Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations. The reasonability of the selected optimal scheme was confirmed by assessing the consistency between its generating AGPP and previous products in spatiotemporal variations and total amount. Random forest regression tree explained 85 % of observed AGPP variations, outperforming other machine learning algorithms and classical statistical methods. Variable combinations containing climate, soil, and biological factors showed superior performance to other variable combinations. Mapping AGPP through predicting AGPP per leaf area (PAGPP) explained 86 % of AGPP variations, which was superior to other approaches. The optimal scheme was thus using a random forest regression tree, combining climate, soil, and biological variables, and predicting PAGPP. The optimal scheme generating AGPP of Chinese terrestrial ecosystems decreased from southeast to northwest, which was highly consistent with previous products. The interannual trend and interannual variation of our generating AGPP showed a decreasing trend from east to west and from southeast to northwest, respectively, which was consistent with data-oriented products. The mean total amount of generated AGPP was 7.03 ± 0.45 PgC yr-1 falling into the range of previous works. Considering the consistency between the generated AGPP and previous products, our optimal mapping way was suitable for mapping AGPP from site measurements. Our results provided a methodological support for mapping regional AGPP and other fluxes.

Organophosphate esters in surface soils from a heavily urbanized region of Eastern China: Occurrence, distribution, and ecological risk assessment.

Organophosphate esters (OPEs) pose increasing concerns for their widespread distribution in soil environments and potential threat to human health. In this study, we investigated the occurrence and associated risks of seven OPEs in surface soils and the potential influence of human activities on soil OPE contamination in a heavily urbanized region of the Yangtze River Delta in Eastern China. All target OPEs were detected in the soil samples (100% of samples) reflecting their widespread distribution in the study region. The total OPE concentration (the sum of the seven OPEs) ranged from 162.7 to 986.0 ng/g on a dry weight basis, with a mean value of 469.3 ± 178.6 ng/g. Tris (2-butoxyethyl) phosphate was the main compound, accounting for 67-78% of the total OPE concentration. Ecological risk assessment showed that tris(2-chloroisopropyl) phosphate, tris(2,3-dichloropropyl) phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate posed a medium potential risk to terrestrial biota (0.1 < risk quotient <1). The human exposure estimation showed insignificant risks to local population. Redundancy analysis revealed that the individual and total OPE contaminations were positively correlated with human activity parameters. The total OPE concentrations were positively correlated to population density (R2 = 0.38, P < 0.001), and urban land use percentage (R2 = 0.39, P < 0.001), while negatively correlated to forest land use percentage (R2 = 0.59, P < 0.001), suggesting a significant contribution of human disturbance to OPE pollution. These results can facilitate OPE contamination control and promote sustainable soil management in urbanized and industrialized regions.

Seasonal variation and ecological risk assessment of dissolved organic matter in a peri-urban critical zone observatory watershed.

Peri-urban ecosystems are among the most intensive areas in terms of competition between different ecosystem components. Dissolved organic matter (DOM) plays a significant role in aquatic carbon cycling. The chemical composition of DOM and associated potential ecological risks in peri-urban aquatic ecosystems are poorly understood. Herein, we used fluorescence excitation-emission matrix and parallel factor analysis (EEM-PARAFAC) to characterize DOM in a peri-urban critical zone observatory watershed in Eastern China. According to the theory of natural disaster risk formation, we calculated the ecological risk of DOM in the peri-urban watershed. Seasonal variation in DOM concentrations was observed, whereas fluorescent DOM concentrations were site-specific across four sub-watersheds. The analysis of DOM absorption properties revealed the presence of DOM components with high aromatic content and large molecular weight in the watershed. Four fluorescent components (two humic-like and two protein-like substances) were identified using the PARAFAC model. Spatial distribution analysis showed that DOM quality was mainly influenced by human activities, and the proportion of protein-like substance (C3) was strongly correlated with anthropogenic parameters. The distribution of optical indices indicated diverse sources of DOM in the watershed. Ecological risk related to DOM was greater in the dry season than the wet season. There was a slight risk in most areas, with an extreme risk in areas experiencing the most intensive human disturbance, which were also extremely or heavily vulnerable. The results emphasize the strong influence of human disturbance on the ecological risk of DOM in peri-urban aquatic ecosystems. Our study provides useful information for ecological risk assessment of DOM that is difficult to obtain using traditional chemical analysis.

Variation in quantity and chemical composition of soil dissolved organic matter in a peri-urban critical zone observatory watershed in Eastern China.

