Distribution characteristics and environmental risk assessment following metal(loid)s pollution incidents at Southwest China mining site

Limited information is available on long-term effects of metal(loid)s pollution incidents. Here, we analyze the distribution characteristics and quantification of elements in the Southwest China Keda mining site, which is one of the most populated sites and enables human health and ecological risk assessments of elemental pollution. The results on modified degree of contamination indicated that the soil and sediment were highly contaminated near Dahu Lake.The health risk of children was almost 2.5 times that of adults in surface water, and 7.1 times in soil, respectively.Moreover, Tl and As were the main health risk contributors in surface water and soil, respectively, and As posed the highest ecological risk both in soil and sediment. These results indicated the potential impact of toxic metal(loid)s on the health of residents and environment. Hence, more scientific attention and proper management need to be paid to this environmental challenge in the future.

Environmental Geochemistry of Heavy Metal Contaminants in Soil and Stream Sediment in Panzhihua Mining and Smelting Area,Southwestern China

Mining and smelting activities are the main causes for the in creasing pollution of heavy metals in soil, water body and stream sediment. An e nvironmental geochemical investigation was carried out in and around the Panzhih ua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the envi ronmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study area. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly c ontaminated. Geochemical maps of I\-\{geo\} of each heavy metal show that the co ntaminated sites are located in V-Ti-magnetite sloping and smelting, gangues d am. The pollution sources of the selected elements come mainly from dusts result ant from mining activities and other three-waste-effluents. The area needs to be monitored regularly for trace metal, especially heavy metal enrichment.

Eco-Environmental Geochemistry of Heavy Metal Pollution in Dexing Mining Area

An eco-environmental geochemical investigation was carried out in and around the Dexing mining area to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective of this study is to assess the environmental situation and evaluate the transferring of heavy metals from mining activities into the food chain. Some samples of water, sediment, topsoil and plant were collected along the Lean River in the Dexing mining area. The total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS, and Hg was analyzed by cold-vapor AAS. Some indices such as ‘contamination degree’, ‘geoaccumulation index’, and ‘biological absorption coefficient’ were used to assess eco-environmental quality. The investigation indicated a highly localized distribution pattern closely associated with the two pollution sources along the Le’an River bank: one is strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and the other is the high concentrations of Pb and Zn in the effluents released from many smelters and mining, processing and extracting activities in the riparian zone. Results from the investigated localities indicated, at least in part, that some problems associated with environmental quality deterioration should be solved in the future.

Simulation on the dynamics of forest area changes in Northeast China

There is plenty of forests in Northeast China which contributes a lot to the conservation of water and land resources, produces timber products, and provides habitats for a huge number of wild animals and plants. With changes of socio-economic factors as well as the geophysical conditions, there are dramatic changes on the spatial patterns of forest area. In this sense, it is of great significance to shed light on the dynamics of forest area changes to find the underlining reasons for shaping the changing patterns of forest area in Northeast China. To explore the dynamics of forest area change in Northeast China, an econometric model is developed which is composed of three equations identifying forestry production, conversion from open forest to closed forest and conversion from other land uses to closed forest so as to explore the impacts on the forest area changes from demographic, social, economic, location and geophysical factors. On this basis, we employ the Dynamics of Land System （DLS） model to simulate land-use conversions between forest area and non-forest cover and the land-use conversions within the sub-classes of forest area for the period 2000-2020 under business as usual scenario, environmental protection scenario and economic growth scenario. The simulation results show that forest area will expand continuously and there exist various kinds of changing patterns for the sub-classes of forest area, for example, closed forest will expand continuously and open forest and shrub will decrease a little bit, while area of other forest will keep intact. The research results provide meaningful decision-making information for conserving and exploiting the forest resources and makJng out the planning for forestry production Jn the Northeast China region.

