Comprehensive investigation and risk assessment of organic contaminants in Yellow River Estuary using suspect and nontarget screening strategies.

Contaminants of emerging concerns (CECs) include numerous chemicals that may pose known and unknown risks to the ecosystem, and identification and risk ranking of these compounds is essential for the environmental management. In this study, liquid and gas chromatography time-of-flight mass spectrometry (LC-QTOF-MS and GC-QTOF-MS) were used to characterize the occurrence of CECs in the surface water of the Yellow River Estuary (YRE). A total of 295 and 315 chemicals were identified by LC-QTOF-MS and GC-QTOF-MS, respectively. The occurrence of two compounds, erucamide and 2-phenylquinoline, was for the first time reported in the aquatic environment in YRE. The concentrations of 121 CECs, including 35 antibiotics, 49 pesticides and veterinary, 16 polycyclic aromatic hydrocarbons and 21 phthalic acid esters were further quantified by target analysis, which showed the detection of 99 compounds in the surface water in the range of 7.07-4611.26 ng/L. Ecological risks of pollutants based on the risk quotient (RQ) method revealed that 13 pollutants posed ecological risks to the aquatic ecosystem (RQ > 1), and pesticides (n = 12) were the main risk contributors. Here, all CECs data sets were finally transformed and ranked in the framework of the toxicological priority index (ToxPi), and a total of 81 priority control pollutants were identified in the surface water of YRE. This study highlighted the necessity of suspect and nontarget screening for CECs in estuaries, and revealed the importance of localized contamination sources in urban and agricultural environment.

[Pollution Characteristics and Health Risk Assessment of Heavy Metals in the Water of Lijiang River Basin].

In order to clarify the pollution levels of heavy metals in the drinking water sources of the Lijiang River Basin, surface water samples were collected from 62 sites throughout the Lijiang River during May 2019. Heavy metals, including As, Cd, Cr, Mn, Cu, Zn, Hg, Co, and Sb, in the water samples were analysed. Health risk assessments associated with these nine heavy metals were conducted using the health risk assessment model from the US EPA. The results indicated that the order of the average concentrations of heavy metals in the water samples were Mn > Zn > As > Cr > Cu > Sb > Co > Cd > Hg. No heavy metals exceeded the limit values of the drinking water health standards in China (GB 5749-2006), and the concentrations were lower than the limitations of Grade Ⅰ level in the environmental quality standards for surface water (GB 3838-2002). According to the spatial distribution, the high contents areas of As, Cr, Zn, and Sb were predominantly distributed downstream of the Lijiang River, while the high contents areas of Cd, Cu, Hg, Co, and Mn were mostly distributed in the upper reaches. Multivariate analysis indicated that Cd, Mn, Cu, and Co were primarily from agricultural production; Cr, Zn, and Sb were mainly from tourism transportation; As was predominantly from the weathering of rock parent material and soil erosion; Hg was mainly from the improper disposal of domestic garbage and atmospheric deposition. The results of the health risk assessment indicated that children were more susceptible to the threat of heavy metal pollution than adults, and the average annual risk of carcinogenic heavy metals to human health through drinking water ingestion were higher than those of non-carcinogenic metals. The maximum personal average annual health risk of Cr was higher than the maximum allowance levels recommended by the International Commission on Radiological Protection (5×10-5 a-1). The average annual risk of non-carcinogenic heavy metals (10-14-10-9 a-1) decreased in the order of Co > Cu > Hg > Zn > Sb > Mn, which were far below the maximum allowance levels recommended by the ICRP.

Groundwater pollution early warning based on QTR model for regional risk management: A case study in Luoyang city, China.

