High-throughput screening of 222 pesticides in road environments in a megacity of northern China: A new approach to urban population exposure.

A large number of pesticides have been widely manufactured and applied, and are released into the environment with negative impact on human health. Pesticides are largely used in densely populated urban environments, in green zones, along roads and on private properties. In order to characterize the potential exposure related health effects of pesticide and their occurrence in the urban environment, 222 pesticides were screened and quantified in 228 road dust and 156 green-belt soil samples in autumn and spring from Harbin, a megacity in China, using GC-MS/MS base quantitative trace analysis. The results showed that a total of 33 pesticides were detected in road dust and green-belt soil, with the total concentrations of 650 and 236 ng/g (dry weight = dw), respectively. The concentrations of pesticides in road dust were significantly higher than that in green-belt soil. Pesticides in the environment were influenced by the seasons, with the highest concentrations of insecticides in autumn and the highest levels of herbicides in spring. In road dust, the concentrations of highways in autumn and spring (with the mean values of 94.1 and 68.2 ng/g dw) were much lower than that of the other road classes (arterial roads, sub-arterial roads and branch ways). Whereas in the green-belt soil, there was no significant difference in the concentration of pesticides between the different road classes. A first risk assessment was conducted to evaluate the potential adverse health effects of the pesticides, the results showed that the highest hazard index (HI) for a single pesticide in dust and soil was 0.12, the hazard index for children was higher than that for adults, with an overall hazard index of less than 1. Our results indicated that pesticide levels do not have a significant health impact on people.

Culturable endophytic fungi community structure isolated from Codonopsis pilosula roots and effect of season and geographic location on their structures.

BACKGROUND: Rhizosphere soil physicochemical, endophytic fungi have an important role in plant growth. A large number of endophytic fungi play an indispensable role in promoting plant growth and development, and they can provide protection for host plants by producing a variety of secondary metabolites to resist and inhibit plant pathogens. Due to the terrain of Gansu province is north-south and longitudinal, different climatic conditions, altitude, terrain and growth environment will affect the growth of Codonopsis pilosula, and the changes in these environmental factors directly affect the quality and yield of C. pilosula in different production areas. However, In C. pilosula, the connection between soil nutrients, spatiotemporal variation and the community structure of endophytic fungi isolated from C. pilosula roots has not been well studied. RESULTS: Seven hundred six strains of endophytic fungi were obtained using tissue isolation and the hyphaend-purification method from C. pilosula roots that picked at all seasons and six districts (Huichuan, HC; Longxi, LX; Zhangxian, ZX; Minxian, MX; Weiyuan, WY; and Lintao, LT) in Gansu Province, China. Fusarium sp. (205 strains, 29.04%), Aspergillus sp. (196 strains, 27.76%), Alternaria sp. (73 strains, 10.34%), Penicillium sp. (58 strains, 8.22%) and Plectosphaerella sp. (56 strains, 7.93%) were the dominant genus. The species composition differed from temporal and spatial distribution (Autumn and Winter were higher than Spring and Summer, MX and LT had the highest similarity, HC and LT had the lowest). physical and chemical of soil like Electroconductibility (EC), Total nitrogen (TN), Catalase (CAT), Urease (URE) and Sucrase (SUC) had significant effects on agronomic traits of C. pilosula (P < 0.05). AK (Spring and Summer), TN (Autumn) and altitude (Winter) are the main driving factors for the change of endophytic fungal community. Moreover, geographic location (such as altitude, latitude and longitude) also has effects on the diversity of endophytic fungi. CONCLUSIONS: These results suggested that soil nutrients and enzyme, seasonal variation and geographical locations have an impact on shaping the community structure of culturable endophytic fungi in the roots of C. pilosula and its root traits. This suggests that climatic conditions may play a driving role in the growth and development of C. pilosula.

Lead time of early warning by wastewater surveillance for COVID-19: Geographical variations and impacting factors.

