Source analysis and risk evaluation of heavy metal in the river sediment of polymetallic mining area:Taking the Tonglüshan skarn type Cu-Fe-Au deposit as an example,Hubei section of the Yangtze River Basin,China

In this paper,25 sampling points of overlying deposits in Tonglushan mining area,Daye City,Hubei Province,China were tested for heavy metal content to explore pollution characteristics,pollution sources and ecological risks of heavy metals in sediments.A geo-accumulation index method was used to evaluate the degree of heavy metal pollution in the sediment.The mean sediment quality guideline quotient was used for evaluating the ecological risk level of heavy metal in the sediment.And a method of correlation analysis,clustering analysis,and principal component analysis was used for preliminary analysis on the source of heavy metal in the sediment.It was indicated that there was extremely heavy metal pollution in the sediment,among which Cd was extremely polluted,Cu strongly contaminated,Zn,As,and Hg moderately contaminated,and Pb,Cr,and Ni were slightly contaminated.It was also indicated by the mean sediment quality guideline-quotient result that there was a high ecological risk of heavy metals in the sediment,and 64%of the sample sites had extremely high hidden biotoxic effects.For distribution,the contamination of branches was worse than that of the main channel of Daye Dagang,and the deposition of each heavy metal was mainly influenced by the distance from this sample site to the sewage draining exit of a tailings pond.The source analysis showed that the heavy metals in the sediment come from pollution discharging of mining and beneficiation companies,tailings ponds,smelting companies,and transport vehicles.In the study area,due to the influence of heavy metal discharging from these sources,the ecotoxicity of heavy metals in the sediment was extremely high,and Cd was the most toxic pollutant.The research figured out the key restoration area and elements for ecological restoration in the sediment of the Tonglüshan mining area,which could be referenced by monitoring and governance of heavy metal pollution in the sediment of the polymetallic mining area.

Flotation behavior and adsorption mechanism of salicylhydroxamic acid in artificial mineral anosovite

Flotation is often employed to separate valuable natural minerals and gangue minerals.However,few studies have been conducted on artificial mineral flotation.Anosovite,the primary mineral in titanium slag,is a typical artificial mineral that can be enriched by flotation.In the present work,flotation behavior and adsorption mechanism of anosovite in salicylhydroxamic acid(SHA)solution were studied.The influence of pH and SHA dosage on anosovite flotability was investigated.Micro-flotation test results show that a pH range of 7–8.5 is available for SHA to collect anosovite.A maximum recovery of 93.26%can be obtained with SHA dosage of only 4×10.5 mol/L.In addition,TOC,zeta potential,FTIR,SEM-EDS,and XPS analyses were used to study the adsorption mechanism.Results demonstrated that SHA adsorption is governed by chemisorption.XPS studies further suggested that chemical adsorption occurred at the Ti sites on the anosovite surface.

Middle Eocene terrestrial paleoweathering and climate evolution in the midlatitude Bohai Bay Basin of eastern China

The middle Eocene climatic optimum(MECO,ca.-42 Ma)is a key time period for understanding Cenozoic cooling of the global climate.Still,midlatitude terrestrial records of climate evolution during MEcO epoch are rare.In this study,continuous high-resolution record of shale sediments in mid-Eocene Shahejie Formation(MES shales)in the Bohai Bay Basin were performed with major-element and wavelet analysis.The midlatitude paleoweathering and paleoclimatic evolution during MEcO epoch were analyzed in this study.The MES shales experienced weak-moderate paleoweathering under a subtropical monsoon paleoclimate with mean annual temperature of 8.3-12.9℃ and mean annual precipitation of 685-1100 mm/yr.The MES shales record a mixed provenance involving intermediate igneous rocks,and low compositional maturity.The nutrient-rich environment led to enrichment in organic matter in the MES shales.Wavelet analysis revealed good periodicity about the paleoclimate and weathering during MECO epoch.In the stage I of MES shales depositional process,the paleolake was high in nutrients,and the MES shales experienced high chemical weathering due to a relatively warmer and more humid climate.In contrast,the climate in stage II was relatively cold and dry,and the maturity of the MES shales was relatively high during this stage,suggesting a relatively stable tectonic background.This work provides more terrestrial records of MEco epoch for midlatitude region,and is benefit for better understanding of the palaeoenvironment when MES shales formed.The implication of organic matters enrichment in this study is meaningful for the shale oil/gas exploration in Nanpu Sag.

Geochronology and Geochemistry of Early Cretaceous A-type Granites in Central-Eastern Inner Mongolia,China:Implications for Late Mesozoic Tectonic Evolution of the Southern Great Xing'an Range

The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.

