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Heavy metals are the most important indicator for farmland soil; however, in China, few provincial and national scales of studies have been done on heavy metals. Herein, by retrieving published studies, we calculated the spatial distribution characters and evaluated the health risks of Cu, Zn, Cd, Ni, Pb, Cr, As, and Hg in the farmland soil of 146 cities in China. Results showed that (1) the range (mean) values of eight (metalloid) heavy metals were as follows in mg/kg: Cu 0.236–251.015 (44.604), Zn 0.151–1547.060 (154.203), Cd 0.014–39.100 (1.497), Ni 0.709–554.420 (41.968), Pb 0.327–495.400 (55.143), Cr 0.078–333.510 (70.093), As 0.836–60.000 (12.207), and Hg 0.008–12.190 (0.371). The coefficient of variation values of Cu, Cr, and As displayed moderate variation, and Zn, Cd, Ni, Pb, and Hg displayed high variation (142.148–364.960%). (2) the Igeo values of As, Cu, Cd, Ni, Zn, Cr, Pb, and Hg were − 4.329 to 1.837, − 7.166 to 2.888, − 3.378 to 8.070, − 5.831 to 3.780, − 9.527 to 3.797, − 10.120 to 1.866, − 6.899 to 3.667, and − 3.681 to 6.966, respectively; in many cities, there was some degree of heavy metal pollution of the farmland soil such as Zn in Pingdu, Pb in Huludao, and Hg in Tongguan, Funshun, Huludao, and Qinglong (Igeo > 3); there were no obvious spatial patterns of Cr, Ni, and As, and Zn, Cu, but Cd, Ni, Pb, and Hg mainly located in some cities in the southwest, central or eastern parts of China. (3) Health risk assessment showed that with the exception of Cd, Cr, and As by the respiration route and Ni, Cr, and As through skin exposure, the average amount of daily exposure of the eight (metalloid) heavy metals all showed values for children > adults, and the HQ and HI values were all lower than 1.0, indicating noncarcinogenic risks; calculation of carcinogenic risks showed there were no carcinogenic risks for As, Cr, Ni, and Cd; however, the value for Cr was the maximum and contributed 98.505% of the total.

Park visits are beneficial for people’s physical and psychological health, as well as for the development of social relationships. This study investigated the degree of recovery of physical, psychological, and social aspects of residents in different types of parks and the influence of socio-demographic factors, personal factors, residential space attributes, and park characteristics on park visitation. The results show that tourists visiting urban parks have higher physiological and social recovery than those visiting suburban parks and that there are significant differences. Physical exercise, rest and relaxation, and spending time with family and children were the three most prevalent factors influencing park visits, while time constraints were the most important reason why residents failed to use parks. Socio demographics, residential spatial attributes, individual variables, and park characteristics explained 13.6%, 16.7%, 4.6%, and 2.9% of the total variance in park visit frequency, respectively. Residential green space, age, children under age seven, time spent in residential green space, willingness to spend time in nature, greenery, maintenance, and amenities were positively associated with park use. Income, education, home price, and distance from home to the park were negatively associated with park use. These findings have implications for park management and for future research.

Due to climate change and excessive human activities, runoff dynamics of the Tarim River in northwest China become more pronounced. Understanding the effects of hydrological alteration on the life strategy and dynamics of the Populus euphratica riparian forests is becoming increasingly important. Forest gaps led by such disturbances change the structure and function of the desert riparian forest ecosystems. However, there is a lack of research on the gap formation and dynamics of this special forest type, for which the main driving force of the gap disturbance has always been unknown. In this study, we investigated several parameters of P. euphratica forest gap, such as gap size, gap age, gap fraction, and gap makers to quantify the gap disturbance regimes in the natural floodplain forests along the Tarim River in arid northwest China. In the middle reaches of the Tarim River, a total number of 263 gap makers and 60 gaps in six 50 m × 50 m plots with a total area of 1.5 hm2 were investigated. The result showed that gap fraction was

