摘要
随着农业氮肥大量施用,大量碳氮营养物质以淋溶或径流形式进入周边灌溉水体,使其成为甲烷(CH4)和氧化亚氮(N_(2)O)的重要排放源.以我国东南部地区典型稻田灌溉河流为研究对象,于2014年9月至2016年9月连续两年原位观测表层水体CH4和N_(2)O溶存浓度及其排放通量,旨在明确稻田灌溉河流CH4和N_(2)O的排放特征、排放强度及其主要驱动因子.结果表明,观测期内c(CH4溶存)的年平均值为(390.57±43.95)nmol·L^(-1)(92.80~1577.54 nmol·L^(-1)),c(N_(2)O溶存)的年平均值为(40.23±3.20)nmol·L^(-1)(10.05~75.40 nmol·L^(-1)).CH4和N_(2)O的排放通量(年平均)分别为(20.73±6.08)mg·(m^(2)·h)^(-1)和(34.30±7.12)μg·(m^(2)·h)^(-1).CH4和N_(2)O溶存浓度和排放通量整体上均呈现出春夏排放高,秋冬排放低的季节变化趋势.两年CH4累计排放总量为(3876.30±1153.96)kg·hm^(-2),N_(2)O累计排放总量为(5.74±0.98)kg·hm^(-2).两者持续性全球增温潜势(SGWP,以CO_(2)-eq计)平均为(87.99±15.73)t·(hm^(2)·a)^(-1).CH4排放通量与水温、底泥可溶性有机碳(DOC)显著正相关,而与水体溶解氧(DO)显著负相关;N_(2)O排放通量与水温、水中铵态氮(NH_(4)^(+)-N)和硝态氮(NO_(3)^(-)-N)显著正相关,而与水体DO显著负相关.该研究可为科学估算我国农业灌溉流域CH_(4)和N_(2)O排放总量提供数据支撑和重要参考.
With the increase in fertilizer application,a large amount of carbon and nitrogen enters the irrigation water around farmland through leaching and runoff,which makes it become an important source of methane(CH4)and nitrous oxide(N_(2)O)emissions.In this study,the dynamic characteristics of dissolved CH4 and N_(2)O concentrations and emissions were observed from Sept.2014-Sept.2016.The purpose of this study was to investigate the inventory and the influencing factors of CH4 and N_(2)O fluxes from a rice-paddy drainage river.The results showed that the dissolved c(CH4)in the rice-paddy drainage river ranged from 92.80 to 1577.54 nmol·L^(-1),with an annual mean value of(390.57±43.95)nmol·L^(-1).The dissolved c(N_(2)O)in the rice-paddy drainage river ranged from 10.05 to 75.40 nmol·L^(-1),with an annual mean value of(40.23±3.20)nmol·L^(-1).The annual mean fluxes of CH4 and N_(2)O were(20.73±6.08)mg·(m^(2)·h)-1 and(34.30±7.12)μg·(m^(2)·h)^(-1),respectively.The seasonal variations in dissolved CH4 and N_(2)O concentrations and fluxes were similar with higher concentrations,and fluxes appeared in spring and summer;lower concentrations and fluxes appeared in fall and winter.The two-year total annual emissions of CH4 and N_(2)O were(3876.30±1153.96)kg·hm^(-2) and(5.74±0.98)kg·hm^(-2),respectively.The annual mean value of the sustained-flux global warming potential(SGWP100a,CO2-eq)over the time span of 100 years was(87.99±15.73)t·(hm^(2)·a)^(-1).The CH4 fluxes were positively correlated with water temperature and sediment-dissolved organic carbon(DOC),while negatively correlated with water dissolved oxygen(DO)concentration in the rice-paddy drainage river.Meanwhile,the N_(2)O fluxes were positively correlated with water temperature,ammonium nitrogen(NH_(4)^(+)-N),and nitrate nitrogen(NO_(3)^(-)-N),while negatively correlated with water dissolved oxygen(DO)concentration.This study may provide important reference for further understanding of total CH_(4) and N_(2)O emissions of agricultural irrigation watersheds.
作者
吴双
杨蔚桐
盛扬悦
方贤滔
张天睿
胡靖
刘树伟
邹建文
WU Shuang;YANG Wei-tong;SHENG Yang-yue;FANG Xian-tao;ZHANG Tian-rui;HU Jing;LIU Shu-wei;ZOU Jian-wen(College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China;Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation,Nanjing 210095,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2021年第12期6014-6024,共11页
Environmental Science
基金
国家自然科学基金青年科学基金项目(41907072)
中央高校基本科研业务费专项(KJQN202021)
国家自然科学基金项目(42077080)。
