Effects of stand density on understory species diversity and soil anti-scourability of Cupressus funebris plantation in Yunding Mountain,Sichuan, China北大核心CSCD

To protect the ecosystem of barren mountains, massive Cupressus funebris plantations were allowed in hilly areas of the central Sichuan Basin in the late 1980s. In recent years, Cupressus funebris plantations have faced problems such as biodiversity decline and soil erosion. To study the effects of different forest densities on understory species diversity and soil anti-scourability of Cupressus funebris plantations in Yunding Mountain, a typical sampling method was used to investigate the five different forest densities (1 100, 950, 800, 650, and 500 trees/hm2) and to analyze the correlation between the species diversity index, soil anti-scourability, and root index. In total, 176 species from 128 genera and 69 families were recorded in this area. The number of species in the herb layer was higher than that in the shrub layer. The species diversity index of the shrub layer first increased and then decreased with the decrease in stand density; and the species richness index D and Shannon–Wiener diversity index H showed peak values at a density of 650 trees/hm2. The species richness index D, Shannon–Wiener diversity index H, and Simpson dominance index H’ in the herb layer showed a bimodal trend of increasing, then decreasing, increasing again, and finally decreasing with the decrease in stand density; and the peak values were found at the densities of 650 and 950 trees/hm2. When soil anti-scourability decreased with stand density, it showed a trend of increasing and then decreasing, reaching a peak at a density of 650 trees/hm2. The positive correlation between the species richness index and soil anti-scourability was evident. Thus, 650 trees/hm2 is relatively more conducive to the stability of species diversity and soil anti-scourability in cypress plantations. © 2022 Authors. All rights reserved.     

Dynamic characteristics of woody plant regeneration in karst secondary forests in central Guizhou北大核心CSCD

Based on community data (2012, 2020) of the Tianlong Mountain evergreen and deciduous broadleaved mixed forest plot in central Guizhou, China, the species composition, importance value index, diversity, and dynamic changes were estimated to explore the renewal and change characteristics of karst secondary forests. The results showed that: (1) the number of individual species in the investigated two hm2 plot encompassing 33 families and 55 genera, totaling 69 species decreased from 10 276 to 7837. Five families, 10 genera, and 18 species were newly added, while seven families, nine genera, and 11 species disappeared. The difference between the importance value indices of the species was obvious; that of Lithocarpus confinis (20.97–23.26) was much higher than that of other species. Except for some species, the overall inter-annual differences were not large, and the status of mesophytic and shaded species has increased. Life forms were dominated by small trees and shrubs or small trees, and the plant number density of different life forms is reduced. (2) The Margalef and Shannon-Wiener indices of shrubs were the largest, and the Pielou indices of shrubs or small trees were the largest. The composition of most life forms has increased; the diversity became richer; and the uniform distribution of individual species has increased, but the change was small. (3) With respect to the spatial distribution pattern, the species were generally clustered, and only a few were randomly distributed. The Cx, I, m*, CA, and G indices of the species were reduced, and those of some species were quite different. A tendency for aggregated distribution was observed over random distribution, but the aggregation degree of Lithocarpus sphaerocephala was still high. The PAI index of most species increased but was not obvious, whereas the K value changed irregularly. Overall, the species composition, importance value index, diversity, and spatial distribution pattern of the main species in this community have changed to some extent but without any significant fluctuations. L. sphaerocephala was still the dominant species in succession, and the species composition of the flora was stable. The restoration of vegetation and the development of the entire community are slow. © 2022 Science Press. All rights reserved.     

Temporal and spatial evolution characteristics of sunshine duration over Qinghai-Tibet Plateau from 1961 to 2020北大核心CSCD