Groundwater pollution early warning has been regarded as an effective tool for regional groundwater pollution prevention, especially in China. In this study, the systemic model was established to assess the groundwater pollution early warning by integrating the present situation of groundwater quality (Q), groundwater quality trend (T) and groundwater pollution risk (R). The model integrated spatial and temporal variation of groundwater quality, and combined the state and process of the groundwater pollution. Q, T and R were assessed by the methods of fuzzy comprehensive assessment, Spearman or nonparametric Mann-Kendall trend test, and overlay index, respectively. Taking the Luoyang City as an example, the groundwater pollution early warning mapping was generated, and verified by corresponding the groundwater quality classes and the early warning degrees. The results showed that the groundwater was dominated by the levels of no warning and light warning, which accounted for 77% of the study area. The serious and tremendous warning areas were affected by the worse trend and relatively bad/bad present situations of groundwater quality with the typical contaminants of total hardness, nitrate, Hg and COD. In summary, the present situation of groundwater quality was the most important factor of groundwater pollution early warning mapping in the study area. The worse trend of groundwater quality played equally a key role in the local regions, as well as the high pollution risk, which was mainly affected by the pollution source loading. Targeted measures for groundwater pollution prevention were proposed in the corresponding degrees of groundwater pollution early warning. The QTR model was proved to be effective for assessing the regional groundwater pollution early warning. The accuracy of the model could be improved if there is further data acquisition of groundwater quality in longer time series and in larger number, and further investigation of pollution sources. The QTR model is proposed and proved to be effective for assessing regional groundwater pollution early warning.

Groundwater nitrate pollution risk assessment of the groundwater source field based on the integrated numerical simulations in the unsaturated zone and saturated aquifer.

Groundwater pollution risk assessment in the groundwater source field (GSF) is crucial to ensure groundwater quality safety. A systematic method of assessing groundwater pollution in the GSF was established by combining the numerical models of groundwater flow and solute transport in the vadose zone and aquifer. It is featured by revealing the paramount fate of contaminant from the surface to receptor "well (wells)" via the pathway of vadose zone and aquifers. The method was verified in the phreatic and semi-confined aquifers of a vital GSF, Beijing-Tianjin-Hebei region (BTHR) in China. Nitrate was selected as the model pollutant. The results indicated that the groundwater pollution risk of the phreatic aquifer was dominated by the mediate level (45.27%), and that the second semi-confined aquifer was mainly ranked as relatively low (30.29%) and mediate (38.17%) levels. The groundwater pollution risk maps of the two aquifers were similar. The high and relatively high risk areas were affected by the high intensities of groundwater pollution sources (GPSIs) or short distances from the pollution sources to the pumping well. The low and relatively low risk areas were controlled by low GPSIs and adequate attenuation and denitrification of nitrate in the aquifer. The groundwater pollution risk in the semi-confined aquifer was lower than that in the phreatic aquifer. The groundwater pollution risk mapping provides a valuable scientific reference for the groundwater pollution prevention and control with the focus on the "pollution source" and "groundwater source field". The proposed method can be further applied to the protections of the GSFs in the BTHR.

Distribution, ecological risk assessment and source identification of heavy metals in surface sediments of Huixian karst wetland, China.

In this study, heavy metals including Cd, Pb, Zn, Mn, Cu, Ni, Cr, As, and Hg, in the surface sediment (0-10 cm) of the Huixian wetland in a karst region were investigated in terms of their spatial distribution, ecological risks, and possible sources. Samples were collected from 13 typical sites throughout the Huixian wetland and were analyzed via inductively coupled plasma-mass spectrometry. The results revealed that the mean concentrations of Cd, Pb, Mn, Cr, As, and Hg were higher than the background and Chinese safe standard values. Based on spatial distribution and ecological risk, the study area was differentiated into three groups of sites with the following order of risk: group 3 > group 2 > group 1. The observed concentrations fluctuated slightly with depth. However, an irregular decreasing trend in the concentration with soil depth was observed among the groups. Multivariate statistical analyses showed that the high accumulation of Cd, Pb, Zn and Cu in the sediments of group 3 sites is due to the natural ancient deposition of minerals rich in heavy metals, while the accumulation of Mn, Cr, As, and Hg is attributed to an anthropogenic origin. Agricultural activities, the use of fertilizers and, pesticides, and local automobile repair stations most probably enriched these heavy metals in the Huixian wetland sediments. Hg and Cd have the highest potential ecological risk, which follows the order Hg > Cd > Pb > As > Ni > Cu > Cr > Mn > Zn. The mean geoaccumulation index (Igeo) values of Pb (0.48) and Hg (1.12) suggested moderate contamination in the study area.

Biouptake Responses of Trace Metals to Long-Term Irrigation with Diverse Wastewater in the Wheat Rhizosphere Microenvironment.

