Antibiotic and metal resistance of Stenotrophomonas maltophilia isolates from Eboling permafrost of the Tibetan Plateau

Environmental Science and Pollution Research - Whole-genome sequencing of pathogenic bacteria Stenotrophomonas maltophilia from a less polluted environment of permafrost can help understand the...     

Distribution and speciation of mercury in the peat bog of Xiaoxing'an Mountain,northeastern China

Most reports on mercury (Hg) in boreal ecosystems are from the Nordic countries and North America. Comparatively little information is available on Hg in wetlands in China. We present here a study on Hg in the Tangwang River forested catchment of the Xiaoxing'an Mountain in the northeast of China. The average total Hg (THg) in peat profile ranged from 65.8 to 186.6 ng g(-1) dry wt with the highest at the depth of 5-10 cm. THg in the peat surface was higher than the background in Heilongjiang province, the Florida Everglades, and Birkeness in Sweden. MethylHg (MeHg) concentration ranged from 0.16 to 1.86 ng g(-1) dry wt, with the highest amount at 10-15 cm depth. MeHg content was 0.2-1.2% of THg. THg and MeHg all decreased with the depth. THg in upland layer of soil (0-20 cm) was comparable to the peat surface, but in deeper layers THg concentration in peat was much higher than that in the forested mineral soil. THg in the peat bog increased, but MeHg decreased after it was drained. THg content in plant was different; THg contents in moss (119 ng g(-1) dry wt, n=12) were much higher than in the herbage, the arbor, and the shrubs. The peat bog has mainly been contaminated by Hg deposition from the atmosphere.     

Polybrominated diphenyl ethers (PBDEs) and mercury in fish from lakes of the Tibetan Plateau

High mountains may act as cold traps for globally transported persistent organic pollutants (POPs) and mercury (Hg). In the present study, 60 fish samples were collected from eight alpine lakes across the Tibetan Plateau. Concentrations of polybrominated diphenyl ethers (PBDEs), total mercury (HgT) and methyl mercury (MeHg) were quantified in the fish muscle tissues to improve the understanding of pollution status and factors regulating the transport and fate of these contaminants on the Plateau. The results showed that lake-averaged ∑₁₄PBDEs concentration was between 0.09 ng g⁻¹ dw and 4.32 ng g⁻¹ dw, which was lower than those reported for European mountains. The total mercury concentration in individual fish ranged from 243 to 2384 ng g⁻¹ dw, and that of MeHg from 131 to 1610 ng g⁻¹ dw, which is much higher than those reported in other mountain fish. The spatial variation of PBDEs and mercury in the Plateau is largely controlled by the specific meteorological patterns.     

Elemental composition of Tibetan Plateau top soils and its effect on evaluating atmospheric pollution transport

The Tibetan Plateau (TP) is an ideal place for monitoring the atmospheric environment of low to mid latitudes. In total 54 soil samples from the western TP were analyzed for major and trace elements. Results indicate that concentrations of some typical “pollution” elements (such as As) are naturally high here, which may cause incorrect evaluation for the source region of these elements, especially when upper continental crust values are used to calculate enrichment factors. Because only particles <20 μm are transportable as long distances, elemental concentrations of this fraction of the TP soils are more reliable for the future aerosol related studies over the TP. In addition, REE compositions of the TP soils are unusual, highly characteristic and can be used as an effective index for identifying dust aerosol from the TP.     

