National Scale In China Research Articles

Distribution and health risk of chromium in wheat grains at the national scale in China

Chromium (Cr) pollution may threaten food safety in China. In this study, the concentration, pollution level, distribution, and non-cancer risk of Cr in wheat grains grown in 186 areas across 28 provinces in China were investigated. Results indicated that mean concentration of Cr was 0.28 ± 2.5 mg/kg, dry mass (dm). Of the samples, 7.5 % were found to be polluted with Cr. The mean concentrations were in the following order: Northwest > Northeast > South > East > North > Southwest > Central China. Based on deterministic models, mean hazard quotient (HQ) values for adult males, adult females, and children were 0.11 ± 3.4, 0.11 ± 3.4, and 0.13 ± 3.5, respectively with < 6 % of HQ values ≥ 1. Eleven sites in northern China were identified as hotspots, whereas Gansu Province and Northwestern China were labeled as priority provinces and regions for risk control. The mean HQ values estimated by probabilistic risk assessment were two times greater than those estimated using deterministic models. The risk probabilities for adult males, adult females, and children were 4.81 %, 3.78 %, and 6.55 %, respectively. This study provides valuable information on Cr pollution in wheat grains and its risks at a national scale in China.

Toxicity threshold and ecological risk of nitrate in rivers based on endocrine-disrupting effects: A case study in the Luan River basin, China

Nitrate, as a crucial nutrient, is consistently targeted for controlling water eutrophication globally. However, there is considerable evidence suggesting that nitrate has endocrine-disrupting potential on aquatic organisms. In this study, the sensitivity of various adverse effects to nitrate nitrogen (nitrate-N) was compared, and a toxicity threshold based on endocrine-disrupting effects was derived. The spatiotemporal variations of nitrate-N concentrations in the Luan River basin were investigated, and the associated aquatic ecological risks were evaluated using a comprehensive approach. The results showed that reproduction and development were the most sensitive endpoints to nitrate, and their distribution exhibited significant differences compared to behavior. The derived threshold based on endocrine-disrupting effects was 0.65 mgL−1, providing adequate protection for the aquatic ecosystem. In the Luan River basin, the mean nitrate-N concentrations during winter (4.4 mgL−1) were significantly higher than those observed in spring (0.7 mgL−1) and summer (1.2 mgL−1). Tributary inputs had an important influence on the spatial characteristics of nitrate-N in the mainstream, primarily due to agricultural and population-related contamination. The risk quotients (RQ) during winter, summer, and spring were evaluated as 6.7, 1.8, and 1.1, respectively, and the frequency of exposure concentrations exceeding the threshold was 100 %, 64.3 %, and 42.5 %, respectively. At the ecosystem level, nitrate posed intermediate risks to aquatic organisms during winter and summer in the Luan River basin and at the national scale in China. We suggest that nitrate pollution control should not solely focus on water eutrophication but also consider the endocrine disruptive effect on aquatic animals.

Greenness change associated with construction and operation of photovoltaic solar energy in China

Photovoltaic (PV) solar energy is considered as a promising solution to mitigate the environmental costs associated with the use of fossil fuels. However, the environmental impacts of constructing and operating PV solar energy remain unclear. This study assesses the environmental consequences of PV construction and operation by examining changes in vegetation greenness on a national scale in China, where PV solar energy has rapidly expanded. Utilizing 30-m vegetation indices and PV maps, we discover that the construction of PV facilities could significantly reduce greenness, with the magnitude of the impacts varying according to local greenness levels. Forests were found to suffer the greatest adverse impacts, while barrens were less affected. Small and medium-sized PV facilities, often established in regions with high levels of greenness, exhibited a stronger negative influence on greenness compared to larger ones. However, during the operational phase, an increase in vegetation greenness is generally observed in PV facilities, particularly in barrens. The magnitude of green recovery may vary considerably across different facilities, with approximately 21 % of PV facilities showing an improvement in greenness compared to their pre-construction levels. This study provides a reference for guiding the synergistic development of renewable energy and environmental protection.