Based on observation data of daily sunshine duration from 1961 to 2020 at 175 meteorological observation stations over Qinghai-Tibet Plateau and its surrounding areas, spatial transformation analysis, climate trend analysis and M-K mutation test were used to analyze the temporal and spatial variation characteristics of the seasonal and annual sunshine duration in the region in the last 60 years. The results show that (1) annual average sunshine duration was 2 323 h, the maximum was 3 487 h in Gaer, Tibet, and the minimum was 771 h in Ya'an, Sichuan. The high-value areas were mostly located in western Tibet, northern Qinghai, western Gansu, and Xinjiang, and the low-value areas were mostly located in Nyingchi in Tibet, the mountainous area on the western edge of the Sichuan Basin, and northwestern Yunnan. The highest sunshine duration was recorded in winter (631 h), and the lowest was recorded in autumn (555 h) among the four seasons. (2) The average decrease in annual sunshine duration was 10.27 h/10 a. The largest rates of decrease were mainly in Gannan of Gansu and Ganzi of Sichuan, with the largest rate of decrease of 130 h/10 a. The areas with large rates of increase were mainly in Hotan area of Xinjiang, Liangshan of Sichuan and Lhasa of Tibet, with the largest increase of 61 h/10 a. Among the four seasons, spring exhibited an upward trend, and the remainder exhibited a downward trend. (3) Before 2017, the annual sunshine duration increased but declined after 2017. Spring sunshine duration had the largest number of mutation years, and the earliest mutation time was 1963. Winter had the fewest number of mutation years and the latest mutation time occurred in 2015. In summary, the annual and seasonal sunshine duration of Qinghai-Tibet Plateau vary greatly in space, but with the general characteristics of more sunshine in the northwest and less in the southeast, and sunshine hours were mainly decreasing, with 2017 as a mutation point of annual sunshine duration. Most areas of Qinghai-Tibet Plateau have great potential for photosynthetic production and are suitable for the development of light-loving plants and high-density planting. Shade-loving or shade-tolerant plants, including tea, are suitable for development in remote mountainous areas with low sunshine values in the western part of the basin, including Ya’an, Sichuan, and other areas, such as Medog, Tibet. © 2022 Science Press. All rights reserved.     

Dynamics of bacterial community of Suillus granulatus mushroom shiro in Pine (Pinus tabuliformis) forests北大核心CSCD

To evaluate bacterial community variation in the mushroom shiro of Suillus granulatus during fruiting, we collected soil samples from the mushroom shiro in the pine (Pinus tabuliformis) forest of mountainous area in Beijing from May to November and evaluated the bacterial community using polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE). Total soil DNA was extracted using a commercial soil DNA isolation kit. PCR amplification and DGGE were performed using bacterial universal primers 338F and 518R. The specific bands were excised from the gel and sequenced. The results revealed that soil bacterial community maintained considerably high level and changed seasonally with the mushroom fruiting. In total, 53 bands of DGGE profiles were sequenced and divided into 5 phyla (Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria and 22 genera (Acidobacterium, Aminobacter, et al). Species from Proteobacteria and Acidobacteria were the dominant bacterial groups sharing considerably high relative abundance, while class a-Proteobacteria was the most abundant group. The variation of the relative abundance of γ-Proteobacteria species was consistent with the mushroom fruiting season. The relative abundance of Acidobacteria species obviously increased before mushroom flush (in July). The fruiting of S. granulatus and the relative abundance of γ-Proteobacteria were correlated with each other. The present study provided a basis for conservation and domestication of mushroom S. granulatus.     

Interspecific association among main plant species in the unstable slope with high-frequency debris flow北大核心CSCD

To determine the characteristics of vegetation community structure and the relationship between species in the frequent watersheds of debris flow in fragile ecological environments, based on sample survey and 2 × 2 joint table techniques, we used analysis of variance test, χ2 test, Jaccard index, Pearson correlation coefficient, and Spearman's rank correlation coefficient test to study the main plant species correlations in the stable zone, instable zone, and deposit zone of the unstable slope. The analysis of variance test showed that all 45 species pairs had a significant negative correlation in the stable zone and instable zone, whereas there was no significant negative correlation in the deposit zone, which showed that the species had an independent distribution trend. The results from the different tests showed that there were 1 pair, 4 pairs, and 4 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association under the χ2 test and the ratios of positive correlation pairs to negative correlation pairs were 0.55, 0.67, and 0.67 in the stable zone, instable zone, and deposit zone, respectively. There were 8 pairs, 5 pairs, and 5 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association from the Pearson correlation analysis test, and the ratios of positive correlation pairs to negative correlation pairs were 0.36, 0.45, and 0.45 in the stable zone, instable zone, and deposit zone, respectively. There were 10 pairs, 6 pairs, and 9 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association from the Spearman's rank correlation analysis test and the ratios of positive correlation pairs to negative correlation pairs were 0.5, 0.55, and 0.6 in the stable zone, instable zone, and deposit zone, respectively. The three test results showed general similarities but there were some differences. Most species pairs did not reach a significant level in the three zones and the number of negatively related species was more than the number of positively related species. In brief, this loose interspecific relationship indicates that the entire plant community was not stable, and the interspecific relationships among species are susceptible to environmental interference in the ecologically fragile areas of the debris flow basin. Therefore, rational selection and configuration of species should be applied to promote community structure development and ecological environmental improvement in vegetation restoration process areas with high-frequency debris flow. © 2018 Science Press. All rights reserved.     