Distribution of organochlorine pesticides (OCPs) in conifer needles in the southeast Tibetan Plateau

Twenty-nine conifer needles in mountain-valley areas from the southeastern Tibet were collected with altitude span from 1520 to 4340m above sea level (m.a.s.l.). They were analyzed for organochlorine pesticides (OCPs), including hexachlorocyclohexanes (alpha-, beta-, gamma- and delta-HCH), dichlorodiphenyltrichloroethane (p,p'-DDE, p,p'-DDD, o,p'-DDT and p,p'-DDT) and hexachlorobenzene (HCB). Concentrations of OCPs in samples ranged from 0.69 to 4.3 ng/g, from 0.39 to 4.9 ng/g and from 1.9 to 20.5 ng/g (dry weight) for HCB, total HCHs and DDTs, respectively. The levels of DDTs found here were noticeably higher than those from other high mountainous regions. Composition of HCH isomers and DDTs was analyzed, and it was found that the high ratio of o,p'-DDT/p,p'-DDT might be caused by the application of dicofol in adjacent regions. A number of environmental factors controlling the distribution of OCPs in regional scale were also discussed in this paper.     

One century sedimentary records of polycyclic aromatic hydrocarbons, mercury and trace elements in the Qinghai Lake, Tibetan Plateau

Sediments from a remote lake of northeastern Tibetan Plateau were analyzed for polycyclic aromatic hydrocarbons (PAHs) and trace metals. USEPA priority PAHs, ranged from 11 in 1860 to 279 ng g⁻¹ in 2002, while, the deposition fluxes were in the range of 0.2-11.4 ng cm⁻² yr⁻¹. Similarly, from 1860 to 2002, an increased trend of Hg flux was observed (0.5-3.2 ng cm⁻² yr⁻¹). Remarkable increase of PAHs and Hg concentration began from 1970, nearly the same period of the “Reform and Open” Policy had been embarked (1978) in China. Good correlations were found between concentrations of Pb, Zn, Cd, As, Hg, and PAHs, which suggested the sources of these chemicals in the sediment is analogous, likely from anthroprogenic sources. Based on isomer ratios, PAHs in core were dominantly from the incomplete combustion of coal. Owing to the proximity to dust source area (Qaidam Basin) and the close association between PAHs, Hg, Pb, and particle matters, atmospheric dust-transport and deposition might be the main pathways that pollutants enter into Qinghai Lake.     

成都东郊稻田土中汞的分布特征研究

选取成都东郊唯一的火力发电厂周围的稻田土为研究对象,对稻田土中各种形态汞的分布特征进行了调查与研究,探讨稻田土中汞的分布规律,为分析和判断稻田土中汞的迁移和转化行为及该区汞污染土壤的修复提供重要依据。结果表明,处于火力发电厂烟尘排污口下风向的1#、2#、3#、4#采样点土样受到了严重的汞污染,呈现出高含汞特征,总汞平均质量浓度在9～41mg/kg,平均值为24.546mg/kg,远远超出《土壤环境质量标准》(GB 15618—1995)二级标准所规定的限值(0.5mg/kg),而处于排污口上风向的5#、6#、7#、8#土样没有受到明显的汞污染,大部分土样的总汞含量与成都市土壤汞平均含量接近;1#、2#、3#、4#土样中5种形态汞的垂直分布均呈现出随着土壤深度增加而减少的特征;1#、2#、3#、4#土样中的各形态汞平均百分比为有机结合态汞>硝酸溶汞>残渣态汞>铁锰氧化态汞>水溶和可交换态汞,土壤中含有的大部分汞化学性质比较稳定,难以被植物吸收利用,而易被植物吸收利用的水溶和可交换态汞虽然仅占极小一部分,但含量还是高于成都市土壤中水溶和可交换态汞的背景值。     

Elemental composition of aerosol in the Nam Co region,Tibetan Plateau,during summer monsoon season

In order to investigate the chemical characteristics of atmospheric aerosols in a remote region of the Tibetan Plateau, total suspended particles were collected continuously at the Nam Co Comprehensive Observation and Research Station from July to October 2005. The PIXE analytical results showed that Si, Ca, Fe, Al, K, and S were the major components of aerosols, ranging from 82 (K)–550 (Si) ng m⁻³. The mean elemental concentrations were comparable with those from other remote sites and significantly lower than those from megacities (e.g. Beijing). The very low presence of anthropogenic elements demonstrates that the Nam Co region is an ideal background site for atmospheric monitoring. Crustal enrichment factor (EF) calculation indicated that several anthropogenic heavy metals (Cr, Ni, Cu, Zn, As) are transported long distances atmospherically. The backward air mass trajectory analysis suggests that South Asia may be the source region of those pollutants.     