Wastewater irrigation is widely practiced and may cause serious environmental problems. However, current knowledge on the effects of long-term irrigation with wastewater from different sources on the biouptake of trace metals (TMs) in the rhizosphere zone by plants in farmlands is limited. Here, we analyzed wheat rhizosphere soil and wheat roots collected from a typical wastewater irrigation area in North China to evaluate the influence of wastewater irrigation from different sources on the bioavailability of trace metals in soils. Results showed that irrigation with tanning and domestic wastewater helped enhance the bioavailability of trace metals in rhizosphere soil by increasing the active organic carbon content, soil redox potential, and catalase activity, thus enhancing the proportion of the potentially bioavailable part of trace metal speciation. Conversely, irrigation with pharmaceutical wastewater can reduce the bioavailability of trace metals in rhizosphere soil by increasing total soil antibiotics and thus decreasing the proportions of bioavailable and potentially bioavailable parts of trace metal speciation. These findings can provide insights into the migration and transformation of trace metal speciation in soil rhizosphere microenvironments under the context of wastewater irrigation.

Comprehensive assessment of groundwater pollution risk based on HVF model: A case study in Jilin City of northeast China.

A comprehensive model for groundwater risk assessment was proposed by combining the hazard of contaminated sources (H), groundwater intrinsic vulnerability (V) and groundwater function value (F), and verified in Jilin City of northeast China. This model is characterized by integrating groundwater resource, ecology, and geological environment under the impact of climate change and human activities. The hazard of potential polluted sources was assessed by quantifying the properties and the potential infiltrating load of contaminants. The groundwater intrinsic vulnerability was evaluated by the DRASTIC model. The groundwater function value was assessed by multiplying seventeen indexes with their corresponding weightings. The groundwater pollution risk mapping of Jilin City was generated based on ArcGIS and validated by the level difference method between the risk classification and the pollution classification. The results showed that groundwater has a relatively low possibility of pollution because the area with less than, or equal to, the medium classification of risk accounted for 67.61% of the study area. The hazard harmfulness from the different contaminant sources played the most important role in determining the high groundwater pollution risk areas. Different influencing factors lead to relatively high pollution risk in specific areas. According to the validation of the level difference method, areas correctly identified by groundwater pollution risk mapping accounted for 95.81% of the study area, which is nearly twice as high as that of specific vulnerability mapping. The HVF model proved to be suitable for assessing groundwater pollution risk in Jilin City of northeast China. The groundwater pollution risk mapping can be applied for the effective protection and sustainable supply of groundwater.

Antibiotics in the aquatic environments: A review of lakes, China.

The potential threat of antibiotics to the environment and human health has raised significant concerns in recent years. The consumption and production of antibiotics in China are the highest in the world due to its rapid economic development and huge population, possibly resulting in the high detection frequencies and concentrations of antibiotics in aquatic environments of China. As a water resource, lakes in China play an important role in sustainable economic and social development. Understanding the current state of antibiotics in lakes in China is important. Closed and semi-closed lakes provide an ideal medium for the accumulation of antibiotics and antibiotic resistance genes (ARGs). This review summarizes the current levels of antibiotic exposure in relevant environmental compartments in lakes. The ecological and health risks of antibiotics are also evaluated. This review concludes that 39 antibiotics have been detected in the aquatic environments of lakes in China. The levels of antibiotic contamination in lakes in China is relatively high on the global scale. Antibiotic contamination is higher in sediment than water and aquatic organisms. Quinolone antibiotics (QNs) pose the greatest risks. The contents of antibiotics in aquatic organisms are far lower than their maximum residual limits (MRLs), with the exception of the organisms in Honghu Lake. The lakes experience high levels of ARG contamination. A greater assessment of ARG presence and antibiotic exposure are urgent.

Life cycle energy efficiency and environmental impact assessment of bioethanol production from sweet potato based on different production modes.

The bioethanol is playing an increasingly important role in renewable energy in China. Based on the theory of circular economy, integration of different resources by polygeneration is one of the solutions to improve energy efficiency and to reduce environmental impact. In this study, three modes of bioethanol production were selected to evaluate the life cycle energy efficiency and environmental impact of sweet potato-based bioethanol. The results showed that, the net energy ratio was greater than 1 and the value of net energy gain was positive in the three production modes, in which the maximum value appeared in the circular economy mode (CEM). The environment emission mainly occurred to bioethanol conversion unit in the conventional production mode (CPM) and the cogeneration mode (CGM), and eutrophication potential (EP) and global warming potential (GWP) were the most significant environmental impact category. While compared with CPM and CGM, the environmental impact of CEM significantly declined due to increasing recycling, and plant cultivation unit mainly contributed to EP and GWP. And the comprehensive evaluation score of environmental impact decreased by 73.46% and 23.36%. This study showed that CEM was effective in improving energy efficiency, especially in reducing the environmental impact, and it provides a new method for bioethanol production.

