带碳循环研究具有重要意义. 

Evolution of Eco-Environment and Carbon Burial of Critical Zones in Xiantao Area,Hubei Province

Lakes in Xiantao area are continuously shrinking, while the eutrophication level and the heavy metal contents of wetland sediments rising, relatively, the ecosystem of the lakes in Jianghan plain weakening increasingly. Enhancing the studies on the eco-environment evolution, analyzing the effects of human activities and eutrophication on lake ecosystem, and discussing the rules of carbon burials in different sedimentary environments are particularly important. Based on the Quaternary geological survey of the key regions in Jianghan plain, we collected and determined sediment samples from 16 key sites in 8 different sedimentary environments (including large fisheries, small fish ponds, vadum, lakes, paddy fields, spillway, dry fields and terrace of Hanjiang River). The total organic carbon(TOC) contents of the surface soils show that the level of organic carbon in the southern area (lake sedimentary environment) is higher than that in the northern region (fluvial and pluvial environment causes), which is consitent with human activity intensity and eutrophication level indicated by pigment, total nitrogen(TN). Carbon burials of shallow core sediments are consistent with the eutrophication level indicated by pigment showing a rising tendency. The rates of carbon burials are various in different sedimentary environments. The highest is in large fisheries (77.71 g·m-2·a-1) while the lowest is in the terrace of Hanjiang River (3.61 g·m-2·a-1). Our study indicates that the carbon aggregation function of lakes is constantly enhancing, and it has important significance to study the carbon cycle of the critical zones in Jianghan plain.