Seasonal variation of microbial populations and biomass in Tatachia grassland soils of Taiwan

To investigate the seasonal variations of microbial ecology in grassland of Tatachia forest, soil properties, microbial populations, microbial biomass, and 16S rDNA clone library analysis were determined. The soil had temperatures 6.6–18.4°C, pH 3.6–5.1, total organic carbon 1.11–10.68%, total nitrogen 0.18–0.78%, and C/N ratios 3.46–20.55. Each gram of dry soil contained bacteria, actinomycetes, fungi, cellulolytic, phosphate-solubilizing microbes, and nitrogen-fixing microbes 4.54 × 10⁴ to 3.79 × 10⁷, 3.43 × 10² to 2.17 × 10⁵, 5.74 × 10³ to 3.76 × 10⁶, 1.97 × 10³ to 1.34 × 10⁶, 8.49 × 10² to 5.59 × 10⁵, and 3.86 × 10² to 3.75 × 10⁵ CFU, respectively. Each gram of soil contained 117–2,482 μg of microbial biomass carbon, 23–216 μg of microbial biomass nitrogen and 9–29 μg of DNA. The microbial populations, microbial biomass, and DNA decreased stepwise with the depth of soil, and they had low values in winter seasons. The microbial populations, microbial biomass carbon, microbial biomass nitrogen, and DNA at the BW2 horizon were 8.42–17.84, 19.26–64.40, 16.84–61.11, and 31.03–46.26% of those at the O horizon, respectively. When analyzing 16S rDNA library, members of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, candidate division TM1, candidate division TM7, Gammatimonadetes, and Verrucomicrobia were identified. Members of Proteobacteria (44.4%) and Acidobacteria (33.3%) dominated the clone libraries. Within the phylum Proteobacteria, α-, β-, and γ-Proteobacteria were most numerous, followed by δ-Proteobacteria.     

Bacterial diversity of the sediments transiting through the gut of Holothuria scabra (Holothuroidea; Echinodermata)

This work analyzes bacterial diversity of sediments transiting through the gut of Holothuria scabra which is an important bioturbator in tropical shallow waters. This edible holothurian species has a social and economic importance for coastal populations in many developing countries. Bacterial biodiversity was analyzed by sequencing the 16S rRNA of bacterial cultures and clones. DAPI and FISH methods were used to determine and compare the number of bacteria found in the various gut compartments. A total of 116 phylotypes belonging to the γ-Proteobacteria (60.5 %), α-Proteobacteria (24.5 %), Bacteroidetes (6 %), Actinobacteria (2.75 %), Fusobacteria (1.75 %), Firmicutes (1.75 %), Cyanobacteria (1.75 %) and δ-Proteobacteria (1 %) were identified. The number of bacteria is significantly greater (1.5×) in the foregut than in the ambient sediments. The number of bacteria significantly decreases in the midgut and remains stable until defecation. Some γ-Proteobacteria, especially Vibrio, are less affected by digestion than other bacterial taxa. The season has an impact on the bacterial diversity found in the sediments transiting through the gut: in the dry season, γ-Proteobacteria are the most abundant taxon, while α-Proteobacteria dominate in the rainy season. Vibrio is the most frequent genus with some well-known opportunistic pathogens like V. harveyi, V. alginolyticus and V. proteolyticus. Findings show that sediment-associated microbial communities are significantly modified by H. scabra during their transit through the gut which supports the view that holothurians play a substantial role in the structuring of bacterial communities at the sediment–seawater interface.     