National investigation of semi-volatile organic compounds (PAHs, OCPs, and PCBs) in lake sediments of China: Occurrence, spatial variation and risk assessment.

In this study, a large scale investigation of semi-volatile organic compounds (SVOCs) in sediments from 52 lakes, located in five geographic regions across China, was conducted to assess sediment quality in terms of organic contaminants. Concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) in sediment were found to range between 17.00-6,633, 0.12-45.24, and 0.03-13.99ngg-1, respectively. Lake sediments from different regions exhibited variation in contamination levels, and in the compositions of isomers. The descending order of contamination levels for the three SVOCs groups (i.e., ∑PAHs, ∑OCPs, ∑PCBs) were as follows: the eastern plain region (EPR)>the Yunnan-Guizhou plateau (YGP)>the northeast China region (NCR)>the Qinghai-Tibet plateau (QTP)>the Mongolia-Xinjiang plateau (MXP). High molecular weight PAHs, OCPs and PCBs were found at high concentrations in parts of the EPR and YGP, while lighter isomers were likely to be atmospherically transported, resulting in their nationwide distribution. The sources and type variation (local input or atmospheric deposition) are the primary controls of spatial variation. Additionally, human related socio-economic factors, and geographic conditions also played important roles in influencing the spatial differentiation. According to simple sediment quality guidelines (SQG), the risks posed by PCBs in sediments were not as serious as those posed by PAHs and DDT.

Novel method of vulnerability assessment of simple landfills area using the multimedia, multipathway and multireceptor risk assessment (3MRA) model, China.

Vulnerability assessment of simple landfills was conducted using the multimedia, multipathway and multireceptor risk assessment (3MRA) model for the first time in China. The minimum safe threshold of six contaminants (benzene, arsenic (As), cadmium (Cd), hexavalent chromium [Cr(VI)], divalent mercury [Hg(II)] and divalent nickel [Ni(II)]) in landfill and waste pile models were calculated by the 3MRA model. Furthermore, the vulnerability indexes of the six contaminants were predicted based on the model calculation. The results showed that the order of health risk vulnerability index was As > Hg(II) > Cr(VI) > benzene > Cd > Ni(II) in the landfill model, whereas the ecology risk vulnerability index was in the order of As > Hg(II) > Cr(VI) > Cd > benzene > Ni(II). In the waste pile model, the order of health risk vulnerability index was benzene > Hg(II) > Cr(VI) > As > Cd and Ni(II), whereas the ecology risk vulnerability index was in the order of Hg(II) > Cd > Cr(VI) > As > benzene > Ni(II). These results indicated that As, Hg(II) and Cr(VI) were the high risk contaminants for the case of a simple landfill in China; the concentration of these in soil and groundwater around the simple landfill should be strictly monitored, and proper mediation is also recommended for simple landfills with a high concentration of contaminants.

Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake: Impacts of sources and sedimentological conditions.

Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development. Assessing the PAH sedimentary records over an approximately 100-year time span, we identified two stages in the PAH inputs and sources (before the 1970s and after the 1970s) in the eastern lake region near a village, whereas three stages (before the 1950s, 1950s-1990s and after the 1990s) were identified in the western lake region near urban and industrial areas. Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin. The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake. Strong positive relationships between PAH concentration and the total organic carbon concentration, sediment grain size (<4µm), as well as the local population and Gross Domestic Product indicated that the sedimentary conditions impact the depositional characteristics of the PAHs; simultaneously, socioeconomic activities, such as energy consumption and the levels of urban industrialization and civilization, affect both the composition and abundance of the PAHs.

Method for screening prevention and control measures and technologies based on groundwater pollution intensity assessment.