Characteristics and management of domestic waste in a rural area of the Tibetan Plateau

In the rural area of the Tibetan Plateau (RATP), the characteristics of domestic waste, people’s environmental awareness, people’s willingness to pay and their influence factors were firstly studied by questionnaires, field samplings and laboratory tests. The results showed that, in the RATP, the generation of domestic waste was 85 g?d-1 per capita and it was mainly composed of plastics, inert waste, kitchen waste, glass and paper. The waste bulk density, moisture content, ash, combustible and low calorific value were 65 kg?m-3, 19.25%, 44.90%, 35.85% and 10,520 kJ?kg-1 respectively. These characteristics are influenced by income sources and geographical position to some extent. Classified collection should be promoted widely on the household and the village basis. Compost, fermentation, landfill, bioreactor landfill and semi-aerobic landfill have been approved as effective techniques to treat domestic waste, except incineration. The distance of 50–800 m between each collection facility and the disposal fee of around $0.8 per month per household are suggested. For suburbs or large population villages, it’s better to treat domestic waste by the centralized way. But for the remote rural areas, a decentralized way is proposed. Significantly, the educational and economic influence should be considered into an effective domestic waste management program.

Implications:?The current situatio n of the environment in the rural areas of the Tibetan Plateau (RATP) was surveyed. There, the generation of organics and moisture of domestic waste were low but ash, recyclables, and combustibles were high. People’s knowledge of domestic waste was absent but their participation in management was strong. Based on the current situation, compost, fermentation, and landfill were effective but incineration was inappropriate. Also, a localized mini landfill for a cluster of villages and or settlements was the best method there.     

Transformations of elemental mercury to inorganic and organic forms in mercury and hydrocarbon co-contaminated soils.

There are many industrial sites, such as gas processing plants, that are contaminated with both mercury and hydrocarbons. These sites tend to be localized but can have very high concentrations of mercury in the soil and heterogeneous distribution of hydrocarbons. The original form of mercury in many cases was elemental mercury from broken manometers. Over time the mercury has become redistributed within soil and has undergone chemical transformations into new forms. The forms of mercury will govern the chemical behavior and the availability of the mercury to biological receptors. The availability of the mercury is important as it will govern the risk associated with the contaminated soil and will also determine the effectiveness of any attempts at remediation. In the present study a chemical extraction protocol was used to determine the forms of mercury in soil originally contaminated by spillage of elemental mercury and petroleum hydrocarbons. Chemical extractions have been used in the past to determine the forms of mercury in uncontaminated soils and several researchers have used them to study contaminated soils. However, to date, no researchers have studied the forms of mercury in soils following years of weathering of elemental mercury after a spill. This study shows that decades after the original spill the elemental mercury has transformed and is dominantly (up to 85%) associated with soil organic matter, and to a lesser extent the mineral fraction of soil.     

重金属元素在冻土与融土中迁移的对比试验

随着寒区经济的发展,冻土地区的矿山开采活动不断加剧,随之产生的重金属污染问题也越来越严重.冻土地区生态环境脆弱,一旦受到破坏就很难恢复.针对此问题,室内模拟了尾矿矿渣在冻土与融土中的填埋及其对填埋场周边土体的影响,通过检测填埋场各处土壤的温度、含水量以及重金属元素的含量,发现温度和水分对重金属元素的迁移影响很大.土壤温度越低,重金属元素的迁移越慢;在温度梯度的作用下,重金属元素均随着水分从土体的暖端向冷端迁徙并聚集于冻结锋面.重金属元素在冻土中的迁移比融土中慢,表明冻土环境不利于重金属元素的迁移.在土壤质地、温度和含水量等相同的情况下,Zn的迁移性较强,Pb和Cu的迁移性相对较弱.     