The global data on the temporal tracking of the COVID-19 through wastewater surveillance needs to be comparatively evaluated to generate a proper and precise understanding of the robustness, advantages, and sensitivity of the wastewater-based epidemiological (WBE) approach. We reviewed the current state of knowledge based on several scientific articles pertaining to temporal variations in COVID-19 cases captured via viral RNA predictions in wastewater. This paper primarily focuses on analyzing the WBE-based temporal variation reported globally to check if the reported early warning lead-time generated through environmental surveillance is pragmatic or latent. We have compiled the geographical variations reported as lead time in various WBE reports to strike a precise correlation between COVID-19 cases and genome copies detected through wastewater surveillance, with respect to the sampling dates, separately for WASH and non-WASH countries. We highlighted sampling methods, climatic and weather conditions that significantly affected the concentration of viral SARS-CoV-2 RNA detected in wastewater, and thus the lead time reported from the various climatic zones with diverse WASH situations were different. Our major findings are: i) WBE reports around the world are not comparable, especially in terms of gene copies detected, lag-time gained between monitored RNA peak and outbreak/peak of reported case, as well as per capita RNA concentrations; ii) Varying sanitation facility and climatic conditions that impact virus degradation rate are two major interfering features limiting the comparability of WBE results, and iii) WBE is better applicable to WASH countries having well-connected sewerage system.

Temporal and spatial variability of water quality in an urban wetland and the effects of season and rainfall: a case study in the Daguan Wetland, China.

Urban wetlands provide multiple functions including water treatment, recreation, and education, but they are also highly vulnerable, so it is important to monitor wetland water quality to ensure wetland health. In this study, water quality parameters of an urban wetland and rainfall were monitored at 6 sites for 1 year. The correlation analysis of water quality parameters and spatial-temporal variability analysis of water quality were carried out. Besides, the effects of season and rainfall on the wetland water quality were evaluated by the comprehensive water quality identification index (CWQII). These results have shown that there is a significant correlation between nutrient pollutants and Chl-a. Wetland water quality changed with the seasons, but it also varied due to changes in rainfall and location. The water quality of the shallow areas both had high susceptibility and response to seasonal changes and rainfall, but the water quality of the deepwater area was relatively stable. The CWQIIs in different seasons were ranked: Winter (5.98) > spring (4.67) > autumn (4.66) > summer (4.26), and the CWQIIs of different rainfall intensities were ranked: torrential rain (5.09) > heavy rain (4.88) > light rain (4.50) > no rain (4.39) > moderate rain (3.95). The results of this study distinctly explained the effects of season and rainfall on water quality in an urban wetland in a subtropical monsoon climate zone and would be helpful to the policymakers and concerned authorities in developing better water quality management strategies for these wetlands.

Plateau river research: spatial-temporal variations of δ18O and δd in the water of the Yarlung Tsangpo River and their controlling factors.

Stable isotope technology has been widely used to trace sources and evolution of water bodies, relationships between different water bodies and pollution sources. Based on δ18O and δD data from the Yarlung Tsangpo River in 2017, this paper analyzes the composition characteristics of δ18O and δD in the river water during the low-flow, high-flow and normal-flow seasons of the entire Yarlung Tsangpo River and further reveals the spatial evolution and influencing factors. The results show that the values of δ18O, δD and d-excess were different in time and space. The δ18O, δD and d-excess values of the Yarlung Tsangpo River in the low-flow season were significantly higher than in the high-flow season. This was mainly due to weak evaporation enrichment and precipitation supply effects on the river water during the wet season. From the perspective of season change, the d-excess in the low-season is significantly higher than in the high-flow season and the normal-flow season; from the perspective of spatial change, the d-excess shows the same spatial variation trend as the δ18O, which first decreases and then increases. Based on the investigation of δ18O and δD in the main and Branch rivers of the Yarlung Tsangpo River Basin, it was found that the upper reaches of the basin were mainly supplied by snowmelt, the lower reaches were mainly supplied by rainfall.

Status of arsenic accumulation in agricultural soils across China (1985-2016).