This paper presents a system for determining the evaluation and gradation indices of groundwater pollution intensity (GPI). Considering the characteristics of the vadose zone and pollution sources, the system decides which anti-seepage measures should be implemented at the contaminated site. The pollution sources hazards (PSH) and groundwater intrinsic vulnerability (GIV) are graded by the revised Nemerow Pollution Index and an improved DRTAS model, respectively. GPI is evaluated and graded by a double-sided multi-factor coupling model, which is constructed by the matrix method. The contaminated sites are categorized as prior, ordinary, or common sites. From the GPI results, we develop guiding principles for preventing and removing pollution sources, procedural interruption and remediation, and end treatment and monitoring. Thus, we can select appropriate prevention and control technologies (PCT). To screen the technological schemes and optimize the traditional analytical hierarchy process (AHP), we adopt the technique for order preference by the similarity to ideal solution (TOPSIS) method. Our GPI approach and PCT screening are applied to three types of pollution sites: the refuse dump of a rare earth mine development project (a potential pollution source), a chromium slag dump, and a landfill (existing pollution sources). These three sites are identified as ordinary, prior, and ordinary sites, respectively. The anti-seepage materials at the refuse dump should perform as effectively as a 1.5-m-thick clay bed. The chromium slag dump should be preferentially treated by soil flushing and in situ chemical remediation. The landfill should be treated by natural attenuation technology. The proposed PCT screening approach was compared with conventional screening methods results at the three sites and proved feasible and effective. The proposed method can provide technical support for the monitoring and management of groundwater pollution in China.

Assessment of the sources and transformations of nitrogen in a plain river network region using a stable isotope approach.

The great spatial and temporal variability in hydrological conditions and nitrogen (N) processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regions. By combining isotopic data with chemical and hydrologic measurements, we determined the relative importance of N sources and biogeochemical N processes in the Taige River in the East Plain Region of China. The river was polluted more seriously by anthropogenic inputs in winter than in summer. Manure and urban sewage effluent were the main nitrate (NO3-) sources, with the nitrification of N-containing organic materials serving as another important source of NO3-. In the downstream, with minor variations in hydrological conditions, nitrification played a more important role than assimilation for the decreasing ammonium (NH4+-N) concentrations. The N isotopic enrichment factors (ε) during NH4+ utilization ranged from -13.88‰ in March to -29.00‰ in July. The ratio of the increase in δ18O and δ15N of river NO3- in the downstream was 1.04 in January and 0.92 in March. This ratio indicated that NO3- assimilation by phytoplankton was responsible for the increasing δ15N and δ18O values of NO3- in winter. The relationships between δ15N of particulate organic nitrogen and isotopic compositions of dissolved inorganic nitrogen indicated that the phytoplankton in the Taige River probably utilized NH4+ preferentially and mainly in summer, while in winter, NO3- assimilation by phytoplankton was dominant.

Arsenic fractionation and contamination assessment in sediments of thirteen lakes from the East Plain and Yungui Plateau Ecoregions, China.

Arsenic (As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecoregions, followed by reducible As and soluble or oxidizable As. The total As is correlated to oxidizable As and residual As in sediment samples from both lake ecoregions. As distribution in sediment samples of lakes of the East Plain Ecoregion appears to be affected by human activity, while the As origin mainly comes from natural sources in sediment samples of lakes in the Yungui Plateau Ecoregion. The potential ecological risk index and geoaccumulation index values suggest "low to moderate" risk degree and "unpolluted to moderately polluted" for As in the studied lake sediments.

Spatial distribution, potential risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Lake Chaohu, China.

Twenty-nine sediment samples were collected from Lake Chaohu, a shallow eutrophic lake in Eastern China, and were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to determine the spatial distribution and exposure risks of PAHs. Three receptor models, the principal component analysis-multiple linear regression (PCA-MLR) model, the positive matrix factorization (PMF) model, and the Unmix model, were used in combination with the PAHs diagnostic ratios to investigate the potential source apportionment of PAHs. A clear gradient in the spatial distribution and the potential toxicity of PAHs was observed from west to east in the sediments of Lake Chaohu. ∑15PAH concentrations and the TEQ were in the range of 80.82-30 365.01 ng g(-1) d.w. and 40.77-614.03, respectively. The highest values of the aforementioned variables were attributed to urban-industrial pollution sources in the west lake region, and the levels decreased away from the river inlets. The three different models yielded excellent correlation coefficients between the predicted and measured levels of the 15 PAH compounds. Similarly, source apportionment results were derived from the three receptor models and the PAH diagnostic ratios, suggesting that the highest contribution to the PAHs was from coal combustion and wood combustion, followed by vehicular emissions. The PMF model yielded the following contributions to the PAHs from gasoline combustion, diesel combustion, unburned petroleum emissions, and wood combustion: 34.49, 24.61, 16.11, 13.01, and 11.78 %, respectively. The PMF model produced more detailed source apportionment results for the PAHs than the PCA-MLR and Unmix models.