The paper used TM image data, land use vector data, and China's high spatial resolution grid data(CHRED) of Urumqi's center area in 2005 and 2012, and studied the change of Urumqi's ecosystem and environment with the conversion of land use. The method of land use conversion, ecosystem service value assessment and carbon emission accounting were employed in this study. Results showed that land use conversion was significant, among which the land conversions of garden land, grassland, urban village, industrial and mining land and unused land were more obvious. The unused land showed the greatest change(1.033×105 hm2) which indicated that the degree of land development in the study area was higher. With the conversion of land use, the value of ecosystem services showed an increasing trend. The net EVS value rose by 892.273 2 million yuan. The land conversion of garden land, grassland and water area contributed most to the increase of ecosystem service value. There was an uptrend in the carbon emission intensity of land use. The highest carbon emissions were induced by urban villages and industrial and mining land. Although the net ecosystem service value of the land use conversion was increasing, the change of land carbon emission intensity was more quickly than the change of the ecosystem service value. Therefore, the balance between the adjustment of land use structure and the protection of the ecological environment should be considered by the government in the low-carbon construction of Urumqi.

Understanding the balance between supply and demand of ecosystem services (ESs) is helpful for sustainable urban management. However, the interactions among multiple ESs supplies and demands remain under-researched, and ESs supply and demand spatial heterogeneity and correlation characteristics at the city level are rarely studied, especially in arid areas. To fill this gap, we established a comprehensive assessment framework of ESs supply and demand through integrating multi-source remote sensing data, social economy, and policy objectives, for the oasis city of Urumqi, China. The ESs supply-demand mismatches were revealed at the city level, and the spatial relationship between the ESs supply and demand was analyzed using spatial statistics. The results demonstrated that: (1) The total quantity of supply and demand of food provision, carbon sequestration, PM10 removal, and recreation services in Urumqi revealed that the demand was greater than the supply, the deficits being 16.10 × 107 kcal/ha, 6.88 × 104 t/ha, 155.86 kg/ha, and 697.26, respectively. (2) The supply and demand assessment of ESs revealed spatial differences from the city center to the suburbs, which further indicated that there are neighborhood similarities between the supply and demand of ESs. (3) The matching types of ESs supply and demand present obvious spatial heterogeneity, which can be divided into four types: High-high, high-low, low-high, and low-low. Owing to rapid urban development in the inner city, the city center is dominated by low-high, whereas the urban-rural ecotone is characterized by high-low, owing to the higher elevation and water resource advantages in the suburbs. Based on the analysis of the supply, demand, and matching of ESs, economic development and sustainable management policies are proposed for different ecological spaces. Integr Environ Assess Manag 2021;17:1293-1304. © 2021 SETAC.

Urban green space (UGS) is crucial to the healthy development of urban residents. However, UGS that is accessible can benefit residents to an even greater degree. Based on the two-step floating catchment area model (2SFCA) and the location quotient (LQ), we analyzed the changes from 1999 to 2019 in UGS walking accessibility and equity in built-up areas of Urumqi at different administrative levels, and how UGS policy affects the improvement of accessibility. The results showed that UGS accessibility and equity are not evenly distributed at different administrative levels and UGS categories. Although the overall UGS accessibility and equity has improved with policy implementation, these changes are caused by metro-level UGS construction in urban fringe areas. The improvement in UGS accessibility at the neighborhood level in densely populated areas is neglected, which leads to a mismatch between UGS construction and population distribution. In addition, the accessibility of UGS is also limited by geographical location, population density, road distribution, and water shortage in arid metropolitan Urumqi. Our research results provide a theoretical basis for Urumqi and other cities in the optimization of UGS structure and the realization of social equity.