Atmospheric mercury distribution in Northern Europe and in the Mediterranean region

Mercury species in air have been measured at five sites in Northwest Europe and at five coastal sites in the Mediterranean region during measurements at four seasons. Observed concentrations of total gaseous mercury (TGM), total particulate mercury (TPM) and reactive gaseous mercury (RGM) were generally slightly higher in the Mediterranean region than in Northwest Europe. Incoming clean Atlantic air seems to be enriched in TGM in comparison to air in Scandinavia. Trajectory analysis of events where high concentrations of TPM simultaneously were observed at sites in North Europe indicate source areas in Central Europe and provide evidence of transport of mercury on particles on a regional scale.     

Suppression of precipitation by dust particles originated in the Tibetan Plateau

Dust aerosols play an important role in modulating the hydrologic cycle. The Tibetan Plateau (TP) is little polluted by human activities as an ideal site to study the effect of dust aerosol on precipitation. In this study, observational data of dust storms and precipitation in the TP and its vicinities as well as CALIPSO satellite data were used to analyze the distributions and vertical structure of dust storms on the plateau. The results showed that dust storms occur with high frequency and raise dust particles into the troposphere from ground level to a height of 5–9 km to modulate the hydrologic cycle in the TP. There are significant negative correlations between dust aerosol and precipitation in the dust source regions during the period of both 40 and 200 years. It is found that the role of precipitation in suppressing dust storms could be unimportant, while dust aerosol may play an important role in suppressing precipitation in the hinterland of the TP. Our study provides a potential approach to better understand the climate changes in the TP.     

Sector analysis of pH values in the northeastern region of Puerto Rico

Acid rain precipitation has become a major environmental concern. Many long-range projects in the United States and Europe are devoted to the problems associated with acid rain pollution. In Puerto Rico, there has been no formal study on acid rain. The rainfall pH values and the air-mass trajectory of the northeastern part of the island of Puerto Rico on the surface were analyzed from January 1998 to December 2000. The air-mass trajectory was classified in five different sectors, according to where it originates. The mean pH value measured during that period showed a tendency toward acidity. The 80% of the air-mass trajectory that arrived at the station occurred in Sector I, with a pH value of 4.30. The lowest pH value measured was 4.16, and it occurred in Sector V, where the air mass originates in the northwest part of the island.     

Organochlorine pesticides and PCBs in fish from lakes of the Tibetan Plateau and the implications

High mountains may play significant roles in the global transport of persistent organic pollutants (POPs). This work aims to investigate the levels, patterns and distribution of semi-volatile organoclorine pollutants and to improve the understanding of the long-range atmospheric transport and fate of contaminants on the Tibetan Plateau. A total of 60 fish samples were collected from eight lakes located between 2813 and 4718 m above sea level across the Plateau. Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) including dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were measured in fish muscle. The results showed that concentrations of DDT, HCH and HCB were comparable to or lower than those found in remote mountains of Europe, Canada and US, while PCB concentrations in fish were, on average, about 4-150 times lower on Tibet than at other mountain areas. The transport and fate of contaminants in the Plateau are significantly influenced by the unique climatological and meteorological conditions, particularly by the summer Indian monsoon and winter westerly jet stream.     

Distribution and trends of mercury in deciduous tree cores

The distribution of total mercury (THg) within common deciduous trees and the applicability of tree cores as biomonitors of historical environmental THg trends were assessed for both contaminated and reference sites around Kingston, Ontario. Samples were collected from Acer spp., Quercus spp. Populus spp. and Salix spp. Bark and wood THg concentrations were found to be highly correlated whereas soil and wood THg concentrations were not. There were no temporal relationships for THg in dated tree rings corresponding with any other known environmental Hg trends. The shoreline speciess, Populus and Salix spp., had the greatest bark and wood Hg concentrations reaching 18 ng/g, significantly higher than for inland trees Quercus and Acer spp. with maximum values of 7 and 1.2 ng/g for bark and wood respectively. While tree cores cannot be reliably used as temporal THg biomonitors, there is promise for tree species such as Populus spp and Salix spp as spatial indicators of local long-term Hg contamination.     