Opportunities for China’s Agricultural Heritage Systems under the “Digital Nomadism” Trend—A Stakeholder-Weighted Approach

Agricultural heritage systems are appreciated worldwide for their significant environmental and cultural values. However, the sustainability of these systems has been compromised by environmental issues due to intensive human activities and socio-economic changes. Research has noticed that “digital nomadism” is providing a new opportunity for the sustainable development and transformation of these systems, regarded as “digital nomad-friendly” destinations. Nevertheless, comprehensive research on this new trend has been limited except for a few individual case studies. This study is the first to investigate the sustainable development of agricultural heritages considering the growing phenomenon of digital nomadism on a large scale. Based on in-depth stakeholder interviews, we introduced the Digital Nomad-Friendly (DNF) score—a comprehensive indicator system chosen and weighted by stakeholders. The DNF scores of 189 China National Important Agricultural Heritage System (China-NIAHS) sites were evaluated, and their distributions were analyzed on a national scale in China. The results highlight the importance of natural landscape and cultural value in the eyes of digital nomads, particularly emphasizing aesthetic landscape features, climatic suitability, and a community atmosphere. Sites with the highest DNF scores are located mostly in the Zhejiang and Yunnan provinces, sharing characteristics that appeal to digital nomads. The DNF scores exhibit regional variations, with high-DNF-score sites being concentrated in southwestern and southeastern China. By enhancing our understanding of digital nomads’ preferences and the influencing factors, this study provides valuable insights for the environmental management, policymaking, and sustainable development of China-NIAHS sites considering contemporary environmental and social changes.

Multi-objective ecological restoration priority in China: Cost-benefit optimization in different ecological performance regimes based on planetary boundaries

In the context of the “United Nations Decade on Ecosystem Restoration”, optimizing spatiotemporal arrangements for ecological restoration is an important approach to enhancing overall socioecological benefits for sustainable development. However, against the background of ecological degradation caused by the human use of most natural resources at levels that have approached or exceeded the safe and sustainable boundaries of ecosystems, it is key to explain how to optimize ecological restoration by classified management and optimal total benefits. In response to these issues, we combined spatial heterogeneity and temporal dynamics at the national scale in China to construct five ecological performance regimes defined by indicators that use planetary boundaries and ecological pressures which served as the basis for prioritizing ecological restoration areas and implementing zoning control. By integrating habitat conservation, biodiversity, water supply, and restoration cost constraints, seven ecological restoration scenarios were simulated to optimize the spatial layout of ecological restoration projects (ERPs). The results indicated that the provinces with unsustainable freshwater use, climate change, and land use accounted for more than 25%, 66.7%, and 25%, respectively, of the total area. Only 30% of the provinces experienced a decrease in environmental pressure. Based on the ecological performance regimes, ERP sites spanning the past 20 years were identified, and more than 50% of the priority areas were clustered in regime areas with increased ecological stress. As the restoration area targets doubled (40%) from the baseline (20%), a multi-objective scenario presents a trade-off between expanded ERPs in areas with highly beneficial effects and minimal restoration costs. In conclusion, a reasonable classification and management regime is the basis for targeted restoration. Coordinating multiple objectives and costs in ecological restoration is the key to maximizing socio-ecological benefits. Our study offered new perspectives on systematic and sustainable planning for ecological restoration.

Spatially non-stationary relationships between landscape fragmentation and soil conservation services in China, 2000–2018

Soil conservation (SC), which supports ecosystems by retaining vegetation, controlling erosion, retaining sediment, cycling nutrients, retaining water, maintaining diversity, and forming soil, is threatened by human-induced soil erosion and landscape fragmentation (LF). Therefore, revealing the spatial relationship between LF and SC can provide a scientific basis for ecosystem conservation policy-making and landscape planning. However, previous studies failed to reveal the spatially non-stationary response of SC to LF, especially at the national scale in China. To compensate for the research gaps, this study first measured the SC at the county scale with the benefit transfer method, then the LF was characterized with landscape pattern indices, and finally the spatial relationships between the SC and LF from global and local perspectives through regression models were analyzed. Results showed that national values of SC services per unit area in 2000, 2010, and 2018 were $134.73/ha, $132.30/ha, and $130.71/ha, respectively, showing a continuous decreasing trend. The high-value areas were distributed in the south of the Qinling-Huaihe River, Greater Khingan Mountains, and Changbai Mountain areas. In contrast, the low-value areas were mainly distributed in northwest China. LF was low in the northwestern region, while Shanxi, Shaanxi, Hebei, and southern Gansu presented highly fragmented landscapes. The spatial regression results showed that the higher the regional LF, the lower the value of SC. Meanwhile, there was significant spatial heterogeneity in the response of SC to LF, which was closely related to population distribution and resource endowment. In the future, landscape planning, land use structure and layout can take the impact mechanism of LF on SC as the essential basis.