Based on 1677 published studies, 1648 sites across China collected from 1985 to 2016 were used to research the concentrations of arsenic in agricultural soils. In order to understand the status of arsenic pollution in agricultural soils in China over the past three decades, and to learn about the arsenic stocks in agricultural soils in various regions, and compared the relationship with annual arsenic emissions in China, and finally evaluated the potential ecological risks and human health risks. The median arsenic concentration in the surface agricultural soils of China was 10.40 mg Kg-1, and it ranged from 0.4 mg Kg-1 to 175.8 mg Kg-1. The inventory of arsenic in Chinese agricultural surface soils was estimated to be 3.71 × 106 t. In this study, the arsenic concentrations were found to be higher in Central, South, and Southwest China than those in other regions. The trend of arsenic pollution in agricultural soils has gradually increased over the past three decades. However, the growth rate of arsenic concentrations pollution in farmlands agricultural in China slowed during 2012-2016. The ecological risk index and geoaccumulation index revealed that arsenic in Chinese agricultural soil poses a low risk to the ecosystem. For human health assessment, the dietary pathway was the main pathway of exposure to arsenic in farmland soil of China. However, children's soil intake also contributed 34.48% to the exposure to arsenic, owing to their behavior. This study can provide a reference for the management of arsenic agricultural pollution in farmland soils in China.

Spatio-temporal analysis of irrigation water use coefficients in China.

Water shortage is a major problem for agriculture in many countries. Agricultural water accounts for more than 60% of total water consumption in China. Improving agricultural strategies in using irrigation water more effectively and efficiently is important to alleviate water shortages and associated environmental problems. In this study, the spatiotemporal distribution differences of irrigation water use coefficient in large, medium and small-scale irrigation districts and pure well irrigation districts in the 31 provinces of China (excluding Hong Kong, Macao and Taiwan) were analyzed by means such as the Zipf's law and spatial autocorrelation. The results showed that the national irrigation water use coefficient had increased from 0.501 in 2010 to 0.542 in 2016. By size of irrigation area, the irrigation water use coefficient in small irrigation areas was higher than that of large- and medium-scale irrigation districts. Regionally, the irrigation water use coefficient in the eastern region was significantly higher than that in the western region, and the coefficient in northern region was higher than that in the southern region. The spatial spillover effect of the national irrigation water use coefficient gradually weakened, and the spatial spillover effect of large and medium-scale irrigation districts was not obvious. The spatial spillover effect of pure well irrigation districts varied greatly over time. All these results give a spatiotemporal overview of agricultural water use in China, which provides a direction for improving irrigation water coefficient in China.

Aniline antioxidants in road dust, parking lot dust, and green-belt soil in Harbin, a megacity in China: Occurrence, profile, and seasonal variation.

Aniline antioxidants (ANs) are widely used as industrial chemicals in products composed of rubber. ANs originate mainly from vehicles, where tire wear particles end up in dust and soil after being deposited on roads. Nowadays, limited information is available on the fate and seasonal variation of ANs in the road environment. In this study, we investigated the occurrence of 32 ANs in dust and soil from different road environments, including road dust, garage dust, parking lot dust, and green-belt soil. The total concentrations of ANs were 369 ng g-1 in road dust, 712 ng g-1 in garage dust, and 687 ng g-1 in parking lot dust. These concentrations are several times higher than that in green-belt soil (128 ng g-1). The highest concentrations of N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6PPD) were found in dust and soil. Furthermore, notable seasonal differences were observed, with significantly higher concentrations of ANs in autumn than those in spring. In the main urban area, roads with high traffic volume exhibited higher concentrations of ANs than those with low traffic volume, indicating that ANs were produced by vehicle-related sources.

Water microecology is affected by seasons but not sediments: A spatiotemporal dynamics survey of bacterial community composition in Lake Changshou-The largest artificial lake in southwest China.

This study aimed to evaluate the correlation between microecology of sediments and water as well as their spatial-temporal variations in Changshou Lake. The results demonstrated that microecology in the lake exhibits spatiotemporal heterogeneity, and microbial diversity of sediments was significantly higher than that of water body. Further, it was found that there was statistically insignificant positive correlation between microecology of sediments and that of water body. PCoA and community structure analysis revealed that the predominant phyla which exhibited significant spatial differences in sediments were Proteobacteria, Actinobacteria and Planctomycetes. While, the distribution of dominant bacteria Actinobacteria and Verrucomicrobia in water body showed significant seasonal differences. Microbial networks analysis indicated that there was a cooperative symbiotic relationship between lake microbial communities. Notably, the same bacterial genus had no significant positive correlation in sediment and water, which suggested that bacteria transport between sediment-water interface does not influence the microecological functions of lake water.

Construction and optimization of ecological security pattern based on the circuit theory: a case study of Hohhot City.

