Soil Heavy Metal Pollution and Health Risk Assessment of Abandoned Land in Coal Mining Areas in Xingren County

Total contents of heavy metals （ Pb, Cr, Cd, Hg, As, Cu, Zn, and Ni） in 68 soil samples were determined to evaluate the contamination level of soil from five coal mine areas in Xingren County, Guizhou province. The pollution levels of heavy metals were characterized by anthro- pogenic influence multiple, and the pollution of heavy metal in soil was evaluated using geo-accumulation index. Based on the health risk models recommended by the U.S. Environmental Protection Agency （ US EPA）, the health risks of heavy metals in the soils were assessed. The results showed that the abandoned land in the five coal mining areas were contaminated by heavy metals, and the order of pollution levels of eight heavy metals was As 〉 Pb 〉 Cu 〉 Hg 〉 Ni 〉 Cr 〉 Cd 〉 Zn. The soils suffered moderate-heavy pollution from As and Pb, and the contents of As and Pb in the soils were 13.16 and 4.76 times higher than the background values of Guizhou Province, followed by Cu, Hg and Ni , while soil pollution from Cr, Cd and Zn was mild. The order of non-caminogenic risks of the heavy metals in the soils was As 〉 Pb 〉 Cr 〉 Ni 〉 Cu 〉 Hg 〉 Cd 〉 Zn, and the non-carcinogenic dsk value of As was higher than that its threshold value 1, which indicated that As had a high potential health risk to adults and children. The order of carcinogen risks of the four heavy metals was As 〉 Cd 〉 Cr 〉 Ni, and the carcinogenic risk value of As was higher than its threshold value, indicating that As had a high carcinogenic risk to adults and children. The carcinogenic risk values of other three heavy metals （ Cd, Cr and Ni） were lower than the threshold value, so they had no carcinogenic risk to human health. Moreover, children were more sensitively affect- ed by heavy metals from the abandoned land. Therefore, the health of children in such areas should be paid more attention to. The HI value of the eight heavy metals to children was seven times higher than that to adults. The contribution rate of HQAs to HI was about 88%, and the contribution rate of CRA, to TCR was about 98%, so As was the most crucial factor influencing non-carcinogenic and carcinogenic dsk in the abandoned soils.

Effects of land-use patterns on soil microbial diversity and composition in the Loess Plateau,China

In the Loess Plateau of China,land-use pattern is a major factor in controlling underlying biological processes.Additionally,the process of land-use pattern was accompanied by abandoned lands,potentially impacting soil microbe.However,limited researches were conducted to study the impacts of land-use patterns on the diversity and community of soil microorganisms in this area.The study aimed to investigate soil microbial community diversity and composition using high-throughput deoxyribonucleic acid(DNA)sequencing under different land-use patterns(apricot tree land,apple tree land,peach tree land,corn land,and abandoned land).The results showed a substantial difference(P<0.050)in bacterial alpha-diversity and beta-diversity between abandoned land and other land-use patterns,with the exception of Shannon index.While fungal beta-diversity was not considerably impacted by land-use patterns,fungal alpha-diversity indices varied significantly.The relative abundance of Actinobacteriota(34.90%),Proteobacteria(20.65%),and Ascomycota(77.42%)varied in soils with different land-use patterns.Soil pH exerted a dominant impact on the soil bacterial communities'composition,whereas soil available phosphorus was the main factor shaping the soil fungal communities'composition.These findings suggest that variations in land-use pattern had resulted in changes to soil properties,subsequently impacting diversity and structure of microbial community in the Loess Plateau.Given the strong interdependence between soil and its microbiota,it is imperative to reclaim abandoned lands to maintain soil fertility and sustain its function,which will have significant ecological service implications,particularly with regards to soil conservation in ecologically vulnerable areas.

Characteristics and driving factors of abandoned cultivated land in the hilly regions of southern China:A case study in Longnan,Jiangxi Province

The abandonment of cultivated land in southern China was gradually obvious.This research aims to provide a reference for solving the abandonment of cultivated land in hilly regions and promote rural development in China.We examined Longnan county located in the hilly regions of southern China as an example,where abandoned cultivated land is very common.We analyzed its land use data with a field survey to identify the abandoned cultivated land and geospatial characteristics.From the two aspects of social and natural factors,we analyzed the factors driving cultivated land abandonment with the help of Geodetector.The results showed that in 2019,the total area of the abandoned cultivated land in Longnan county was 4,962.35 hm^(2),covering 39.51% of this region.Among the topographic factors,the abandonment rate is positively correlated with elevation and slope gradient,but not with slope direction.Among the land parcel conditions,the abandonment rate is positively correlated with the access to road network and cultivation distance from settlement.At the county level,the abandonment of cultivated land in study area was affected by multiple factors,among which,the direct factor was the reduction in the labor force,such as the decrease of farming laborers and the increase of female population,which made farming unsustainable.Changes in production factors also promoted transformations in farmers’motivation to engage in production,such as the decrease of grain crops and the increase of cash crops,which was the indirect factor affecting cultivated land abandonment.The development of the rural nonagricultural industry affected farmers’enthusiasm,such as the decrease of farming households,which was the fundamental factor leading to cultivated land abandonment in this area.

