| In recent decades,people in order to pursue the increase of food production and there is a preference for fertilizers,which resulted in the reduced of soil fertility,soil acidification and harden,soluble salt accumulation in the surface of the soil and other phenomena.Organic fertilizer has a significant contribution to improving soil physicochemical properties,soil aging,activating soil nutrients,providing a large number of organic and inorganic nutrients,hydroponic fertilizer,soil heavy metal purification,but now the quality of organic fertilizer is not as good as before,there are many reports on the excessive of of heavy metals content in organic fertilizer,organic fertilizer like this applied into soil will also bring pollution to the soil.With the application of organic fertilizer,heavy metals accumulate on the surface of the soil,and heavy metals can also affect the quality of the groundwater through the leaching of rainwater or irrigation.Whether it is the contaminated soil by heavy metal or the contaminated water bodies by heavy metal,it is likely to be concentrated in the human body,endangering the health of people’s lives.A total of 102 commercial organic fertilizer samples were randomly collected from 18 cities and counties of Hainan province in this study,content of 7 kinds of heavy metals and 11 kinds of antibiotics contained in the samples as well as their influencing factors were analyzed.The aging experiment and the soil column leaching experiment of organic fertilizer and lead in soil were set,in order to study the effect of lead-polluted organic fertilizer on morphology of lead in soil and the effect of organic fertilizer on morphology of lead in soil under the condition of exogenous lead as well as the effect of organic fertilizer applied on Pb-polluted soil leaching solution to water quality,the results are as follows:(1)The average content of 7 kinds of heavy metals(Pb,Cr,Cd,Cu,Zn,As,Hg)of Hainan commercial organic fertilizers were 58.16,69.55,1.34,48.65,178.03,10.75,0.24mg·kg-1 respectively,referring to the limits of the organic fertilizer agricultural industry standard NY525-2012 to heavy metals of Pb,Cr,Cd,As,Hg and control standard of Mao Jianhua’s import of toxic and harmful substances in organic fertilizer to Cu Zn,Pb,Cr,Cd,Cu,Zn,As and Hg exceed the standard by the rate of 26.47%,3.92%,4.90%,8.82%,25.49%,17.65%and 0%,the number of samples of 7 kinds of heavy metals are all within the standard accounted for only 47.06%of the total collected organic fertilizers.In this study,the Pb and Zn exceeded standard phenomenon is the most serious,and the second was As.(2)The average contents of oxytetracycline,tetracycline,chlortetracycline,doxycycline,sulfadiazine,sulfamerazine and sulfamethazine,sulfamethoxazole,ciprofloxacin,enrofloxacin and difloxacin in Hainan commercial organic fertilizer were 176.54,834.22,2010.10,627.37,112.82,149.85,195.67,110.47,82.26,146.70,199.18μg·kg-1.Of the 102 organic fertilizer samples,only 18 samples were not detected any antibiotics.In this study,the detected number of ciprofloxacin in commercial organic fertilizer samples in Hainan was the highest,and the number of tetracycline was the least.(3)The organic fertilizer need to be marked origin,raw materials,heavy metal content,antibiotics,etc.on the packaging bags.(4)After the application of organic fertilizer with lead pollution,lead speciation in the soil mainly existed in residual morphology and exchangeable morphology,followed by Iron-manganese oxide morphology and organic matter bound morphology as well as carbonate bound morphology.With the increase of organic fertilizer application,exchangeable lead transform to organic matter bound lead.(5)Under the condition of adding exogenous lead,the proportion of exchangeable lead,Iron-manganese oxide lead and carbonate bound lead was the largest in organic fertilizer applied soil.With the increase of the amount of fertilizer,the proportion of exchangeable lead in the Ge Ruilong organic fertilizers decreased in the soil,carbonate bound lead,Iron-manganese oxide lead,organic matter bound lead,and residual lead ratio increased.The exchangeable lead and carbonate lead ratio decreased,organic matter bound lead and Iron-manganese oxide lead ratio increased in Rongda organic fertilizer treatment in soil,the residue lead ratio changes little.(6)Only available lead is easily absorbed by crops,even organic fertilizer with lead pollution applied into soil,after enough long time aging,all lead forms will be transformed into a stable state,so the organic fertilizer plays a positive role on lead polluted soil.However,because of the poor mobility of heavy metal lead,it will accumulate in the soil surface,so it should be tested before the application of organic fertilizer,then use organic fertilizer with low heavy metal content to improve soil.(7)Lead contaminated soil with organic fertilizer showed a greater amount of leaching in the early stage of leaching,and with the increase of the amount of fertilizer,the content of lead in the leachate increased.(8)If the soil is polluted by lead and the lead content is over the nation second grade quality standards of soil,most of groundwater after leaching is not suitable for drinking,therefore,the use of organic fertilizer to the soil with high content of lead should be careful. |
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