Factors and mechanism driving the land-use conversion in Jiangxi Province

This article explores the factors and mechanism driving the land-use conversion at regional level by developing and using an econometric approach which is called the simultaneous equations model （SEM）. A case study in Jiangxi Province of China is conducted by establishing the SEM, which consists of three equations including agricultural production, land conversion of cultivated land to built-up area and land conversion of cultivated land to forest cover/grassland from 1988 to 2005. And then this paper employs the method of piecewise estimation to represent the influences of the factors such as population, society, economy, location and geophysical conditions on the process of land-use conversion in Jiangxi Province. Estimation results show that population is a predominant factor driving the land-use conversion at counties, while social and economic factors are determinant factors in the short term for the entire Jiangxi Province. Specifically, the size of agricultural population and the magnitude of agricultural input determine the agricultural production to a large extent; population size, plain area proportion at counties and land management policies together affect the direction and magnitude of conversion between cultivated land and built-up area; agricultural population proportion, terrain slope, grain production and non-agricultural industry promote the conversion of cultivated land to forest cover/grassland. Furthermore, the explored mechanism also reveals the underlying causes of the land use changes driven by a series of factors in Jiangxi Province. Finally, this paper concludes that factors proven to play an important role in driving the land-use conversion need to be considered when the land management agencies make out the land use planning to optimize the land use, expand the agricultural production, and conserve the cultivated land.

Seepage simulation of high concrete-faced rockfill dams based on generalized equivalent continuum model

This research focused on the three-dimensional(3 D) seepage field simulation of a high concrete-faced rockfill dam(CFRD) under complex hydraulic conditions. A generalized equivalent continuum model of fractured rock mass was used for equivalent continuous seepage field analysis based on the improved node virtual flow method. Using a high CFRD as an example, the generalized equivalent continuum range was determined, and a finite element model was established based on the terrain and geological conditions, as well as structural face characteristics of the dam area. The equivalent seepage coefficients of different material zones or positions in the dam foundation were calculated with the Snow model or inverse analysis. Then, the 3 D seepage field in the dam area was calculated under the normal water storage conditions, and the corresponding water head distribution, seepage flow, seepage gradient, and seepage characteristics in the dam area were analyzed. The results show that the generalized equivalent continuum model can effectively simulate overall seepage patterns of the CFRD under complex hydraulic conditions and provide a reference for seepage analysis of similar CFRDs.

Layout effects and optimization of runoff storage and filtration facilities based on SWMM simulation in a demonstration area

The layout effects and optimization of runoff storage and filtration facilities are crucial to the efficiency and management of the cost of runoff control, but related research is still lacking. In this study, scenarios with different layouts were simulated using the storm water management model(SWMM), to investigate the layout effects on control efficiency with different precipitations. In a rainfall event with 50 mm of precipitation in two hours, 1820 scenarios with different layouts of four facilities constructed in 16 sub-catchments were simulated, the reduction rates of internal flow presented a standard deviation of 10.9%, and the difference between the maximum and minimum reduction rates reached59.7%. Based on weighting analysis, an integrated ranking index was obtained and used to determine the optimal layout scenarios considering different rainfall events. In the optimal scenario(storage and filtration facilities constructed in sub-catchments 14, 12, 7, and 2), the reduction rates of the total outflow reached 31.4%, 26.4%, and 14.7%, respectively, with 30, 50, and 80 mm of precipitation. The reduction rate of the internal outflow reached 95% with 50 mm of precipitation and approximately 56% with 80 mm of precipitation.

Simulation and control strategy for the variational influent of WWTP

With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.

A Comparison of Incentive Policies for the Optimal Layout of CCUS Clusters in China’s Coal-Fired Power Plants Toward Carbon Neutrality

1.Introduction China has announced that it will adopt forceful policies and measures and strive to achieve peak carbon dioxide(CO_(2))emissions before 2030 and carbon neutrality before 2060—aims that are largely consistent with the goal to limit warming to 1.5C[1].Achieving this target requires the deep decarbonization of China’s entire economy,with a particular focus on coal-fired power plants(CFPPs).

The concept, connotation and method of representation of watershed water environment carrying capacity （WWECC）

Based on the relationship between water environment system and human society, water environment carrying capacity （WECC） probes into supporting ability of complex water environment system to the human society. Recent years, due to the shortage of water resources and serious water pollution in several watersheds in China, the research of watershed water environment carrying capacity （WWECC） becomes very important. The conception, connotation and method of representation of WWECC are discussed deeply in this paper. It shows that WWECC is a kind of index that instructs whether the water environment system in watershed can continue to support the development of social economy and ecology, it is dimensionless number.

