Mitigative Effect of La on Glycine max seedlings under Pb-Cd Compound Pollution

Mitigative effect of La on Glycine max seedlings under combined Pb and Cd pollution was studied through pot culture experiment. The results show that the growth and metabolism of Glycine max seedlings are inhibited by the solution with 500 mg.L-1 Pb + 100 mg.L-1 Cd. When 30 mg. L-1 LaCl3 is used to spray Glycine max seedlings once, the injury effect of combined Pb and Cd pollution is reduced. The experiment proves that the effect is related to La which can raise photosynthetic rate, chlorophyll content and activity of nitrate reductase, and reduce cell membrane permeability, content of Pb and Cd, and keep TTC reduction ability of Glycine max seedling.

Compound pollution of Cd,Pb,Cu,Zn,As in plant-soil system and its prevention

By means of both pot and field tests,this paper studied the contents of Cd,Pb,Cu,Zn and As and their ecological effects on plant-soil system.in tissues of crops and soil microorganisms.It was found that there exist synergistic effect among these five elements,especially for Cd in combination.The reclaniation of soil polluted by these elements in combination is rather difficult to be carried out.The distinctive ecological and chemical behaviors between Cd and As make various reclamation measures less applicable,and thus,further research measures are necessary.

Synergistic PM_(2.5)and O_(3)control to address the emerging global PM_(2.5)-O_(3)compound pollution challenges

In recent years,the issue of PM_(2.5)-O_(3)compound pollution has become a significant global environmental concern.This study examines the spatial and temporal patterns of global PM_(2.5)-O_(3)compound pollution and exposure risks,firstly at the global and urban scale,using spatial statistical regression,exposure risk assessment,and trend analyses based on the datasets of daily PM_(2.5)and surface O_(3)concentrations monitored in 120 cities around the world from 2019 to 2022.Additionally,on the basis of the common emission sources,spatial heterogeneity,interacting chemical mechanisms,and synergistic exposure risk levels between PM_(2.5)and O_(3)pollution,we proposed a synergistic PM_(2.5)-O_(3)control framework for the joint control of PM_(2.5)and O3.The results indicated that:(1)Nearly 50%of cities worldwide were affected by PM_(2.5)-O_(3)compound pollution,with China,South Korea,Japan,and India being the global hotspots for PM2.5-O3 compound pollution;(2)Cities with PM_(2.5)-O_(3)compound pollution have exposure risk levels dominated by ST t ST(Stabilization)and ST t HR(High Risk).Exposure risk levels of compound pollution in developing countries are significantly higher than those in developed countries,with unequal exposure characteristics;(3)The selected cities showed significant positive spatial correlations between PM_(2.5)and O_(3)concentrations,which were consistent with the spatial distribution of the precursors NOx and VOCs;(4)During the study period,52.5%of cities worldwide achieved synergistic reductions in annual average PM_(2.5)and O_(3)concentrations.The average PM_(2.5)concentration in these cities decreased by 13.97%,while the average O_(3)concentration decreased by 19.18%.This new solution offers the opportunity to construct intelligent and healthy cities in the upcoming low–carbon transition.

Studies on Heavy Metal Pollution in Soil-Plant System:A Review

Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry. The heavy metal pollution status in soil-plant system in China, the research progress on the bioavailability of heavy metals (affecting factors, extraction methods, free-ion activity model, adsorption model, multivariate regression model, Q-I relationship, and compound pollution), and soil remediation are reviewed in the paper. Future research and monitoring is also discussed.

Review on the Effects of Combined Pollution of Lead and Chromium on Soil Microorganisms and Treatment Methods

Heavy metals—Pb and Cr are important causes of environmental pollution, and they often coexist in nature. At present, the effects of Pb and Cr toxicity on soil microorganisms have been less studied, in soil environment which is extremely complex. Simulating soil environment and studying microbial reaction under various heavy metal conditions are of great significance for revealing microbial tolerance to heavy metals. In this paper, firstly, the related concepts of soil rechecking pollution are discussed, and the physical and chemical properties and forms of lead and chromium are introduced accordingly. Secondly, the effects of combined pollution of lead and chromium on soil microbial biomass, soil microbial community structure and soil microbial activity were discussed. Finally, the relevant treatment methods of heavy metal contaminated soil were put forward.

Fixation of Multiple Metals in Contaminated Soil by Different Passivators

The effects of 4 passivators, zeolite, lime, red mud and peanut shell biochar, on the fixation of Cd, Pb, Cu and Zn in acidic multi-metal contaminated soils were studied by passivator culture experiment in order to screen out the passivator with better fixation effects. The results showed that the soil pH values of zeolite, lime, red mud and peanut shell biochar increased significantly by 0.511.02, 0.821.29, 0.720.89 and 0.300.35 respectively. The effects of 4 passivators on the fixation of Cd and Zn in soil are lime>red mud>zeolite>peanut shell biochar. The order of effects on the fixation of Pb is red mud>lime>zeolite>peanut shell biochar. The order of the fixation effects of Cu is red mud>lime>peanut shell carbon>zeolite. The contents of Cd, Pb, Cu and Zn in the extractable state of CaCl2 decreased with the increase in the dosage of 4 passivators. Lime and red mud showed good fixation effects on Cd, Pb, Cu and Zn. The contents of Cd, Pb, Cu and Zn in the extractable state of CaCl2 at the low dosage(2.5 g/kg) of lime and red mud decreased by 41%, 84%, 76% and 83% respectively. Soil pH value was negatively correlated with CaCl2-Cd, Pb, Cu and Zn(P<0.01). Lime and red mud had significant fixation effects on Cd, Pb, Cu and Zn in acidic multi-metal contaminated soils at low application dosages.