Soil organic matter plays a fundamental role in terrestrial ecosystems. However, little is known about the spectral characteristics and fluorescent components of soil dissolved organic matter (DOM) in peri-urban ecosystems and their influencing factors. In this study, we used the fluorescence excitation-emission matrix and parallel factor analysis (EEM-PARAFAC) to characterize soil DOM in a peri-urban Critical Zone Observatory watershed in Eastern China. Soil samples were collected at depths of 0-10 cm, 10-20 cm, and 20-40 cm from 82 sites (29 forest, 11 orchard, and 42 cropland). The results showed that soil organic carbon and water-soluble organic carbon content varied with land use type, and both were significantly higher in forest than cropland and orchard samples. Three fluorescent components, humic-, fulfic-, and protein-like substances, were derived from soil DOM using the PARAFAC model. All these components were distributed differently in the three land use types, as were their UV and fluorescence indices. The spatial distribution of soil DOM showed that the quantity and chemical composition of DOM were affected by environmental variables and human disturbance, among which pH and altitude significantly affected DOM content. Anthropogenic parameters such as distance to road and distance to town strongly influenced the chemical composition and characteristics of soil DOM. Negative correlations were observed between humic-like substances and distance to road or town, while positive correlations were observed between protein-like substances and these two parameters. These results demonstrate the pronounced influence of human activities on DOM composition and characteristics in the watershed area. The findings highlight the value of soil DOM characterization to better understand the origin, composition, and fate of DOM in soils in peri-urban critical zones.

Impact of High-Density Urban Built Environment on Chronic Obstructive Pulmonary Disease: A Case Study of Jing'an District, Shanghai.

Respiratory health is a focus of interdisciplinary studies involving urban planning and public health. Studies have noted that urban built environments have impacts on respiratory health by influencing air quality and human behavior such as physical activity. The aim of this paper was to explore the impact of urban built environments on respiratory health, taking chronic obstructive pulmonary disease (COPD) as one of the typical respiratory diseases for study. A cross-sectional study was conducted including all cases (N = 1511) of death from COPD in the high-density Jing'an district of Shanghai from 2001 to 2010. Proxy variables were selected to measure modifiable features of urban built environments within this typical high-density district in Shanghai. A geographically weighted regression (GWR) model was used to explore the effects of the built environment on the mortality of COPD and the geographical variation in the effects. This study found that land use mix, building width-height ratio, frontal area density, and arterial road density were significantly correlated to the mortality of COPD in high-density urban area. By identifying built environment elements adjustable by urban planning and public policy, this study proposes corresponding environmental intervention for respiratory health.

Application of triolein-embedded cellulose acetate membrane (TECAM) passive sampler to study phase distribution of hexabromocyclododecanes (HBCDs) in sediment.

Hexabromocyclododecanes (HBCDs) are a class of widely used brominated flame retardants (BFRs) that exhibit strong hydrophobicity. The ubiquity and persistence of HBCDs in sediment have attracted significant attention because of public health concerns. The environmental fate and ecological risks of HBCDs closely depend on their phase distribution in sediments. However, little information is available regarding the freely dissolved concentrations (Cfree) of HBCDs in sediment porewater. In this study, we developed a method to measure Cfree of HBCDs in sediment porewater using triolein-embedded cellulose acetate membranes (TECAM). The TECAM-to-water partitioning coefficient (log KTECAM) was 4.69, 4.77, and 4.63 for α-HBCD, ß-HBCD, and γ-HBCD, respectively. In sediments, HBCDs sorbed to the sediment solid phase accounted for more than 99% of the total chemical mass. The dissolved organic carbon (DOC)-water partition coefficient (KDOC) values were derived from TECAM measurements, and the log KDOC values ranged from 5.77 to 6.23 for the three HBCD diastereomers, suggesting a strong tendency for HBCDs to sorb to DOC. The high sorption of HBDCs for DOC implies a potential for DOC-facilitated transport which may enhance the environmental mobility of HBCDs.

Quantifying and managing food-sourced nutrient metabolism in Chinese cities.

