耕地土壤环境质量监测网最优网格尺度识别研究——以珠三角耕地土壤镉为例  

Identify Optimal Grid Scale on Soil Environmental Quality Monitoring Network as An Example of Cultivated Soil Cadmium in the Pearl River Delta

作　　者：谢志宜[1] 罗小玲[1] 郭庆荣[1] 陈丹青[1] 吕小明[1] 陆泗进[2] 王业耀[2] 梁耀杰 朱晓辉[1] 

机构地区：[1]广东省环境监测中心,广东广州510308 [2]中国环境监测总站,北京100012

出　　处：《生态环境学报》2015年第9期1519-1525,共7页Ecology and Environmental Sciences

基　　金：国家自然科学基金(41201540);环保公益行业专项(201509031);省自然科学基金(S2011040001105);省长人才培养基金

摘　　要：最优采样密度的确定是土壤环境调查、监测及监测网建设过程中的热点和难点科学问题,但当前对土壤环境监测最优网格尺度识别的研究较少。文章在对珠江三角洲地区耕地土壤按照2 km×2 km的网格加密调查的基础上,采用经典统计方法、地统计法和空间插值等方法开展土壤镉最优监测网格尺度研究。结果表明:(1)2 km×2 km、4 km×4 km、8 km×8 km和16 km×16 km 4种网格尺度下,采样点间距离均小于空间相关距离,具有中等的空间自相关性;8 km×8 km网格的变程及拟合度最大,说明利用地统计学方法进行珠三角耕地土壤镉含量变量的空间分析,8 km×8 km网格的空间表达能力最强;(2)不论从交叉验证模型,还是独立验证模型以及空间分布模式均可发现,2 km×2 km、4 km×4 km和8 km×8 km等3种采样尺度均可较可靠地反映珠三角区域耕地土壤镉含量的空间变异,而16 km×16 km的采样尺度则无法保证可靠性;(3)在置信水平为95%,相对误差为15%的条件下,采用Cochran公式获取的最佳采样数量为169个,而2 km×2 km、4 km×4 km和8 km×8km满足此条件的点位数均大于169个,此时误差小于《土壤环境监测技术规范》(HJ/T 166─2004)中实验室允许的最大误差25%。总之,在珠江三角洲区域尺度上,以土壤镉作为评价目标的土壤采样中,8 km×8 km是比较适宜的采样尺度。Confirming what would be the optimal sampling density is one of the difficulties for soil environment investigation, monitoring and the construction of monitoring station networks. There are only a few studies that have been conducted on the optimal grid scale for soil environment investigations. This paper is based on the investigation of a 2 km×2 km dense grid of arable soil in the Pearl River Delta, and describes the research carried out to determine the optimal monitoring grid for measuring soil cadmium content by classical statistical methods, geo-statistical methods and spatial interpolation. The results indicate that: (1) Under different monitoring sizes of cells (2 km×2 km, 4 km×4 km, 8 km×8 km, and 16 km×16 km), the distances between the sampling points with intensive spatial autocorrelation are all smaller than the distance of spatial dependence;with the fitting degree increasing, the expressive ability of spatial variability of soil Cd concentration strengthen, indicating the expressive ability of 8 km×8 km grid is strongest;(2) The monitoring grids, except for the 16 km×16 km one, was able to accurately reflect the spatial variability of the arable soil cadmium content in the Pearl River Delta;And (3) the confidence level of the grids (2 km×2 km, 4 km×4 km, 8 km×8 km) to the Cochran Equation is 95%and the relative error is 15%. Under these conditions, the sampling error of the grids (2 km×2 km, 4 km×4 km, 8 km×8 km) was smaller than the permissible laboratory error as specified in the Soil Environmental Monitoring Technical Specifications (HJ/T 166─2004). In conclusion, the 8 km×8 km grid is the theoretical sampling grid for measuring soil cadmium content as the evaluation target on the scale of the Pearl River delta.

关 键 词：土壤环境质量 空间变异 监测网络 地统计 空间插值 

分 类 号：X833[环境科学与工程—环境工程]