The microbial role in hot spring silicification

Recent experimental studies indicate that microorganisms play a passive role in silicification. The organic functional groups that comprise the outer cell surfaces simply serve as heterogeneous nucleation sites for the adsorption of polymeric and/or colloidal silica, and because different microorganisms have different cell ultrastructural chemistry, species-specific patterns of silicification arise. Despite their templating role, they do not appear to increase the kinetics of silicification, and at the very most, they contribute only marginally to the magnitude of silicification. Instead, silicification is due to the polymerization of silica-supersaturated hydrothermal fluids upon discharge at the surface of the hot spring. Microorganisms do, however, impart an influence on the fabric of the siliceous sinters that form around hot spring vents. Different microorganisms have different growth patterns, that in turn, affect the style of laminations, the primary porosity of the sinter and the distribution of later-stage diagenetic cementation.     

A silent epidemic of environmental metal poisoning?

The main objective of this paper is to provoke and stimulate debate on the health effects of long-term, low-level exposure of human populations to toxic metals. Over one billion (10(9)) human guinea pigs are now being exposed to elevated levels of toxic metals and metalloids in the environment. The number of persons suffering from subclinical metal poisoning is believed to be several million. A large portion of the cases are in developed countries but the urban areas of developing countries have become 'hot-spots' of metal pollution, and the populations of such countries are particularly susceptible to environmental toxins. As a global problem, the potential health effects of metallic hazards should be a matter of public health concern, especially if the emissions of toxic metals into the environment continue at the current rate.     

Arsenic and chlordecone contamination and decontamination toxicokinetics in Sargassum sp.

Environmental Science and Pollution Research - Massive Sargassum sp. beachings have been occurring on Caribbean shores since 2011. The sargassum involved in such events are S. fluitans and S....     

固定化鼠尾藻Sargassum thunbergii对水中重金属锌的生物吸附效应

采用海藻酸钠-聚乙烯醇联合固定鼠尾藻与活性炭的方法对废水中重金属Zn2+进行生物吸附研究。结果表明：当固定化材料配比为15 g·L-1鼠尾藻粉,2%海藻酸钠溶液、6%聚乙烯醇溶液,1.5%活性炭时,固定化小球对废水中Zn2+的吸附率最大。溶液在不同环境因素条件下吸附率不同,吸附率随着pH升高而升高,当pH为6时吸附率达到最大,随后开始下降;当温度为30 ℃,投放量为60 g·L-1时吸附率上升至最大值后趋于平衡,吸附率不再随着条件的增加而增加;前30 min吸附过程为快速吸附阶段,并在60 min后吸附率趋于平衡。在实验室规模的流化生物反应器中,固定化颗粒可以连续高效处理模拟矿山废水,同时经过多次吸附解吸循环后仍然具有较好的吸附效果,为固定化鼠尾藻的实际应用奠定了基础。     

The accumulation of alkylphenols in submersed plants in spring in urban lake, China

The concentrations of alkylphenols (APs) were investigated in water, sediments and submersed macrophytes from the Moon Lake, Wuhan city, China. The water samples contained APs, ranging up to 26.4 microg l-1 for nonylphenol (NP) and 0.68 microg l-1 for octylphenol (OP). APs were found in the sediment samples with concentrations ranging from 4.08 to 14.8 for NP and from 0.22 to 1.25 microg g-1 dry weight for OP. The samples from the site near former sewage inlet showed the highest concentrations of APs in both water and sediments. The results of distribution pattern and dynamics of NP and OP in submersed macrophytes of the Moon Lake showed that the two pollutants were all found in Myriophyllum verticillatum, Elodea nuttallii, Ceratophyllum oryzetorum, and Potamageton crispus collected from the Moon Lake. For NP, M. verticillatum had the highest capacity of accumulation, followed by E. nuttallii, C. oryzetorum and P. crispus. However the distribution pattern of OP differed from that of NP, and the highest amount of accumulation was observed in E. nuttallii, followed by M. verticillatum, P. crispus, and C. oryzetorum. The temporal pattern of APs was also observed in submersed macrophytes from March to May, and the highest accumulation period was in May.     