Precision co-composting of multi-source organic solid wastes provide a sustainable waste management strategy with high eco-efficiency: a life cycle assessment.

With the increase of organic solid wastes (OSWs), current waste management practices, such as landfill, incineration, and windrow composting, have shown weaknesses in both resource recycling and environmental protection. Co-composting has been used to achieve nutrient and carbon recycling but is accused of high ammonia emission and low degradation efficiency. Therefore, this study developed a precision co-composting strategy (S3, which adds functional bacteria generated from food processing waste to a co-composting system) and compared it with the current OSW treatment strategy (S1) and traditional co-composting strategy (S2) from a life cycle assessment (LCA) perspective. The results showed that compared with S1, the eco-efficiency increased by 31.3% due to the higher economic profit of S2 but did not directly reduce the environmental cost. The addition of bacterial agents reduced ammonia emissions and shortened composting time, so compared with S1 and S2, the environmental cost of S3 was reduced by 37.9 and 43.6%, while the economic profit increased by 79.8 and 24.4%, respectively. The changes in environmental costs and economic benefits resulted in a huge improvement of S3's eco-efficiency, which was 189.6 and 121.7% higher than S1 and S2. Meanwhile, the adoption of S3 at a national scale in China could reduce the emission of 1,4-dichlorobenzene by 99.9% compared with S1 and increase profits by 6.58 billion USD per year. This study proposes a novel approach that exhibits high eco-efficiency in the treatment of OSWs.

A 2020 forest age map for China with 30 m resolution

Abstract. A high-resolution, spatially explicit forest age map is essential for quantifying forest carbon stocks and carbon sequestration potential. Prior attempts to estimate forest age on a national scale in China have been limited by sparse resolution and incomplete coverage of forest ecosystems, attributed to complex species composition, extensive forest areas, insufficient field measurements, and inadequate methods. To address these challenges, we developed a framework that combines machine learning algorithms (MLAs) and remote sensing time series analysis for estimating the age of China's forests. Initially, we identify and develop the optimal MLAs for forest age estimation across various vegetation divisions based on forest height, climate, terrain, soil, and forest-age field measurements, utilizing these MLAs to ascertain forest age information. Subsequently, we apply the LandTrendr time series analysis to detect forest disturbances from 1985 to 2020, with the time since the last disturbance serving as a proxy for forest age. Ultimately, the forest age data derived from LandTrendr are integrated with the result of MLAs to produce the 2020 forest age map of China. Validation against independent field plots yielded an R2 ranging from 0.51 to 0.63. On a national scale, the average forest age is 56.1 years (standard deviation of 32.7 years). The Qinghai–Tibet Plateau alpine vegetation zone possesses the oldest forest with an average of 138.0 years, whereas the forest in the warm temperate deciduous-broadleaf forest vegetation zone averages only 28.5 years. This 30 m-resolution forest age map offers crucial insights for comprehensively understanding the ecological benefits of China's forests and to sustainably manage China's forest resources. The map is available at https://doi.org/10.5281/zenodo.8354262 (Cheng et al., 2023a).

Urbanization-Driven Anthropogenic and Environmental Factors Shape Soil Dissolved Organic Matter in Mangrove Ecosystems

Mangrove ecosystems play a critical role in supporting ecological service values and regulating the global carbon cycle. They have become one of the most highly vulnerable ecosystems in the Anthropocene under the long-term influence of diverse human perturbations. Soil dissolved organic matter (DOM) is an active fraction within the carbon cycle in mangrove ecosystems. However, it remains unclear how human perturbations regulate DOM dynamics. Here, we used the fluorescence method and structural equation modeling to quantify the anthropogenic and environmental influence on soil DOM across the urban development gradient on a national scale in China. Anthropogenic activities (urban construction and sewage discharge) and environmental factors (salinity, metals, pH, and soil organic carbon) were striking forces that shaped DOM quality in mangrove soils. Both indirect and direct effects played critical roles in the soil DOM heterogeneity across the gradient of urbanization. Environmental factors can act as cofactors mediating human impact on DOM pools and as promoters transforming soil DOM in mangroves. Our study provided novel insights into the relationship between coastal developments and mangrove soil DOM heterogeneity and improved knowledge of coastal ecosystems as blue carbon sinks.