Rapid agricultural land expansion and urbanization have accelerated land use and land cover changes (LUCC) in the Northern Tianshan Mountain Economic Zone and have significantly impacted on the ecosystem services (ESs). However, the spatiotemporal variations of ecosystem service value (ESV) to LUCC are not well understood. Based on the land use and land cover (LULC) data from 1980 to 2019, we used a CA-Markov model to predict LUCC in 2020 and 2030, assess the spatial-temporal changes of ESV and LULC during 1980–2030, and explore the elastic response of ESV to LUCC. We found that cropland and built-up land expanded rapidly by 34.38% and 196.66%, respectively between 1980 and 2030, while grassland and unutilized land decreased significantly by 11.45% and 10.26%, respectively. The ESV of water body, cropland, grassland and forestland accounts for more than 90% of the total ESV. Our research shows that the ESV of cropland increased 32 million yuan from 1980 to 2030, mainly due to the expansion of cropland area. However, the loss caused by the reduction of grassland area was 45 million yuan. Water conservation, waste treatment, soil formation and retention, and biodiversity conservation are the primary ecosystem service function, accounting for 71.82% of the total ESV. Despite notable increases in the ESV from 1980 to 2010, grassland degradation still remains a main ecological and environmental issue from 2010 to 2030. The results suggest that effective land use policies should be developed to control the expansion of croplands and protect water body, grassland and forestland to maintain more sustainable ESs.

Ecosystem service and human activity assessment are essential for effective natural resources allocation; however, these were seldom researched in arid region. This study used the theory proposed by Millennium Ecosystem Assessment to analyse ecosystem services provided by the floodplain forest in the lower reaches of the Tarim River. Results showed the following: (a) In the research area, the ecosystem service values of approximately US$216.78 × 108 occurring from 1972 to 2015 showed a decreasing trend; (b) the total ecosystem service values for floodplain forest and water area for all land use and land cover types accounted for 87.43% of the total value in the research area, and water supply, biodiversity protection, and waste treatment accounted for 55% of the total function values—these were the highest service values; (c) this research showed that the estimated ecosystem service values of research area were inelastic to value coefficients. This study showed that future work should allow land use and Ecological Water Conveyance Project to follow with rigorous environmental impact analyses. These analyses will be crucial to maintain the stability and sustainable development in the lower reaches of the Tarim River and also can provide references for research in the arid regions of Northwest China and Central Asia.

The water-sediment interface of lakes is an important and unique area of the water environment; the geochemical behavior of nutrients in this area has a significant impact on the quality of the water environment and ecosystems, especially in shallow lakes. However, most studies do not provide direct in situ evidence for this in shallow lakes in arid regions; in order to explore the coupling relationship between phosphorus (P) and iron (Fe) in a sediment profile, we conducted a high-resolution analysis of liable Fe and P in sediments taken from the Chaiwopu Lake using ZrO-Chelex thin film diffusion gradient technology (ZrO-Chelex DGT). The results show that (1) the vertical spatial distribution trend of the liable P and Fe in the sediments from each sampling site is essentially similar. The contents of the liable P and Fe ranged from 0.004–0.125 mg/L and 0.050–0.190 mg/L, respectively, and the synchronous distribution of the micro-interface concentration reflects the coupling relationship between them. (2) The correlation analysis of the liable P and Fe concentrations showed that there were significant linear correlations between them (P

Changes in land use and land cover are known to impact ecosystem services and functions. In this study, land use characteristics were combined with global and China-specific ecosystem coefficients to quantify land-use and ecosystem service changes in Charchan Oasis. Results indicated that: (i) the total values of ecosystem services in Charchan Oasis were increased 8·4 M$ from 1972 to 2013; (ii) the aggregated ecosystem service values for water bodies, grasslands, forest lands, and barren lands were 98·90% of the total value for all land types; (iii) waste treatment, soil formation, biodiversity protection, and water supply were ecological functions with the highest service values, contributing approximately 65% of the total service values; and (iv) ecosystem service values estimated in this study were inelastic with respect to the value coefficients, therefore, the estimation results were believable. Copyright © 2016 John Wiley & Sons, Ltd.