Food supply and consumption are critical for sustaining urban system functions, and are key determinants of the quantity and pathways of nutrient flow in cities. Nutrient elements from urban food consumption are becoming major pollutant sources in urban environments. Therefore, understanding flow magnitude and pathways, the role of a growing population, and changing dietary structure and technology in future nutrient metabolism are essential to understand cities as ecosystems and urban environmental management. Taking the city of Xiamen, a rapid urbanizing area of Southeast China as a case study, we simulated urban metabolism of three major food-sourced nutrient elements (carbon, nitrogen, and phosphorus or CNP) over 1991-2010 and environmental emissions. Impacts of future population growth, dietary habit change, and waste treatment improvement on various environments were forecast by scenario analysis. A sensitivity analysis was conducted to test how different waste treatment technologies affect environmental emissions from food-sourced nutrients. Our results show that the food-sourced CNP had various metabolic fluxes through urban systems, with carbon mostly emitted into the air and nitrogen and phosphorus mostly discharged into landfills and water. Population growth and dietary structure change will accelerate increases of nutrient emissions to the environment, whereas enhancing current waste treatment technology can just alter emissions to different environments. Based on the results, we discuss how food-sourced nutrient metabolism can be better managed, to enhance connectivity between cities and their hinterlands and maintain environmental emissions within the carrying capacity of the cities.

Urbanization and health in China, thinking at the national, local and individual levels.

BACKGROUND: China has the biggest population in the world, and has been experiencing the largest migration in history, and its rapid urbanization has profound and lasting impacts on local and national public health. Under these conditions, a systems understanding on the correlation among urbanization, environmental change and public health and to devise solutions at national, local and individual levels are in urgent need. METHODS: In this paper, we provide a comprehensive review of recent studies which have examined the relationship between urbanization, urban environmental changes and human health in China. Based on the review, coupled with a systems understanding, we summarize the challenges and opportunities for promoting the health and wellbeing of the whole nation at national, local, and individual levels. RESULTS: Urbanization and urban expansion result in urban environmental changes, as well as residents' lifestyle change, which can lead independently and synergistically to human health problems. China has undergone an epidemiological transition, shifting from infectious to chronic diseases in a much shorter time frame than many other countries. Environmental risk factors, particularly air and water pollution, are a major contributing source of morbidity and mortality in China. Furthermore, aging population, food support system, and disparity of public service between the migrant worker and local residents are important contributions to China's urban health. CONCLUSIONS: At the national level, the central government could improve current environmental policies, food safety laws, and make adjustments to the health care system and to demographic policy. At the local level, local government could incorporate healthy life considerations in urban planning procedures, make improvements to the local food supply, and enforce environmental monitoring and management. At the individual level, urban residents can be exposed to education regarding health behaviour choices while being encouraged to take responsibility for their health and to participate in environmental monitoring and management.

Spectroscopic characterization of dissolved organic matter derived from different biochars and their polycylic aromatic hydrocarbons (PAHs) binding affinity.

In recent years, biochar has received a great attention due to its high application in different sectors of environment. The feasibility of biochar applications is depended on its physical and chemical properties and biochar-derived dissolved organic matter (DOM) characteristics. This study was conducted to investigate the spectroscopic characteristics of biochar-derived DOM and its binding capacity of hydrophobic organic chemicals (HOCs). DOM solutions were isolated from five different biochars prepared through pyrolysis and analyzed for dissolved organic carbon (DOC) contents. The optical analysis with UV-visible absorption and excitation-emission matrix (EEM) fluorescence spectroscopes and DOC water distribution coefficient (KDOC) were calculated in the presence of PAHs and DOM. The DOC contents and the estimated aromaticity (SUVA254) were different for selected biochars. The DOM derived from soybean straw biochar (SBBC) showed the highest DOC contents followed by rice straw biochar (RSBC). The SBBC and RSBC peak position in the fluorescence excitation/emission matrix at longer wavelength corresponded to the peak position of other three biochars indicating that SBBC and RSBC had relatively higher degree of humification. This was well correlated with the observed KDOC values, suggesting that the KDOC value(')s dominant factor was the degree of biochar-derived DOM humification. The results of this study indicate that the optical analysis may provide valuable information regarding the characteristics of biochar-derived DOM and its application as environmental amendments for minimization of toxic organic compounds.

Levels of flame retardants HBCD, TBBPA and TBC in surface soils from an industrialized region of East China.

Hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA) are of increasing concern because of their potential environmental persistence, bioaccumulation and toxicity. Tris-(2,3-dibromopropyl)isocyanurate (TBC) is another brominated flame retardant (BFR) which has recently been found in the environment and begun to attract attention. The objective of this study is to determine the concentration of these three BFRs in surface soil samples collected from a heavily industrialized and urbanized region in East China. Levels of ∑HBCDs ranged from below detection limits (0.020 ng g(-1)) to 102.6 ng g(-1) on a dry weight basis (dw) with a median level of 15.8 ng g(-1) dw. For TBBPA, the concentration ranged from below detection limits (0.025 ng g(-1)) to 78.6 ng g(-1) dw with a median level of 9.17 ng g(-1) dw. TBC was found at relatively lower concentrations ranging from below detection limits (0.024 ng g(-1)) to 16.4 ng g(-1) dw with a median level of 0.95 ng g(-1) dw. The concentrations of these three BFRs are significantly positively correlated, indicating a common source. Variable BFRs levels were found in different types of soils, with significantly higher concentrations observed at waste dumping sites and industrial areas. The diastereoisomer profiles of HBCDs in most of the soil samples differed from those of the commercial products. The mass inventories of HBCDs, TBBPA and TBC in this region gave preliminarily estimates of 6.68, 2.67 and 0.85 kg, respectively. Therefore, the ubiquitous contamination of soils by these BFRs may well reflect their widespread usage in the study area.