Effects of pH, organic acids, and competitive cations on mercury desorption in soils

The effects of pH, organic acids, and competitive cations on Hg(2+) desorption were studied. Three representative soils for rice production in China, locally referred to as a yellowish red soil (YRS), purplish clayey soil (PCS), and silty loam soil (SLS) and classified as Gleyi-Stagnic Anthrosols in FAO/UNESCO nomenclature, were, respectively, collected from Jiaxin County, Deqing County, and Xiasha District of Hangzhou City, Zhejiang Province. Most of the added Hg(2+) was adsorbed at low initial concentrations (<2 mg l(-1)). Desorption of the adsorbed Hg(2+) in 0.01M KCl (simulating soil solution) was minimal, but was significantly enhanced by the change of pH, and the presence of organic acids or competitive cations. The desorption of Hg(2+) in the soils decreased with pH from 3.0 to 5.0, leveled off at pH 5.0-8.0, but increased with pH from 7.0 to 9.0. The presence of organic ligands enhanced Hg(2+) desorption in the soils except for YRS, in which the addition of tartaric, malic, or oxalic acid reduced Hg(2+) desorption at low concentrations (<10(-4)M), but Hg(2+) desorption generally increased with organic acid concentration. Citric acid was most effective in increasing Hg(2+) desorption, followed by tartaric acid and malic acid; and oxalic acid was the least effective. Desorption of adsorbed Hg(2+) increased with increasing concentrations of added Cu(2+) or Zn(2+). Applied Cu(2+) increased Hg(2+) desorption more than Zn(2+) at the same loading rate. CAPSULE: The effects of organic acids and competitive cations on Hg desorption in soil-water system are related to their concentrations, basic chemical properties, and soil properties.     

Water quality in the Tibetan Plateau: metal contents of four selected rivers

The water used by 85% of the Asian population originates in Tibetan Plateau. During April and May of 2006, water samples were collected from four major Asian rivers in the Plateau (i.e. the Salween, Mekong, Yangtze River and Yarlung Tsangpo) and analyzed for Cu, Pb, Zn, Ag, Mo, Cd, Co, Cr, Ni, Li, Mn, Al, Fe, Mg and Hg. The results showed that elements such as Mg were rather high in Tibetan rivers, giving a mean electrical conductance of 36 mS/m. In a few locations, the results also showed relatively high concentrations of Al and Fe (>1 mg/L). However, the concentrations of Cu, Zn, Ag, Cd, and Cr were generally low. Contamination with Pb was identified at a few locations in the Salween and Ni at a few sites in the Yangtze River.     

Potential application of a semi-quantitative method for mercury determination in soils, sediments and gold mining residues

An alternative, low cost method for analyzing mercury in soil, sediment and gold mining residues was developed, optimized and applied to 30 real samples. It is semiquantitative, performed using an acid extraction pretreatment step, followed by mercury reduction and collection in a detecting paper containing cuprous iodide. A complex is formed with characteristic color whose intensity is proportional to mercury concentration in the original sample. The results are reported as range of concentration and the minimum detectable is 100 ng/g. Method quality assurance was performed by comparing results obtained using the alternative method and the Cold Vapor Atomic Absorption Spectrometry techniques. The average results from duplicate analysis by CVAAS were 100% coincident with alternative method results. The method is applicable for screening tests and can be used in regions where a preliminary diagnosis is necessary, at programs of environmental surveillance or by scientists interested in investigating mercury geochemistry.