摘要
淡水生态系统被认为是大气温室气体排放的重要来源,尤其在人类活动影响下,其排放强度可能进一步增强。城市小型景观水体是城市生态系统的重要组成,具有面积小、数量大以及人类干扰强的特征,其温室气体排放特征及影响因素尚不清楚。选择重庆市大学城8个景观水体和周边2个自然水体为对象,于2019年1、4、7、10月,利用漂浮箱和顶空法分析了水体CO_(2)与CH_(4)的溶存浓度及排放通量,旨在揭示城市小型景观水体CO_(2)与CH_(4)排放强度、时空变异特征以及影响因素。结果表明,10个小型水体CO_(2)、CH_(4)的溶存浓度范围分别为10.75—116.25μmol/L和0.09—3.61μmol/L(均值分别为(47.6±29.3)μmol/L、(1.13±0.56)μmol/L),均为过饱和状态;漂浮箱法实测的8个景观水体CO_(2)和CH_(4)排放通量均值分别为(72.7±65.9)mmol m-2 d-1和(2.31±3.48)mmol m-2 d-1(顶空法估算值为(69.7±82.0)mmol m-2 d-1和(3.69±2.92)mmol m-2 d-1),是2个自然水体的3.5—6.1和2.0—4.5倍,呈较强的CO_(2)、CH_(4)排放源;居民区景观水体CO_(2)和CH_(4)排放略高于校园区,均显著高于对照的自然水体;CO_(2)排放夏季最高,秋季次之,冬、春季最低,CH_(4)呈夏季>秋季≈春季>冬季的季节模式,温度和水体初级生产共同影响CO_(2)和CH_(4)排放的季节模式;水生植物分布对景观水体CO_(2)、CH_(4)排放有显著影响,有植物分布的水域比无植物水域平均高1.97和2.94倍;漂浮箱法和顶空法测得气体通量线性关系较好,但顶空法测得CO_(2)通量在春季明显偏低,而CH_(4)则普遍偏高。相关分析表明,景观水体碳、氮浓度、pH值以及DO等对CO_(2)排放具有较好的指示性,CH_(4)排放通量主要与水体中碳、磷浓度有关。城市小型景观水体CO_(2)、CH_(4)排放通量远高于大部分已有自然水体的研究结果,呈一种较强的大气温室气体排放源,在区域淡水系统温室气体排放清单中具有重要贡献,未来研究中应给以更多关注。
Freshwater ecosystem,as sink of the terrestrial and anthropogenic carbon,is the most active bioreactor for global carbon biogeochemical processes and an important emitter of greenhouse gases(i.e.CO_(2)and CH_(4))to atmosphere,and then influences the global climate change and carbon cycling.CO_(2)and CH_(4)emissions from freshwaters have been extensively attentional in recent years given their importance,particularly that the emissions would be further enhanced by the increasing human activities.The urban small-scale landscape water bodies(including landscape pond,lake),featured by small area and large quantity,are a crucial component of urban ecosystem and strongly influenced by human activities.However,greenhouse gases emissions from such artificial-dominated waters are rarely studied and have been badly neglected.In the present study,for exploring the spatiotemporal variations and controls of CO_(2)and CH_(4)emissions from urban small landscape waters,we selected eight landscape water bodies and two natural water bodies in Chongqing,and carried out four seasonal investigations of CO_(2)and CH_(4)concentrations and emissions from the surface water in January,April,July and October in 2019 through the static chamber-gas chromatography technique and headspace method.Meanwhile,the vegetated and non-vegetated zones in the sampling water were monitored separately to identify the hydrophyte's disturbance.The result showed that CO_(2)and CH_(4)concentrations in urban landscape waters in Chongqing were widely supersaturated with range of 10.75—116.25μmol/L(averaged(42.5±28.7)μmol/L)and 0.09—3.61μmol/L(average of(0.98±0.80)μmol/L),respectively;the average CO_(2)and CH_(4)fluxes measured by the floating box method were(72.7±65.9)and(2.3±3.5)mmol m-2 d-1 respectively,indicating that the urban landscape waters were the net CO_(2)/CH_(4)emission source.CO_(2)and CH_(4)emissions from the residential landscape waters were slightly higher than those from the landscape waters in campuses,but both were significantly higher than the two natural waters which were almost impervious to urban activity,suggested that the urban landscape waters could play a crucial contribution to the inland water CO_(2)and CH_(4)emissions on regional scale.In addition,the distribution of aquatic plants had a significant impact on the CO_(2)and CH_(4)emissions of landscape waters with that the emission flux from non-vegetated water was universally smaller than that from vegetated zone.CO_(2)and CH_(4)fluxes from urban landscape waters presented obviously seasonal patterns,there into,CO_(2)fluxes were the highest in summer,followed by autumn,and the lowest in winter and spring,while CH_(4)fluxes in summer were higher than that in autumn and spring,significantly higher than winter.Temperature was the critical factor determining the seasonal variation of CH_(4)and CO_(2)emissions,while CO_(2)flux was also affected by water primary production.CO_(2)emissions of landscape waters were significantly associated with the factors such as pH,nitrogen,carbon concentration and dissolved oxygen.Meanwhile,CH_(4)emissions were mainly related to the carbon and phosphorus concentrations in surface water.The CO_(2)and CH_(4)fluxes from urban small landscape water bodies in this study were much higher than most of the previous survey on natural lakes,reservoirs and ponds,which highlighted the landscape waters may be a strong source of greenhouse gas emissions to the atmosphere,and plays a vital role in the greenhouse gas emission inventory from global or regional freshwater system,and thus more attention should be paid in future.
作者
黄婷
王晓锋
刘婷婷
庞吉丽
陈彦蓉
吴文洁
赵舒宁
吴胜男
王继龙
HUANG Ting;WANG Xiaofeng;LIU Tingting;PANG Jili;CHEN Yanrong;WU Wenjie;ZHAO Shuning;WU Shengnan;WANG Jilong(Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River,Chongqing 401331,China;Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station,Chongqing 405400,China;College of Geography and Tourism,Chongqing Normal University,Chongqing 401331,China;State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China)
出处
《生态学报》
CAS
CSCD
北大核心
2021年第15期6024-6037,共14页
Acta Ecologica Sinica
基金
国家自然科学基金项目(41807321)
重庆市基础研究与前沿探索项目(cstc2018jcyjAX0672)
重庆市教委科学技术研究项目(KJZDK202000502)
地理科学重庆市本科一流专业立项建设项目。
