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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.

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.

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.

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.