The construction of ecological security pattern aims to determine the bottom line of ecological land supply and effective spatial distribution and provides a scientific basis for ensuring regional ecological security. The basic paradigm of "source recognition-resistance surface creation-corridor identification-key areas determination" was used to construct the ecological security pattern of Hohhot City in 2009 and 2019. The circuit theory was employed to determine the demand for protection and restoration of crucial ecological area and to divide the core ecological protection and restoration area, the core restoration area, the core protection area, and the general ecological protection area; then, the optimization of Hohhot's ecological security pattern could be proposed. The results show that there was no interconnected and closed ecological network in 2009 and 2019 in the study area, and the area of significant ecological elements were decreasing: ecological source areas decreased from 266.97 to 261.21 km2, the number of ecological corridors decreased from 10 to 6, and the total area of ecological protection and restoration areas decreased from 342.15 to 199.91 km2. The results show that in the past 10 years, the ecological space in Hohhot had problems such as quality degradation, fragmentation intensifying, and effective landscape connectivity declining. It is urgent to optimize the ecological sources layout, strengthen the restoration of barrier areas and the protection of pinch point areas, and improve habitat connectivity to ensure the improved regional ecological security. Our results can provide a scientific reference for coordinating ecological protection and economic development, as well as the policy formulation and implementation of relevant departments.

Distribution of and Temporal Variation in Volatiles in Tea (Camellia sinensis) Flowers during the Opening Stages.

Tea (Camellia sinensis) flowers emit a large amount of volatiles that attract pollinators. However, few studies have characterized temporal and spatial variation in tea floral volatiles. To investigate the distribution of volatiles within tea flowers and their variation among opening stages, volatile components from different parts of tea flowers and different opening stages were collected by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. A total of 51 volatile compounds of eight chemical classes were identified in the tea flowers. Volatile compounds were most abundant in tea flowers of the Shuchazao cultivar. Acetophenone, 1-phenylethanol, 2-phenylethanol, and benzyl alcohol were the most abundant volatiles. Terpenes were common in the sepals, and benzoids were common in the stamens. The fatty acid derivatives were mainly distributed in the pistils and receptacles and were less abundant in the petals, sepals, and stamens. During the opening phase of tea flowers, the volatile content increased 12-fold, which mainly stemmed from the increase in benzoids. These results enhance our understanding of the formation of volatiles in tea flowers.

Occurrence, Sources, and Health Risks of Polycyclic Aromatic Hydrocarbons in Road Environments from Harbin, a Megacity of China.

To obtain a comprehensive understanding about that occurrence, sources, and effects on human health of polycyclic aromatic hydrocarbons (PAHs) in road environmental samples from Harbin, concentrations of 32 PAHs in road dust, green belt soil, and parking lot dust samples were quantified. The total PAH concentrations ranged from 0.95 to 40.7 µg/g and 0.39 to 43.9 µg/g in road dust and green belt soil, respectively, and were dominated by high molecular weight PAHs (HMW-PAHs). Despite the content of PAHs in arterial roads being higher, the composition profile of PAHs was hardly influenced by road types. For parking lot dust, the range of total PAH concentrations was 0.81-190 µg/g, and three-ring to five-ring PAHs produced the maximum contribution. Compared with surface parking lots (mean: 6.12 µg/g), higher total PAH concentrations were detected in underground parking lots (mean: 33.1 µg/g). The diagnostic ratios of PAHs showed that petroleum, petroleum combustion, and biomass/coal combustion were major sources of PAHs in the samples. Furthermore, according to the Incremental Lifetime Cancer Risk model, the cancer risks of three kinds of samples for adults and children were above the threshold (10-6). Overall, this study demonstrated that PAHs in the road environment of Harbin have a certain health impact on local citizens.

Assessment of natural radioactivity level before and after a mud-volcano eruption: A study from Piparo mud-volcano, Trinidad and Tobago.

