Huanjing Kexue/Environmental Science最新文献

A variety of pollutants have frequently been detected in the Yangtze River Basin with the rapid economic development, the population increase, and the acceleration of urbanization, which threaten the aquatic ecosystem and human health. A multi-criteria comprehensive evaluation method was developed to identify the characteristic pollutants, and the risk quotient method was used to derive the risk pollutants in water and sediment samples in this article. A total of 155 pollutants from 11 categories were detected in the Yangtze River Basin according to the literature research. Then, the K-means method was used to analyze the cluster of pollutant comprehensive scores. All pollutants were graded based on their scores and recorded as Ⅰ-Ⅵ according to the number of cases in each cluster. A total of 43 pollutants with high scores of Ⅰ and Ⅱ were listed as the characteristic pollutants, which included 11 polycyclic aromatic hydrocarbons, 11 organochlorine pesticides, 10 polychlorinated biphenyls, eight dioxins, two heavy metals, and one phthalate ester. The top five median concentrations of contaminants in water and sediment samples were heavy metals, polycyclic aromatic hydrocarbons, phthalates esters, bisphenols, and pharmaceuticals and personal care products. According to the principle of risk maximization, the risk entropy value （RQ） was calculated based on the highest pollutant concentration. A total of 38 risky pollutants were screened in the water samples （RQ ≥ 0.1）. There were eight high-risk pollutants with RQ ≥ 1, which included benzo[a,h]-anthracene, anthracene, benzo[a]anthracene, pyrene, methoxychlor, aldrin, 2,4'-dichlorodiphenyl, and cadmium. There were 15 high-risk contaminants in the sediment, which included benzo[b]fluoranthene, anthracene, acenaphthene, fluoranthene, cadmium, lead, chromium, arsenic, selenium, dibutyl phthalate, dimethyl phthalate, diisobutyl phthalate, norfloxacin, perfluorobutyric acid, and bisphenol A. The risk pollutants contained emerging pollutants, which included ten pollutants in water samples and nine pollutants in sediments. Antibiotic pollutants accounted for the largest proportion of these emerging pollutants. The information provided in this article may be useful for the relevant departments to monitor the pollutants and propose management programs for the Yangtze River Basin. Additionally, it is of great significance for the ecological environmental protection and management of the Yangtze River Basin.

Considering the extremely high content of soil mineral elements in high geological background areas, it is crucial to understand the transportation and health risks of mineral elements in soil-plant systems. In this study, 30 soil and apple-paired samples were collected from the main apple production areas of Yunnan's high geological background region to determine the contents of mineral elements. The aim was to research the enrichment characteristics, nutritional values, and health risks associated with 12 mineral elements in apples. The results revealed that Cd, As, Pb and Cr contents in soil samples exceeded their corresponding risk screening values with percentages of 50%, 17%, 48%, and 30%, respectively. However, only 13.3% of Pb content in apple samples exceeded the safety limit （0.1 mg·kg^-1, fresh fruit）. In addition to the toxic elements, apples had higher contents of K, Ca, Mg, Mn, and Zn, with average contents of 1.241 g·kg^-1, 0.045 g·kg^-1, 0.061 g·kg^-1, 0.648 mg·kg^-1, and 0.944 mg·kg^-1, respectively. The nutritional evaluation results showed that the index （INQ） of K and Cu were higher than 2 through the consumption of apples, suggesting that apple consumption was one of the primary sources of K and Cu intake. The health risk assessment revealed that the target hazard quotient （THQ） of a single heavy metal was： Cu > As > Cr > Pb > Zn > Cd； the hazard index （HI） of all heavy metals was far lower than 1, indicating that apple consumption did not pose significant heavy metal exposure risks. The results of this study will provide a scientific insight into the nutritional aspects and health risks associated with mineral elements in soil-plant systems within high geological background areas.

