基于GIS和GPS的沱江中游土壤镉和铅空间变异研究

采用ArcGIS9.0和GPS技术对沱江中游314个土壤样点的耕层中(0～20 cm)镉和铅含量空间变异分布特征及影响因素进行了研究.结果表明,该区土壤镉和铅呈对数正态分布,土壤镉平均含量为(0.11±0.13)mg·kg~(-1),铅平均含量为(30.03±9.82)mg·kg~(-1).土壤镉空间分布是以赵家镇为高值区(0.15～0.30 mg·kg~(-1)),并向东南和西北两侧条带状递减,东南部土壤镉含量主要为0.06～0.15 mg·kg~(-1);土壤铅空间分布以西北部钦北-关帝庙(35～38 mg·kg~(-1))和东南部广兴-带(>38 mg·kg~(-1))两个高值中心分别向两侧逐渐减少.影响因素研究表明,不同质地间土壤镉含量差异不显著,但粘土的铅含量显著高于其他质地土壤.pH与土壤镉含量呈显著正相关,与铅含量呈极显著正相关;酸性、中性土壤镉和铅含量均极显著少于碱性和强碱性土壤.有机质与土壤镉和铅含量均呈极显著相关性,林地、旱地、果园、宅基地林盘和水田5种土地利用方式中镉和铅含量依次增加.土壤镉和铅含量与坡度的相关性关系,表现出土壤镉和铅含量与坡度呈正相关渐变的过程.

Spatial Distribution Characteristics of Soil Cadmium and Lead in the Middle Reaches of Tuojiang River Basin Based on GIS and GPS

According to the chemical analysis data of Cd and Pb content which were from the 314 random sampling points in topsoil(0~20 cm), we studied the spatial distribution characteristics and influential factors of soil Cd and Pb in the middle reaches of Tuojiang River Basin based on the software ArcGIS9.0 and the software of Statistical Product and Service Solutions. The results indicated that the contents of soil Cd and Pb were (0.11±0.13) mg·kg~(-1) and(30.03±9.82)mg·kg~(-1), respectively. The highest value regions(>0.15 mg·kg~(-1)) of Cd content were mainly distributed in the northeast part of study area, and then reduced gradually towards both sides, presenting zonal shapes. On the other hand, the lowest value regions (<0.06 mg·kg~(-1)) were located in north and the south part of study area. Taking the middle part as the center, the Pb content first increased to the both sides and then decreased towards its southeast and northwest. Further more, the highest value region (>38 mg·kg~(-1)) was mainly distributed in the east part, while the lowest value region (<22 mg·kg~(-1)) was distributed in the middle part of the study area. The analysis of influential factors showed that the content and spatial distribution of Cd and Pb was influenced by soil texture, pH, and the content of organic matter, land use types and slopes. In different soil texture, the content of Cd was highest in light loam (0.150±0.105) mg·kg~(-1)], then in heavy loam (0.107±0.064)mg·kg~(-1)] and loam (0.097±0.072 )mg·kg~(-1)], it was lowest in clay (0.096±0.065)mg·kg~(-1)] and sandy loam (0.086±0.040)mg·kg~(-1)]; The content of Pb in clay (31.65±8.15)mg·kg~(-1)] was significantly higher than that of heavy loam (28.15±6.94)mg·kg~(-1)], loam (27.63±7.73 )mg·kg~(-1)] and sandy soil (23.60±4.85)mg·kg~(-1)]. pH was the power positive correlation with soil Cd content, and highly positive correlative with soil Pb content. The concentrations of Cd and Pb in acid and neutral soil were significant- ly lower than those in alkali and strong alkali soils. Correlation analyses indicated that the relationships between soil organic matter and the content of Cd or Pb were highly significance. The contents of Cd and Pb were decreased from woodland, dry field, orchard, house site to paddy field. Furthermore, both Cd and Pb contents in soils were highly significantly grew as the increase of the slopes.