基于高通量测序的工业园区地下水和土壤细菌群落结构比较研究

为探究工业园区地下水和土壤细菌群落结构、多样性变化特征,采用高通量测序技术对地下水和土壤细菌16S r RNA基因高变区域进行序列测定。通过对Alpha多样性、物种组成、丰度和群落结构的分析,比较地下水和土壤细菌群落结构的异同。Alpha多样性的比较结果表明,土壤细菌群落多样性和丰富度明显高于地下水,地下水细菌群落多样性指数反映出地下水已受到周边污染源的影响。物种注释结果表明,地下水样品共检出48个细菌门,土壤样品共检出50个细菌门。变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)是地下水细菌群落的优势类群,共占93.54%,且该工业园区地下水细菌群落呈现出典型的淡水种群特征;土壤中优势细菌门为Proteobacteria、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、Firmicutes和芽单胞菌门(Gemmatimonadetes),共占85.21%。由于地下水和土壤两者的生态系统和理化环境的差异,致使Actinobacteria、Acidobacteria、绿弯菌门(Chloroflexi)、硝化螺旋菌门(Nitrospirae)、α-变形菌纲(Alphaproteobacteria)、δ-变形菌纲(Deltaproteobacteria)和Gemmatimonadetes占比在地下水和土壤细菌群落间差异显著,同时使地下水和土壤细菌群落各含有一些特有的优势细菌属(地下水2个,土壤4个)。基于高通量测序技术对工业园区样品的测序结果可以为地下水和土壤环境的生态评价提供方法依据。     

Organochlorine pesticides (HCHs and DDTs) in soils along the north coastal areas of the Bohai Sea,China

A systematic survey of organochlorine pesticides (OCPs) including hexachlorocyclohexane isomers (α-HCH, β-HCH, γ-HCH, δ-HCH and ΣHCH) and dichlorodiphenyltrichloroethane metabolites (p,p′-DDT, p,p′-DDE, o,p′-DDT, p,p′-DDD and ∑DDT) in soils along the north coastal areas of the Bohai Sea, China, has been lacking. In this study, 31 representative surface soil samples were collected along the north coastal and riverine areas of the Bohai Sea to characterise the potential for adverse effects of ∑HCH, ∑DDT and their individual isomers and transformation products. Concentrations of ΣHCH and ΣDDT in soils ranged from less than the limit of detection (1 ng · g^?1 dw (mean: 3.5 ng · g^?1 dw) and2 ng · g^?1 dw (mean: 1.7 × 10¹ ng · g^?1 dw), respectively. Compared with studies of OCPs in soils from other locations, concentrations of HCHs and DDTs observed in this study were moderate. Concentrations of OCPs observed in soils were generally less than proposed reference values. HCH residues were a mixture of historical technical HCH and current lindane sources. The pattern of DDTs was consistent with historical releases of technical DDTs. Selected soil physicochemical properties did not explain the sorption and/or partitioning of HCHs or DDTs.     

铜胁迫对农田土壤酶活性、细菌和古菌数量的影响

为了研究铜矿周边农田土壤中不同Cu含量对土壤酶活性、细菌和古菌基因拷贝数的影响,在铜矿周边农田土壤中采集了8个不同Cu含量的土壤,测定土壤的酶活性、细菌和古菌基因拷贝数,结果表明,土壤总Cu含量为28.30~1 019.27mg·kg~(-1),酸可提取态Cu含量为335~415.11 mg·kg~(-1),细菌16S rRNA基因拷贝数在每克干土3.10×10~(10)~1.84×10~(11)个之间,古茵16S rRNA基因拷贝数在每克干土737×10~8~6.82×10~9个之间。土壤总Cu和酸可提取态Cu含量对土壤脲酶活性影响较大,但对土壤脱氢酶和转化酶活性影响不显著。土壤细菌基因拷贝数均与总Cu含量、各形态Cu含量呈极显著的负相关关系,同样土壤古菌基因拷贝数与总Cu含量、各形态Cu含量也均呈极显著的负相关关系,说明Cu胁迫对土壤细菌和古菌活性具有较大的抑制作用。     

Concentrations,input prediction and probabilistic biological risk assessment of polycyclic aromatic hydrocarbons (PAHs) along Gujarat coastline

A comprehensive investigation was conducted in order to assess the levels of PAHs, their input prediction and potential risks to bacterial abundance and human health along Gujarat coastline. A total of 40 sediment samples were collected at quarterly intervals within a year from two contaminated sites—Alang-Sosiya Shipbreaking Yard (ASSBRY) and Navlakhi Port (NAV), situated at Gulf of Khambhat and Gulf of Kutch, respectively. The concentration of ΣPAHs ranged from 408.00 to 54240.45 ng g^?1 dw, indicating heavy pollution of PAHs at both the contaminated sites. Furthermore, isomeric ratios and principal component analysis have revealed that inputs of PAHs at both contaminated sites were mixed-pyrogenic and petrogenic. Pearson co-relation test and regression analysis have disclosed Nap, Acel and Phe as major predictors for bacterial abundance at both contaminated sites. Significantly, cancer risk assessment of the PAHs has been exercised based on incremental lifetime cancer risks. Overall, index of cancer risk of PAHs for ASSBRY and NAV ranged from 4.11 × 10^?6–2.11 × 10^?5 and 9.08 × 10^?6–4.50 × 10^?3 indicating higher cancer risk at NAV compared to ASSBRY. The present findings provide baseline information that may help in developing advanced bioremediation and bioleaching strategies to minimize biological risk.     

