Using cemented paste backfill to tackle the phosphogypsum stockpile in China:A down-to-earth technology with new vitalities in pollutant retention and CO_(2) abatement

Phosphogypsum(PG),a hard-to-dissipate by-product of the phosphorus fertilizer production industry,places strain on the biogeochemical cycles and ecosystem functions of storage sites.This pervasive problem is already widespread worldwide and requires careful stewardship.In this study,we review the presence of potentially toxic elements(PTEs)in PG and describe their associations with soil properties,anthropogenic activities,and surrounding organisms.Then,we review different ex-/in-situ solutions for promoting the sustainable management of PG,with an emphasis on in-situ cemented paste backfill,which offers a cost-effective and highly scalable opportunity to advance the value-added recovery of PG.However,concerns related to the PTEs'retention capacity and long-term effectiveness limit the implementation of this strategy.Furthermore,given that the large-scale demand for ordinary Portland cement from this conventional option has resulted in significant CO_(2) emissions,the technology has recently undergone additional scrutiny to meet the climate mitigation ambition of the Paris Agreement and China's Carbon Neutrality Economy.Therefore,we discuss the ways by which we can integrate innovative strategies,including supplementary cementitious materials,alternative binder solutions,CO_(2) mineralization,CO_(2) curing,and optimization of the supply chain for the profitability and sustainability of PG remediation.However,to maximize the co-benefits in environmental,social,and economic,future research must bridge the gap between the feasibility of expanding these advanced pathways and the multidisciplinary needs.

Analysis of the Fertilizing and Bioremediation Potential of Leaf Litter Compost Amendment in Different Soils through Indexing Method

This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investigation encompassed the impact of various organic compost amendments, including leaf compost, cow dung manure, kitchen waste compost, municipal organic waste compost, and vermicompost. The study employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to evaluate soil nutrient levels and concentrations of Potentially Toxic Elements (PTEs) such as arsenic, chromium, cadmium, mercury, lead, nickel, and lithium. The fertilization and bioremediation potential of these compost amendments are quantified using an indexing method. Results indicated a substantial increase in overall nutrient levels (carbon, nitrogen, phosphorus, potassium, and sulfur) in soils treated with leaf compost and other organic composts. Fertility indices (FI) are notably higher in compost-amended soils (ranging from 2.667 to 3.938) compared to those amended with chemical fertilizers (ranging from 2.250 to 2.813) across all soil samples. Furthermore, the mean concentrations of PTEs were significantly lower in soils treated with leaf compost and other organic compost amendments compared to those treated with chemical fertilizers amendments. The assessment through the indexing method revealed a high clean index (CI) for leaf compost amendment (ranging from 3.407 to 3.58), whereas the chemical fertilizer amendment exhibits a relatively lower CI (ranging from 2.78 to 3.20). Consequently, leaf compost and other organic composts exhibit the potential to enhance sustainable productivity, promoting soil health and environmental safety by improving nutrient levels and remediating potentially toxic elements in the soil.

Contamination assessment,source apportionment and associated health risks of PTEs in agricultural soil under five land-use patterns in Sanya,China

To understand the levels of potentially toxic elements(PTEs)contamination in soils and their effects on human health from different agricultural land use in Sanya,China.128 soil samples(64 topsoil samples and corresponding subsoil samples)were collected from the five representative land-use patterns.Inductively coupled plasma mass spectrometry(ICP-MS),Atomic fluorescence spectrometry(AFS),and Inductively coupled plasma optical emission spectrometry(ICP-OES)were used to determine the content of PTEs(As,Cd,Hg,Cu,Cr,Ni,Pb,Zn,Co,Mo,Sb,and V).Correlation analysis and factor analysis were used to determine the source of PTEs.Geo-accumulation index(I_(geo)),hazard quotient(HQ),and total carcinogenic risk index(TR)were used to measure the PTEs contamination and its relative health impacts.Results showed that the average values of 12 PTEs in topsoil were higher than the Hainan soil geochemical baseline,showing different degrees of PTEs accumulation effect.The concentration of PTEs in the topsoil was lower than those in the subsoil except for Cd and Hg.The I_(geo)revealed that the major accumulated element in soils was As followed by Mo.Source apportionment suggested that parent materials and agricultural practices were the dominant factors for PTEs accumulation in the topsoil.Noncarcinogenic risks of soil samples from five land-use patterns presented a trend of paddy field>dry field>woodland>orchard>garden plot.However,the HQ values of 12 PTEs were less than the recommended limit of HQ=1,representing that there are no non-carcinogenic risks of PTEs for children and adults in the study area.The TR values are within 6.95×10^(-6)-1.38×10^(-5),which corresponds to the low level.Therefore the PTEs in the agricultural soil of the study area show little influence on the health status of the local population.