Suitable Weir Heights to Improve the Provision of Environmental Flows in Urban Rivers

Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban rivers.In addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans,we propose that designing weir heights without explicitly considering e-flows is another major cause of this problem.In this paper,we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design stage.We establish a new weir height determination framework that would more effectively satisfy the required e-flows.The new framework differs from previous frameworks,in which flood control and water retention are the major concerns and the flow during floods is set as the inflow.In the new framework,e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the inflow.As a case study of the new framework’s effectiveness,we applied it to the Shiwuli River,a typical channelized urban river in Hefei,China.The old framework specified too-high weir height to meet the e-flow requirements,whereas the new framework offered more reasonable heights that improved e-flow provision.

The Increasing Role of Synergistic Effects in Carbon Mitigation and Air Quality Improvement, and Its Associated Health Benefits in China

A synergistic pathway is regarded as a critical measure for tackling the intertwined challenges of climate change and air pollution in China. However, there is as yet no indicator that can comprehensively reflect such synergistic effects;hence, existing studies lack a consistent framework for comparison. Here, we introduce a new synergistic indicator defined as the pollutant generation per gross domestic product (GDP) and adopt an integrated analysis framework by linking the logarithmic mean Divisia index (LMDI) method, response surface model (RSM), and global exposure mortality model (GEMM) to evaluate the synergistic effects of carbon mitigation on both air pollutant reduction and public health in China. The results show that synergistic effects played an increasingly important role in the emissions mitigation of SO_(2), NOx, and primary particulate matter with an aerodynamic diameter no greater than 2.5 μm (PM2.5), and the synergistic mitigation of pollutants respectively increase from 3.1, 1.4, and 0.3 Mt during the 11th Five-Year Plan (FYP) (2006–2010) to 5.6, 3.7, and 1.9 Mt during the 12th FYP (2011–2015). Against the non-control scenario, synergistic effects alone contributed to a 15% reduction in annual mean PM2.5 concentration, resulting in the prevention of 0.29 million (95% confidential interval: 0.28–0.30) PM2.5-attributable excess deaths in 2015. Synergistic benefits to air quality improvement and public health were remarkable in the developed and population-dense eastern provinces and municipalities. With the processes of urbanization and carbon neutrality in the future, synergistic effects are expected to continue to increase. Realizing climate targets in advance in developed regions would concurrently bring strong synergistic effects to air quality and public health.

Spatial Distribution and Environmental Determinants of Denitrification Enzyme Activity in Reed-Dominated Raised Fields

Denitrification is an important process of nitrogen removal in lake ecosystems.However,the importance of denitrification across the entire soil-depth gradients including subsurface layers remains poorly understood.This study aims to determine the spatial pattern of soil denitrification enzyme activity(DEA) and its environmental determinants across the entire soil depth gradients in the raised fields in Baiyang Lake,North China.In two different zones of the raised fields(i.e.,water boundary vs.main body of the raised fields),the soil samples from 1.0 m to 1.1 m depth were collected,and the DEA and following environmental determinants were quantified:soil moisture,p H,total nitrogen(TN),ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3–-N),total organic carbon(TOC),and rhizome biomass of Phragmites australis.The results showed that the soil DEA and environmental factors had a striking zonal distribution across the entire soil depth gradients.The soil DEA reached two peak values in the upper and middle soil layers,indicating that denitrification are important in both topsoil and subsurface of the raised fields.The correlation analysis showed that the DEA is negatively correlated with the soil depth(p < 0.05).However,this phenomenon did not occur in the distance to the water edge,except in the upper layers(from 0.2 m to 0.7 m) of the boundary zone of the raised fields.In the main body of the raised fields,the DEA level remained high;however,it showed no significant relationship with the distance to the water edge.The linear regression analysis showed significant positive correlation of the DEA with the soil TN,NO3–-N,NH4+-N,and TOC;whereas it showed negative correlation with soil p H.No significant correlations with soil moisture and temperature were observed.A positive correlation was also found between the DEA and rhizome biomass of P.australis.

