高强度人类活动干扰下河流水体CO2分压及其排放通量的时空分异:以巢湖流域为例OA

Rivers constitute significant sources of atmospheric carbon dioxide(CO2),with global emissions surpassing half of the annual carbon sequestration by terrestrial ecosystems;these fluxes are further susceptible to substantial alteration under intense an-thropogenic disturbance.The present study investigated the aquatic partial pressure of CO2(pCO2)and CO2 efflux across the water interface during wet,dry,and normal hydrological seasons based on field measurements at Lake Chaohu Basin,a region subject to intense anthropogenic pressure.Results revealed pronounced spatial variability:pCO2 levels were highest in urban rivers(e.g.,Nanfei River:(3855±951)μatm),followed by suburban(Pai River:(2381±538)μatm),agricultural(Zhao River:(817±163)μatm),and lakeside wetland rivers(Tangxi River:(550±250)μatm).Although seasonal differences were not statistically significant,mean pCO2 was elevated during the dry season((2881±1778)μatm)relative to normal((2381±1717)μatm)and wet((1430±993)μatm)periods.Statistically,pCO2 correlated positively with discharge,total nitrogen(TN),total phosphorus,and ammonia nitrogen,and negatively with dissolved oxygen,pH,and chlorophyll-a,with multiple regression identifying TN and pH as primary explanatory variables.Consequently,the basin-wide mean CO2 flux was 78.80 mmol/(m2·d),with urban rivers exhibiting efflux rates 7 times and 21-85 times greater than agricultural and lakeside wetland rivers,respectively.These findings underscore the role of heavily modified urban rivers as extreme emission hotspots and highlighted the necessity of incorporating an-thropogenic intensity into future fluvial carbon cycling models.