Present Situation And Evaluation Of Farmland Soil Quality In Yangling Demonstration Zone

Yangling High-tech Demonstration Zone,which has a long history,has been one of the most developed agricultural areas in ancient China for more than 4,000 years.Nowadays,Yangling ranks among the first-level development axes of the country's macroeconomic layout and is a traditional Guanzhong economic zone in Shaanxi Province.The soil in this area belongs to the deep soil and rapidly formated and also with qualities of fertile,good ploughability,convenient irrigation,suitable for crop growth,is a relatively high-quality and valuable land resource,is also a key area for the country to vigorously develop agriculture,so investigating the local farmland soil environment and evaluating the level of heavy metal hazards in the soil will be very important.Based on the data of heavy metal content in farmland soils in Yangling area,this study combined various soil heavy metal evaluation methods and ArcGIS technology to evaluate the status of farmland soils in Yangling demonstration area.Based on the content of heavy metals in soil and crops,the intake rate of heavy metal through mouth ingestion,skin contact,and inhalation was calculated in these three ways to bring non-carcinogenic risks and carcinogenic risks to local residents,to explore the heavy metal pollution in soil-crop systems and to make further health risks to the human body Analyze and systematically investigate the status of heavy metal pollution in the local soil and the overall pollution level.The main results are as follows:1.Through field visits and surveys,we found that the local soil environment is exposed to many potential hazards of heavy metals,and its main sources include?1?direct and indirect pollution of farmland soils by agricultural production activities;?2?hazards of domestic wastes got into the farmland soils;?3?Heavy metals from livestock and poultry excrement entered farmland soil;?4?Heavy metal emissions from burning of coal and surrounding traffic.To understand the the impact of fertilizers and pesticides used in agricultural production activities and the impact of domestic waste on the soil environment,which have a greater impact on the soil environment,requires further determination and evaluation of heavy metal content in farmland soils and crops.2.According to the reference material of heavy metal background value in farmland soil of the country,except for As and Cr,the farmland soil in Yangling Demonstration Zone has a certain degree of accumulation,and the over-standard rate of Cd and Ni is the highest.Taking the"China's Environmental Quality Standards for Agricultural Producing Areas"as a reference,the average heavy metal content in farmland soil of the Yangling Demonstration Zone was lower than the standard,but there was still an excess of Cd,Cr,and Ni in several soil samples.Based on the results of single-factor index evaluation,Nemerow index evaluation,and geoaccumulation index evaluation,it can be concluded that the cumulative Cd and Hg concentrations in farmland soil of Yangling Demonstration Area were more prominent,and the comprehensive pollution level of heavy metals in farmland soil has reached a light level or moderate pollution,corresponding policies should be taken out in future.At present,the sources of heavy metals in farmland soil in Yangling Demonstration Zone vary,among which Pb,Cu,and Ni are mainly accumulated in farmland soils in Yangling Demonstration Zone through road traffic,and Cd,Hg,As,and Cr and Ni were from the same source,and the main sources was over-investment of agricultural fertilizers and pesticides.3.The content of heavy metals in cereals,vegetables and fruits in the farmland of Yangling Demonstration Zone is lower than the national food hygiene standard limit.There is no significant difference in the heavy metal content of these three types of crops.The calculated heavy metal pollution index is relatively low,and the heavy metals accumulation in local crops is not serious and does not reach pollution levels.Based on the content of heavy metals in soil and crops,the non-carcinogenic risk cofficient and carcinogenic risk cofficient that are calculated by direct ingestion of soil and crops,skin contact with soil,and inhalation of soil particulates can be calculated.The highest non-carcinogenic risk and carcinogenic risk?were obtained through direct ingestion of soil.As,Ni,and Cu have the highest non-carcinogenic risk cofficient,the non-carcinogenic risk cofficient of As was 1.18,which was slightly higher than the acceptable risk limit.The calculated risks of carcinogenicity of As,Cd,Cr,and Pb were also calculated,the highest risks of carcinogenicity was As and Cr,but they were significantly lower than the acceptable cancer risk level set by the United States Environmental Protection Agency?USEPA?(10^-610^-4),illustrating that the risk of heavy metals for residents of Yangling Demonstration Zone does not include carcinogenic risk.In summary,the rural environment in Yangling Demonstration Zone has a certain degree of damage to the agricultural environment.At present,there are accumulations of heavy metals in the local farmland soil,with Cd and Ni exceeding the highest standards.The content of heavy metals in the local crops did not exceed the standard,residents faced a certain degree of non-carcinogenic risk,but there is no risk of heavy metal cancer,it is needed to pay attention.