CO flux of soil respiration in natural recovering karst abandoned farmland in Southwest China

To estimate carbon sequestration potential in the karst area,soil respiration in a natural recovering karst abandoned farmland in Shawan,Puding,Guizhou,southwest China was continuously and automatically monitored for more than two years.The results show that the CO2flux of soil respiration(2.63±1.89 lmol m^-2s-^1)is higher in the karst area than in non-karst areas under similar conditions but that regional value(1.32 lmol m-2s-1)is lower because of larger rock fragment coverage(~50%).A the same time,the temperature sensitivity of soil respiration(Q10)in this study area is significantly higher than that of non-karst areas under similar conditions.Soil respiration has an obvious temporal variation,which is reflected in a significant exponential relationship between soil respiration and soil temperature,but the relationship between soil respiration and soil moisture is very complex.Especially soil respiration has an obvious spatial variation,which is likely affected by different diffusion or water-rock reaction processes.

城市污泥在矿山废弃地复垦的应用探讨

Based on the analysis of the existing problems in reclaiming abandoned mining land and their negative effect on the ecological environment,and in view of the limited factors to reclaim abandoned mining land,this paper puts forward the suggestions of using sewage sludge as an alternative in mining land reclamation.Application of sewage sludge in reclamation has beneficial effects, such as increasing organic matter content, preventing soil erosion,recovering vegetation,and promoting microbial population and its activities Unfavorable factors including heavy metal and organic pollutant for applications of sewage sludge and their countermeasures are also discussed.

Woody biochar potential for abandoned mine land restoration in the U.S.:a review

There are thousands of abandoned mine land(AML)sites in the U.S.that need to be restored to reduce wind and water erosion,provide wildlife forage,shade streams,and improve productivity.Biochar created from woody biomass that would normally be burned in slash piles can be applied to soil to improve soil properties and is one method to restore AML soil productive capacity.Using this‘waste’biomass for biochar and reclamation activities will reduce wildfire risk,air pollution from burning,and particulates released from burning wood.Biochar has the potential to improve water quality,bind heavy metals,or decrease toxic chemical concentrations,while improving soil health to establish sustainable plant cover,thereby preventing soil erosion,leaching,or other unintended,negative environmental consequences.Using forest residues to create biochar also helps reduce woody biomass and improves forest health and resilience.We address concerns surrounding organic and inorganic contaminants on the biochar and how this might affect its’efficacy and provide valuable information to increase restoration activities on AMLs using biochar alone or in combination with other organic amendments.Several examples of AML biochar restoration sites initiated to evaluate short-and long-term above-and belowground ecosystem responses are presented.

Phenology and classification of abandoned agricultural land based on ALOS-1 and 2 PALSAR multi-temporal measurements

Agricultural crop abandonment negatively impacts local economy and environment since land,as a resource for agriculture,is not optimally utilized.To take necessary actions to rehabilitate abandoned agricultural lands,the identification of the spatial distribution of these lands must be acknowledged.While optical images had previously illustrated potentials in the identification of agricultural land abandonment,tropical areas often suffer cloud coverage problem that limits the availability of the imageries.Therefore,this study was conducted to investigate the potential of ALOS-1 and 2(Advanced Land Observing Satellite-1 and 2)PALSAR(Phased Array L-band Synthetic Aperture Radar)images for the identification and classification of abandoned agricultural crop areas,namely paddy,rubber and oil palm fields.Distinct crop phenology for paddy and rubber was identified from ALOS-1 PALSAR;nonetheless,oil palm did not demonstrate any useful phenology for discriminating between the abandoned classes.The accuracy obtained for these abandoned lands of paddy,rubber and oil palm was 93.33%±0.06%,78%±2.32%and 63.33%±1.88%,respectively.This study confirmed that the understanding of crop phenology in relation to image date selection is essential to obtain high accuracy for classifying abandoned and non-abandoned agricultural crops.The finding also portrayed that PALSAR offers a huge advantage for application of vegetation in tropical areas.

Do historical maps show the maximal anthropopressure in the Carpathians?