Atmospheric deposition fluxes and health risk assessment of potentially toxic elements in Caohai Lake(Guizhou Province,China)

In this study,the sources of potentially toxic elements(PTEs)from atmospheric deposition in the waters of Guizhou’s Caohai Lake were investigated in addition to the potential risks to human health.Moss bags were used to enrich PTEs from atmospheric deposition,and eight monitoring sites that best represented geographic variation were established around Caohai Lake.Moss bags were collected and examined at every 3 months to identify spatiotemporal patterns of dry and wet atmospheric deposition of PTEs.Zn was the most abundant metal identified from deposition in Caohai(72.07%–95.94%),followed by Pb and Cd,while Hg was the least abundant(0.008%–0.354%).The contributions of wet deposition of PTEs were greater than those of dry deposition,and deposition during the heating season from December to April was greater than that between April to July.Hg was mainly derived from atmospheric dry deposition(65.38%–84.44%).Spatial distribution analysis indicated that atmospheric deposition was associated with the intensity of human activities and heating emissions.Exposure via hand-to-mouth contact accounted for over 99%of the total exposure risk although overall exposure was lower than threshold acceptable levels for carcinogenic and non-carcinogenic metals,indicating an overall lack of risk towards human health.Nevertheless,the health risk from atmospheric deposition of PTEs in Caohai Lake may be reduced by focusing on Zn,Pb,and Cd deposition in rainfall and minimizing the hazards associated with hand-to-mouth exposure to PTEs.

Geochemical and mineralogical evaluations of coal,shale,and mine waste overburden from Makum coalfield of the Northeast India

The Cenozoic-age Makum coal from northeastern India offers numerous research opportunities because of its diverse geochemical and geological characteristics.Due to its high sulfur content,the coal has been found to be less useful for industrial purposes.It can,however,serve as a hub for ongoing research on coal-based derivative products.The aim of this research work is to investigate the mineralogical and geochemical compositions of the coal,mine overburden(MOB)and shale samples taken from the Makum coal field and also on establishing a mutual relationship between them.To characterize the geochemical controlling factors of the Makum coal field,the study employs coal petrography,FTIR,mineralogical,and geochemical analysis.According to X-ray diffraction analysis,the major minerals like quartz,kaolinite,haematite,illite,pyrite,and calcite are present in coal and MOB.Pyrite is observed by SEM-EDS analysis as cubic-shaped particles that are smaller than a fewμm in size.The presence of sulfide minerals represents a phase of pyrite mineralization.The petrography study was used to better understand the environment that existed during the formation of the plant material,which aids us in determining the quantity of detrital mineral sediment contained in the coal.According to the ICP-MS analysis,the samples indicate significant levels of rare earth elements including yttrium.The present study reveals higher concentrations of poten-tial hazardous elements in the coal samples,with V,Cr,Ni,Cu,and Zn content in coal being considerably enriched compared to world-average concentrations.The correlation analysis reveals that the potential hazardous elements like Co,Ni,As,and Cu are associated with pyrite as they have strong affinity towards pyrite.Thus,numerous minerals and rare earth elements(REEs)exist,opening up a fresh avenue for more research in the area.This study also assists researchers in understanding the significance of Makum coal and provides numerous ideas for coal characterization.

Artisanal Mining and Soil Quality in the Sudano-Sahelian Climate: Case of the Artisanal Mining Site of Yimiougou in Burkina Faso, West Africa

The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining activities. The methodology adopted consisted in sampling and characterizing the main types of soil. In order to assess the level of soil pollution by artisanal mining, parameters such as the geo-accumulation index (Igeo) and the contamination factor (CF) are calculated. A prediction of acid mine drainage (AMD) was also carried out on samples of mine tailings which are potential sources of pollution of these soils. The results obtained show that the soils in Yimiougou are of nil to low agronomic interest. The Igeo shows that for lead, copper, zinc and arsenic the levels found in the different morphological units are partly attributable to human action and specifically artisanal mining. The values of the contamination factor indicate contamination. Cobalt presents the lowest contamination. For cadmium, the different types of soil are moderately contaminated except for the FITLC type, which has a CF value of 0.50, therefore synonymous with low or absent contamination. The various morphological units studied are very heavily contaminated with zinc, copper, lead and arsenic. The pH and conductivity values indicate that the mine tailings samples are non-acidogenic, therefore not yet oxidized. As for the sulphide contents, they show that only samples S17, S22, S23 and S24 present values that are strictly above the threshold (0.3%) and therefore potentially acid-generating. The comparative study of the acid potential (AP) and the neutralization potential (NP) reveals that the neutralization potentials of the different samples are clearly higher than the acid potentials even for the samples which present a proven acidification potential (S17, S22, S23 and S24). These results show that the mine tailings have the natural capacity to neutralize any possible mine drainage, given the presence of acid-eating minerals such as the carbonates associated with the mineralization.