Use of Biotic Community Structure as a Measure of Ecological Degradation

The benthic macroinvertebrate communities of two lotic aquatic habitats,namely,the Churni River(C-R)and the Jalangi River(J-R)were compared in this study.One lotic aquatic system(C-R)was polluted by organic pollutants due to discharge of unprocessed sewage water,while the other(J-R)was not affected by such pollution.Evaluations of various physico-chemical properties of water,sediment and different macroinvertebrate communities of the two tropical lotic systems were done in a period from January,2002 to December,2003.A long term temporal change in the macroinvertebrate communities was recorded due to increase in sediment rH value.Sediment redox potential affected by the anthropogenic activities was found to be an important factor for alteration of macroinvertebrate communities in these aquatic ecosystems.A positive correlation has been established between rH and Margalef index in this study.Potassium and the total count of coliform bacteria in water showed significantly higher values for the polluted Churni River than those for the Jalangi River.Fig 3,Tab 4,Ref 34     

Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients and heavy metals

The aim of this study was to investigate the benthic bacterial communities in different depths of an urban river sediment accumulated with high concentrations of nutrients and metals. Vertical distributions of bacterial operational taxonomic units （OTUs） and chemical para- meters （nutrients： NH4＋, NO3, dissolved organic carbon, and acid volatile sulfur; metals： Fe, Zn, and Cu） were characterized in 30 cm sediment cores. The bacterial OTUs were measured using the terminal restriction fragment length polymorphism analysis. Biodiversity indexes and multivariate statistical analyses were used to characterize the spatial distributions of microbial diversity in response to the environmental parameters. Results showed that concentrations of the nutrients and metals in this river sediment were higher than those in similar studies. Furthermore, high microbial richness and diversity appeared in the sediment. The diversity did not vary obviously in the whole sediment profile. The change of the diversity indexes and the affiliations of the OTUs showed that the top layer had different bacterial community structure from deeper layers due to the hydrological disturbance and redox change in the surface sediment. The dominant bacterial OTUs ubiquitously existed in the deeper sediment layers （5-27 cm） corresponding to the distributions of the nutrients and metals. With much higher diversity than the dominant OTUs, the minor bacterial assemblages varied with depths, which might be affected by the sedimentation process and the environmental competition pressure.     

Spatial and temporal patterns of soil erosion in the Tibetan Plateau from 1984 to 2013北大核心CSCD

Soil erosion has a critical effect on ecological security and socioeconomics, which may deteriorate ecosystem services and common human well-being. The revised universal soil loss equation (RUSLE) was applied to assess soil erosion from 1984 to 2013 in the Tibetan Plateau and analyzed the temporal and spatial variation of soil erosion intensity. Furthermore, the temporal and spatial variation rates of soil erosion were explored across different ecosystems. The results indicated that the annual soil erosion fuctuated in the Tibetan Plateau, the soil erosion intensity decreased from south to north, and the most serious soil erosion was mainly distributed in the southern Tibetan Plateau (Xigaze and Changdu regions, Lhasa, and north of the Shannan region). The soil erosion intensity was higher in shrub, alpine meadow, and sparse vegetation ecosystems. The highest soil erosion was found in alpine meadow (2.17 × 1010 t), followed by alpine grassland (1.59 × 1010 t) and sparse vegetation (1.30 × 1010 t) ecosystems. Meanwhile, although the most serious soil erosion intensity was found in the regions of 3 000-4 000 m altitude, the soil erosion was mainly observed in the regions of 4 000-5 000 m altitude. In the three most recent decades, annual soil erosion decreased at a rate of-1.78 × 108 t/a. Additionally, soil erosion mainly increased in south of the Qiangtang Plateau and in the periphery of the Qaidam basin. Decreased soil erosion was mainly found along the Hengduan Mountains, central Himalayas. Although the increased annual normalized difference vegetation index (NDVI) had positive effects for soil protection, changes in soil erosion was mainly controlled by the change of annual precipitation. Thus, the fragility of ecological systems and increased rainfall erosivity accounted for the obviously increased soil erosion in the alpine grassland ecosystem (1.19 × 10 t/a). However, increased ecosystem stability and decreased rainfall erosivity contributed to the decreased soil erosion in forest and shrub ecosystems, by-0.77 × 10 t/a and-1.65 × 10 t/a, respectively. The slightly decreased rainfall erosivity accounted for a decrease of soil erosion in the sparse vegetation ecosystem (-0.44 × 10 t/a). Meanwhile, soil erosion has decreased in the alpine meadow ecosystem over the past 30 years, which may owing to the relatively higher NDVI that neutralized the increase of rainfall erosivity to some extent. This study revealed serious soil erosion regions and ecosystems in the Tibetan Plateau and explored possible reasons for variations in soil erosion in different ecosystems, which may provide a scientific reference for soil erosion conservation and control in the near future. © 2018 Science Press. All rights reserved.     