A New Method of Assessing Environmental Flows in Channelized Urban Rivers

Assessing environmental flows （e-flows） for urban rivers is important for water resources planning and river protection, Many e-flow assessment methods have been established based on species＇ habitat pro- vision requirements and pollutant dilution requirements, To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearance of valuable species, With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers, For these rivers, the e-flows determined by tradi- tional methods will be very small, and will consequently lead to a low priority being given to river pro- tection in future water resources allocation and management, To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological con- nectivity （high, medium, and low）, in addition to the pollutant dilution water requirement determined by the mass-balance equation, In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days （which is designed to further reduce e-flows）, The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness, The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects,

Effects of the adaptations to climate changes on the income of herdsmen in Qinghai Province

This study aims to implement the empirical analysis of the effects of the adaptive measures on the income of herdsmen in the context of the climate change with the positive mathematical programming(PMP)model.The survey was first implemented in three counties in the Three Headwaters Region.Finally the measures and recommendations suitable for the economic development in the ecologically fragile areas were proposed.The main conclusions are as follows:priority can be given to the measures to prevent the damage from rats and the engineering measures for pasture maintenance in Zeku County,where the geological conditions and grass quality are inferior,while the fiscal subsidy can be prioritized in Tongde County where the grassland area is relatively less.These recommendations can not only provide good reference for the protection of grassland resources,but they also lay a foundation for the implementation of more suitable measures to help the herdsmen in the ecologically fragile areas to adapt to the climate change.

STATISTICAL CHARACTERISTICS AND NUMERICAL SIMULATION OF SEA-LAND BREEZES IN HAINAN ISLAND

The sea-land breeze circulation(SLBC) occurs regularly at coastal locations and influences the local weather and climate significantly. In this study, based on the observed surface wind in 9 conventional meteorological stations of Hainan Island, the frequency of sea-land breeze(SLB) is studied to depict the diurnal and seasonal variations. The statistics indicated that there is a monthly average of 12.2 SLB days and an occurrence frequency of about 40%, with the maximum frequency(49%) in summer and the minimum frequency(29%) in autumn. SLB frequencies(41%) are comparable in winter and spring. A higher frequency of SLB is present in the southern and central mountains due to the enhancement effect of the mountain-valley breeze. Due to the synoptic wind the number of SLB days in the northern hilly area is less than in other areas. Moreover, the WRF model, adopted to simulate the SLBC over the island for all seasons, performs reasonably well reproducing the phenomenon, evolution and mechanism of SLBC. Chiefly affected by the difference of temperature between sea and land, the SLBC varies in coverage and intensity with the seasons and reaches the greatest intensity in summer. The typical depth is about 2.5 km for sea breeze circulation and about 1.5 km for land breeze circulation. A strong convergence zone with severe ascending motion appears on the line parallel to the major axis of the island, penetrating 60 to 100 km inland. This type of weak sea breeze convergence zone in winter is north-south oriented. The features of SLBC in spring are similar both to that in summer with southerly wind and to that in winter with easterly wind. The coverage and intensity of SLBC in autumn is the weakest and confined to the southwest edge of the central mountainous area. The land breeze is inherently very weak and easily affected by the topography and weather. The coverage and intensity of the land breeze convergence line is significantly less than those of the sea breeze. The orographic forcing of the central mountain exhibits significant impacts on low-level airflow. A windward land breeze front usually occurs along the coastline between the wee hours and the morning in summer, with an arc-shaped convergence zone about 10 to 30 km off shore. In winter the arc-shaped convergence zone is weak and appears only in the southeast coastal area. Landing on the flat regions of northern to western parts of the island and going inland from there, the sea breeze front at the leeward side meets with that at the windward side in the centre of the island when sea breeze fully develops, causing an intense convergence zone throughout the whole island. Consistent with prevailing winds in direction, the windward sea breeze and leeward land breeze develop quickly but are not distinguishable from background winds.

An extended input-output table for environmental and resources accounting

Environmentally Extended Input-Output(EEIO)tables have become a powerful element in supporting information-based environmental and economic policies.National-and provincial-level 10 tables are currently published by the National Bureau of Statistics of the People's Republic of China according to well-defined conventions.However,county-level 10tables are not provided as a rule by official statistics organizations.This paper conducts an overview of compiling EEIO tables for environmental and resources accounting at the county level and then answers several questions:First,what kind of data should be prepared for the compilation of county-level EEIO tables?Second,how can we set up comprehensive EEIO tables at the county level?Third,regarding the survey methods and the indirect modeling,which one should be chosen to build EEIO tables at the county level?Finally,what policy questions could such a table answer?EEIO tables at the county level can be used to predict the economic impacts of environmental policies and to perform trend and scenario analysis.