Preliminary Study of Groundwater Quality Using Hierarchical Classification Approaches for Contaminated Sites in Indigenous Communities Associated with Crude Oil Exploration Facilities in Rivers State, Nigeria

Background: Groundwater is an important source of water. Since the control and removal of pollution are expensive, it is essential to identify the possible sources of contamination and to correctly classify groundwater on the basis of its intrinsic and integrated vulnerability. Objectives: To group ground water chemical ions and heavy metals parameters into similar groups. Method: The investigation made use of standard analytical procedures. All sampling, conservation, transportation and analysis followed standard procedures described in APHA (2012). To prevent degradation of the organic substances, all obtained samples were transferred to the laboratory, while kept in an icebox. Results: Sampling records from the same area are generally assigned to the same cluster during hierarchical cluster analysis (HCA). The cluster diagram shows the grouping of the heavy metal in the study area during wet and dry seasons. It reveals that 5 distinct clusters were identified for wet season and 4 clusters were identified during dry season. Also, it reveals that 5 distinct clusters were identified for wet season and for dry season, 4 distinct clusters were identified. Conclusion: The findings of this study are significant for policymakers and agencies in terms of dealing with the issues identified to enhance sustainable livelihood practices in the oil rich Niger Delta region of Nigeria. Therefore, decision-makers should take proper initiatives to get local people aware of the endangered zones before use, as drinking water is key to good health. Similarly, multinational oil companies will find it useful in their quest for viable social corporate responsibility and remediation plans in their respective host communities. The method proved to be a useful and objective tool for environmental planning.

Volcanic emissions and atmospheric pollution:A study of nanoparticles

The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies have evaluated their influence in road dust composition.Air quality in urban areas is significantly affected by nonexhaust emissions(e.g.road dust,brake wear,tire wear),however,natural sources such as volcanoes also impact the chemical composition of the particles.In this study,elements from volcanic emissions such as Si>Al>Fe>Ca>K>Mg,and Si-Al with K were identified as complex hydrates.Similarly,As,Hg,Cd,Pb,As,H,Cd,Pb,V,and salammoniac were observed in nanoparticles and ultrafine material.Mineral composition was detected in the order of quartz>mullite>calcite>kaolinite>illite>goethite>magnetite>zircon>monazite,in addition to salammoniac,a tracer of volcanic sources.The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health.The road dust load(RD_(10))ranged between 0.8 and 26.8 mg m^(−2)in the city.

Heavy metal: a misused term?

The use of the term"heavy metal"is regularly questioned by the scientific community.Here,we followed the evolution(1970–2020)in the number of published papers including this term in their title.Thus,we can evidence a continuous,albeit sometimes stabilizing,increase especially in environmental journals.After several other warning opinions,we propose that it should be replaced in the scientific literature by terms like"metal","metalloid","trace metal elements"or"potentially toxic element".

Metal-enriched nanoparticles and black carbon:A perspective from the Brazil railway system air pollution

Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public transport.This study measured,for the first time in Brazil,nanoparticles(NPs)and black carbon(BC)on two groundlevel platforms and inside trains of the Metropolitan Area of Porto Alegre(MAPA).An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy techniques.The results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger densities.Also,internal and external sources of pollution at the stations were identified.The predominance of NPs enriched with metals that increase oxidative stress like Cd,Fe,Pb,Cr,Zn,Ni,V,Hg,Sn,and Ba both on the platforms and inside trains,including Fe-minerals as hematite and magnetite,represents a critical risk to the health of passengers and employees of the system.This interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols.