Polycyclic aromatic hydrocarbons (PAHs) in multimedia environment of Heshan coal district,Guangxi: distribution,source diagnosis and health risk assessment

Mining activities are among the major culprits of the wide occurrences of soil and water pollution by PAHs in coal district, which have resulted in ecological fragilities and health risk for local residents. Sixteen PAHs in multimedia environment from the Heshan coal district of Guangxi, South China, were measured, aiming to investigate the contamination level, distribution and possible sources and to estimate the potential health risks of PAHs. The average concentrations of 16 PAHs in the coal, coal gangue, soil, surface water and groundwater were 5114.56, 4551.10, 1280.12 ng g^?1, 426.98 and 381.20 ng L^?1, respectively. Additionally, higher soil and water PAH concentrations were detected in the vicinities of coal or coal gangue dump. Composition analysis, isomeric ratio, Pearson correlation analysis and principal component analysis were performed to diagnose the potential sources of PAHs in different environmental matrices, suggesting the dominant inputs of PAHs from coal/coal combustion and coal gangue in the soil and water. Soil and water guidelines and the incremental lifetime risk (ICLR) were used to assess the health risk, showing that soil and water were heavily contaminated by PAHs, and mean ICLR_{coal/coal-gangue} and mean ICLR_soil were both significantly higher than the acceptable levels (1 × 10^?4), posing high potential carcinogenic risk to residents, especially coal workers. This study highlights the environmental pollution problems and public health concerns of coal mining, particularly the potential occupational health hazards of coal miners exposed in Heshan.     

Characterisation and identification of carbofuran-utilising bacteria isolated from agricultural soil

A total of 96 bacterial cultures were isolated from soil. Seventeen bacterial isolates were selected following their cultivation on solid media containing 100 mg · L^?1 carbofuran as the sole source of carbon and nitrogen. Of the 17 isolates, 10F, 11M, 17N, 23B and 26M were specifically chosen because of their relatively higher growth efficiency and genetic diversity based on Box-polymerase chain reaction analysis. These bacterial cultures had 16S rRNA gene sequences that were most similar to Acinetobacter baumannii (10F), Agrobacterium tumefaciens (11M), Ochrobactrum anthropi (17N), Escherichia coli (23B) and Agrobacterium tumefaciens (26M) with 97, 95, 93, 95 and 94% similarity in their 16S rDNA gene sequence, respectively. Degradation rates of carbofuran in soil inoculated with these isolates were 1.9, 1.5, 1.6, 1.7 and 1.6 times, respectively, faster in comparison with uninoculated soil after 10 days of incubation. The maximum degradation rates of carbofuran (45 and 91%) were detected in soil inoculated with A. baumannii (10F) after 10 and 20 days’ incubation, respectively. These data indicate that these isolates may have the potential for use in bioremediation of pesticide contaminated soil.     

Spatial distributions,source apportionment and ecological risk of SVOCs in water and sediment from Xijiang River,Pearl River Delta

Xijiang River is an important drinking water source in Guangxi Province, China. Along the Xijiang River and surrounding tributary, the pollution profile of three important groups of semi-volatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), was analyzed. Relatively low levels of PAHs (64–3.7 × 10² ng L^?1) and OCPs (16–70 ng L^?1), but high levels of PAEs (7.9 × 10²–6.8 × 10³ ng L^?1) occurred in the water. Comparatively, low levels of OCPs (39–1.8 × 10² ng g^?1) and PAEs (21–81 ng g^?1), but high levels of PAHs (41–1.1 × 10³ ng g^?1) were found in sediment. Principal component analyses for source identification indicated petroleum-derived residues or coal and biomass combustion, and vehicular emission was the main sources for PAHs. The OCPs sources of each category were almost independent, whereas the new input of HCHs and p,p′-DDTs probably existed in some areas. PAEs were mainly originated from personal care products of urban sewage, plastic and other industrial sources. Ecological risk through the risk quotient analysis indicated a small or significant potential adverse effect on fish, daphnia and green algae. Nevertheless, the integrated risk of all pollutants should be taken into account in future study.     

