福建海坛海峡赤潮灾害潜在生态风险评估

Potential ecological risk assessment of red tide disaster in Haitan Strait of Fujian Province

基于赤潮灾害风险评估理论和海坛海峡的浮游生物与水文常规监测数据,采用层次分析法(AHP,Analytic Hierarchy Process)构建了海坛海峡赤潮灾害风险评估指标体系,运用熵值法与变异系数法组合赋予权重,建立了较为合理可信的评估模型,并初步给出了海坛海峡赤潮灾害生态风险等级区划图。结果表明:春季,中级-较高级风险区主要分布在海峡北部,海峡南部主要为低风险等级;夏季,较高级风险区存在于南部,绝大部分海区属低风险海域;秋季,以低中风险等级为主,中级风险区主要分布在海峡的西北部与东南部;冬季,较高级与高级风险海域位于海峡的西北部和东北部。研究海域的富营养化程度较高,且富营养化指数权重较大,减少氮磷入海可降低致灾、孕灾危险度,进而能够降低赤潮灾害发生的风险。通过多年的赤潮事件结合验证表明,赤潮发生的时空特征与致灾危险度分布具有较好的关联性。

Based on the risk assessment theory of red tide disaster and the conventional monitoring data of plankton and hydrology in the Haitan Strait,the index system of red tide disaster assessment in the Haitan Strait was constructed by using the method of Analytic Hierarchy Process(AHP),and the weight was assigned by entropy method and coefficient of variation method.A scientific and credible assessment model was established,and the thematic maps of ecological risk disaster of the Haitan Strait were obtained.The results are as follows.The medium-to-high risk areas were mainly distributed in the north of the strait in spring;the southern part of the strait was mainly at low risk.In summer,most of sea areas of the strait had low risk,while the south of the strait faced high risk.In autumn,the risk levels were mainly low and medium,and the medium risk areas were mainly distributed in the northwest and southeast of the strait.In winter,high-risk areas and highest-risk areas were concentrated in the northwest or northeast part of the strait.Because the eutrophication degree of the strait was high and the eutrophication index had a large weight,reducing nitrogen and phosphorus inputs into the strait can reduce the risk of red tide disasters.In addition,it displayed a good temporal and spatial correlation distribution between the red tide events for many years and disaster-causing factor level distribution.