Interactive Effects of Lead and Bensulfuron-Methyl on Decomposition of ^(14)C-Glucose in Paddy Soils

Little information is available on the interactive effects of inorganic and organic pollutants on carbon utilization by soil microorganisms.This study examined the effects of two common soil pollutants,lead(Pb) and bensulfuron-methyl herbicide(BSM),on decomposition of an adscititious carbon source(14C-glucose).Two contrasting paddy soils,a silty clay soil and a clay loam soil,were incubated with different concentrations and combinations of pollutants for 60 days.Orthogonal rotatable central composite design was adopted to design the combinations of the pollutant concentrations so that rate response curves could be derived.Rapid decomposition of 14C-glucose occurred in the first three days for both soils where no Pb or BSM was added(control).Overall,63%-64% of the added 14C-glucose was decomposed in the control over the 60-day incubation.The addition of Pb or BSM significantly decreased the decomposition of 14C-glucose during the first week but increased the decomposition thereafter;as a result,the percentages of 14C-glucose decomposed(57%-77%) over the 60-day period were similar to or higher than those of the control.Application of the pollutants in combination did not further inhibit decomposition compared with the control.Overall,decomposition rates were lower in the silty clay soil than in the clay loam soil,which was related to the soil texture,cation exchange capacity,and pH.The relationship between the decomposition rates and the pollutants could be well characterized by the quadratic regression orthogonal rotation model.The initial antagonistic effects of the pollutants followed by the synergistic effects on microbial activity might result from changes of the concentrations of the pollutants.

Effect of Polyethylene (LDPE) Microplastic on Remediation of Cadmium Contaminated Soil by <i>Solanum nigrum</i>L.

Solanum nigrum L. has a delightful prospect as a hyperaccumulation plant for cadmium pollution remediation, and microplastic is a new type of pollution that has received wide attention. In this study, the effects of polyethylene microplastics (LDPE) (0.135, 0.27, 0.81 and 1.35 mg·kg-1) and cadmium (20 mg·kg-1) on the growth indexes and soil physical and chemical properties of Solanum nigrum L. were investigated in a 17-day microcosm experiment. The results showed that single LDPE contamination showed a trend of low concentration promotion and medium-high concentration inhibited the growth index of Solanum nigrum L. and soil physicochemical index, and single Cd contamination was more stressful to plants than single LDPE contamination, while low concentration of LDPE could reduce the effect of Cd on soil physical and chemical properties and promote plant growth and uptake of soil nutrients. These findings suggest that high concentrations of microplastics can inhibit the growth of Solanum nigrum L. alone or in combination with Cd, rather than reducing the toxicity of Cd.

Trichoderma viride F7 improves peanut performances while remediating cadmium-contaminated soil with microplastics

Microplastics(MPs)and cadmium(Cd)in soil have serious negative impacts on plant growth.As a bioremediator,Trichoderma viride may modulate the impacts of MPs and/or Cd on plant growth and heavy metal uptake.In this study,T.viride F7 was used to treat Cd-contaminated soil with and without the presence of polylactic acid MPs to investigate its effects on peanut growth,Cd uptake efficiency,and soil properties.Results showed that F7 increased soil pH,dissolved organic carbon,cation exchange capacity,microbial biomass nitrogen,and microbial biomass carbon,which resulted in increases of 2.10%-19.83%in peanut biomass and mitigated the negative effects of MPs and Cd on peanut growth.Trichoderma viride F7 reduced the soil bioavailable Cd and plant Cd concentrations by 16.68%-34.20%and 5.37%-25.84%,respectively.Regression path analysis showed that F7 could improve peanut performances by altering soil properties and reducing peanut Cd concentrations in MP-Cd-contaminated soil.Soil fungal community analysis indicated that the microbial community was altered via F7 inoculation,which antagonized Fusarium and promoted peanut growth.This study reveals the mechanisms of F7 in mitigating Cd contamination in the soil with the presence of MPs,which provides new ideas for managing MP-heavy metal-contaminated soil and improving soil health.

Effects of pH on photochemical decomposition of perfluorooctanoic acid in different atmospheres by 185 nm vacuum ultraviolet

Perfluorooctanoic acid （PFOA）, a persistent organic pollutant, receives increasing concerns due to its worldwide occurrence and resistance to most conventional treatment processes. The photochemical decomposition by 185 nm vacuum ultraviolet （VUV） is one of the efficient methods for PFOA decomposition. The effects of pH on PFOA decomposition in nitrogen atmosphere or oxygen atmosphere were investigated. At its original pH （4.5） of PFOA aqueous solution, PFOA decomposed efficiently both in nitrogen and in oxygen atmosphere. However, when the pH increased to 12.0, PFOA decomposition was greatly inhibited in oxygen atmosphere, while it was greatly accelerated in nitrogen atmosphere with a very short half-life time （9 rain）. Furthermore, fluorine atoms originally contained in PFOA molecules were almost completely transformed into fluoride ions. Two decomposi- tion pathways have been proposed to explain the PFOA decomposition under different conditions. In acidic and neutral solutions, PFOA predominantly decomposes via the direct photolysis in both atmospheres; while in the alkaline solution and in the absence of oxygen, the decomposition of PFOA is mainly induced by hydrated electrons.