The sensitivity of soil enzymes,microorganisms and spring wheat to soil contamination with carfentrazone-ethyl

Herbicides pose a significant threat to the natural environment, in particular in soils that are most exposed to plant protection agents. Prolonged herbicide use leads to changes in soil metabolism and decreases soil productive potential. In this study, the influence of carfentrazone-ethyl (CE) on the microbiological and biochemical properties of soil and the yield of Triticum aestivum L. was evaluated. Carfentrazone-ethyl was applied to sandy loam (pH_KCl – 7.0) in doses of 0.000, 0.264, 5.280, 10.56, 21.18, 42.24, 84.48 and 168.96 µg kg^?1 DM soil. Soil samples were subjected to microbiological and biochemical analyses on experimental days 30 and 60. Carfentrazone-ethyl disrupted the biological equilibrium in soil by decreasing the abundance and biodiversity of soil-dwelling microorganisms, the activity of soil enzymes, the values of the biochemical activity indicator and spring wheat yields. Carfentrazone-ethyl had the most adverse effects when applied in doses many fold higher than those recommended by the manufacturer. The toxic effects of CE were also determined by its soil retention time. Soil treated with CE was characterized by higher counts of oligotrophic bacteria, organotrophic bacteria, bacteria of the genus Azotobacter, actinomycetes and fungi on day 60, and spore-forming oligotrophic bacteria on day 30. The activity of dehydrogenases, urease, alkaline phosphatase and β-glucosidase was higher on day 30 than on day 60.     

Mobility of dimethoate residues from spring broccoli field

Dimethoate [O, O-dimethyl-S-(N-methylcarbamoyl-methyl) phosphorodithioate] is a broad-spectrum systemic insecticide currently used worldwide and on many vegetables in Kentucky. Dimethoate is a hydrophilic compound (log K_OW = 0.7) and has the potential of offsite movement from the application site into runoff and infiltration water. The dissipation patterns of dimethoate residues were studied on spring broccoli leaves and heads under field conditions. Following foliar application of Dimethoate 4E on broccoli foliage at the rate of 0.47 L acre^?1, dimethoate residues were monitored in soil, runoff water collected down the land slope, and in infiltration water collected from the vadose zone. The study was conducted on a Lowell silty loam soil (pH 6.9) planted with broccoli under three soil management practices: (i) soil mixed with municipal sewage sludge, (ii) soil mixed with yard waste compost, and (iii) no-mulch rototilled bare soil. The main objective of this investigation was to study the effect of mixing native soil with municipal sewage sludge or yard waste compost, having considerable amounts of organic matter, on off-site movement of dimethoate residues into runoff and infiltration water following spring rainfall. The initial deposits of dimethoate were 6.2 and 21.4 μ g g^?1 on broccoli heads and leaves, respectively. These residues dissipated rapidly and fell below the maximum residue limit of 2 μ g g^?1 on the heads and leaves after 10 and 14 d, respectively, with half-lives of 5.7 d on broccoli heads and 3.9 d on the leaves. Dimethoate residues detected in top 15 cm of soil (due to droplet drift and wash off residues from broccoli foliage) one day (d) following spraying, were 30.5 ng g^?1 dry soil in the sewage sludge treatment, and 46.1 and 134.5 ng g^?1 dry soil in the yard waste and no mulch treatments, respectively. Water infiltration was greater from yard waste compost treatment than from no mulch treatment, however concentrations of dimethoate in the vadose zone of the three soil treatments did not differ.     

北京市春季大气颗粒物污染特性研究

为研究北京市春季大气颗粒物污染特性,2008年3月至2008年5月,对北京市西三环大气颗粒物进行采样分析.测定了总悬浮颗粒物(TSP)与可吸入颗粒物(PM10)的日平均质量浓度,使用扫描电子显微镜(SEM)观察大气颗粒物的微观形貌,并通过X射线能谱仪(EDX)对样品中的元素组成进行分析.结果表明,TSP和PM10日平均质量浓度以初春最高,春天次之,春夏交际最低;PM10/TSP以春夏交际最高,初春次之,春天最低;大气颗粒物形态有规则和不规则2类,以不规则形态居多,同时发现花粉颗粒存在.EDX分析表明,大气颗粒物所附着的重金属中Pb所占的质量分散最高,并且集中吸附在细粒子颗粒物上.     