An Integrated Analysis on the Synergistic Reduction of Carbon and Pollution Emissions from China’s Iron and Steel Industry

Decarbonization and decontamination of the iron and steel industry(ISI),which contributes up to 15%to anthropogenic CO_(2) emissions(or carbon emissions)and significant proportions of air and water pollutant emissions in China,are challenged by the huge demand for steel.Carbon and pollutants often share common emission sources,indicating that emission reduction could be achieved synergistically.Here,we explored the inherent potential of measures to adjust feedstock composition and technological structure and to control the size of the ISI to achieve carbon emission reduction(CER)and pollution emission reduction(PER).We investigated five typical pollutants in this study,namely,petroleum hydrocarbon pollutants and chemical oxygen demand in wastewater,particulate matter,SO_(2),and NO_(x) in off gases,and examined synergies between CER and PER by employing cross elasticity for the period between 2022 and 2035.The results suggest that a reduction of 8.7%-11.7%in carbon emissions and 20%-31%in pollution emissions(except for particulate matter emissions)could be achieved by 2025 under a high steel scrap ratio(SSR)scenario.Here,the SSR and electric arc furnace(EAF)ratio serve critical roles in enhancing synergies between CER and PER(which vary with the type of pollutant).However,subject to a limited volume of steel scrap,a focused increase in the EAF ratio with neglection of the available supply of steel scrap to EAF facilities would lead to an increase carbon and pollution emissions.Although CER can be achieved through SSR and EAF ratio optimization,only when the crude steel production growth rate remains below 2.2%can these optimization measures maintain the emissions in 2030 at a similar level to that in 2021.Therefore,the synergistic effects between PER and CER should be considered when formulating a development route for the ISI in the future.

A single micro-LED manipulation system based on micro-gripper

Micro-LEDs(μLEDs)have advantages in terms of brightness,power consumption,and response speed.In addition,they can also be used as micro-sensors implanted in the body via flexible electronic skin.One of the key techniques involved in the fabrication ofμLED-based devices is transfer printing.Although numerous methods have been proposed for transfer printing,improving the yield ofμLED arrays is still a formidable task.In this paper,we propose a novel method for improving the yield ofμLED arrays transferred by the stamping method,using an innovative design of piezoelectrically driven asymmetric micro-gripper.Traditional grippers are too large to manipulateμLEDs,and therefore two micro-sized cantilevers are added at the gripper tips.AμLED manipulation system is constructed based on the micro-gripper together with a three-dimensional positioning system.Experimental results using this system show that it can be used successfully to manipulateμLED arrays.

Efficient Metal Recovery from Industrial Wastewater:Potential Oscillation and Turbulence Mode for Electrochemical System

Efficient metal recovery from industrial wastewater facilitates addressing of the environmental hazards and resource requirements of heavy metals.The conventional electrodeposition recovery method is hampered by the limitations of interfacial ion transport in charge-transfer reactions,creating challenges for simultaneous rapid and high-quality metal recovery.Therefore,we proposed integrating a transient electric field(TE)and swirling flow(SF)to synchronously enhance bulk mass transfer and promote interfacial ion transport.We investigated the effects of the operation mode,transient frequency,and flow rate on metal recovery,enabling determination of the optimal operating conditions for rapid and efficient sequential recovery of Cu in TE&SF mode.These conditions included low and high electric levels of 0 and 4 V,a 50%duty cycle,1 kHz frequency,and 400 L·h^(-1)flow rate.The kinetic coefficients of TE&SF electrodeposition were 3.5-4.3 and 1.37-1.97 times that of single TE and SF electrodeposition,respectively.Simulating the deposition process under TE and SF conditions confirmed the efficient concurrence of interfacial ion transport and charge transfer under TE and SF synergy,which achieved rapid and highquality metal recovery.Therefore,the combined deposition strategy is considered an effective technique for reducing metal pollution and promoting resource recycling.