贵州草海高原湿地系统湖泊水体重金属多源性研究

As a critical part of Caohai wetland system in Guizhou plateau, the lake play an important role in maintains ecological balance and equitable climate change mitigation to ensure the healthy and harmonious development of species diversity. The water deterioration is accelerating under the stress of frequent interference of human activities increasingly, while the risk of heavy metals pollution in water has been presenting. Based on the complex factors of natural and human influence in the heavy metals pollution of water in Caohai, this study researches the heavy metals source orientation from the space axis of "space-ground-lake bottom". A method of the biological absorption by MossBag is used to study the flux amount of heavy metals from atmospheric sedimentation source. Through laboratory-simulation experiments of static and dynamic release rules in sediments, the release of heavy metals from sediment to water is detected. The heavy metals content from runoff is monitored under different land use patterns around the lake, to find out the relationship between human activities on heavy metal pollution in water of Caohai. The rules of temporal and spatial changes of heavy metal pollution in water under the warm-moist climatic condition and complex geologic and geomorphologic environment of Guizhou plateau lakes is clarified, aimed to ascertain the characteristics of water heavy metal pollution sources under the both stress of high background value of heavy metals and frequent human activities, to provide a scientific evidence for protection water and balance wetland ecosystem in Caohai.

湖泊是贵州草海高原湿地系统的重要组成部分，维系着区域生态平衡和气候变化平稳，保障物种多样性健康和谐发展。在人类活动日趋频繁的胁迫下，草海水环境质量恶化呈加速态势，水体重金属污染风险已然显现。本项目针对草海水体重金属污染复杂的自然和人为影响因素，从“大气—地面—湖底”空间轴上开展重金属源向性研究。提出采用苔藓袋（MossBag）生物吸收的方法研究水环境重金属的大气沉降源通量，通过室内模拟沉积物重金属静态、动态释放规律，探明水体重金属的沉积物释放源规律，并进一步开展湖泊周边不同土地利用方式下地面径流重金属含量监测，摸清人类活动对草海水环境重金属污染的危害性。阐明贵州温湿多雨气候条件和复杂交错的地质地貌环境下，高原湖泊重金属污染发生的时间、空间变化规律，揭示在重金属的高背景值以及频繁人类活动双重胁迫下，水体重金属污染源的贡献特征，为草海湿地生态系统平衡和水环境质量保护措施的合理制定提供科学依据

草海是贵州省最大的天然高原淡水湖泊，作为喀斯特地区典型且完整的高原退化湿地生态系统，其脆弱性、典型性、重要性、生物多样性等都具有代表意义。碳酸盐岩地质发育使其重金属具有天生的“高背景”特性，为探明草海湖泊水体重金属来源及污染水平，项目从“大气—地面—湖底”空间轴上开展重金属源向性研究，探明草海水体重金属输入源及其对水体重金属污染贡献。取得的主要创新性成果包括：（1）在整个空间垂直系统中，以大气沉降为重金属运输通道，水为载体，沉积物为归趋的多环境链上，区域处于Hg、Cd严重污染状况。（2）Mossbag采集大气沉降重金属通量显示，冬季采暖是区域大气沉降重金属重要贡献源，而Hg沉降为大气作用的远距离传输，重金属大气沉降尚不构成人群健康风险。（3）自然条件下，沉积物中Hg、As向水体释放，而水体Cr、Cd、Pb、Zn则有被沉积物吸附的趋势。（4）水体中DOM吸附重金属在一定时间上可以沉淀到沉积物中。（5）草海湖泊重金属虽然总量高，在化学形态上却以稳定的残渣结合态存在，环境稳定性高，对水生生物尚未构成危害。相关成果已发表论文13篇，出版专著1部，申请发明专利4项，培养硕士研究生2名，参加学术交流会议4次，并作专题报告1次。