Prelimenery Research On The Concentration And Plant Uptake Of Siver In Sewage Sludge

Because of their unique properties,silver nanoparticles(AgNPs)are widely used and enter into the soil environment through various routes,causing harm to the environment.Long-term irrigation with wastewater and application of sewage sludge and various pesticides have led to the serious problems of AgNPs pollution on the agricultural soils.The migration and transformation of AgNPs into the soil,phytotoxicity and its influencing factors? In this study,two pot experiments were carried out on the background of investigation of silver(Ag)content in the sewage sludge of major provincial capital cities.In order to explore the environmental effects of Ag with sludge in agriculture and the comparison with adding to AgNPs,the influencing factors of plant absorption AgNPs.The main contents are summarized as follows.1.Through the investigation of the concentrations of Ag in 55 sewage sludges collected from 32 provincial capital city.The results showed that the concentration of Ag in sewage sludge was between 0.64 and 9.92 mg kg-1,There was significant difference among the different sludge types in the concentration of Ag,as follows,industrial sludge > mixed flow sludge > domestic sludge.However,there was no significant difference in the Ag concentration between different geographical areas,so the geographic location did not affect the Ag concentration in the sewage sludge.2.The results showed that the accumulation and distribution of Ag in soils under different pollution levels sewage sludges and different soil types were studied.The results showed that the total amount of Ag in the soil increased gradually,with the application of sludge fertilizers.By 2013,the concentration of Ag in the soils treated with SS1 and SS2 was 0.87 mg kg-1 and 2.04 mg kg-1,respectively.Compared with the control group,increased by 4 times and 10 times,respectively.The amount of Ag in the soil decreased after the stop application of sludge,and by the year of 2015,the total amount of Ag decreased by 4.42 % ~ 23.9 %.3.The recent gradual increase in the use of silver nanoparticles(AgNPs)has resulted in a rapid increase in the release of silver(Ag)to the environment and has led to serious environmental risk.A glasshouse pot experiment was conducted in which treatments with and without sewage sludge application were set up with addition of AgNPs at concentrations ranging from 0 to 10 mg kg-1.The effects of AgNP addition at different concentrations and from different sources to Sedum plumbizincicola on plant growth and Ag,cadmium(Cd),and zinc(Zn)uptake from the soil were studied.The results indicate that: 1)AgNPs treatment alone had no significant effect on the growth of S.plumbizincicola at a concentration range of 0-10 mg kg-1 but the application of sewage sludge significantly inhibited the growth and biomass of S.plumbizincicola plants(p<0.05);and 2)as the AgNP concentration increased there was no significant change in Ag concentration in S.plumbizincicola shoots but the concentration in the roots increased markedly with a maximum concentration of 2.07 mg kg-1.The enrichment factor of Ag in the roots(0.177-0.330)was significantly higher than that in the aboveground parts(0.00101-0.00402).Cadmium and Zn concentrations in the soil did not change significantly after planting of S.plumbizincicola.The amounts of Cd and Zn taken up by potted plants from the test soils were 2.62-7.14 % and 2.39-7.65 %,respectively.Irrespective of whether AgNPs were added directly or mixed with sewage sludge they exerted no significant effect on the uptake of Cd or Zn by S.plumbizincicola.