Polybrominated diphenyl ethers in plastic products,indoor dust,sediment and fish from informal e-waste recycling sites in Vietnam: a comprehensive assessment of contamination,accumulation pattern,emissions, and human exposure

Residue concentrations of polybrominated diphenyl ethers (PBDEs) in different kinds of samples including consumer products, indoor dust, sediment and fish collected from two e-waste recycling sites, and some industrial, urban and suburban areas in Vietnam were determined to provide a comprehensive assessment of the contamination levels, accumulation pattern, emission potential and human exposure through dust ingestion and fish consumption. There was a large variation of PBDE levels in plastic parts of obsolete electronic equipment (from 1730 to 97,300 ng/g), which is a common result observed in consumer plastic products reported elsewhere. PBDE levels in indoor dust samples collected from e-waste recycling sites ranged from 250 to 8740 ng/g, which were markedly higher than those in industrial areas and household offices. Emission rate of PBDEs from plastic parts of disposed electronic equipment to dust was estimated to be in a range from 3.4 × 10^?7 to 1.2 × 10^?5 (year^?1) for total PBDEs and from 2.9 × 10^?7 to 7.2 × 10^?6 (year^?1) for BDE-209. Some fish species collected from ponds in e-waste recycling villages contained elevated levels of PBDEs, especially BDE-209, which were markedly higher than those in fish previously reported. Overall, levels and patterns of PBDE accumulation in different kinds of samples suggest significant emission from e-waste sites and that these areas are potential sources of PBDE contamination. Intakes of PBDEs via fish consumption were generally higher than those estimated through dust ingestion. Intake of BDE-99 and BDE-209 through dust ingestion contributes a large proportion due to higher concentrations in dust and fish. Body weight normalized daily intake through dust ingestion estimated for the e-waste recycling sites (0.10–3.46 ng/day/kg body wt.) were in a high range as compared to those reported in other countries. Our results highlight the potential releases of PBDEs from informal recycling activities and the high degree of human exposure and suggest the need for continuous investigations on environmental pollution and toxic impacts of e-waste-related hazardous chemicals.     

Seasonal variations in physicochemical characteristics and cyanobacterial diversity of a lake in Northern India

Physicochemical analyses and cyanobacterial diversity of Ramgarh Lake water were performed at five sampling sites during winter, summer, and monsoon seasons. Higher load of solids, carbon, and nutrients were persistent throughout the analysis that indicates the conversion of lake from oligotrophic to eutrophic nature. High nutrients load enhanced cyanobacterial biomass, while low nutrients load produced relatively less biomass. The physicochemical parameters of water samples revealed minimum 2.9 mg L^?1 dissolved oxygen (DO) at site-1 during summer, while maximum (5.6 mg L^?1) at site-4 in monsoon season. Maximum biochemical oxygen demand (BOD) (40 mg L^?1) and chemical oxygen demand (COD) (126 mg L^?1) were recorded at site-1 during summer, whereas minimum BOD (18 mg L^?1) and COD (52 mg L^?1) were evident at site-3 in monsoon season. Minimum concentration of nitrate (0.72 mg L^?1) was recorded at site-3 in summer, whereas maximum 2.7 mg L^?1 was present at site-5 in winter season. The phosphate concentration was maximum (0.52 mg L^?1) at site-5 in summer, and minimum (0.18 mg L^?1) was observed at site-4 in monsoon season. Cyanobacterial diversity was higher during all the seasons, and dominated by the species of Microcystis at all the five sampling sites.     