The present study was conducted in the Piparo mud-volcano, which is situated in the central part of the island of Trinidad, is geologically connected with the Central Fault Range Zone (CFRZ). This fault zone is a neotectonic (active) strike-slip fault system and an extension of the Andes Mountain chain. This study was aimed at detecting the possible gamma radiation level in Piparo MV after its eruption in September 2019 and finding the change in the ambient radiation level after that eruption. To achieve this aim, gamma radiation data were collected for 6 months (three times at 3 months interval) after this eruption. As a pilot study, gamma radiation measurements were measured with the help of a portable Geiger Muller counter from 32 locations. Radiation levels were nearly 2 times higher than the average background levels in the country indicating Piparo mud-volcano could have controlled the elevated radiation levels in the area. Good correlations were also found between elevated radiation in the northern and western sides of the main crater and presence of auxiliary craters in the same sides. Previous studies reported that the northern side of the crater was more active, and the present study also supported their observation. Good correlation (with coefficient >0.9) indicates that these radioactivity values might be syngenetic. Continuous release and slow reduction of radiation levels (only 13% over 6 months) may indicate a continuous activity in Piparo mud-volcano and may support CRFZ as a creep fault.

[Spatio-temporal dynamics of gross primary productivity in China from 1982 to 2017 based on different datasets]. / 不同数据集的1982­2017年中国总初级生产力的时空动态.

Understanding the spatio-temporal variations of gross primary productivity (GPP) of terrestrial ecosystem and its relationship with climatic factors can provide important basis for vegetation restoration and protection. Based on meteorological data and three public GPP datasets (EC-LUE GPP, GLASS GPP, and NIRv GPP), we syste-matically analyzed the spatial-temporal variations of GPP and its response to climate change in China during 1982-2017. All the results based on the three GPP datasets showed that the annual and seasonal GPP in China increased annually from 1982 to 2017, with that in 1998 and 2002 significantly being higher than the average level during the study period, and that in 1989 and 1992 significantly being lower than the average annual GPP. From 1982 to 2017, GPP showed a significant upward trend in most regions of China, with the regions with significant increases accounting for 75.7%, 73.0%, and 69.6% of the whole study area, respectively. There was a significant positive correlation between annual GPP and precipitation and temperature, but spatial heterogeneity was strong. Among them, the regions with positive correlation between GPP and temperature were mainly distributed in Northwest and Central China, while the regions with positive correlation between GPP and precipitation were mainly distributed in North China. There was obvious spatial-temporal heterogeneity in regions that GPP being affected by temperature and precipitation in different seasons. Temperature was the limiting factor of GPP in spring, autumn and winter, while summer GPP was mainly affected by precipitation.

[Source Apportionment of PM2.5 Based on Hybrid Chemical Transport and Receptor Model in Chongqing].

In order to further improve the accuracy of fine particulate matter (PM2.5) source apportionment results, a hybrid source apportionment approach (CTM-RM) combining the capabilities of a receptor model (RM) and chemical transport model (CTM) was developed. The CTM-RM method was evaluated and applied according to a typical PM2.5 pollution process from January 21 to 27, 2019 in Chongqing. The average value of square prediction error based on CTM-RM was 84.58% lower than that of CAMx/PSAT during the campaign. Compared with that of CAMx/PSAT, the fractional error of PM2.5 and its chemical component concentrations decreased by 15.69%-92.86%. Furthermore, the temporal and spatial variations in PM2.5 source impacts could be obtained using the CTM-RM method in Chongqing. The average adjustment factor (R) values were 1.39±0.38 (agriculture sources), 1.54±0.48 (industrial sources), 1.01±0.13 (power sources), 1.02±0.58 (residential sources), 0.86±0.59 (transportation sources), and 0.58±0.67 (other sources) in the main urban areas of Chongqing. Additionally, the cumulative distribution functions of R were found to be distinct among the six sources. The residential and industrial sources were the main sources of PM2.5, with contributions of 46.23% and 28.23%, respectively. In contrast to that of the other sources, the transportation source impacts of PM2.5 (8.62%) increased significantly from the clear period to pollution period (P<0.001), indicating that the increase in PM2.5 concentrations was mainly driven by vehicular emissions during the pollution period in the main urban areas of Chongqing. The fitting functions between the initial simulated concentrations and R values of each source in the main urban areas of Chongqing could be used to evaluate PM2.5 concentrations at 47 air quality monitoring stations in Chongqing, and the correlation between the refined simulated concentrations and measured concentration of PM2.5 was significant (r=0.82, P<0.001). Compared with that during the clear period, the increases in the percentages of industrial source impacts of PM2.5 in Northeast Chongqing and residential source impacts of PM2.5 in Southeast Chongqing were 17.20% and 9.15% higher, respectively, than that in other areas during the pollution period. By contrast, the increasing percentage of transportation source impacts of PM2.5 in the main urban areas of Chongqing (66.39%) and Western Chongqing (84.16%) from the clear period to the pollution period were higher than that in other areas. The results of CTM-RM on January 26 indicated that the residential source impacts in Northeast Chongqing (64.56%) were higher than those in other areas, and the industry source impacts of PM2.5 were primarily observed in the main urban areas of Chongqing and Western Chongqing, with contributions of 25.26% and 21.20%, respectively.

