Study On Soil Salinization Characteristics Of Tianjin Coastal Region And Its Surrounding Areas

Tianjin coastal region and its surrounding areas are one of the main areas of the coastal saline-alkali soil,and the saline soil is widely distributed.In the context of rapid urban development,it is a great challenge for Tianjin coastal region and its surrounding areas to scientifically utilize saline soil resources according to local conditions.The proper assessment of soil salinization characteristics is the prerequisite for sustainable utilization of saline soil resources.Focused on typical sample area Sino-Singapore Tianjin Eco-City,based on the field acquisition of vertical three layers of a total of 542 soil samples data,the methods of classical statistics and geostatistics,with the aid of spatial interpolation,numerical simulation and remote sensing inversion technology,comprehensive analyzed of soil salinization characteristics of Tianjin coastal region and its surrounding areas,the results showed that:1?The soil salinization is serious in the sample area,and the proportion of salt is over 50%.The soil texture is clay loam,with a density of 1.53 g/cm~3,the capillary porosity is 11.93%,and the contents of each heavy metal element are in the category of minor ecological hazards.The soil surface salinity of the sample area has a strong spatial variability,the middle layer and the depth of medium space variation,with the increase of depth decrease gradually.In the horizontal direction,the spatial variation scale of the salinity of the soil layers is the same,and the spatial correlation intensity is medium.In the vertical direction,the spatial correlation gradually increases with depth.According to the relationship between the layers of salt distribution,soil profiles can be divided into three categories:surface,middle and bottom salt accumulative profile,respectively,26.6%,12.9%,60.5%of the total number of profile,distribution influence by factors such as climate condition,landform,groundwater,vegetation,land use.The proportion of salt ion content in each soil layer is stable,and Na~+and Cl~-in the composition of salt ions are the absolute advantage,which is chloride-type saline soil.The main component analysis showed that the water soluble salt content,Na~+,Cl~-and pH were the key factors to limit soil nutrient accumulation and plant growth.2?In the comparison of spatial interpolation methods of soil salinity in coastal region,on the whole,the interpolation precision of geostatistical interpolation methods is better than deterministic methods'and sequential Gaussian simulation has relatively highest prediction accuracy.Statistical features of simulation results and the measured data are of high consistency,the interpolation surface of sequential Gaussian simulation can reflect the local details accurately.Mean value of sufficient sequential Gaussian simulation can effectively improve the prediction accuracy of the method.Furthermore,in the uncertainty assessment with the threshold of soil salt content at 0.6%,sequential Gaussian simulation can quantify the environmental risk through multiple simulations.It is a effective measure to manage saline soil resources in coastal areas scientifically.3?Landsat 8 OLI as data source,there may be a complex nonlinear relationship between soil salinity and 4 categories 11 characteristic spectrum indexes as indirect characterization of soil salinity conditions.The prediction accuracy of BP neural network inversion model is significantly higher than nonlinear regression model and multiple linear stepwise regression model.The inversion results show that the salinization condition is serious in Tianjin coastal region and its surrounding areas,and the spatial variability of soil salinity is stronger,soil salinity is generally decreasing in the direction from coastal beach to hinterland.