Seasonal concentrations of lead in outdoor and indoor dust and blood of children in Riyadh,Saudi Arabia

Because detrimental effects of exposure to lead (Pb) on human health have been observed, we previously investigated concentrations of Pb in water supplies and blood of adult residents of Riyadh, Saudi Arabia. The objectives of the present study were to: (1) examine seasonal rates of deposition of Pb in dust in several areas of Riyadh city, (2) measure concentrations of Pb in both outdoor and indoor dust, (3) compare concentrations of Pb in dust in Riyadh with those reported for other cities, and (4) quantify Pb in blood of children living in Riyadh. Mean, monthly deposition of PB in outdoor dust was 4.7 × 10¹ ± 3.6 tons km^?2, with a mean Pb concentration of 2.4 × 10² ± 4.4 × 10¹ μg/g. Mean, monthly deposition of Pb in indoor dust was 2.7 ± 0.70 tons km^?2, with a mean concentration of 2.9 × 10¹ ± 1.5 × 10¹ μg Pb/g. There was a significant (P < 0.01) correlation between concentrations of Pb in outdoor and indoor dust. There was no correlation between concentrations of Pb in indoor dust and that in blood of children of Riyadh, whereas there was a weakly significant (P < 0.05) correlation between concentrations of Pb in outdoor dust and that in blood of children. The mean (±SD) concentration of Pb in blood of children in Riyadh was 5.2 ± 1.7, with a range of 1.7–1.6 × 10¹ μg/dl. Concentrations of Pb in blood of 17.8 % of children in Riyadh were greater than 10 μg/dl, which is the CDC’s level of concern.     

The evolution of pollution profile and health risk assessment for three groups SVOCs pollutants along with Beijiang River,China

Three important groups of semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), organic chlorinated pesticides (OCPs) and phthalate esters (PAEs), were produced by various human activities and entered the water body. In this study, the pollution profiles of three species including 16 PAHs, 20 OCPs and 15 PAEs in water along the Beijiang River, China were investigated. The concentrations of Σ₁₆PAHs in the dissolved and particulate phases were obtained as 69–1.5 × 10² ng L^?1 and 2.3 × 10³–8.6 × 10⁴ ng g^?1, respectively. The levels of Σ₂₀OCPs were 23–66 ng L^?1 (dissolved phase) and 19–1.7 × 10³ ng g^?1 (particulate phase). Nevertheless, higher levels of PAEs were found both in the dissolved and particulate phases due to abuse use of plastic products. Furthermore, non-cancer and cancer risks caused by these SVOCs through the ingestion absorption and dermal absorption were also assessed. There was no non-cancer risk existed through two kinds of exposure of them at current levels, whereas certain cancer risk existed through dermal absorption of PAHs in the particulate phase in some sampling sites. The results will show scientific insights into the evaluation of the status of combined pollution in river basins, and the determination of strategies for incident control and pollutant remediation.     

Effects of ethyl 2-methyl acetoacetate (EMA) on the growth of Phaeodactylum tricornutum and Skeletonema costatum

We investigated the effects of ethyl 2-methyl acetoacetate (EMA) on growth of the marine diatom algae Phaeodactylum tricornutum (P. tricornutum) and Skeletonema costatum (S. costatum). Growth of P. tricornutum was significantly inhibited by the minimum concentration (3.5 mmol·L ^?1) of EMA at lower initial algal densities (IADs) (3.6×10⁴ and 3.3×10⁵ cells·mL ^?1). However, at the highest IAD, significant growth inhibition was found at above 7 mmol·L ^?1 of EMA exposure. In S. costatum, EMA concentrations of 10.5 mmol·L ^?1 or more significantly inhibited growth at lower IAD (3×10⁴ and 1.8×10⁵ cells·mL ^?1); at the highest IAD, only EMA concentrations above 14 mmol·L ^?1 obviously inhibited the growth of S. costatum. Changes in specific growth rates and pigment were consistent with algal growth, but only at higher EMA concentrations or lower IAD values was the ratio of chlorophyll a (Chla) to carotenoid significantly lower than the control. Medium effective concentration (EC ₅₀) values were in the order 4.07, 8.03 and 12.27 mmol·L ^?1 for P. tricornutum and 7.48, 11.92 and 17.22 mmol·L ^?1 for S. costatum. All these results show that the effect of EMA on the growth of algae was species specific and mainly depended on IAD, which might be an important factor to influence algal growth.     

Mercury pollution in the Sonbhadra district of Uttar Pradesh,India, and its health impacts

The Sonbhadra district in the Singrauli area of Uttar Pradesh, India, has many coal mines and thermal power plants and is a critically polluted area. Many residents of this area reported adverse health conditions which may be linked to metal pollution, especially of mercury investigated here.

