河口混合区划定及营养盐标准限值构建

河口是河流和海洋生态系统的过渡带,目前中国缺乏河口区划界和水质评价标准,河口区及其附近海域环境质量评价直接使用《海水水质标准》(GB 3097-1997)对标评价的方式,评价结果往往与实际不符,对河口地区开发建设和管理保护不利。笔者系统分析了中国河口区划分及水质评价的现状和存在问题,以北部湾主要入海河口钦州湾为例比较了河口区营养盐背景值与海洋营养盐背景值,两者差异显著,认为使用《海水水质标准》(GB 3097-1997)对河口区进行评价不能很好地反映环境质量。因此依据现行的《地表水环境质量标准》(GB 3838-2002)、《海水水质标准》(GB 3097-1997)和《近岸海域环境功能区管理办法》,提出使用盐度等数据探讨河口混合区划定及建立河口混合区水质营养盐标准限值的方法。在钦州湾的应用案例中,河口混合区的划定和河口区营养盐标准限值确定,都具有科学性和可操作性。使用河口混合区营养盐标准进行评价的结果比直接使用《海水水质标准》(GB 3097-1997)评价能更准确地反映环境质量,可为河口区划界及水质评价提供方法参考。

Study on Estuarine Mixed Zone Delimitation and Nutrient Standard Iimits Construction Method

Estuaries are transitional zones between rivers and marine ecosystems.At present,the criteria for delimitation of estuaries and evaluation of water quality are lacking in China.Environmental quality assessment of estuaries and adjacent sea areas directly uses the method of Sea Water Quality Standard for evaluation of water quality.The evaluation results are often inconsistent with the reality,which is not conducive to the development,construction,management and protection of estuaries.This paper systematically analyses the present situation and existing problems of estuary division and water quality evaluation in China.Taking Qinzhou Bay,the main estuary of Beibu Gulf,as an example,the background values of nutrients and marine nutrients in the estuary area are compared.The difference between the two values is significant.It is considered that the evaluation of estuary area by using the Water Quality Standard of Seawater cannot reflect the environmental quality very well.Therefore,based on the current Surface Water Environmental Quality Standard,Sea Water Quality Standard and Management Measures for Environmental Functional Areas in Coastal Sea Area,this paper puts forward a method to delimit estuarine mixed zones and establish the standard limits of water quality and nutrients in estuarine mixed zones by using salinity data.In the application case of Qinzhou Bay,the delimitation of estuarine mixed zone and the determination of nutrient standard limits in estuarine zone are both scientific and operable.The results of evaluation using nutrient standard in estuarine mixed zone can reflect the environmental quality more accurately than that using Sea Water Quality Standard directly.It can provide a method reference for the division of estuary area and the evaluation of water quality.