The current study focused on the Bortala River - a typical inland river located in an oasis of arid area in northwestern China. The sediment and soil samples were collected from the river and drainage basin. Results showed that: (1) the particle size of the sand fraction of the sediments was 78-697 µm, accounting for 78.82% of the total samples; the average concentrations of eight heavy metals fell within the concentration ranges recommended by the Secondary National Standard of China, while the maximum concentrations of Pb, Cd, and Hg exceeded these standards; (2) results from multivariate statistical analysis indicated that Cu, Ni, As, and Zn originated primarily from natural geological background, while Cd, Pb, Hg and Cr in the sediments originated from human activities; (3) results of the enrichment factor analysis and the geo-accumulation index evaluation showed that Cd, Hg, and Pb were present in the surface sediments of the river at low or partial serious pollution levels, while Zn, Cr, As, Ni, and Cu existed at zero or low pollution levels; (4) calculation of the potential ecological hazards index showed that among the eight tested heavy metals, Cd, Pb, Hg, and Cr were the main potential ecological risk factors, with relative contributions of 25.43%, 22.23%, 21.16%, and 14.87%, respectively; (5) the spatial distribution of the enrichment factors (EF(S)), the Geo-accumulation index (I(geo)), and the potential ecological risk coefficient (E(r)(i)) for eight heavy metals showed that there was a greater accumulation of heavy metals Pb, Cd, and Hg in the sediments of the central and eastern parts of the river. Results of this research can be a reference for the heavy metals pollution prevention, the harmony development of the ecology protection and the economy development of the oases of inland river basin of arid regions of China, Central Asia and also other parts of the world.

In this study, we first reviewed the current research progress regarding the presence of environmental microplastics (MPs) in environment in China from 2010 to 2019. Results showed that: (1) current research has primarily focused on river and marine environments rather than soils and dusts, mainly located in eastern China, i.e., the Yangtze river, Poyang lake, Dongting lake, Yellow sea, and Bohai sea; (2) the abundance of MPs found in water bodies (sediments) of the rivers in China ranged from 3.9 to 7900 items·m−3 (19.0 × 103-13600.5 × 103 items·km−2), and 20–24300 items·kg−2 (170–5500 × 106 items·km−2) in the sediments, respectively; in lake water the range was 340–8900 items·m−3 (5 × 103-340 × 105 items·km−2) and 8 to 1200 items·m−2/25–300 items·kg−1 in the sediments, respectively; in marine water the range was 0.003–540 items·m−3 (0–380,100 item·km−2) and 1.3–14700 item·kg−1 in the sediments, respectively; in fish, shellfish, and natural planktons from ocean and freshwater, the range was 0–57 items·individuals−1 (0–168 items·g−1); (3) The absorption and toxicological effects of MPs in freshwater and oceans have mainly focused on polyethylene (PE), polypropylene (PP), and polystyrene (PS); (4) the sources of microplastics in soils and dusts primarily come from urban/town activities; for rivers and lakes (estuary), they primarily come from urban activities; for coastal waters, fishing gear and nets, and the maritime activities were the main sources.