Soil organic carbon （SOC） and soil total nitrogen （STN） serve as important indicators of the elemental balance within forest ecosystems reflecting soil fertility and quality. Accurate knowledge regarding the spatial variability of regional SOC, STN, and C∶N ratio and their influencing factors is of great significance for precise fertilization and soil health. In this study, a total of 117 topsoil samples （0-20 cm in depth） based on a 1 km×1 km grid were collected in the Torreya grandis cv. Merrillii plantation in Zhejiang Province. A combination of multi-dimensional statistical approaches （random forest model, structural equation model, redundancy analysis, and variation partitioning analysis） and diverse spatial analytical techniques （geostatistics, Moran's I index, etc.） were applied to reveal the spatial distributions and influencing factors of SOC, STN, and C∶N ratio in the Torreya. grandis cv. Merrillii region. The results showed that the average ω（SOC）, ω（STN）, and C∶N ratio were 17.63 g·kg^-1, 1.48 g·kg^-1, and 12.65, respectively, and their coefficients of variation were 68.08%, 67.41%, and 46.03%, respectively, indicating a moderate degree of variability. In general, the SOC, STN, and C∶N ratio of the Torreya grandis cv. Merrillii plantations were at an intermediate level in the national plantation. The semi-variance results showed that the nugget/sill values of SOC, STN, and C∶N ratio were 49.98%, 45.88%, and 49.93%, respectively, demonstrating a moderate level of spatial autocorrelation. The spatial distribution results showed that SOC, STN, and C∶N ratio decreased from northeast to southwest, with the majority of the region exhibiting above-medium fertility levels of SOC. The results of correlation analysis and redundancy analysis indicated that AN, AP, and AK were significantly correlated with both SOC, STN, and C∶N ratio （P<0.05）. The results of random forest, structural equation model, and variation partitioning analysis evidenced that the main influencing factors of SOC and STN were soil-available nutrients （AN, AP, and AK）. Therefore, our results could provide important insights for enhancing soil carbon and nitrogen pools in special plantations in Zhejiang Province, enhancing the capacity of plantations to adapt to regional climate change through ecological measures such as appropriate fertilization practices and strategic understory vegetation cultivation.

Clarifying the temporal and spatial changes in the carbon budget in the Chongqing metropolitan area and exploring the spatial correlation of land use carbon budget are of great significance for realizing the regional "double carbon" goal. Using 21 districts and counties in Chongqing metropolitan area as the research scale, the IPCC inventory method, carbon emission coefficient method, Gini coefficient, gravity model, and social network analysis were used to estimate the net carbon emissions from land use in Chongqing metropolitan area from 2000 to 2020, and the spatial correlation of the carbon budget was obtained. The results revealed that： ① In the past 20 years, the carbon budget of the Chongqing metropolitan area showed an overall upward trend, with an average annual growth rate of 2.83%, and the spatial distribution was "higher in the north and south, higher in the east and west, and lower in the middle." ② During the past 20 years, the spatial difference of net carbon emissions in the Chongqing metropolitan area became highly average, and the overall Gini coefficient decreased by 11.42%, whereas the intra-group difference was the largest in key development zones. ③ In the past 20 years, the overall structure of the spatial correlation network of land use carbon budget in the Chongqing metropolitan area has become stable and complex, and the network density and network correlation number have increased by 0.43 and 180, respectively, the network correlation degree has increased to 1, and the network health degree has improved. ④ In the individual network structure of land use carbon budget in the Chongqing metropolitan area, the degree centrality of each district and county has increased, and the increase in the central urban area was the most significant, with an increase of 81, whereas the decline in intermediate centrality and proximity centrality has promoted the regional coordinated development and integration process in the metropolitan area. ⑤ In the past 20 years, the density of net carbon emissions in the Chongqing metropolitan area has increased as a whole, with the density of the core area increasing by 0.35 and the density of the core-edge area increasing by 0.34. By exploring the change and spatial correlation of land use carbon budget in the Chongqing metropolitan area, this study clarified the spatial distribution difference of carbon budget and provided support for regional green development.

To improve the phenomenon of the volatile organic compounds （VOCs） odor pollution nuisance in industrial parks and to promote the synergistic control of atmospheric VOCs and their odor-causing substances, based on the field observation of atmospheric VOCs in residential living areas and five different types of industrial clusters in industrial parks, we analyzed the pollution characteristics of atmospheric VOCs and their odor-causing volatile organic compounds （O-VOCs） in the residential living areas and each industrial cluster, evaluated the characteristics of the odor activity of the O-VOCs in the industrial parks, and identified the key odor-causing species and their main sources. The results showed that the mean values of atmospheric φ （TVOCs） and φ（O-VOCs） in the residential living area of the industrial park were 102.57×10^-9 and 72.33×10^-9, respectively. φ（TVOCs） and φ（O-VOCs） were significantly higher in the industrial clusters of basic chemical industry and pharmaceutics than in the other industrial clusters, and the sum （OAV_sum） and maximum （OAV_max） of the odor activity values of these two clusters were relatively high, with a potential risk of odor nuisance. Overall, the O-VOCs species with higher odor intensity were similar in residential living areas and the five industrial clusters, and effective control of O-VOCs species such as acrolein, p-diethylbenzene, p-xylene, and 1,3-diethylbenzene is essential to mitigate or eliminate organic odor pollution. The results of the source apportionment of O-VOCs in the residential area showed that the sources of O-VOCs in the residential area were mainly influenced by natural gas chemical and pharmaceutics, and the coefficients of divergence （CD_O-VOCs） between the O-VOC chemical profiles from residential areas and those from natural gas chemical and pharmaceutics were 0.31 and 0.38, respectively. Principal component analysis （PCA） also confirmed this result, with residential O-VOCs mainly originating from natural gas chemicals and pharmaceutics, followed by iron and steel manufacturing and automobile manufacturing, with the lowest contribution from the basic chemicals.