Simultaneous quantification of several classes of antibiotics in water,sediments, and fish muscles by liquid chromatography-tandem mass spectrometry

Precise and sensitive methods for the simultaneous determination of different classes of antibiotics, including sulphonamides, fluoroquinolones, macrolides, tetracyclines, and trimethoprim in surface water, sediments, and fish muscles were developed. In water samples, drugs were extracted with solid-phase extraction （SPE） by passing 1000 mL of water through hydrophilic lipophilic balanced （HLB） SPE cartridges. Sediment samples were solvent-extracted, followed by tandem SPE （strong anion exchange （SAX） ＋ HLB） clean-ups. Fish muscles were extracted by a mixture of acetonitrile and citric buffer （80：20, v/v） solution, and cleaned by SPE. Liquid chromatography-tandem mass spectrometry （LC-MS/ MS） with multiple reaction monitoring （MRM） detection was employed to quantify all compounds. The recoveries for the antibiotics in the spiked water, sediment, and fish samples were 60.2%-95.8%, 48.1%-105.3%, and 59.8%- 103.4%, respectively. The methods were applied to samples taken from Dianchi Lake, China. It showed that concentrations of the detected antibiotics ranged from limits of quantification （LOQ） to 713.6 ng- L1 （ofloxacin） in surface water and from less than LOQ to 344.8 μg·kg-1 （sulphamethoxazole） in sediments. The number of detected antibiotics and the overall antibiotic concentrations were higher in the urban area than the rural area, indicating the probable role of livestock and human activities as important sources of antibiotic contamination. In fish muscles, the concentration of norfioxacin was the highest （up to 38.5 μg·kg-1）, but tetracyclines and macrolides were relatively low. Results showed that the methods were rapid and sensitive, and capable of determining several classes of antibiotics from each of the water, sediment, and fish matrices in a single run.     

Hematology and Some Biochemical Parameters of Wild Rodents in Pistachio Gardens of Kerman Province, Southeast Iran

Wild rodents were collected using live snap traps in pistachio gardens of Kerman Province, Southeast Iran from 2007 to 2009, then some physiological parameters of them were measured. The samples were identified as follow: Nesokia indica, Meriones persicus, Meriones lybicus and Tatera indica. Blood samples were obtained from the heart, then the blood parameters (glucose, cholesterol, triglyceride, total protein, HDL, red and white blood cell number) in wild species of rodents and laboratory rat were compared. The results showed that there were no significant differences in serum glucose, triglyceride, HDL and total protein levels among different experimental groups. The concentration of cholesterol in T. indica was more than that in N. indica (P < 0.01). The total numbers of red blood cells also showed significant difference between wild garden rodent species and laboratory rat (P < 0.01), while the numbers of white blood cells showed no significant difference.     

Bacterial community structure in waterlogged bamboo slips excavated from the Laoguanshan Han Dynasty Tomb of Chengdu北大核心CSCD