Regulation of Precipitation on Soil Dissolved Organic Matter in Perturbed Mangrove Ecosystems

Carbon sinks in mangrove soils play a critical role in climate change mitigation globally. Soil dissolved organic matter (DOM) is a major form of labile organic matter and influences carbon cycling in wetland ecosystems. However, the factors regulating DOM pools in mangrove soils on a regional scale are not well understood. Here, we used a novel approach to assess soil DOM dynamics and its environmental drivers in mangrove wetlands on a national scale in China. Soil samples were collected from 43 sampling sites and distributed in mangroves across the coastline of China. DOM extracted from mangrove soils was characterized by fluorescence spectroscopy. We estimated that dissolved organic carbon (DOC) content ranged from 0.20 ± 0.02 g/kg to 3.85 ± 0.09 g/kg and nationally averaged 0.73 ± 0.07 g/kg in mangrove soils. Soil DOM was composed of humic-like substances, including humic acid-like (53.46 ± 8.74%) and fulvic acid-like (46.54 ± 8.74%). DOM pools in mangrove soils were identified to be perturbed by terrestrial inputs. Besides, the coupling interactions of environmental controls on the soil DOM pool were validated by establishing the structural equation modeling (SEM). We found that precipitation is the most important driver, which controlled directly the inputs and outputs of DOM pools. It also indirectly influenced DOM pools by regulating soil parameters through the cascade reactions. Cu, salinity, and clay are key mediators among soil parameters for precipitation affecting DOM pools. Precipitation influences soil DOC negatively and CDOM and FDOM positively markedly. The results provide novel insights into the labile carbon pool in mangrove soils and are beneficial for improving the assessment frameworks in the blue carbon ecosystems.

Dynamic changes in net primary productivity of marsh wetland vegetation in China from 2005 to 2015

Wetlands are one of the world's three major ecosystems. Marsh wetland vegetation, with its unique characteristics, is playing an increasingly prominent role in absorbing atmospheric carbon dioxide and mitigating climate warming. This study estimated the annual, seasonal, and monthly trends of marsh wetland vegetation net primary productivity (NPP) in China from 2005 to 2015 based on the Carnegie–Ames–Stanford approach (CASA) model. The temporal and spatial characteristics of NPP were analyzed and the driving factors were discussed. The results showed that the annual marsh wetland vegetation NPP had an increasing trend from 2005 to 2015 on national scale in China, with the lowest and highest values in 2005 (202.03 gCm−2a−1) and 2015 (222.58 gCm−2a−1), respectively. The monthly seasonal variations in marsh wetland vegetation NPP consistent with the typical growth pattern of vegetation observed in China. Monthly marsh wetland vegetation NPP showed a unimodal distribution, and May to September were the main months for NPP accumulation. The highest vegetation NPP values occurred during the summer season. Marsh wetland vegetation types did impact the NPP distribution, Gramineous marsh vegetation contributed most to the total NPP (29%). Spatially, the NPP was higher in east than in the west, and higher in the center than in the south and north. An overall positive impact of precipitation and temperature on the Chinese marsh wetland vegetation NPP was revealed. The study recommended to give greater attention the conservation of Gramineous vegetation alongside the overall protection of Chinese marsh wetlands. Our findings can offer important evaluation results and guidance for the future addressing climate change and conservation and maintenance of the carbon sink capacity of marsh wetland vegetation in China.