Assessment of pollution of potentially harmful elements in soils surrounding a municipal solid waste incinerator, China

We assessed the contamination levels of Mn, Zn, Cr, Cu, Ni, Pb, As and Hg and the risks posed by these potentially harmful elements in top-soils around a municipal solid waste incinerator （MSWI）. We collected 20 soil samples, with an average pH of 8.1, and another fly ash sample emitted from the MSWI to investigate the concentrations of these elements in soils. We determined the concentrations of these elements by inductively coupled plasma-optical emission spectrometer （ICP-OES）, except for Hg, which we measured by AF-610B atomic fluorescence spectrometer （AFS）. We assessed the risks of these elements through the use of geoaccumulation index （/geo）, potential ecological risk index （R/）, hazard quotient （HQi） and cancer risk （Riski）. The results showed that concentrations of potentially harmful elements in soil were influenced by the wind direction, and the concentrations of most elements were higher in the area northwest of the MSWI, compared with the area southeast of the incinerator, with the exception of As; these results were in accordance with those results acquired from our contour maps. According to the I^o values, some soil samples were clearly polluted by Hg emissions. However, the health risk assessment indicated that the concentrations of Hg and other elements in soil did not pose non-carcinogenic risks to the local populations. This was also the case for the carcinogenic risks posed by As Cr and Ni. The carcinogenic risk posed by As was higher in the range 6.49 × 10 -9.58 × 10 -6, but this was still considered to be an acceptable level of risk.

The concentration and probabilistic risk assessment of potentially toxic elements in fillets of silver pomfret(Pampus argenteus):A global systematic review and meta-analysis

The contamination of fish type products such as silver pomfret fish fillets by potentially toxic elements(PTEs)has raised global health concerns.Related studies regarding the concentration of PTEs in fillets of silver pomfret fish were retrieved among some international databases such as Scopus,Pub Med and Embase between 1 January 1983 and 10 March 2020.The pooled(mean)concentration of PTEs in fillets of silver pomfret fish was meta-analyzed with the aid of a random-effect model(REM).Also,the non-carcinogenic risk was estimated via calculating the 95 th percentile of the total target hazard quotient(TTHQ).The meta-analysis of 21 articles(containing 25 studies or data reports)indicated that the ranking of PTEs in fillets of silver pomfret fish was Fe(11,414.81μg/kg wet weight,ww)>Zn(6055.72μg/kg ww)>Cr(1825.79μg/kg ww)>Pb(1486.44μg/kg ww)>Se(1053.47μg/kg ww)>Cd(992.50μg/kg ww)>Ni(745.23μg/kg ww)>Cu(669.71μg/kg ww)>total As(408.24μg/kg ww)>Co(87.03μg/kg ww)>methyl Hg(46.58μg/kg ww).The rank order of health risk assessment by country based on the TTHQ for adult consumers was Malaysia(2.500)>Bangladesh(0.886)>Iran(0.144)>China(0.045)>Pakistan(0.020)>India(0.015),while the corresponding values for child consumers was Malaysia(11.790)>Bangladesh(4.146)>Iran(0.675)>China(0.206)>Pakistan(0.096)>India(0.077).The adult consumers in Malaysia and children in Malaysia and Bangladesh were at considerable non-carcinogenic risk.Therefore,following the recommended control plans in order to reduce the health risk associated with the ingestion of PTEs via consumption of silver pomfret fish fillets is crucial.

Wear of the working parts of agricultural tools in the context of the mass of chemical elements introduced into soil during its cultivation

For the manufacture of working parts of agricultural tools operating in soil,various structural materials are used:alloy and low-alloy steels,weld materials for hardfacing,and plates made from cementedcarbide.Manufacturers design new construction solutions to obtain components that are resistant to abrasive wear and impact.These components are subject to wear during soil cultivation,due to which wear products remain in the soil.In this work,the mass of chemical elements remaining in soil from materials used in selected working parts of agricultural tools intended for soil cultivation was estimated.During the operation of the tested parts,it was found that the following elements were introduced into the soil:Al,B,C,Co,Cr,Cu,Fe,Mo,Nb,Ni,P,Pb,S,Si,Ti,V,Wand Zr.Iron was introduced into the soil in the highest amount(15.907e222.004 g∙ha-1).Among the chemical elements reaching the soil,there were also elements that may pose a toxicological threat.It was found that the mass of chemical elements introduced into the soil depends on their content in the used structural materials and also on the conditions of cultivation,which determine the wear intensity of the parts.