Many landscapes bear the marks of historical land use.These marks can be the basis for a reconstruction of a historical land use structure as some of them are typical of different types of human activity.The aim of this paper is to determine whether Austrian cadastral maps from the 19th century present the image of the most transformed environment in the Western Carpathians as a result of agricultural activity.Land use structure and terrain forms were detected based on Austrian cadastral maps from 1848,airborne laser scanning and field studies.In two of the test areas,the percentage of arable fields was higher among the plots with stone mounds than the percentage among the plots without them.In the third test area,the relationship was reversed.Also,lynchets,terraces and stone walls sometimes occur in plots that were not arable fields in 1848.Thus,the Austrian cadastral maps from 1848 could not reflect the maximal range of arable fields in the Carpathians in the 19th century.However,it is impossible to determine the historical structure of land use precisely.Nevertheless,an inventory of terrain forms can be used to assess land use when historical maps have not preserved or when available maps do not present land use in detail.

Measures of Vegetation Restoration in Abandoned Mined Lands

By 2004, the occupied and disturbed land area had reached 3.393 million ha by mining, of which forest land took 532 000 ha; In addition, mining also caused 3.721 million -5.316 million ha of degraded forests and woodlands. The impact of mining on environment is multi-fold and deep. Thus it is necessary and significant to approach effective methods to speed up vegetation restoration in abandoned mined lands. Phytoremediation is a relatively new technology (in the lastest decade) and the numbers of plant species have been identified to accumulate high levels of heavy metals, which implies that phytoremediation is available, practical and effective. Thereby the main procedure of ecosystem restoration in abandoned mined lands by mean of phytoremediation is discussed in the paper, such as site preparation, species selection, planting techniques, maintenance and tending methods.

Distribution and effects of tree leaf litter on vegetation composition and biomass in a forest–grassland ecotone

Aims After abandonment of grasslands,secondary succession leads to the invasion by woody species.This process begins with the accumulation of tree litter in the forest–grassland ecotone.Our objectives were to determine the relationships between litter amounts and vegetation composition and cover along natural forest–grassland ecotones and to experimentally study the initial effects of tree litter accumulation on grassland vegetation and on microsite conditions.Methods We established 11 transects varying from 12 to 15 m in length in different forest–grassland ecotones in the Lahn-Dill highlands,Germany,and measured the mass and cover of tree litter and the cover and composition of vegetation at five sequential positions along each transect by using 1 m2 plots with five replications.In a field experiment,we established plots subjected to different litter amounts(0,200 and 600g m^(−2))and evaluated changes in grassland vegetation,soil temperature and soil nutrient availability below the litter layer.Important Findings Tree litter amounts decrease from 650 to 65g m^(−2) across the forest–grassland ecotone.Vegetation changed from shrubs and annual species(adapted to more stressful conditions)in the forests edge to grasses,rosettes and hemirosette species(with higher competitive abilities)in the grassland.These anthropogenic forest–grassland ecotones showed abrupt edges,and the two adjacent ecosystems were characterized by different species pools and functional groups.In the field experiment,the presence of a litter layer reduced vegetation biomass and cover;the species richness was only reduced in the treatment with high litter(600g m^(−2)).Additionally,adding litter on top of vegetation also reduced thermal amplitude and the number of frost days,while increasing the availability of some nutrients,such as nitrogen and aluminium,the latter being an indicator of soil acidification.Adding a tree litter layer of 600g m^(−2) in grassland areas had strong effects on the composition and diversity of grassland vegetation by reducing the cover of several key grassland species.In,or near,forest edges,litter accumulation rapidly changes established vegetation,microsite conditions and soil nutrients.

Alien plant species coexist over time with native ones in Chilean Mediterranean grasslands

Aims Alien species are commonly considered as harmful weeds capa-ble of decreasing native biodiversity and threatening ecosystems.Despite this assumption,little is known about the long-term patterns of the native-alien relationships associated with human disturbed managed landscapes.This study aims to elucidate the commu-nity dynamics associated with a successional gradient in chilean Mediterranean grasslands,considering both native and alien species.Methods Species richness(natives and aliens separately)and life-form(annu-als and perennials)were recorded in four chilean post-agricultural grazed grasslands each covering a broad successional gradient(from 1 to 40 years since crop abandonment).A detrended correspondence analysis(DcA),mixed model effects analyses and cor-relation tests were conducted to assess how this temporal gradient influenced natives and aliens through community dynamics.Important Findings Our results show different life-form patterns between natives and aliens over time.Aliens were mainly represented by annuals(especially ruderals and weeds),which were established at the beginning of succession.Annual aliens also predominated at mid-successional stages,but in old grasslands native species were slightly more representative than alien ones within the community.In the late successional states,positive or no correlations at all between alien and native species richness suggested the absence of competition between both species groups,as a result of differ-ent strategies in occupation of the space.community dynamics over time constitute a net gain in biodiversity,increasing natives and maintaining a general alien pool,allowing the coexistence of both.Biotic interactions including facilitation and/or tolerance processes might be occurring in chilean post-agricultural grasslands,a fact that contradicts the accepted idea of the alien species as contenders.