The impacts of ship emissions on ozone in eastern China

Tropospheric ozone (O3), which is one of the main pollutants impeding air quality compliance, has received considerable attention in China. As maritime transportation continues to expand, the effect of ship emissions on air quality is becoming increasingly important. In this study, the Weather Research and Forecast model (WRF), the Community Multiscale Air Quality model (CMAQ), and the integrated process rate (IPR) module provided in the CMAQ are applied to evaluate the impacts of ship emissions on O3 concentration at a national scale in China, including the spatiotemporal characteristics and influencing pathways. Ship emissions can increase or decrease O3 concentrations, with varying effects in different seasons and regions. In the winter, spring, and fall, ship emissions were predicted to decrease O3 concentrations in most areas, whereas in the summer, they increase the O3 concentration, even in regions far away from the coastline, thus adversely affecting the Yangtze River Delta (YRD) and Pearl River Delta (YRD). Additionally, owing to differences in the emissions of volatile organic compounds and nitrogen oxides, the northern and southern regions of the YRD respond differently to ship emissions. Additionally, the influence of ship emissions on the diurnal variation of O3 in the summer was investigated, where significant differences were indicated between cities. The IPR was used to investigate the individual processes contributing to changes in the O3 concentration caused by ship emissions. The transport process appears to be the primary contributor to O3 production, whereas chemistry and dry deposition played key roles in O3 loss. This study provides an in-depth insight into the impacts of ship emissions on O3 in China, which can facilitate the formulation of corresponding environmental policies.

Novel macromolecular synthetic phenolic antioxidants in sludge on a national scale in China: Their distribution, potential transformation products, and ecological risk

To fulfill the growing demand for retarding the oxidation of polymers and minimizing their migration from various products, new macromolecular synthetic phenolic antioxidants (SPAs) have emerged in the market. There is a concern that these SPAs may be released into wastewater streams during their manufacturing and use, eventually ending up in wastewater treatment plants (WWTPs). Nevertheless, information regarding the occurrence of these SPAs in sludge, particularly on a national scale, is scarce. In this study, several macromolecular SPAs and their transformation products (TPs) were investigated in sludge samples from 45 Chinese municipal WWTPs. All 14 analytes were detected in the sludge samples, among which, 12 analytes were first reported in sludge. 2,4,6-tri-tert-butylphenol (AO246) and 2 macromolecular SPAs, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (AO1010) and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (AO1076), were the most dominant SPAs, with geometric mean (GM) concentrations of 547, 212, and 35.2 ng/g dw, respectively. Two TPs, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid (fenozan) and 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH), were found in some sludge samples (48.9–71.1 %) with GM of 45.5 and 12.8 ng/g dw, respectively. By using LC-Q-TOF-MS/MS analysis, we tentatively identified previously unknown TPs of 10 macromolecular SPAs in sludge. This suggests that there are still unclear mechanisms modulating the transformation of these SPAs, which underscores the complexity of their fate. Additionally, using the freshwater photobacteria Vibrio qinghaiensis sp.-Q67 (Q67) as model organism, the acute and chronic EC50 of the 14 analytes were assessed for ecological risk assessment. By considering toxicity data obtained from algae, daphnia, and fish collected or predicted from various databases, we found that these analytes, including their mixture at low detected concentrations, pose risks to aquatic systems that should not be disregarded. Overall, the current study provides a comprehensive overview of novel SPAs and their TPs in sludge, offering valuable insights for investigating their environmental behavior, fate, and risks.

Decades performance of marine science and education by region and discipline in China

Strengthening scientific research, technological capacity and sustainable use of oceans in developing countries are the goals of the UN’s 2030 Agenda for Sustainable Development. Marine science and education as the key foundation for achieving these goals has been seldom evaluated quantitatively and collectively. This paper adopted the DEA modelling from economics for analyzing the long-term input and output performance of marine science and education at a national scale in China both by region and discipline. It is found that China’s marine science and education level has been improving annually in the last decade. The input/output efficiency of science and education in 11 coastal provinces however has slightly declined except Guangdong. The input/output performance among 14 research disciplines was further evaluated and was found the similar improving trends. The input/output efficiency of 70% research disciplines showed an increasing trend while 30% of which showed a slightly declining trend. The results could provide important references for prioritizing the science and education resources allocation both in different coastal regions and marine research disciplines to save the investment and achieve more progress.