Urban transformation of a metropolis and its environmental impacts: a case study in Shanghai.

PURPOSE: The aim of this paper is to understand the sustainability of urban spatial transformation in the process of rapid urbanization, and calls for future research on the demographic and economic dimensions of climate change. Shanghai towards its transformation to a metropolis has experienced vast socioeconomic and ecological change and calls for future research on the impacts of demographic and economic dimensions on climate change. We look at the major questions (1) to explore economic and demographic growth, land use and land-cover changes in the context of rapid economic and city growth, and (2) to analyze how the demography and economic growth have been associated with the local air temperature and vegetation. METHOD: We examine urban growth, land use and land-cover changes in the context of rapid economic development and urbanization. We assess the impact of urban expansion on local air temperature and vegetation. The analysis is based on time series data of land use, normalized difference vegetation index (NDVI), and meteorological, demographic and economic data. RESULTS AND DISCUSSION: The results indicate that urban growth has been driven by mass immigration; as a consequence of economic growth and urban expansion, a large amount of farmland has been converted to paved road and residential buildings. Furthermore, the difference between air temperature in urban and exurban areas has increased rapidly. The decrease of high mean annual NDVI has mainly occurred around the dense urban areas.

Urbanisation and human health in China: spatial features and a systemic perspective.

BACKGROUND, AIMS AND SCOPE: Current studies have paid little attention to the dynamism in urban spatial expansion and its possible environmental and health effects or to the health effects of rapid urban environmental change at different points along the urbanisation gradient. This study adopts a public health ecology approach to systematically understand the relationship between urbanisation, urban environmental change and human health in China. METHOD: Remote sensing image analysis, based on night light data at five different time periods in recent decades, was used to determine changes to the overall urban area. Through a review of the evidence on the relationships between environmental health, urbanisation and health, we advance a pathway framework for explaining urban human health ecology. The Spearman rank correlation coefficient was used to measure the correlation between disease prevalence and urbanisation level, adding a further dimension to a systemic understanding of urban health. RESULTS AND CONCLUSIONS: Urban areas have been increasing spatially, but unevenly, in recent decades, with medium and small cities also expanding rapidly in the past decade. Urbanisation and urban expansion result in changes to land use/coverage change, the urban environment and the residents' lifestyle, which result in human health problems. Regions with the highest urbanisation level were more inclined to have a high prevalence of chronic disease in recent decades. An ecological public health approach provides insights into the multiple types of data which need to be routinely collected if human disease is not to become a barrier to social and economic development.

[Semen quality of the men from six districts in Chongqing].

OBJECTIVE: To investigate the quality and spatial distribution features of semen and to evaluate the reproductive health of the males in the Chongqing section of the Three-Gorge Reservoir area. METHODS: We collected semen samples by masturbation after 2 -7 days of abstinence from the men in Nan'an, Shapingba, Zhongxian, Wanzhou, Yunyang and Wushan of Chongqing, which are geographically and demographically representative of the Three-Gorge Reservoir area. We analyzed the semen quality of all the samples and evaluated the reproductive health of the men. RESULTS: The mean value of the five semen parameters of the male subjects from the six districts was within the normal range, including semen volume, sperm concentration, total sperm count, rapid progressive motile sperm, and total motile sperm. Those from Shapingba, Yunyang and Zhongxian exhibited abnormal sperm motility. According to the WHO criteria, normal value of all the semen parameters was found in less than 50% of the semen samples from the six districts, in 47% of those from Yunyang, and only 16% of those from Wanzhou. Spatial distribution maps of the semen parameters revealed significant spatial differences in seminal quality among the six districts, the highest in Yunyang, and the lowest in Wanzhou and Wushan that are located in the middle and lower reaches of the Three-Gorge Reservoir area. CONCLUSION: The mean value of semen parameters was low in a large proportion of men in the Chongqing section of the Three-Gorge Reservoir area, with spatial differences along the Changjiang river.

Identifying environmental risk factors for human neural tube defects before and after folic acid supplementation.

