水文地质工程地质2025，Vol.52Issue(1)：12-22,11.DOI:10.16030/j.cnki.issn.1000-3665.202409063
砂质海岸地下水营养盐迁移转化过程与入海排泄
Nutrient dynamics and discharge in a coastal sandy beach aquifer
摘要
Abstract
It is of great significance to understand the behavior of nutrients in the groundwater seawater mixing zone(GSMZ)and quantify the input of terrestrial nutrients into the sea.This study focuses on the coastal sandy beach of Beijin Bay,Guangdong Province.Based on the stratified sampling and analysis of the hydrochemical composition of coastal groundwater,this study investigated the distribution characteristics,migration,and transformation of nutrients in coastal groundwater.The submarine groundwater discharge(SGD)and associated nutrient flux into the sea were also evaluated,exploring the potential environmental impacts on coastal water.The results show that compared with surface water,coastal groundwater had higher nutrient content.The concentrations of nitrate and nitrite(NOx-),phosphate(PO43-)and silicate(Si)in groundwater gradually decreased from land to sea and from shallow layer to deep layer.Non-conservative removal of NOx- and PO43- occurred after passing through the GSMZ.NO-xwas mainly removed by denitrification reaction,with the concentration decreasing by 95.81％from land to sea,while PO43- was mainly removed primarily by the adsorption to iron oxide/hydroxide end products.A hotspot of ammonia nitrogen(NH4+)was generated in the middle of the aquifer,and non-conservative addition of NH4+occurred,mainly due to the decomposition and release of organic matter.The estimated SGD rate was 1.49×106 m3/d,comparable to local river discharge.SGD-derived nutrients were estimated to be 983.0 kg/d for dissolved inorganic nitrogen(DIN),37.00 kg/d for PO43-,and 4 023 kg/d for Si,making SGD a a significant source of nutrients to coastal waters.In addition,groundwater had a high ratio of nitrogen to phosphorus(mean:139.6)and ratio of silicon to phosphorus(mean:274.1),while the ratios in seawater were 21.03 and 33.12,respectively.SGD with high ratio of nitrogen to phosphorus had important impacts on the nutrient structure of coastal seawater.Sandy beaches are widely distributed,and the findings of this study can provide scientific basis for the management of ecological environment in similar areas.关键词
砂质海滩/咸淡水过渡带/营养盐/海底地下水排泄/北津湾Key words
sandy aquifer/coastal groundwater mixing zone/nutrients/submarine groundwater discharge(SGD)/Beijin Bay分类
天文与地球科学引用本文复制引用
王学静,郭祎钒,于胜超,汪迁迁,李海龙,郑春苗..砂质海岸地下水营养盐迁移转化过程与入海排泄[J].水文地质工程地质,2025,52(1):12-22,11.基金项目
国家自然科学基金项目(42077173 （）
41890852 （）
42107055) （）