Congruent responses of vascular plant and ant communities to pastoral land-use abandonment in mountain areas throughout different biogeographic regions

Background:There is a long-term trend towards the abandonment of agro-pastoral activities in the mountain areas of Europe:the following encroachment process of semi-natural grasslands by shrubs is one of the main severe threats to the conservation of biodiversity in mountain environments.To better understand the impact of land abandonment,we analysed the reliability of plant functional groups,ant traits,and ant functional groups as indicators of land use changes.We carried out the research in Italy at four sites along a latitudinal/altitudinal gradient in three biogeo-graphic regions(Mediterranean,Continental,Alpine).We identified three stages of a chronosequence at each site as representative of the plant succession in response to pastoral land-use abandonment.Results:As expected,both the plant and ant assemblages considerably differed across sites at the species level and,within each site,among the three stages.This trend was found also using ant traits,functional groups of ants,and plant functional groups.Ant and plant communities were related in terms of composition and functionality.Harvester ants and ants with collective foraging strategy were associated with annual legumes and grasses(Therophytes);ants with a strictly individual foraging strategy with Phanerophytes.Ant traits and plant functional groups indicated significant differences among the three stages of the chronosequence.However,ant functional groups could not discriminate between the stages represented by secondary grasslands currently grazed and shrub-encroached grasslands ungrazed.Conclusion:Despite some limitations of ant functional groups in explaining the succession stages of land abandonment,our results suggest that ants are a good surrogate taxon and might be used as bioindicators of land-use changes and ecosystem functioning.Furthermore,our findings indicate that the functional group approach should be applied to other European ecosystems.Finally,reducing the taxonomic complexity could contribute to developing predictive models to detect early environmental changes and biodiversity loss in mountain habitats.

Functional diversity and trait composition of butterfly and bird communities in farmlands of Central Romania

Cultural landscapes all over the world harbor species communities that are taxonomically and functionally diverse.In Eastern Europe,but also in many other regions of the world,the conservation of this farmland biodiversity is threatened by land use intensification and abandonment.In order to counteract the negative effects of land use change in such landscapes,a thorough understanding of the functional relationships between species and their environment is crucial.In this study,we investigated the relationship of functional traits of butterfly and bird communities and environmental conditions in 120 sites in traditional farmlands of southern Transylvania,Romania.First,we compared taxonomic diversity(i.e.,Shannon diversity)with functional diversity(i.e.,functional dispersion),and second,we linked species traits to environmental variables by performing RLQ analyses.Functional traits indicating reproduction,movement,and feeding behavior related with environmental variables describing heterogeneity,amount of woody vegetation,and topography at three different spatial scales.We found positive relationships between taxonomic and functional diversity,as well as strong linkages between species traits and environmental conditions for both groups.Specifically,butterfly composition was most strongly influenced by land use type and life-history strategies.Bird composition was most strongly related to the amount of woody vegetation and nesting and foraging strategies.We conclude that maintaining the typical features of traditional farming landscapes,especially a small-scale heterogeneity in arable land and gradients of woody vegetation cover,would be desirable in order to sustain a high functional diversity in southern Transylvania in the future.

Extent and spatial distribution of terrace abandonment in China

Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces.The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects.A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China,and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China.The main findings are as follows:(1)The phenomenon of terrace abandonment was widespread throughout the country,with 54% of the total surveyed villages exhibiting terrace abandonment,and the area of abandoned terraces accounting for 9.79% of the total.(2) The degree of terrace abandonment is high in the south and low in the north.The most serious region with abandonment was the hilly and mountainous areas in the south,especially in the middle and lower Yangtze River region.(3)The main driving factors of terrace abandonment were rural labor migration,agricultural mechanization level,irrigation conditions,and transportation conditions for cultivation.Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment.Measures such as improving terrace mechanization are universally applicable.Specifically,low-quality terraces can be withdrawn orderly,and for high-quality terraces,multiple measures are needed to consolidate agricultural production,such as adjusting the planting structure,strengthening agricultural infrastructure construction,and encouraging the transfer of land-use rights as well as large-scale operation.