The Study On Inactivity Of Cadmium And Arsenic In Farmland Soil Of Pearl River Delta

In recent years,the remediation of farmland soil contaminated with mild heavy metals has been widely concerned and become a hot topic in the academic community.Based on organic materials?mushroom dreg and vegetable stalk compost,chicken manure and rice straw compost?and inorganic materials?lime,montmorillonite and zero-valent iron?,this paper studied the behevior of cadmium and arsenic in the farmland environment in the Pearl River Delta and aimed to provide a basic insight for the remediation of farmland soil and to achieve sustainable production.The mushroom dreg and vegetable stalk compost coupled with inorganic material was MC series,and the chicken manure and rice straw compost coupled with inorganic material was JD series.Through laboratory experiments and pot experiments,the bio-availability of cadmium and arsenic in the red soil and the translocation and accumulation of the cadmium and arsenic in the Lactuca sativa L were studied systematically.And the behavior of mechanism of the cadmium and arsenic in soil-plant were discussed.The results showed as follow:1.Organic materials improved the physicochemical properties of soil and increased the yield of Lactuca sativa L by 0.53⁴.27 times.The pH increased by-0.58⁰.75treated with MC series.The pH increased by 0.90¹.08 treated with JD series.Organic materials significantly increased the salinity of red soil to 1.00¹.43.The ammonia nitrogen and available phosphorus was increased by 14.05²0.91 mg/kg,3.7¹6.0mg/kg treated with JD seies,respectively.The ammonia nitrogen was decreased by6.86⁸.20 mg/kg treated with MC series,there was no significant effect on available phosphorus.2.In 30d,compared with the control group,organic materials decreased the content of DTPA-Cd and CaCl₂-Cd by 8.96-10.45%,16.30-93.08%,respectively,but increased the content of HCl-As by 88.41-1639.13%.Organic materials coupled with lime,montmorillonite and low concentration zero-valent iron?0.05%?decreased the content of DTPA-Cd and CaCl₂-Cd by 16.42²9.85%,22.99⁹3.91%,respectively,however increased the content of HCl-As by 59.42¹595.65%.Coupled with zero-valent iron?0.5%?,the content of DTPA-Cd and CaCl₂-Cd decreased by 23.88-34.33%,90.63-96.01%,respectively,and the content of HCl-As reduced by 37.68%in MC-SM-Fe-2,but the content of HCl-As increased by 407.25%in JD-SM-Fe-2.3.In 30⁹0d,the content of DTPA-Cd and CaCl₂-Cd decreased by-1.52-27.27%,-14.41-80.17%in MC series.However,the JD series increased the content DTPA-Cd by 1.52²7.27%and reduced the content of CaCl₂-Cd by 93.41¹00%.The content of HCl-As decreased by 38.36⁴4.44%in MC-SM-Fe-2,while it increased by27.78¹900.00%in other treatments.4.Different treatment had different effects on cadmium accumulation in Lactuca sativa L.The cadmium content in the shoot of Lactuca sativa L was 0.63¹.07 mg/kg treated by the MC series and increased by-1.56⁶7.43%contrasted with control group?0.64 mg/kg?.But the cadmium content was 0.47⁰.71 mg/kg treated by JD series,which reduced by-11.47²6.51%than that of the control group.5.Cadmium is easily transferred from the root to the shoot in Lactuca sativa L.The shoot?0.02⁰.04 mg/kg?of Lactuca sativa L had higher content of cadmium than root?0.016⁰.032 mg/kg?.