Analysis of the contributions of human factors and natural factors affecting the vegetation pattern in coastal wetlands

Introduction:Accurate identification of the dominant factors affecting coastal wetlands can provide a reference for vegetation rehabilitation.In this study,quantitative analysis was performed on the Yancheng coastal wetland using ANOVA and geostatistical methods.Outcomes/other:The results indicated that in the directions perpendicular and parallel to the coastline,the soil moisture and salinity in the study area exhibited relatively significant(p<0.05)spatial variability.Vegetation in the southern experimental zone was in a low-moisture,low-salinity ecological niche,whereas vegetation in the northern experimental zone was in a high-moisture,high-salinity ecological niche.Soil salinity exhibited higher spatial variability than soil moisture,and it was most correlated with unvegetated mudflats,followed by areas with Spartina alterniflora,Suaeda glauca,and Phragmites australis.Discussion:The fitting of the semivariogram showed that the nugget and sill of the ratio were relatively low(<25%)for soil moisture and salinity in the northern experimental zone and northern buffer zone,whereas these values were relatively high(>75%)for soil moisture and salinity in the southern experimental zone and southern buffer zone.Conclusion:Compared with the northern study area,the contribution of human disturbance to the spatial heterogeneity of soil moisture and salinity in the southern study area is higher.

Analysis of intrinsic value and estimating losses of “blue carbon”in coastal wetlands:a case study of Yancheng, China

Introduction:Large stocks of“blue carbon”exist in the ecosystems of coastal wetlands.This paper presents a case study of the Chinese city of Yancheng.First,through field surveys and laboratory analysis,changes in the organic carbon(OC)content in typical plant communities throughout the study area are described in detail.Second,an OC burial rate and economic value model is constructed to analyze the composition of the carbon sink values.Outcomes/other:The results are as follows:Of the typical plant communities,Spartina alterniflora has the highest OC content(5.80 g·kg-1),followed by Suaeda glauca(4.78 g·kg-1)and Phragmites australis(3.76 g·kg-1);the contemporary OC sedimentation rates are 2.01,1.48,and 1.22 cm·yr-1,respectively.Spartina alterniflora communities have the highest annual average carbon sink value($418.74/ha)in the study area,followed by Phragmites australis($176.29/ha)and Suaeda glauca($101.54/ha).Discussion:As a result of both the expansion of the Spartina alterniflora area and coastal erosion,the total OC value since 1987 has displayed two-stage characteristics:it first increased and then decreased.Conclusion:In recent years,the annual average decline in OC value has ranged from approximately$82,100 to$123,100(reference:the Sweden carbon tax provided by the World Bank,130$/ton)

Study of the Population Carrying Capacity of Water and Land in Hainan Province

In recent years, the rapid growth of population in Haikou and Sanya has caused extensive concern about the carrying capacity of Hainan Province. To formulate scientific population and environmental policies, it is necessary to research the relationship between population, carrying capacity and economic growth. In this paper, three indicators, grain production, nutrient composition of agricultural products and water resources, are used to measure carrying capacity quantitatively;the employment elasticity coefficient method is used to set the employment elasticity coefficient and the growth rate of regional GDP to estimate the total population needed to support economic growth;PADIS-INT population forecasting software that has parameters to track total fertility rate and net migration rate is used to predict demographic changes. The results show that, as of 2050, the total population of Hainan Province will not have exceeded the upper limit of the carrying capacity of land and water resources. In general, there is no overpopulation problem in the province, but there may be structural problems related to population, such as a large proportion of elderly people, labor shortages, and a high social dependency ratio. It is suggested that the local government should adopt positive population policies, improve the management of natural resources and the environment, and guide the balanced development of population in the province.

Paleoenvironment controls on organic matter accumulation in transitional shales from the eastern Ordos Basin,China

To investigate the paleoenvironmental controls on organic matter accumulation of Upper Paleozoic shales in the eastern Ordos Basin,China,26 shale samples were collected from two wells drilled into the Shanxi and Taiyuan Formations.The total organic carbon(TOC)content,mineral compositions and elemental geochemistry of the samples were analyzed.Quartz(35.42%)and clay minerals(48.34%)are the dominant minerals and trace elements(Li,Cs,Cu,V,Co,and Cr)are commonly enriched in the shale samples compared to the Upper Continental Crust.C-values(ranging from 0.2 to 4.5),chemical indices of weathering(CIW)values(48.82 to 99.11),and Sr/Cu ratios(1.00 to 11.05)suggest that the paleoclimate was humid in the study area during the Late Paleozoic.Elemental redox indices(e.g.,Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3)),V/Cr,Ni/Co,V/(V+Ni)and U/Th)indicate a dysoxic to oxic paleoenvironment characterized by transi-tional sedimentary deposits in a continental margin setting.In addition,chemical index of alteration(CIA,ranging from 77.92%to 98.36%)and CIW(89.19%to 99.11%)values suggest that there was intense chemical weathering in the study area,while the Al_(2)O_(3)-CaO^(*)+Na_(2)O-K_(2)O(A-CN-K)ternary diagram demonstrates that the shales were not subjected to potassium metasomatism during diagen-esis.Al_(2)O_(3)/TiO_(2)and TiO_(2)/Zr ratios,as well as REE characteristics suggest a felsic source rocks and discount seawater as an REE source.Ce anomalies indicate an oxic environment with terrigenous input during black shale deposition,and LREE enrichment with negative Eu anomalies suggests that both shale formations were affected by detrital input rather than hydrothermal fluids.The correlation of TOC(ranging from 1.10%to 6.39%,with an average of 2.77%)with trace elemental redox indices(Sr/Cu,Sr/Ba,V/Cr,and U/Th)indicates that a warm-humid,dysoxic to oxic environment preserved much of the organic matter.