作物群体CO2通量和水分利用效率的快速测定

In this paper,Eddy Correlation (EC) method was employed to measure the latent heat and CO₂ flux density and to calculate Water Use Efficiency (WUE) of winter wheat community in Yucheng district,Shandong Province in 1997.The results showed that the CO₂ flux density had an obvious diurnal change,with a maximum about1.5 mg·s^-1·m^-2,which appeared at about 9:00～10:00 am in general.The WUE of wheat community presented a fall trend from morning to afternoon,and the CO₂ flux density and WUE also had an obvious seasonal change,being lower in the early and late growth stages,and higher in the middle growth stage.The ranges of daily mean CO₂ flux density and WUE were 0.2～0.9 mg·s^-1·m^-2 and 5～20 gCO₂·kg^-1 H₂O,respectively.     

作物群体CO2通量和水分利用效率的快速测定

In this paper, Eddy Correlation (EC) method was employed to measure the latent heat and CO2 flux density and to calculate Water Use Efficiency (WISE) of winter wheat community in Yucheng district, Shandong Province in 1997. The results showed that the CO2 flux density had an obvious diurnal change, with a maximum aboutl. 5 mg·s^-1·m^-2, which appeared at about 9 : 00-10 : 00 am in general. The WUE of wheat community presented a fall trend from morning to afternoon, and the CO2 flux density and WUE also had an obvious seasonal change, being lower in the early and late growth stages, and higher in the middle growth stage. The ranges of daily mean CO2 flux density and WUE were 0.2 - 0.9 mg·s^-1·m^-2 and 5 - 20 gCO2·kg^-1 1H2O, respectively.     

深圳市大气污染时空分布及其与景观格局的关系

气溶胶和臭氧是我国大部分地区的两种主要大气污染物,对城市生态环境和人类身体健康影响严重。以深圳市为研究区,利用大气监测站点提供的监测数据和普通kriging空间插值法,从年、季、月尺度上开展近5年（2015-2019）深圳全市PM_2.5和臭氧的时空分布研究,通过皮尔逊分析和显著性检验从月尺度上分析土地覆盖类型及其景观格局对大气污染的影响。结果表明：（1）近5年内深圳市PM_2.5浓度总体呈现下降趋势,臭氧浓度则先降后升,二者季节性和月度差异显著。（2）PM_2.5和臭氧在年、季、月尺度上空间差异明显,全市PM_2.5浓度整体为西北高、东南低;臭氧浓度西北、东南较高,其余区域相对较低。（3）植被占比的增多对PM_2.5浓度有明显的抑制和调控作用,植被斑块间距离越近,对PM_2.5浓度的调控作用越明显;水体占比的增高会导致臭氧浓度增高和变化幅度增大。研究结果可为城市大气污染防治和景观格局规划管理提供参考。     

基于多源遥感数据的城市热环境响应与归因分析——以深圳市为例

城市热环境是城市局部气候与环境的综合表现,它与土地利用格局密切相关,但是相应的机制研究还不充分。以深圳市为例,首先基于2018年LANDSAT 8遥感影像,采用支持向量机方法和线性光谱混合模型提取土地利用与覆盖度信息,分析了城市土地覆盖对地表温度以及热量收支状况的影响。基于2003-2018的MODIS地表温度数据,进一步研究了深圳市城市热岛现象的时空变化,从地表能量的角度分析城市热岛变化背后的形成机制。结果表明,深圳市地表温度从西北到东南逐渐降低,城市不透水面温度显著高于植被覆盖区域,城市热岛效应明显。不透水面和城市植被共同影响深圳市的地表温度与热量收支状况,不透水地表与感热具有较好的相关性,城市植被与潜热具有较好的相关性。长时间序列分析表明深圳的城市热岛现象在夏季较高而冬季较低,月均热岛强度为2.14℃;对于年际变化,深圳在2003-2018表现出显著的下降趋势。归因分析显示感热通量的影响在深圳起主导作用,这一模式在全年和季节上都较为明显。结果表明深圳市经过高速扩张阶段,目前发展方向是提高建成区的利用效率,该现象强调了热传输在加强城市热岛效应过程中对近地面湍流的干扰作用。本研究可以为缓解热岛效应与景观格局优化研究提供借鉴。