To determine the optimal film management technique for garlic planting, this study aimed to investigate the effects of various film cover methods on soil quality and garlic yield in garlic cropping systems. To achieve these goals, trials with different film cover methods were conducted at the Jiangsu Academy of Agricultural Sciences in Nanjing. To investigate the impact of changes in soil quality and garlic yield, we set up four treatments： no film treatment （CK）, black polyethylene film treatment （HPE）, black poly（butylene- adipate-co-terephthalate） （PBAT） with straw composite film treatment （HSJ）, and white PBAT film treatment （BJ） in a garlic cropping system. Our results indicated that specific mulch coverings had a positive effect on both soil quality and garlic yield. The film cover treatments resulted in significant changes in soil physicochemical properties and bacterial and fungal biomasses and indirectly improved soil quality. Compared to that under the no film treatment, the BJ treatment boosted soil quality by 70%, with the most significant impact, followed by that under the HPE and HSJ treatments, with improvements of 52% and 36%. Random forest modeling indicated that soil organic matter and total nitrogen were the most important factors influencing soil quality. The different film covers significantly increased the diameter of garlic bulbs and single quality. The HSJ treatment exhibited the most significant increase in garlic yield, with 46%, 19%, and 6% improvement compared to that in the CK, HPE, and BJ treatments, respectively. Correlation analysis showed that soil quality under film cover was significantly correlated with the starch content of garlic bulbs, garlic diameter, and single quality. This study highlights that selecting the appropriate mulch film aids in the production of garlic and helps to develop farmland that produces both high-quality and high-yield crops.

To understand the pollution status, distribution characteristics, and pollution sources of soil heavy metals in tourist cities in northwest China, the soil content of heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the main areas of Dunhuang City was collected and analyzed. The soil heavy metal pollution level was quantitatively evaluated by the methods of the geo-accumulation index and improved Nemerow pollution index, and the sources of heavy metal pollution were quantitatively analyzed using cluster analysis and the positive matrix factorization （PMF） model. The contribution rate of each pollution source to ecological risk was determined by combining the PMF model and comprehensive ecological risk index. The results showed that except for the mean contents of As and Ni, the mean contents of Cd, Cr, Cu, Hg, Pb, and Zn were all higher than the background values in Gansu Province. However, the average content of the eight elements was lower than the screening value of construction land in the Standard for Soil Pollution Risk Control of Soil Environmental Quality Construction Land （trial） （GB 36600-2018）. Among them, the enrichment of Cd, Pb, and Hg was more serious, and the exceedance rate was higher than 90%. The results of the geo-accumulation index indicated that urban soils were mainly polluted by Hg in the study area, and Cd, Cr, Cu, Pb, and Zn pollution also existed in different degrees. The improved Nemerow pollution index illustrated that the comprehensive pollution degree of the soil was clean to moderate pollution, and the overall pollution was light pollution. Based on the PMF model, we could conclude that soil heavy metals in the study area were affected by natural sources, industrial deposition sources, industrial sources, traffic sources, and comprehensive sources, and the contribution rates were 29.28%, 25.86%, 20.13%, 16.5%, and 8.23%, respectively. The specific source-integrated ecological risk assessment model found that the industrial deposition source contributed the most to the ecological risk in the study area and could be regarded as the priority control pollution source, and Hg was considered to be the priority control pollution element for ecological risk.

Accurately assessing the changes in soil organic carbon storage （SOCS） before and after the Grain for Green Project （GFG） in the Loess Plateau （LP） and exploring the relationship between its spatial and temporal distribution and the influencing factors were important references for the development of regional recycling as well as the formulation of ecological protection policies. Based on the data of climate, human activities, and SOCD in the surface （0-20 cm） and deep （0-100 cm） soil before and after GFG in the LP from 2001 to 2020, we investigated the changes in SOCD at different spatial and temporal scales by using the methods of trend analysis, the kriging method, and variance partitioning analysis. The results showed that： ① Before and after the GFG, the surface SOCS of the whole region increased by 8 338.7×10⁴ t； the deep SOCS increased by 1 160.02×10⁴ t. ② In each bioclimatic subregion, the whole-region average SOCD of Ⅰ （Semi-Humid Forest Region）, Ⅱ （Semi-Humid Semi-Arid Forest and Grassland Region）, and Ⅲ （Semi-Arid Typical Grassland Region） showed a significant increasing trend, with a decreasing trend in Ⅳ （arid semi-arid desert grassland area） and Ⅴ （arid desert area）. ③ The average surface SOCS increase in different ecosystems was ranked as follows： cropland > grassland > woodland > shrubs > bare land and sparse vegetation. The deep soil increase was ranked as follows： grassland > cropland > woodland > shrubs > bare land and sparse vegetation. ④ Climate factors were the most important driving factors for changes in SOCD； the annual average temperature and precipitation were significantly positively correlated with changes in SOCD. The results of the study could provide data support for regional ecological management and land use policy formulation to promote high quality development of the ecological environment in the LP.