Microbial responses towards biochar application in potentially toxic element(PTE)contaminated soil:a critical review on effects and potential mechanisms

Soil harbors a huge diversity of microorganisms and serves as the ecological and social foundation of human civilization.Hence,soil health management is of utmost and consistent importance,aligning with the United Nations Sustainable Development Goals.One of the most hazardous contaminants in soil matrix is potentially toxic elements(PTEs),which can cause stress in soil indigenous microorganisms and severely jeopardize soil health.Biochar technology has emerged as a promising means to alleviate PTE toxicity and benefit soil health management.Current literature has broadly integrated knowledge about the potential consequences of biochar-amended soil but has focused more on the physical and chemical responses of the soil system than microbiological attributes.In consideration of the indispensable roles of soil microbials,this paper first introduces PTE-induced stresses on soil microbials and then proposes the mechanisms of biochar’s effects on soil microbials.Finally,microbial responses including variations in abundance,interspecific relationships,community composition and biological functions in biochar-amended soil are critically reviewed.This review thus aims to provide a comprehensive scientific view on the effect of biochar on soil microbiological health and its management.

Moderate sewage sludge biochar application on alkaline soil for corn growth:a field study

In view of the risks induced by the inhibitory effects of applying impracticably large amounts of sewage sludge biochar(SSB)to the alkaline soil,this field study investigated the influence of moderate biochar amendments(0,1500,4500,and 9000 kg/hm2)on corn growth,alkaline soil properties,and the uptake of potentially toxic elements(PTEs).The results showed that applying more SSB would decrease the ammonium nitrogen concentration and increase the available phosphorus and potassium concentrations,which inhibited corn plant growth because of high background nutrient levels of the alkaline soil.When the alkaline soil was amended with 1500 kg/hm2 SSB,the dry weight of 100 niblets increased from 32.11 g in the control to 35.07 g.There was no significant variation in the total concentration of PTEs in the soil.The concentrations of Mn,Ni,Cu,and Zn in niblets decreased from 5.54,0.83,2.26,and 27.15 mg/kg in the control to 4.47,0.62,1.30,and 23.45 mg/kg,respectively.Accordingly,the health risk from corn consumption was significantly reduced.Furthermore,the combination of SSB and fertilizer improved corn growth and reduced the risk of consumption of PTEs.Therefore,considering the increase in corn fruit yield and the decrease in consumption risk,applying 1500 kg/hm2 of biochar to alkaline soils is a realistically achievable rate,which can broaden the utilization of SSB for remediation of different types of soil.

Low-carbon stabilization/solidification of municipal solid waste incineration fly ash

Municipal solid waste incineration(MSWI)fly ash(FA)is classified as hazardous waste,which requires additional treatment before disposal or further utilization.Stabilization/solidification(S/S)is regarded as a low-cost and high-efficient method for MSWI FA treatment.“Low-carbon S/S”has captured extensive interest in recent years,which could treat hazardous wastes and enable resource recycling in a sustainable way.This article introduced the state-of-art low-carbon S/S strategies for MSWI FA treatment.The immobilization mechanisms of pollutants in various matrices were also discussed.Prospects were raised to foster the actualization of sustainable management of MSWI FA.

Multi-media compartments for assessing ecological and health risks from concurrent exposure to multiple contaminants on Bhola Island,Bangladesh

In this study,a set of coupled multi-media compartments(i.e.,sediment,soil,water and vegetable)was used to assess ecological and health risks from the ingestion of 11 PTEs(Pb,Cd,Cr,As,Hg,Cu,Zn,Ni,Co,Fe,and Mn)and their transportation routes in the water-soil-plant system from the coastal Bhola Island,Bangladesh.The mean concentrations of Cd,Pb,and Co for soil and Cd,Co,and As for sediment were higher than their reference values.In contrast,Cd,Pb,and Ni concentrations in water surpassed the acceptable limits set by national and international laws and were considered unsuitable for drinking purposes.Vegetables demonstrated high Pb and Cd contents,demonstrating a potential food safety risk to the inhabitants.Results of principal component analysis(PCA)revealed that Cd,Pb,Hg,Cu,Ni and Zn sources were likely to be anthropogenic,especially agro-farming inputs,whereas the Fe,As,Cr,Mn,and Co sources were similar to natural origin.So,Cd,Pb and Co are the key contaminants in the study area and pose the elevated health and ecological risks in the coastal area.Cd and Pb exhibited higher ecological risks in soils and sediments,as Pb had the highest bio-accessibility(BA;0.02±0.003)and Cd possessed a high bioaccumulation factor(BCF;0.004±0.006).The self-organizing map analysis recognized three spatial patterns which are good agreement with PCA.The average hazard index(HI)values for soil were above the permissible level(HI>1)set by the respective agency;two times higher HI values were noticed for children than adults,suggesting children are highly susceptible to health risk.Continuous monitoring and source controls for Cd and Pb,along with agro-farming management practices,need to be implemented to reduce the risk of PTE contamination to the aquatic ecosystem and its inhabitants.