Neonicotinoid Insecticides Threaten Surface Waters at the National Scale in China

This study was conducted in response to the current situation in our country in which neonicotinoid pesticides (NNIs) are used in large quantities and their concentration in surface water is gradually increasing. Based on the species sensitivity distribution (SSD), the hazard quotient (HQ) and probabilistic risk assessment (PRA) were used to compare single and mixture risks of NNIs in the surface water in China. The target and recommended values of NNIs in China's surface water quality supervision were also presented. The results showed that:① in the single acute hazard assessment, imidacloprid (IMI) was the most harmful insecticide, and in the single chronic hazard assessment, imidacloprid (IMI) and acetamiprid (ACE) were more harmful. Furthermore, insects were the most sensitive creatures. ② Hainan province was the region with the highest single acute and chronic hazard in the study area. ③ Based on the joint probability curves of five neonicotinoids, the probability in which 5% of species would be affected by long-term exposure was approximately 91.12%. Thus, the combined ecological risk of these five neonicotinoids cannot be ignored. ④ Based on the toxicity reference value from SSD and the combined results of HQ and PRA, the regulatory values of surface water quality in China were as follows:acetamiprid (ACE) 0.04 μg·L-1, clothianidin (CLO) 0.22 μg·L-1, imidacloprid (IMI) 0.01 μg·L-1, thiacloprid (THI) 0.03 μg·L-1, and thiamethoxam (THIA) 0.24 μg·L-1. In short, the concentration of NNIs in the surface water in China has threatened the safety of aquatic organisms, and its supervision must be improved.

A hybrid spatiotemporal convolution-based cellular automata model (ST-CA) for land-use/cover change simulation

Accurate land-use/-cover change (LUCC) simulation is of great significance to issues closely related to regional planning and policy-making. Many models have been committed to conducting LUCC simulations for better decision-making. However, LUCC is a nonlinear spatiotemporal process with complex links and feedback as well as latent dependencies in both spatial and temporal neighborhoods. They are challenging to be integrally utilized using existing models that employ conventional statistical or machine learning methods, inevitably leading to inaccurate LUCC simulations. Aiming to handle this problem, this paper innovatively proposed a hybrid spatiotemporal convolution-based cellular automata model (ST-CA) by coupling nonlinear spatiotemporal dependency learning and CA-based spatial allocation. A three-dimensional convolutional neural network (3D-CNN) was introduced in the model to assimilate both the nonlinear driving mechanism and spatiotemporal dependencies. It contributes to generating more elaborate development potentials to increase simulation accuracy. To evaluate the model performance, an LUCC simulation was applied on a national scale in China by ST-CA. Four traditional CA models, namely, logistic regression (LR)-CA, random forest (RF)-CA, full-connected neural network (FCN)-CA, and convolutional neural network (CNN)-CA, were also developed for accuracy comparisons. The results demonstrate that the simulation by ST-CA reached an FoM of 18.42%, which outperformed the other models with accuracy increases of 11.65%, 13.11%, 7.01%, and 2.29%, respectively. The proposed model incorporating 3D-CNN effectively captured the nonlinear spatiotemporal properties in the LUCC process, which is promising for more accurate LUCC simulations.

Emergence of Neonatal Sepsis Caused by MCR-9- and NDM-1-Co-Producing Enterobacter hormaechei in China.

Mobile colistin resistance (mcr) genes represent an emerging threat to public health. Reports on the prevalence, antimicrobial profiles, and clonality of MCR-9-producing Enterobacter cloacae complex (ECC) isolates on a national scale in China are limited. We screened 3,373 samples from humans, animals, and the environment and identified eleven MCR-9-positive ECC isolates. We further investigated their susceptibility, epidemiology, plasmid profiles, genetic features, and virulence potential. Ten strains were isolated from severe bloodstream infection cases, especially three of them were recovered from neonatal sepsis. Enterobacter hormaechei was the most predominant species among the MCR-9-producing ECC population. Moreover, the co-existence of MCR-9, CTX-M, and SHV-12 encoding genes in MCR-9-positive isolates was globally observed. Notably, mcr-9 was mainly carried by IncHI2 plasmids, and we found a novel ~187 kb IncFII plasmid harboring mcr-9, with low similarity with known plasmids. In summary, our study presented genomic insights into genetic characteristics of MCR-9-producing ECC isolates retrieved from human, animal, and environment samples with one health perspective. This study is the first to reveal NDM-1- and MCR-9-co-producing ECC from neonatal sepsis in China. Our data highlights the risk for the hidden spread of the mcr-9 colistin resistance gene.