Assessment of humification degree of dissolved organic matter from different composts using fluorescence spectroscopy technology.

This study was conducted to assess the degree of humification in dissolved organic matter (DOM) from different composts, and their environmental impact after soil amending based on fluorescence measurements (emission, excitation, synchronous scan, and excitation-emission matrix [EEM]). The compost sources studied included dairy cattle manure (DCM), kitchen waste (KW), cabbage waste (CW), tomato stem waste (TSW), municipal solid waste (MSW), green waste (GW), chicken manure (CM), and peat (P). Conventional and EEM fluorescence spectroscopy indicated that the DOM of these composts contained compounds similar in structure but comparisons between conventional fluorescence parameters and fluorescence regional integration of EEM fluorescence spectra showed that the DOM was different in degree of humification. Regression analysis demonstrated significant corrections between major fluorescence parameters. In hierarchical cluster analysis, these composts were clustered into 2 groups and 4 subgroups, and projection pursuit regression analysis further ranked the compost sources as KW, CW, P>CM, DCM, TW, GW>MSW in their degree of humification in DOM.

Establishing eutrophication assessment standards for four lake regions, China.

The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lake eutrophication assessment standard was established through a frequency distribution method based on chlorophyll-a concentration. The assessment standards under the oligotrophic state for lakes in the Eastern plain, Yungui Plateau, Northeast Plain and Mountain Mongolia-Xinjiang regions are total phosphorus of 0.068, 0.005, 0.011, 0.005 mg/L; total nitrogen of 1.00, 0.16, 0.37, 0.60 mg/L; Secchi depth of 0.60, 8.00, 1.55, 3.00 m; and COD(Mn) of 2.24, 1.00, 5.11, 4.00 mg/L, respectively. Moreover, a region-specific comprehensive trophic level index was developed to provide an understandable assessment method for the public. The results indicated that the frequency distribution analysis based on chlorophyll-a combined with trophic level index provided a useful metric for the assessment of the lake trophic status. In addition, the difference of eutrophication assessment standards in different lake regions was analyzed, which suggested that the sensitivities of algae to nutrients and the assessment standard of trophic status possessed significant regional differences for the four lake ecoregions. Lake eutrophication assessment standards would contribute to maximizing the effectiveness of future management strategies, to control and minimize lake eutrophication problems.

[Research based on 3MRA model about the risk assessment methods and applications of the landfill waste].

Seven major contaminations of the landfill were selected from northeast of China, and the migration and transformation of contaminations environmental medias were studied by using the multimedia multipathway and multireceptor risk assessment (3MRA) model. The results show, the order of the radical concentration of the seven contaminations is Ni2+ > Benzene > Cd > Pb > Cr6+ > As > Hg. The radical concentration of benzene, As and Hg in human is similar to that of ecology, respectively. The radical concentration of Cd and Ni2+ in human is higher than that of ecology, while the radical concentration of Cr6+ in ecology is higher than that of human. The risk and hazard quotient of the groundwater in the landfill is 5.06 x 10(-7), 2.3 x 10(-1), respectively.

Case study on incentive mechanism of energy efficiency retrofit in coal-fueled power plant in China.

An ordinary steam turbine retrofit project is selected as a case study; through the retrofit, the project activities will generate emission reductions within the power grid for about 92,463 tCO(2)e per annum. The internal rate of return (IRR) of the project is only -0.41% without the revenue of carbon credits, for example, CERs, which is much lower than the benchmark value of 8%. Only when the unit price of carbon credit reaches 125 CNY/tCO(2), the IRR could reach the benchmark and an effective carbon tax needs to increase the price of carbon to 243 CNY/tce in order to make the project financially feasible. Design of incentive mechanism will help these low efficiency enterprises improve efficiency and reduce CO(2) emissions, which can provide the power plants sufficient incentive to implement energy efficiency retrofit project in existing coal-fuel power generation-units, and we hope it will make a good demonstration for the other low efficiency coal-fueled power generation units in China.