基于沉积物摇蚊亚化石畸变指数的长三角和珠三角水体环境健康演化历史评价

Environmental pollution, especially the trace metal pollution, seriously threaten the health of lentic ecosystems. It’s hard to find a suitable and reliable biological indicator in such severely metal-polluted waterbodies. Chironomidae (Insecta, Diptera) are one of the most abundant zoobenthic families in polluted systems. The mentum deformities of chironomids have been used as potentially suitable indicators for in situ bioassessment and biomonitoring of contamination stress in lakes and reservoirs for decades. However, the mechanisms by which the deformities are induced by metals are not yet well understood, what’s more, few study has been involved in the palaeolimnology field. In order to detect their concentration-effect relationships between metal concentration and deformity frequency, and verify the usefulness of application in reflecting the historic pollution change, three different approaches will be performed, including: 1) To create the relation between the dose and deformities, and the deformed types associated with certain toxic metals, the laboratory experiments under the control condition will be conducted to expose the chironomid (Chironomus kiiensis) to single substances, binary mixtures, tri-mixtures as well as the lake sediments in situ. 2) To check the deformity incidents in the real field condition, deformed larval capsule will be collected from reference sites and impaired sites. 3) To test the reliability in the reconstruction in the past environmental changes, deformed chironomid subfossil will be extracted from the sediment cores. The results suggest that the chironomid mentum deformity can be used reliably in the assessment of historical environmental changes of lakes and reservoirs.

环境污染，特别是重金属污染，严重威胁着水体健康。在评价此类水体时很难找到一种合适并且敏感的生物指标。摇蚊幼虫，作为污染水体中的代表类群，其颏板畸变常常用来原位监测和水体健康评价。虽然此指标推广应用已达半个世纪，但其颏板畸变与污染梯度的内部机理仍然不详，且鲜有个案应用到古环境演变研究中。长三角和珠三角是我国环境污染较为突出的地区，本项目计划选取该区域内的典型重污染湖泊或水库为研究对象，通过室内剂量控制实验（铜、镉、铅）、野外活体幼虫采集以及沉积柱亚化石的综合研究，探讨摇蚊畸变类型的界定、畸变率与污染物剂量的关系。在上述研究基础之上，通过对沉积岩心中摇蚊亚化石的提取分析，建立摇蚊畸变复合指数，构建水环境健康演化序列，并与其它沉积地球化学指标作对比，验证摇蚊亚化石畸变指数在古湖沼学应用的可行性和有效性。

高度经济发达区域经常伴随着水体污染加剧问题，如何量化这些污染对风险生物的毒害效应成了公众最为敏感的话题。本项目通过对珠三角和长三角的特定水体，开展了摇蚊颏板畸变与环境污染要素关联的相关研究。结果表明，摇蚊颏板畸变是一种非常具有潜力的生物标志物，能够有效的反演过去湖泊污染历史，而且颏板畸变类型是对当时特定污染环境的精细注释。室内模拟实验表明，单个重金属或多个重金属的慢性毒理表明，均与颏板畸变无明显相关性，但却作用一些骨化较弱的结构，如，触角、肛管或者叶感器、感觉毛等，或影响每个发育历程的长短和体重。推测颏板畸变可能的主要原因是污染物相互叠加作用的结果或污染物影响了幼虫体内的生理结构，改变了其摄食行为，使得利用颏板牙齿过渡，但无论如何，这种畸变表型均是对一定空间内全部污染总量的整体表现。