In May 2012, samples of water (23), soil (7), blood, hair, and nails from persons showing adverse health conditions selected at random were collected and analyzed for total mercury by atomic absorption spectrometry.

Twenty percent drinking water samples contained mercury from 3 to 26 μg L^?1 (3–26 times the permissible limit). Soil samples had 0.5–10.1 mg kg^?1 Hg.

The average concentrations of mercury in human blood, hair, and nails were found to be 34 μg L^?1, 7.4 mg kg^?1, and 0.8 mg kg^?1, respectively. Mercury concentrations in the blood of these persons were 45 and 28 μg L^?1 on average in the case of men and women. This is much higher than the safe level of 5.8 μg L^?1 set by the United States Environmental Protection Agency (USEPA).

It was concluded that all residents of Sonbhadra sampled could be suffering from mercury toxicity as the area is polluted by Hg released from the coal-fired thermal power plants.     

Solar-induced generation of singlet oxygen and hydroxyl radical in sewage wastewaters

Singlet oxygen (¹O₂) and hydroxyl radical (·OH) play an important role in the degradation of pollutants in surface waters. However, the mechanism underlying the photochemical generation of ¹O₂ and ·OH in wastewaters is poorly known. Here we studied the photo-induced generation of ¹O₂ and ·OH in different sewage treatment plant units. The correlation between the generation of ¹O₂ and ·OH and the water constituents was discussed. Our results show that in sewage units the ¹O₂ formation rate ranges from 2.19 × 10^?8 to 6.74 × 10^?8 mol L^?1 s^?1, and the ·OH formation rate ranges from 1.7 × 10^?11 to 3.06 × 10^?10 mol L^?1 s^?1. The average ¹O₂ formation rates in the various sewage units are similar to those in wetland and estuarine waters containing rich dissolved organic matter and 2–4 times higher than those in lake and seawater samples. The average ·OH formation rates of the sewage units are 5–50 times higher than for other water samples reported. The ·OH generation rate increased with the iron content with a correlation coefficient of 0.85, which indicates that the photo-Fenton reaction plays a dominant role in ·OH generation in sewage wastewater.     

Environmental impact of CO<Subscript>2</Subscript>, Rn,Hg degassing from the rupture zones produced by Wenchuan <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript> 8.0 earthquake in western Sichuan,China

The concentrations and flux of CO₂, ²²²Radon (Rn), and gaseous elemental mercury (Hg) in soil gas were investigated based on the field measurements in June 2010 at ten sites along the seismic rupture zones produced by the May 12, 2008, Wenchuan M _s 8.0 earthquake in order to assess the environmental impact of degassing of CO₂, Rn and Hg. Soil gas concentrations of 344 sampling points were obtained. Seventy measurements of CO₂, Rn and Hg flux by the static accumulation chamber method were performed. The results of risk assessment of CO₂, Rn and Hg concentration in soil gas showed that (1) the concentration of CO₂ in the epicenter of Wenchuan M _s 8.0 earthquake and north end of seismic ruptures had low risk of asphyxia; (2) the concentrations of Rn in the north segment of seismic ruptures had high levels of radon, Maximum was up to level 4, according to Chinese code (GB 50325-2001); (3) the average geoaccumulation index I _geo of soil Hg denoted the lack of soil contamination, and maximum values classified the soil gas as moderately to strongly polluted in the epicenter. The investigation of soil gas CO₂, Rn and Hg degassing rate indicated that (1) the CO₂ in soil gas was characterized by a mean \(\updelta^{13}C_{CO2}\) of ?20.4 ‰ and by a mean CO₂ flux of 88.1 g m^?2 day^?1, which were in the range of the typical values for biologic CO₂ degassing. The maximum of soil CO₂ flux reached values of 399 g m^?2 day^?1 in the epicenter; (2) the soil Rn had higher exhalation in the north segment of seismic ruptures, the maximum reached value of 1976 m Bq m^?2 s^?1; (3) the soil Hg flux was lower, ranging from ?2.5 to 18.7 n g m^?2 h^?1 and increased from south to north. The mean flux over the all profiles was 4.2 n g m^?2 h^?1. The total output of CO₂ and Hg degassing estimated along seismic ruptures for a survey area of 18.17 km² were approximately 0.57 Mt year^?1 and 688.19 g year^?1. It is recommended that land-use planners should incorporate soil gas and/or gas flux measurements in the environmental assessment of areas of possible risk. A survey of all houses along seismic ruptures is advised as structural measures to prevent the ingress of soil gases, including CO₂ and Rn, were needed in some houses.     