The administrative units of 17 provinces （autonomous regions and municipalities directly under the Central Government） along the "Belt and Road" were selected as basic spatial units to calculate the provincial traffic carbon emissions along the "Belt and Road" from 2000 to 2021. On the basis of analyzing the spatial and temporal characteristics of traffic carbon emissions by using the spatial autocorrelation method, the spatial and temporal heterogeneity of influencing factors of traffic carbon emissions was explored by combining a fixed-effect regression model and geographic detector. The results show that： ① The provincial traffic carbon emissions along the "Belt and Road" had significant spatial positive correlation, and the overall trend was upward. Additionally, the cluster evolution of high and low values of traffic carbon emissions presented the characteristics of polarization in space. The high value cluster area was mainly distributed in the open leading area, and the low value cluster area was mainly distributed in the core area of the silk road. ② Opening-up level and vehicle ownership were the positive driving factors of carbon emissions from transportation, whereas energy intensity, transportation structure, industry development scale, and government intervention were the negative driving factors. ③ Energy intensity and transportation structure were the main driving factors for the spatial variation of transportation carbon emissions, and most of them would produce nonlinear enhancement when they were spatially superimposed with other factors, that is, there was strong synergy among driving factors. The results showed that the provincial traffic carbon emissions along the "Belt and Road" were affected by the surrounding areas, the influence degree was increasing, and there was synergy between the key driving factors of traffic carbon emissions. Therefore, it is suggested that the provinces along the "Belt and Road" should fully consider the spatial and temporal heterogeneity of traffic carbon emission influencing factors and formulate differentiated traffic carbon emission reduction policies.

The prevalence of selenium-cadmium （Se-Cd） symbiosis in soils of geologically high background areas directly affects the safe utilization of Se-rich land resources. To investigate the migration and accumulation characteristics and bio-effectiveness of Se-Cd in the soil-crop system in typical geological high background areas of Southwest China and to realize the safe use of natural Se-rich land resources in geological high background areas, we collected 84 samples of agricultural crops （maize） and their supporting root systems and analyzed the Se-Cd content and physicochemical properties. Se-Cd accumulation characteristics, influencing factors, and bio-effectiveness of the soil-crop system were evaluated using geostatistics, bioenrichment factors, and geographic detectors. The results showed that the Se-Cd content in the study area was significantly higher than the background value of the soil in the whole country and in Yunnan Province. Influenced by the geological background, secondary enrichment in the process of soil formation, and agricultural activities, the accumulation and enrichment characteristics of Se in the root soil varied from no enrichment to slightly enriched, and the occurrence form was dominated by the residue state. The accumulation index of soil Cd was mainly in the medium pollution level, and the occurrence form was mainly in the residual state and the combined state of iron and manganese. The Se-enrichment rate of crop seeds reached 98.8% （DB 50/T 524-2013 standard）, and the average value of bioconcentration factor was 5.8%. The exceeding rate of Cd content in crop seeds was only 1.19% （GB 2762-2022 standard）, and the average value of Cd bioconcentration factor was 2.11%, so the ecological risk of heavy metal Cd in crop seeds was relatively low. In the Se-Cd symbiosis area under geological background, the weak alkaline environment of the soil could effectively reduce the bioavailability of Cd in crop seeds, and the Se-rich soil could inhibit the uptake of Cd by the crops to a certain extent. Correlation analysis showed that the migration and accumulation of Se and Cd from soil to crop seeds in the soil-crop system were affected by the elemental accumulation pattern and the physical and chemical properties （pH） of the soil, and at the same time, there was a certain synergistic-antagonistic effect between Se and Cd in the soil-crop system. Correlation analysis showed that the migration and accumulation of Se and Cd from soil to crop seeds in the soil-crop system was influenced by the occurrence of elements, soil physicochemical properties （pH）, and other factors, and there was also a certain synergistic-antagonistic interaction between Se and Cd in the soil-crop system.