甬江流域氮素收支估算及驱动因素分析  

Estimation of Nitrogen Budget and Its Driving Factors in the Yongjiang River Basin

作　　者：杨宏伟 黄国鲜 罗艳 雷坤[2] 郎琪 翁巧然 王文辉 彭嘉玉[2] 李晓光[2] YANG Hongwei;HUANG Guoxian;LUO Yan;LEI Kun;LANG Qi;WENG Qiaoran;WANG Wenhui;PENG Jiayu;LI Xiaoguang(School of Civil Engineering and Water Resources,Qinghai University,Xining 810016,China;State Environmental Protection Key Laboratory of Estuarine and Coastal Environment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China;Ningbo Research Institute of Ecological and Environmental Sciences,Ningbo 315012,China)

机构地区：[1]青海大学土木水利学院,青海西宁810016 [2]中国环境科学研究院,生态环境部河口与海岸带环境重点实验室,北京100012 [3]宁波市生态环境科学研究院,浙江宁波315012

出　　处：《环境科学研究》2024年第7期1435-1445,共11页Research of Environmental Sciences

基　　金：国家重点研发计划项目(No.2021YFC3101705)。

摘　　要：近年来,大量农业氮肥施用、化石燃料使用等人为活动的扰动增加了生态系统的氮输入,导致河流硝酸盐超标、湖库与近岸海域富营养化和土壤酸化等环境问题。长江口-杭州湾是我国近岸海域劣四类水质分布的主要区域,甬江作为汇入杭州湾的重要河流之一,近年来其入海断面总氮浓度和氮通量反弹明显,开展甬江流域的氮收支估算是开展流域氮污染治理与管控、改善近岸海域水质的重要前提。本文利用2021年甬江流域的基本统计数据和相关参数对该区域氮的收支进行估算,阐明了氮收支的主要驱动因素及其对环境的影响。结果表明:2021年甬江流域氮输入量为5.1×10^(4 )t;氮盈余量高达2.17×10^(4) t,占氮输入量的42.56%;流域氮负荷[172.56 kg/(hm^(2)·a)]和陆地氮通量[105.8 kg/(hm^(2)·a)]均高于全国平均水平。氮输入源主要包括人畜排泄、化学氮肥、大气沉降,占比依次为39.11%、26.33%、20.91%;氮输出中,有48%被作物收获带走,有26.98%通过反硝化、氮挥发进入大气,有21.47%以径流的形式进入水环境;从空间分布上,鄞州、镇海等地区面临较为严峻的氮污染潜势。冗余分析(RDA)显示,人口密度、人口数量、农作物种植面积、畜禽数量以及与人类活动有关的工业企业总产值、城镇化程度和GDP是甬江流域氮盈余、氮负荷以及陆地氮通量的主要驱动因素。鉴于甬江流域显著的氮盈余状况,建议采用氮素源头减排治理管控措施以消除氮素盈余对甬江流域氮平衡造成的负面影响。甬江流域氮收支平衡估算可为合理制定氮污染治理管控措施,科学调控流域氮收支和改善近岸海域水环境质量提供科学依据和支撑。In recent years,the interference of large-scale agricultural nitrogen fertilizers and fossil fuel has increased the nitrogen input into the ecosystem,leading to environmental problems such as excessive nitrate content in rivers,eutrophication of lakes,reservoirs,and nearshore waters,and soil acidification.The Yangtze Estuary and Hangzhou Bay are the primary zones where water quality has dropped to Class Ⅳ(Sea Water Quality Standard(GB 3097-1997)).As one of the important rivers flowing into Hangzhou Bay,the total nitrogen concentration and flux of the Yongjiang River have increased significantly in recent years.The current estimation of nitrogen budget in the river basin is of great significance and guidance for carrying out nitrogen pollution control and management in the basin and improving water quality in the nearshore waters.The basic statistical data and related parameters of the river basin in 2021 were collected and used to estimate the nitrogen balance.The main driving factors of nitrogen balance and their impact on the environment were clarified.The results show that the nitrogen input in the Yongjiang River Basin in 2021 was 51,060 t and the nitrogen surplus was as high as 21,730 t,accounting for 42.56% of the nitrogen input.The average nitrogen load in the watershed(172.56 kg/(hm^(2)·a))and land nitrogen flux(105.8 kg/(hm^(2)·a))were both higher than the national spatial scale average.The main sources of nitrogen input included human and animal excretion,chemical nitrogen fertilizer,and atmospheric deposition,accounting for 39.11%,26.33% and 20.91%,respectively.Among nitrogen output,48% was taken away by crop harvest,26.98% entered the atmosphere through denitrification and ammonia volatilization,and 21.47% entered the water environment in the form of runoff.From the perspective of spatial distribution,areas such as Yinzhou and Zhenhai faced a relatively serious potential risks of nitrogen pollution.Redundancy analysis(RDA)showed that population density,population size,crop planting area,livestock

关 键 词：氮素收支 甬江流域 氮负荷 陆地氮通量 驱动因素 环境影响 

分 类 号：X52[环境科学与工程—环境工程]