Long-term assessment of the environmental fate of heavy metals in agricultural soil after cessation of organic waste treatments

The current study examined the anthropogenic accumulation and natural decrease in metal concentrations in agricultural soils following organic waste application. Three common organic wastes, including municipal sewage sludge, alcohol fermentation processing sludge, and pig manure compost (PMC), were applied annually to an agricultural soil under field conditions over 7 years (1994–2000) at a rate of 12.5, 25, and 50 ton ha^?1 year^?1 and the soil accumulation of three metals of concern (Cu, Pb, and Zn) was monitored. Subsequently, organic waste amendments ceased and the experimental plots were managed using conventional fertilization for another 10 years (2001–2010) and the natural decrease in metal concentrations monitored. Although Cu and Zn concentrations in all experimental plots did not exceed the relevant guideline values (150 mg kg^?1 for Cu and 300 mg kg^?1 for Zn), significant increases in metal concentrations were observed from cumulative application of organic wastes over 7 years. For instance, PMC treatment resulted in an increase in Cu and Zn from 9.8 and 72 mg kg^?1 to 108.2 and 214.3 mg kg^?1, respectively. In addition, the natural decrease in Cu and Zn was not significant as soils amended with PMC showed only a 16 and 19 % decline in Cu and Zn concentrations, respectively, even 10 years after amendment ceased. This research suggested that more attention must be paid during production of organic waste-based amendments and at the application stage.     

Influence of slope aspect on soil physico-chemical and biological properties in the mid hills of central Nepal

This study assessed the influence of slope aspect and land use on soil physio-chemical and biological properties (soil quality indicators) on contiguous south- and north-facing slopes of the mid hills in central Nepal, having the same climate, vegetation and parent material. In each aspect, two treatments (agriculture and forest) were chosen and four replicates taken for each treatment. Soil sample collection and microarthropod extraction was done according to the standard methodology: soil core samples (10 × 10 × 5 cm) and extraction with the modified Berlese–Tullgren funnel. The investigated soil variables were temperature, moisture, faunal abundance and diversity, organic matter, organic carbon, bulk density and pH. Except in a few cases, all considered soil properties showed significant differences between aspects and land use. Soils of the north-facing slope had higher SOC content, moisture, faunal abundance and diversity, and lower temperature and pH. Variations due to topographic aspect induced varied microclimates, causing differences in faunal abundance and diversity; soil moisture, temperature and organic matter trends affected soil fertility and ultimately soil quality. Further studies are required to clarify the complex interactions between soil properties (physio-chemical and biological), vegetation and slope aspect in Nepal, as well as to develop soil biological indicators as a tool to assist in sustainable land management.     

贵阳市西郊水厂所供管网末梢水重金属污染物季节性特征及潜在健康风险评价

以贵阳市西郊水厂2014年3月和7月所供管网末梢水中10种重金属污染物检测数据为基础,进行了季节性特征分析,并采用美国环保局(USEPA)推荐的健康风险评价模型进行了潜在健康风险评价。结果表明,贵阳市西郊水厂所供管网末梢水中10种重金属的浓度均符合国家饮用水卫生标准;重金属污染物的浓度随季节呈现出不同的特征,汞、锌、硒、钼和钡5种重金属的平均浓度呈现枯水期高于丰水期的特征,而铅、铜、锰和镍4种重金属正好相反,砷浓度的季节性特征不显著;成年人的年平均致癌风险显著大于儿童,但两者年平均非致癌风险接近;儿童和成年人2类人群经口暴露途径的健康风险值均大于皮肤暴露,其中致癌风险分别在2.49×10-6~9.16×10-6和3.26×10-8~9.59×10-8之间,非致癌风险在2.29×10-8~3.20×10-8和1.85×10-10~4.14×10-10之间,且致癌风险均大于非致癌风险。贵阳市西郊水厂所供管网末梢水中10种重金属污染物致癌风险和非致癌风险均未超过最大可接受水平,未对该供水区居民的健康造成威胁。