[Temporal and Spatial Variation Characteristics and Source Analysis of Agricultural Non-point Source Pollution Load in Guangdong During the Past 20 Years].

The agricultural non-point source pollution (ANPSP) load in Guangdong province is very large and has a serious impact on the regional ecological environment. Inventory analysis was used to assess and analyze the temporal and spatial variation characteristics of the ANPSP load of Guangdong province during 1999-2019, and the sources of ANPSP were discussed, as well as the relationship between them. The results showed that, during the past 20 years, the total ANPSP pollution loads of Guangdong province decreased by 6.08%, and the pollution loads of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) increased by -11.88%, 4.99%, and 26.17%, respectively. The input intensity of chemical fertilizers and pesticides increased by 112.19% and 60.38%, respectively. The Pearl River Delta had the highest ANPSP loads in Guangdong province, followed by those in northern, western, and eastern Guangdong. Livestock and poultry breeding were the main sources of COD, the total percent fertilizers and livestock and poultry breeding were the main sources of TN, and livestock and poultry breeding and aquaculture were the main sources of TP. In addition, the contribution of pollutants discharged from aquaculture showed an obvious increasing trend. There were certain differences in the pollution sources in different regions. In western Guangdong, northern Guangdong, and eastern Guangdong, livestock and poultry breeding were the main sources of COD and TP, and fertilizer was the main source of TN; by contrast in the Pearl River Delta, aquaculture had become the main source of TN and TP pollution loads. The correlation results showed that the decline in the total ANPSP in Guangdong province was mainly due to the increase in high urbanization rate and the decrease in the proportion of rural population. In general, there were stage changes in the time and differences in spatial characteristics and sources of ANPSP in Guangdong province. A combination of comprehensive treatment and targeted pollution treatment should be adopted, and fertilizer reduction measures and pollution treatment in the aquaculture should be strengthened in an all-around way, focusing on strengthening the treatment of pollution from aquaculture in the Pearl River Delta region and the treatment of rural life pollution in northern Guangdong.

[Spatiotemporal Distribution and Source Apportionment of Suspended Polycyclic Aromatic Hydrocarbons in Surface Water].

Polycyclic aromatic hydrocarbons (PAHs) are a type of typical environmental pollutant with carcinogenic effects and high ecological risk. With the development of industry, surface water acts as a primary sink for PAHs. Owing to their low solubility, a significant amount of PAHs are adsorbed onto suspended particulate matter in surface water, which presents a serious risk to human health and the ecological environment. To protect human health and aquatic organisms, a systematic assessment of the trends in PAHs exposure risk is essential. Based on long-term monitoring data from 2002 to 2016, this study systematically evaluated the spatiotemporal distribution and source apportionment of PAHs adsorbed on suspended particulate matter in surface water. The results of the Mann-Kendall test indicated that pollution levels of PAHs decreased from 2012 to 2016. The maximum average content was 6239 µg·kg-1, and the minimum was 2760 µg·kg-1. Benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, and benzo(a)anthracene showed significant declines from 2002-2016 (P<0.05). Levels of benzo(a)pyrene, dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene were steady. Wavelet analysis showed that the pollution level of PAHs had significant periodic oscillations for surface water. Midstream and downstream Σ16PAHs showed significant declines from 2002-2016 (P<0.05), whereas upstream Σ16PAHs were steady. ANOVA analysis showed that the spatial difference was significant and occurred in the following order:midstream (6168 µg·kg-1)>upstream (5407 µg·kg-1)>downstream (3412 µg·kg-1). Diagnostic ratio analysis and the positive matrix factorization model suggested that the major sources of PAHs were traffic sources, coal burning sources, and biomass combustion sources, which accounted for 40.9%, 33.7%, and 25.4%, respectively. The contribution of traffic sources decreased by 25.9%. The contributions of coal burning sources and biomass combustion sources increased by 4.8% and 21.1% from 2002-2009 to 2010-2016, respectively. These results provide scientific reference for risk analysis and the control of PAHs pollution in surface water.