Rapid urbanization and climate change significantly contribute to worsening urban human thermal comfort: A national 183-city, 26-year study in China

Urban residents are gradually being exposed to increasing urban high temperatures and extreme heatwave events under rapid urbanization and global warming. Although there is an increase in air and surface temperatures observed, spatiotemporal changes in urban human thermal comfort and their drivers are rarely considered when assessing the urban thermal environment, especially at a national scale in China. Based on weather stations, we combined daily meteorological data, including air temperature, solar radiation, wind speed, and humidity, to comprehensively assess the annual dynamics of urban thermal comfort and their relationship with rapid urbanization and climate change in 183 Chinese cities from 1990 to 2016. Our results show that urban air temperature and solar radiation have increased, and urban humidity and wind speed have decreased at the national scale. Following these changes, urban residents' thermal comfort is deteriorating, with physiological equivalent temperature and uncomfortable days increasing in 68% and 59% of cities, respectively, during summer in China, predominantly located in temperate monsoon and continental climatic zones. The worsening of urban thermal comfort was largely explained by climate change, and rapid urbanization contributed 10.9% in our study. Climate change (e.g., global warming, precipitation, and wind speed decrease) and rapid urbanization had positive effects (P < 0.05) on the deteriorative urban thermal environment. Our findings could enrich the knowledge on spatiotemporal changes in the urban thermal environment under climate change and rapid urbanization.

Perchlorate occurrence, sub-basin contribution and risk hotspots for drinking water sources in China based on industrial agglomeration method

Perchlorate is a persistent inorganic contaminant which has attracted wide attention because of its harmful effects on physical health. Despite the potential adverse effects to humans via drinking water, related research at the national scale in China are scarce. In this study, the occurrence of perchlorate in major river basins in China was investigated from 2009 to 2020. Generally, except for the Yangtze River Basin, perchlorate concentrations in the surface water of other river basins were low, ranging from < 0.01 to 8.53 μg/L. The results of a specialized field sampling and tracking program in the Yangtze River Basin in 2019 showed that the Xiangjiang River basin is the greatest contributor of perchlorate in the Yangtze River Basin, accounting for 58.63% of the total perchlorate input. Furthermore, based on correlation analysis between production enterprise information and measured concentrations in sampled sites, fireworks and explosives production industries were identified as the major sources of perchlorate contamination in surface water. The risk map showed that the central-southern part of China and the central part of Xinjiang province were risk hotspots for perchlorate contamination. The results gave insights into how to conduct more precise risk assessment and policy intervention towards prevention of perchlorate contamination.

Modeling climatically suitable areas for soybean and their shifts across China

CONTEXTCrop suitability determines its distribution and yield in a given region and can be greatly affected by climate change. In recent decades, the distribution of soybean cultivation has undergone significant spatial shifts in China. However, whether this change matches with climatic suitability for soybean at a national scale has not been reported. OBJECTIVEOur objectives were to investigate the spatial distribution and shifts in climatically suitable areas for soybean from 1961 to 2017 and to determine whether actual production matches with climatic suitability in China. METHODSThe MaxEnt model was used to simulate the presence probability of soybean from 1961 to 2017 based on soybean occurrence data and climate data across China. Regions were classified as climatically unsuitable or as having low, moderate, or high climatic suitability. Then, the overlay analysis was performed to assess spatial changes of soybean suitability and the consistency between climatic suitability and actual production. RESULTS AND CONCLUSIONSAccumulated temperature ≥ 10 °C, humidity index during the potential growing season, and annual temperature range were the major climatic factors that affected soybean distribution. Areas of high climatic suitability were mainly located in the Northeast and North-central Regions, and the total acreage of high suitability was 129.88 × 106 ha. Unsuitable areas for soybean contracted over the study period, whereas highly suitable areas migrated westward and southward. The climatic suitability for soybean across China has increased overall in the past decades. The area of improved climatic suitability from 1961 to 2017 comprised 14.60% of the entire land area of China and was concentrated primarily in the Northwest and North-central Regions. Nonetheless, consistency between climatic suitability and actual production decreased from 83.47% in 1985 to 65.16% in 2015. This may pose a risk to soybean production, especially in emerging major planting areas of the Southwest Region. SIGNIFICANCEThis study described the distribution of climatically suitable areas for soybean, used spatial analysis to illustrate the extent to which climatically suitable areas overlap with actual production areas, and discussed possible solutions for improving soybean production at a national scale in China. This work has practical significance for optimizing the regional layout of soybean production and implementing countermeasures to address future climate change.