To investigate the bacterial community structure features of soak solutions used to preserve bamboo slips that were excavated from Han dynasty tomb located in Laoguanshan of Chengdu and to reveal the diversity of bacteria in these soak solutions, PCR-DGGE was employed. Subsequently, the major DGGE bands were excised and sequenced to analyze the phylogeny of bacteria. The richness (S), Shannon-Wiener index (H), and Simpson index (D) of deionized water (0#) without the soaked bamboo slips were higher than those of the other samples. Among the bamboo slip soak solution samples, there were significant differences in these indicators; the bacterial genetic diversity of sample 121# was the highest and that of sample 1# was the lowest. Principal Component Analysis (PCA) showed that there were comparatively large differences among the samples, and the similarity between sample 1# and others was the lowest. Based on the sequence analysis, the major community of bacteria in soak solution were belonged to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, including Cupriavidus, Aquabacterium, Comamonas, Albidiferax, Hyphomicrobiaceae, Azospirillum, Nevskia, Streptococcus, Staphylococcus, Sediminibacterium, and Propionibacterium, among which Cupriavidus of the β-Proteobacteria class was detected in all samples. The bacterial community structure of the soak solutions that were collected from different bamboo slips was quite complex and significantly different. The analysis of the main bacterial community revealed the potential bacteria species that may trigger the damage in bamboo slips; the result provided a reference to prevent waterlogged bamboo slips from microbial diseases in the future. © 2018 Science Press. All rights reserved.     

Variation characteristics of thermal resources in Qinghai-Tibet Plateau in recent 50 years北大核心CSCD

To provide scientific support for the rational development and utilization of thermal resources and avoid climate risks, the distribution of thermal resources in Qinghai-Tibet Plateau in the context of climate change was analyzed in this study. Based on meteorological data from 1961 to 2020 at 149 stations in Qinghai-Tibet Plateau, the changes in thermal resources over the past 50 years were analyzed using inclination rate analysis and Mann-Kendall inspection, combined with JAVA and Python programming. The results showed that: (1) the annual average temperature in Qinghai-Tibet Plateau shows an obvious warming trend, and the temperature increases greatly after the 1990s, with the climate tendency rate from 1961 to 2020 reaching 0.298 ℃/10 a. (2) The accumulated temperature and lasting days steadily above 0 ℃, 5 ℃ and 10 ℃ increased significantly, and the accumulated temperature increases were not entirely determined by the duration of the lasting days. (3) The beginning dates of accumulated temperature steadily above 0 ℃, 5 ℃, and 10 ℃ were generally advanced, while the deadlines were delayed, and the trend of early start dates was stronger than that of deadlines. In conclusion, this study shows that, in the context of global warming, thermal resources in Qinghai-Tibet Plateau have undergone substantial changes, which will play an important role in the introduction and extension of crops. © 2022 Science Press. All rights reserved.     

Genotoxicity evaluation of surface waters located in urban area of Xi’an City using Vicia faba bioassays

In this study, micronucleus （MCN） and chromosome aberration （CA） tests in Vicia faba root tip cells were carried out in order to assess the water quality and the comprehensive genotoxic potential of surface waters located in the urban area of Xi＇an City, China. For these evaluations, water samples from different surface waters （four rivers, two lakes, two biological treatment plant effluents） were collected, the ultra-pure water and methyl methanesulfonate solution was used as the negative and positive control, respectively. In our results, highly significant differences in MCN perrnillage （average number of micronuclei per 1000 cells）, CA frequencies and PI （pollution index） values were found among three rivers and two WWTP effluents, the tested samples from two rivers caused the decrease of mitotic index over 22% compared with the negative control. No significant changes were observed in micronuclei and chromosome aberrations frequencies at one river and two lakes during the period of test （wet season）. These results point out a poor state of the water quality and genotoxic activity of the main surface waters in Xi＇an City. It is recommended to establish a monitoring program for the presence of genotoxic agents in these surface waters.     

Abundance and distribution of ammonia-oxidizing archaea in Tibetan and Yunnan plateau agricultural soils of China

As low oxygen and high ultraviolet （UV） exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea （AOA） in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR （q-PCR） and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria （AOB）, and characterize the community structures of AOA in the samples. The number of AOA cells （9.34 × 10^7-2.32× 10^8 g^-1 soil） was 3.86-21.84 times greater than that of AOB cells （6.91 × 10^6-1.24 × 10^8 g^-1 soil） in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall＇s correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.     

A model of 90Sr distribution in the sea near Daya Bay Nuclear Power Plant in China

The impact on the environment ofradionuclide release from nuclear power plants has attracted increased attention, especially after the accident at Fukushima Daiichi Nuclear Power Plant in Japan. Based on the mechanisms of adsorption/desorption at solid/liquid interfaces and a surface micromorphology model of sediments, a theoretical expression of the distribution coefficient Kd is derived. This coefficient has significant effects on the distribution of radionuclide in seawater, suspended sediment and seabed sediment. Kd is then used to simulate ^90Sr transport in the sea near the Daya Bay Nuclear Power Plant. The simulation results are compared with field measurements of tidal level, current velocity, suspended sediment concentration and ^90Sr concentrations in the same period. Overall, the simulated results agree well with the field measured data. Thus, the derived expression for Ka is capable of interpreting realistic adsorption/desorption processes. What＇s more, conclusion is drawn that about 40% ^90Sr released by Daya Bay Nuclear Power Plant will be adsorbed by suspended sediment and 20% by seabed sediment, only about 40% ^90St will remain in the sea near Daya Bay Nuclear Power Plant in South China Sea.     