A five-year investigation of water quality and heavy metal mass flux of an industrially affected river.

This study investigated the water quality parameters (dissolved oxygen, electrical conductivity, salinity, pH, and temperature) and the mass flux of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in five years (2015-2019) of the Houjing River. The river flows through a heavily-industrialized zone in Kaohsiung City in southern Taiwan. The surface water was sampled 4 times per year from five sampling locations: upstream sites (H1 and H2), industrial wastewater discharge point sites (H3 and H4), and downstream (H5). Our findings show that the water quality parameters improved in the study period, especially dissolved oxygen. However, some parameters, such as electrical conductivity (mean = 1152.50 ± 414.21 µS cm-1), were still higher than the Taiwan water quality irrigation standards. The heavy metal pollution was investigated in the aspect of mass fluxes and sources contribution. The spatial variation of the total heavy metal mass flux increased gradually from upstream to downstream, with H5 having the highest total mass flux of 74.1 kg d-1. H2, located near an industrial zone, had a total mass flux of 33.7 kg d-1 and contributed to the most Ni, Cr, Pb, Zn, and Hg fluxes. This study indicates that the water quality improvements observed are still not enough to meet the regulations. Stricter enforcement is required as well as further investigation to identify any illegal pollution sources.

Temporal and spatial dynamics of gastrointestinal parasite infection in Père David's deer.

BACKGROUND: The Père David's deer (Elaphurus davidianus) population was established from only a small number of individuals. Their genetic diversity is therefore relatively low and transmissible (parasitic) diseases affecting them merit further attention. Parasitic infections can affect the health, survival, and population development of the host. However, few reports have been published on the gastrointestinal parasites of Père David's deer. The aims of this study were: (1) to identify the intestinal parasites groups in Père David's deer; (2) to determine their prevalence and burden and clarify the effects of different seasons and regions on various indicators of Père David's deer intestinal parasites; (3) to evaluate the effects of the Père David's deer reproductive period on these parasites; (4) to reveal the regularity of the parasites in space and time. METHODS: In total, 1,345 Père David's deer faecal samples from four regions during four seasons were tested using the flotation (saturated sodium nitrate solution) to identify parasites of different genus or group, and the McMaster technique to count the number of eggs or oocysts. RESULTS: Four groups of gastrointestinal parasites were found, of which strongyles were dominant; their prevalence and burden were significantly higher than other groups. Significant temporal and spatial effects on gastrointestinal parasitic infection were found. Parasite diversity, prevalence, parasite burden, and aggregation were the highest in summer. Among the four regions, parasite diversity, prevalence, and burden were the highest in the Dongting Lake area. In addition, parasite diversity and burden during the reproductive period of Père David's deer was significantly higher than during the post-reproductive period. CONCLUSIONS: The summer season and the reproductive period of Père David's deer had great potential for parasite transmission, and there is a high risk of parasite outbreaks in the Dongting Lake area.

[Mercury in tree rings: Advances, problems and prospects]. / æ ‘æœ¨å¹´è½®æ±žè®°å½•: 进展、问题和展望.

As a highly biotoxic element, mercury (Hg) can be enriched by the food chain and has negative effect on ecosystems. Changes of Hg flux and reserves in forest have important effects on its biogeochemical cycle in forest ecosystem. Due to limitation of temporal and spatial monitoring, there is not comprehensive understanding on Hg distribution. Widely distributed trees can be used as effective bio-monitors and Hg records in tree rings can be used to study Hg temporal and spatial distribution. Hg accumulated by root, leaf, bark, and other tissues can be detained in bole and record environmental Hg variations. Therefore, historical Hg trends can be restructured by analyzing Hg concentration in tree rings and the biogeochemical characteristics can be understood with Hg isotope ratio. We reviewed the method of measurement of Hg concentration and isotope ratio and application of reconstruction using Hg concentration in tree ring. We suggested the great application potential of Hg isotope ratio in atmospheric Hg construction and biogeochemistry cycle and raised concerns in further studies.