扎龙湿地叶绿素a浓度的协同克里格插值

Spatial Interpolation of the Chlorophyll-a Concentration in Zhalong Wetland Based on Cokriging

研究扎龙湿地叶绿素a含量的空间分布情况,可以为水环境质量监测提供依据。选取分布在扎龙湿地西北部的克钦湖,中部的仙鹤湖,西南部的南山湖等3个较大的湖为研究区,采用协同克里格方法,以随机抽取的48个采样点的叶绿素a含量数据为目标变量,并以这48个采样点的反射率数据为辅助变量,对3个湖水中叶绿素a含量进行插值分析。结果表明:克钦湖的水体叶绿素a浓度分布总体上是南湖比较低,北湖较高,总趋势是由南向北递增。仙鹤湖的叶绿素a浓度大致趋势是东部偏中心的位置浓度较高。南山湖的水体叶绿素a浓度总体比较高,西北—西南区域比东北—东南区域高。这与同步的水质采样数据基本一致,反映了3个湖富营养化状态的实际情况。

The content of chlorophyll-a not only reflect the water plankton and the distribution of primary productivity,but also the change of content is often used as a basic indicator to measure the extent of eutrophication water.It is useful for monitoring the quality of the water to understand the space distribution features of chlorophyll-a,in order to achieve the timely discovery and make measures to management purpose.The spatial distribution of chlorophyll-a concentration in Zhalong Wetland was useful to water environmental quality.Keqin Lake was located in northwestward of Zhalong Wetland,Xianhe Lake was located in central section of Zhalong Wetland,and Nanshan Lake was located in southwestward of Zhalong Wetland.The three lakes were selected as study area.The correlation was well between the reflectivity of water and the content of chlorophyll.The reflectivity of water could be directly obtained by spectrometer,so it could be used as auxiliary variables in the Cokriging.Based on Cokriging,48 measured data of the chlorophyll-a concentration were selected as target variable,reflectance as auxiliary variable in Zhalong Wetland.The results of interpolation showed that the chlorophyll-a concentration in southern part of Keqin Lake was low,the value of number was 2.01-5.04 μg/L,and the chlorophyll-a concentration in northern part of Keqin Lake was high,the value of number was 8.13-11.85 μg/L.General trend was increasing from south to north.The chlorophyll-a concentration in central section of Xianhe Lake was the higher.In the three lakes,the chlorophyll-a concentration of Nanshan Lake was the highest,the highest value of number was 20.83.88-23.41 μg/L.The author analyzed the reason of this phenomenon.It was because there were some villages and many cultivated land around the Nanshan lake.Xianhe Lake was the clearest,the bottom of the lake could be seen and the concentration of chlorophyll-a was the lowest;Keqin Lake was grey and the concentration of chlorophyll-a was higher;Nanshan lake was deep grey and the concentration of chlorophyll-a was highest.On the whole,the interference of human factors were serious in southwest of wetland.The results of interpolation were almost consistent to measured data,which reflected the actual situation of eutrophication level of three lakes.