Quantitative characterization of Cu binding potential of dissolved organic matter （DOM） in sediment from Taihu Lake using multiple techniques

Dissolved organic matter （DOM） plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the third largest freshwater and a high eutrophic lake in the downstream of the Yangtze River, China. In the lake, frequent breakout of algae blooms greatly increased the concentration of different organic matters in the lake sediment. In this study, sediment samples were collected from various part of Taihu Lake to explore the spatial difference in the binding potential of DOM with Cu. The titration experiment was adopted to quantitatively characterize the interaction between Cu（II） and DOM extracted from Taihu Lake sediments using ion selective electrode （ISE） and fluorescence quenching technology. The ISE results showed that the exogenous DOM had higher binding ability than endogenous DOM, and DOM derived from aquatic macrophytes had a higher binding ability than that derived from algae. The fluorescence quenching results indicated that humic substances played a key role in the complexation between DOM and Cu（II） in the lake. However, because of the frequent breakout of algae blooms, protein-like matters are also main component like hnmic matters in Taihu Lake. Therefore, the metals bound by protein-like substances should be caused concern as protein-like substances in DOM were unstable and they will release bound metal when decomposed.     

Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

Mobilization of arsenic in groundwater of Bangladesh: evidence from an incubation study

The extensive extraction of arsenic (As)-contaminated groundwaters for drinking, household and agricultural purposes represents a serious health concern in many districts of Bangladesh. This laboratory-based incubation study investigated the sources and mechanisms of As mobilization in these groundwaters. Several incubation studies were carried out using sediments collected from the Bangladesh aquifer that were supplemented, or not, with different nutrients, followed by an analysis of the sediment suspensions for pH, ORP (oxidation-reduction potential), EC (electrical conductivity) and As and Fe(ΙΙ) concentrations. In the substrate-amended sediment suspensions incubated under anaerobic environment, there was a mobilization of As (maximum: 50–67 μg/l) and Fe(ΙΙ) (maximum: 182 μg/l), while the ORP value decreased immediately and drastically (as much as −468 mV to −560 mV) within 5–6 days. In the sediment suspensions incubated under control and aerobic conditions, no significant As mobilization occurred. The simultaneous mobilization of As and Fe(ΙΙ) from sediments is a strong indication that their mobilization resulted from the reduction of Fe oxyhydroxide by the enhanced activity of indigenous bacteria present in the sediments; this phenomenon also provides insights on the mobilization mechanism of As in groundwater. The concentrations of As in the sediments used in the incubation studies were strongly linked to the gradients of redox potential development that was stimulated by the quantity of organic nutrient (glucose) used. The penetration of surface-derived organic matter into the shallow aquifer may stimulate the activity of microbial communities, thereby leading to a reduction of iron oxyhydroxide and As release.     

Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

Impacts of de-icing salt pollution on urban road greenspace: a case study of Beijing

De-icing salt contamination of urban soil and greenspace has been a common issue of concern in many countries for years. In the 2009/2010 winter, Beijing experienced a contamination accident resulting from the overuse of deicing salt, reported as almost 30000 tons, which severely damaged urban vegetation alongside roadways. The methods of sampling and rating for both soil contamination and response of the plant populations were developed to rapidly assess this emergency environmental event. Results showed that the shrubs were more severely damaged than the arbors in terms of both degree and extent, as almost all of the surveyed shrubs were severely damaged from the salt contamination, while only about 1/4 of the recorded arbors were rated as ＂severely injured＂ according to the integral plant injury index. The rating of the injury level showed that the trees like Pinus bungeana, Sophora japonica, and the shrubs like Euonymus japonicus, Sabina vulgaris showed less tolerance to de-icing salt pollution. The patterns of vegetation damage demonstrated that the ever-green shrubs alongside roads and the deciduous arbors in the center of roads were most vulnerable to the salt damage.