BACKGROUND: Birth defects are a major cause of infant mortality and disability in many parts of the world. Neural tube defects (NTDs) are one of the most common types of birth defects. In 2001, the Chinese population and family planning commission initiated a national intervention program for the prevention of birth defects. A key step in the program was the introduction of folic acid supplementation. Of interest in the present study was to determine whether folic acid supplementation has the same protective effect on NTDs under various geographical and socioeconomic conditions within the Chinese population and the nature in which the influence of environmental factors varied after folic acid supplementation. METHODS: In this study, Heshun was selected as the region of interest as a surrogate for helping to answer some of the questions raised in this study on the impact of the intervention program. Spatial filtering in combination with GIS software was used to detect annual potential clusters from 1998 to 2005 in Heshun, and Kruskal-wallis test and multivariate regression were applied to identify the environmental risk factors for NTDs among various regions. RESULTS: In 1998, a significant (p < 0.100) NTDs cluster was detected in the west of Heshun. After folic acid supplementation, the significant clusters gradually moved from west to east. However, during the study period, most of the clusters appeared in the middle region of Heshun where more than 95 percent of the coal mines of Heshun are located. For the analysis, buffer regions of the coal mine zone were built in a GIS environment. It was found that the correlations between environmental risk factors and NTDs vary among the buffer regions. CONCLUSION: This suggests that the government needs to adapt the intervention measures according to local conditions. More attention needs to be paid to the poor and to people living in areas near coal mines.

Analysis of geographical clustering of birth defects in Heshun county, Shanxi province.

Birth defects remain the leading cause of stillbirth and infant mortality in China, especially in rural areas. The objective of this research is to seek evidence of clustering of cases of birth defects within a highly endemic area and to identify the environmental and landscape characteristics associated with increased risk for birth defects in Heshun county. This study uses four years of data, 1998-2001, to identify clusters of birth defects in Heshun county. A spatial scan statistic was employed to examine the spatial and spatio-temporal clustering of birth defects in the study area. Statistically significant clusters with high relative risk (RR = 2.981, p = 0.008) were identified using a spatial scan statistic. The spatial cluster located in southeast Heshun county has a radius of 7.52 km and includes 27 villages and 27 cases, accounting for 21.25% of the total cases during the study period. The methodology applied in this study was useful for evaluating the spatial distribution of birth defects in Heshun county from 1998-2001. The identified areas may be critical to control birth defects and may provide important direction for further study and targeted interventions.

High prevalence of NTDs in Shanxi Province: a combined epidemiological approach.

BACKGROUND: Shanxi Province has historically reported a high prevalence of NTDs. In order to establish baseline rates for NTDs and discuss the risk factors associated with sociodemographic, maternal characteristics, and geographic factors, we performed the present study using an approach combining population and hospital-based methodologies. METHODS: We used chi(2) and Fisher's exact tests to evaluate variation in the prevalence by selected covariates and computed crude ORs and 95% CIs. Adjusted odds ratios (AORs) were performed using logistic regression with all the covariates included in the model. RESULTS: The overall NTD prevalence during the 3 year study period was 199.38 per 10,000 births, with a higher NTD prevalence clustered in 46 villages within this geographic area. However, no statistical significance was found between NTD prevalence and the elevation of the villages or their distance from coal plants. AORs revealed women aged 20 and above had a lower risk of NTDs compared to those younger than 20 (AOR range 0.4-0.5). A higher risk of NTDs was observed among female infants (AOR 1.50; 95% CI: 1.04-2.17), women with four or more previous births (AOR 2.80; 95% CI: 1.20-6.52), and a previous history of birth defects (AOR 3.23; 95% CI: 1.46-7.12). CONCLUSIONS: This study has documented a high prevalence of NTDs in Shanxi. Similar variations to other reports were found in the risk of NTDs by maternal demographic characteristics and a clustering of NTDs in certain villages that require further exploration.

[Regional correlation analysis of birth defects in Heshun county, Shanxi Province].

OBJECTIVE: To study the regional correlation analysis of birth defects in Heshun county, Shanxi province from 1997 to 2001. METHODS: Exploratory data analysis, especially the parallel coordinate plot (PCP) method, and geographic information system were used to analysis the regional correlation of birth defects. In this paper, we selected 1997 to 2001 five groups variables of birth defects to plot the PCP. RESULTS: Yangguangzhan and Hengling have stronger positive correlation on the region. Liyang and Niuchuan have weak correlation. Yixing and Songyan have no correlation and other towns have no positive correlation on the region. CONCLUSION: The results indicate that this studied region has the regional correlation of birth defects.