A total of 469 surface soil samples were collected from the Yanqi basin in northwest China and evaluated for levels of ten heavy metals. Multivariate statistical analyses were used to study sources of and map the spatial distribution of heavy metals, as well as determine the relationship between land use types and soil source materials. It was found that: (1) the average amounts of ten heavy metals in the Yanqi basin were all below the national soil environmental quality standards of China (GB15618-1998), but the average amount of Cd, Hg, Mn, Ni, Pb, and Zn all exceeded the heavy metal background levels of soil in Xinjiang, China and exhibited accumulation. The ten heavy metals analyzed in this study can be categorized into four principal components as follows: Principal component 1 was Co, Cr, Mn, Ni, and Zn, and principal component 3 was As and Cu. Both of these originated from a natural geological background. Principal component 2 consisted of Cd and Pb and originated from industrial, agricultural and transportation influences. Principal component 4 consisted of Hg and was due to industrial influences. Our study found that Pb and Zn were a large part in the principal components 1 and 3 and were influenced by a combination of geologic background and human activity. (2) Heavy metals Cd and Hg were at high levels in construction land and farmland, while Co, Cr, Cu, Mn, and Ni were significantly higher in lacustrine deposits than in sandy shale from weathered material, coarse crystalline rock weathered material, and diluvial material. The land use types correlated significantly with the accumulation of Cd and Hg, and the soil parent material was the major factor for the accumulation of As, Co, Cr, Cu, Mn, and Ni. (3) The single element, element integration and the corresponding principal component presented similar spatial patterns of hazardous risk. Following comprehensive assessment of all elements, the high risk regions were found to be located in densely-populated urban areas and western parts of the study area. This was attributed to the higher geological background in the western part and strong human influence in the central part. Research shows that Cd, Hg, Pb, and Zn were locally enriched in the basin and this warrants increased attention.

The riparian vegetation in the lower reaches of the Tarim River is an irreplaceable natural resource for its ecosystem, and also a guarantee for the transportation safety in this area. Here, we analyzed different plant influences on soil erosion and evaluate the main ecosystem service functions served by the riparian vegetation to study area. Results showed that the total amount of sand-fixation in the study area was 4.14×1013 t and that Tamarix chinensis had a greater influence on wind speed and sediment transport than Populus euphratica, and the Tamarix chinensis can be used as suitable vegetation for wind erosion measures and provide scientific basis for the optimization of vegetation matching and reasonable allocation scheme for ecological construction in arid areas. The total ecosystem service value was calculated to be $11.03×1011. Of the main ecosystem service functions, riparian vegetation primarily served as sand fixation. Results show that, this research was identical, and the construction of shelterbelt plays an important role in the promotion of wind and sand control measures. Finally, our findings highlights the need for further research on how vegetation function as windbreak and sand fixation.

In this study, we sought to explore the changes of soil moisture and soil electrical conductivity (EC), as well as to study the relationships between these soil properties and the vegetative indexes of plant coverage, height and crown density and diameter during the Phragmites australis (P. australis) growth period. By combining floristic and edaphic variables (soil moisture and EC), we found that at 0–10 cm depth, the soil moisture varied greatly, while the soil moisture at 10–50 cm depth, EC at 0–50 cm depth, and vegetation properties varied only moderately. A great amount of evaporation offered a possible reason for this moderate variability in soil moisture and EC. Geostatistical analyses revealed that the soil moisture at 0–50 cm depth, and the density of P. australis (Cav.) had a strong spatial autocorrelation, while the EC at 0–50 cm depth had only a weak spatial autocorrelation depending on the nugget effect. Furthermore, there was a positive correlation between the soil moisture and vegetation characteristics at the depth of 0–50 cm, but there was a negative correlation between EC and vegetation characteristics at the depth of 30–50 cm. Furthermore, an increase in soil moisture had a positive effect on P. australis (Cav.) growth, while an increase in EC had a negative effect.

Bosten Lake, a typical rump lake in an oasis in northwest China, was chosen to evaluate the distribution, sources, pollution status, and potential ecological risk of heavy metals. Sediment samples were collected from the lake, and results showed that the values of the eight heavy metals all fell within the Second Soil National Standard, while the average and maximum values of the metals were higher than the background values of the study. Multivariate statistical analysis showed that sediment concentrations of Cd, Pb, Hg, and Zn were mainly influenced by man sources. In comparison, Cu, Ni, Cr, and As were primarily natural in origin. Enrichment factor analysis (EF) and the geo-accumulation index evaluation method (I geo) showed that Cd, Hg, and Pb fell under low and partial serious pollution levels, while Zn, As, Cr, Ni, and Cu mainly were characterized under no pollution and low pollution levels. The potential ecological hazards index (RI) showed that among the eight heavy metals, Pb, Hg, and Cd posed the highest potential ecological risk, with potential ecological hazards indices (RI) of 29.06, 27.71, and 21.54 %, respectively. These findings demonstrated that recent economic development in the area of the basin has led to heavy metal accumulation in the surface sediments of the lake.

