底栖有孔虫对广东海门湾和汕头港的环境污染监测与评价

Benthic foraminiferal community is the most important part of the seafloor ecosystem. These organisms possess the capability of detecting the changes of the ambient environments, and have been recognized as a kind of bio-indicator for marine pollution. Numerous filed experiences reveal that marine pollution has adverse effects on foraminifera, for example, the decrease of abundance and community diversity, variation in the community composition and percentage of different species, and the increasing abnormal test as well. Foraminifera respond to the influence of pollution on coastal ecosystem at both the population-level and the individual-level. The relationship between foraminifera and pollutants serves to assess the ecological influence of marine pollution and bio-monitoring, while the standard methods of field survey and analysis procedures have not set down yet. Our previous works provided proof that the community structure and geographic distribution of the estuarine and near-shore foraminifera are closely related to the percentages of heavy metals and organic carbon in sediments. This project plans to carry out pollution monitoring and assessment using foraminifera in the Haiman Bay and Shantou Harbor, Guangdong province. Based on field survey of the two areas on spring, summer, fall, and winter seasons by repeated sampling, we analysis the distribution patterns and seasonal fluctuations of foraminiferal community and marine pollutants, including heavy metals and organic pollution. The main aims are: (1) to study the relationship between the foraminiferal abundance, diversity and species proportions and the contents of sedimentary contamination, for example positive or negative correlation and the significance of the correlation; (2) to find the historical changes of heavy metals and organic pollutants, and those of foraminiferal abundance and diversity over the last 100 years, all of which are highly influenced by anthropogenic activities like pollution discharge; (3) to explore foraminifera response to pollution stress in historical sediments, including the migration of exogenetic species, the appearance of fortunate species and colonizing, and the disappear of sensitive species; (4) to establish transformation functions between foraminiferal species and heavy metals and organic pollution, respectively. Based on transformation functions, foraminifera quantity indexes for pollution indication can be classified and termed. These indexes are subsequently applied and checked in the historical sediment studies. This work will promote the foraminifera studies in environmental bio-monitoring and pollution evaluation in Chinese near-shore areas.

底栖有孔虫是海底生态系统重要组成部分，能敏感感知环境变化，是一类环境指示生物。海洋污染给有孔虫带来不利影响，如降低有孔虫丰度和多样性，改变属种百分含量，诱发异常壳体等。有孔虫群落和个体变化是对海洋污染的响应，有孔虫与污染定性定量关系能用于海洋污染对生态系统的影响评价和环境监测，但还没有形成标准的方法。前期研究表明河口近岸有孔虫分布与沉积物中的重金属和有机碳有关。本项目以广东海门湾和汕头港为试点，开展有孔虫环境污染监测和评价，在春、夏、秋、冬四个季节重复调查基础上，研究底栖有孔虫群落和重金属、有机污染物的空间分布和季节变化，有孔虫丰度、群落多样性、属种百分含量和污染物之间的关系。研究100年来人类活动对有孔虫群落的影响及有孔虫对污染的响应。建立有孔虫与重金属、有机污染物转换函数，构建指示污染程度的有孔虫定量指标并应用于地层检验。该研究将推动有孔虫在我国近岸海域有孔虫污染监测与评价中的应用。

底栖有孔虫是最丰富、分布最广的微型底栖生物。它们具有个体小、丰度高、多样性高、生活史短、能迅速响应环境变化和对污染耐受能力强等优点，被认为是十分理想的污染指示生物。目前，底栖有孔虫已广泛用于河口、海湾、港口、泻湖、排污口和养殖场等多种环境的污染监测。课题组率先将底栖有孔虫用于我国近岸沿海的海洋污染监测与评价。在广东海门湾和汕头港开展了秋季（11月）、冬季（1月）、春季（4月）和夏季（8月）4个季节底栖有孔虫和重金属污染监测。另外在海南铺前湾、澄迈湾和墩头湾也开展了一次调查。重要结果表明：（1）有孔虫丰度和群落多样性夏季最高，秋季最低，春季和冬季则相差不大。一部分有孔虫属种百分含量夏季最高，秋季最低，而另一部分有孔虫属种百分含量夏季最低，秋季最高。相比之下，重金属没有季节性变化规律。（2）比较四个季节有孔虫对重金属污染的指示作用，结果发现秋季有孔虫与重金属的关系最强，且不同区域的有孔虫群落能很好地区分，而冬季有孔虫与重金属的关系最弱，且不能区分不同区域的有孔虫群落；因此，有孔虫对污染的指示秋季最好，冬季最差。（3）利用有孔虫属种与重金属的定量关系和Loess拟合，将有孔虫划分为三类，对污染的反应分别是敏感的、无影响的和耐受的。同时，依据有孔虫属种百分含量与As拟合曲线的形状，将属种划分为5个生态组：敏感种（EGI）、随遇种（EGII）、忍耐种（EGIII）、二阶机会种（EGIV）和一阶机会种（EGV）。计算FSI指数和Foram-AMBI指数的有孔虫指标，用于环境质量评价。并使用逻辑回归、k最邻接、支持向量机、决策树、随机森林等机器学习方法来评估和预测Foram-AMBI指数环境质量评价结果。