Primary Study of Effects of Phosphogypsum on Growth of Winter Wheat and Environmental Risk Assessment in Costal Saline-sodic Soil Under Different Soil Moistures
Based on previous experiments of effective phosphogypsum(PG)application,a pot experiment of costal saline-sodic soil osmosis-based physiological drought was simulated in lab with 45 000 kg/hm2 of PG was added to test the effects of different soil moistures on wheat growth and possible environmental risk,in which,seven treatments of 90％,80％,70％,60％,50％,40％and 30％soil water-holding capacity(SHWC)were designed.Results showed that wheat height and biomass under 30％SHWC were decreased by 32.06％and 44.17％than those under 80％SHWC respectively,while wheat root weight and malondialdihyde(MDA)were increased by 106.06％and 98.37％respectively,root/shoot ratio and leaf anti-oxidase activities were also increased;The concentrations of Cd,Pb,Cu and soluble F in soil were increased by 3.2％,7.2％,50.9％and 150％respectively,and the contents of Cd,Pb,soluble F in wheat leaves were increased by 50％,33.3％and 275％respectively.Applying PG to amend saline-sodic soil affected wheat growth under water stress resulting in the increase of Cd and soluble F in soil and wheat leaves.The contents of toxic elements increased in soil and wheat leaves were far from the national limits of heavy metals in soil and grains,however toxic elements in soil and groundwater will be accumulated with the continued application of PG.Meantime toxic elements in wheat leaves transported to grain may cause grain safety risk.The use of PG in saline-sodic soil in drought region and physiological drought caused by soil high-salt osmosis may lead to the ecological and environmental risks of soil,ground water and food safety,thus,special study and monitor are suggested in order to minimize the ecological and environmental and food safety risks.
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