In this paper, the temporal variation and causes of groundwater depth, total dissolved solids (TDS), and NO3 −-N in groundwater, as well as salt and water in soil profiles in the Yutian oasis, northwest China from 2001 to 2010 have been studied. The results showed that: (1) during this period, the NO3 −-N in the groundwater showed an increasing trend with the order of mean values at 2010 > 2005 > 2001, while the average values of the groundwater depth and TDS in groundwater were both in the order of 2010

Bosten Lake, a typical rump lake in an oasis in northwest China, was chosen to evaluate the distribution, sources, pollution status, and potential ecological risk of heavy metals. Sediment samples were collected from the lake, and results showed that the values of the eight heavy metals all fell within the Second Soil National Standard, while the average and maximum values of the metals were higher than the background values of the study. Multivariate statistical analysis showed that sediment concentrations of Cd, Pb, Hg, and Zn were mainly influenced by man sources. In comparison, Cu, Ni, Cr, and As were primarily natural in origin. Enrichment factor analysis (EF) and the geo-accumulation index evaluation method (I geo) showed that Cd, Hg, and Pb fell under low and partial serious pollution levels, while Zn, As, Cr, Ni, and Cu mainly were characterized under no pollution and low pollution levels. The potential ecological hazards index (RI) showed that among the eight heavy metals, Pb, Hg, and Cd posed the highest potential ecological risk, with potential ecological hazards indices (RI) of 29.06, 27.71, and 21.54 %, respectively. These findings demonstrated that recent economic development in the area of the basin has led to heavy metal accumulation in the surface sediments of the lake.

In this paper, we used land use/cover ecosystem service value estimation model and ecological economic coordination degree model to analyze the changes of the ecosystem service value by the land use/cover changes during 1985, 1990, 1996, 2000, 2005 and 2011 in Yanqi Basin, Xin-jiang. Then we evaluated the ecology-economy harmony and the regional differences. The results showed that during 1985-2011, there was an increasing trend in the areas of waters, wetland, sand, cultivated land and construction land in Yanqi Basin. In contrast, that of the saline-alkali land, grassland and woodland areas exhibited a decreasing trend. The ecosystem service value in Yanqi Basin during this period presented an increasing trend, among which the waters and cultivated land contributed most to the total value of ecosystem services, while the grassland and the woodland had obviously declined contribution to the total value of ecosystem services. The research showed that the development of ecological economy in the study area was at a low conflict and low coordination level. So, taking reasonable and effective use of the regional waters and soil resources is the key element to maintain the ecosystem service function and sustainable and harmonious development of economy in Yanqi Basin.

In this paper, we used land use/cover ecosystem service value estimation model and ecological economic coordination degree model to analyze the changes of the ecosystem service value by the land use/cover changes during 1985, 1990, 1996, 2000, 2005 and 2011 in Yanqi Basin, Xin-jiang. Then we evaluated the ecology-economy harmony and the regional differences. The results showed that during 1985-2011, there was an increasing trend in the areas of waters, wetland, sand, cultivated land and construction land in Yanqi Basin. In contrast, that of the saline-alkali land, grassland and woodland areas exhibited a decreasing trend. The ecosystem service value in Yanqi Basin during this period presented an increasing trend, among which the waters and cultivated land contributed most to the total value of ecosystem services, while the grassland and the woodland had obviously declined contribution to the total value of ecosystem services. The research showed that the development of ecological economy in the study area was at a low conflict and low coordination level. So, taking reasonable and effective use of the regional waters and soil resources is the key element to maintain the ecosystem service function and sustainable and harmonious development of economy in Yanqi Basin.