Mobility of dimethoate residues from spring broccoli field

Dimethoate [O, O-dimethyl-S-(N-methylcarbamoyl-methyl) phosphorodithioate] is a broad-spectrum systemic insecticide currently used worldwide and on many vegetables in Kentucky. Dimethoate is a hydrophilic compound (log KOW = 0.7) and has the potential of offsite movement from the application site into runoff and infiltration water. The dissipation patterns of dimethoate residues were studied on spring broccoli leaves and heads under field conditions. Following foliar application of Dimethoate 4E on broccoli foliage at the rate of 0.47 L acre(-1), dimethoate residues were monitored in soil, runoff water collected down the land slope, and in infiltration water collected from the vadose zone. The study was conducted on a Lowell silty loam soil (pH 6.9) planted with broccoli under three soil management practices: (i) soil mixed with municipal sewage sludge, (ii) soil mixed with yard waste compost, and (iii) no-mulch rototilled bare soil. The main objective of this investigation was to study the effect of mixing native soil with municipal sewage sludge or yard waste compost, having considerable amounts of organic matter, on off-site movement of dimethoate residues into runoff and infiltration water following spring rainfall. The initial deposits of dimethoate were 6.2 and 21.4 micro g g(-1) on broccoli heads and leaves, respectively. These residues dissipated rapidly and fell below the maximum residue limit of 2 micro g g(-1) on the heads and leaves after 10 and 14 d, respectively, with half-lives of 5.7 d on broccoli heads and 3.9 d on the leaves. Dimethoate residues detected in top 15 cm of soil (due to droplet drift and wash off residues from broccoli foliage) one day (d) following spraying, were 30.5 ng g(-1) dry soil in the sewage sludge treatment, and 46.1 and 134.5 ng g(-1) dry soil in the yard waste and no mulch treatments, respectively. Water infiltration was greater from yard waste compost treatment than from no mulch treatment, however concentrations of dimethoate in the vadose zone of the three soil treatments did not differ.     

The effects of Asian Dust on particulate matter fractionation in Seoul,Korea during spring 2001

The concentrations of three different fractions of particulate matter (PM) including PM2.5, PM10, and TSP were determined concurrently during March-May 2001. Measurements of three PM fractions were made at hourly intervals from four different observatory sites located within the city boundary of Seoul. On the basis of this study, we attempted to describe relationships between the occurrences of the Asian Dust (AD) event and its influences on the PM distribution characteristics. The results of our study demonstrated distinct differences between concentrations of PM fractions at AD and non-AD (NAD) periods. The increase of PM observed during the AD episode appeared to be dominated by the coarse, rather than fine, fraction of PM. In addition, it was found that TSP/PM10 ratios were almost constant, while the coarse/fine or TSP/PM2.5 ratios changed noticeably between AD and NAD periods. In most cases, differences in environmental conditions between AD and NAD periods were prominent and proven to be statistically significant. Moreover, the regression relationships between PM and N-oxides indicate that the source processes governing PM levels between the AD and NAD period can be different. The overall results of our analysis were hence helpful enough to distinguish competing processes in AD and NAD periods, while suggesting indirectly the possible control of different source processes on PM fractionation.     

Characterization of the Khamaseen (spring) dust in Jordan

During the spring each year, the Eastern Mediterranean is affected by Khamaseen dust cyclones sourced from the North African Sahara. In order to characterize Khamaseen dust in Jordan, we collected dust from ten localities during the spring of 2006. The collected dust was analyzed for grain size, mineralogy, and chemical composition. The dust is predominantly aluminosilicates (clay minerals and feldspars), quartz and carbonates with minor amounts of phosphate. The particles are mostly subrounded to subangular and generally between 5 and 20 μm in size. The majority of the elements analyzed have a natural abundance and distribution. However, several elements such as As, Cd, Cr, Cu, Pb, Se and Zn have higher than natural abundances due to anthropogenic enrichment by various enrichment factors. The analyzed dust samples are chemically homogenous, indicating a similar provenance and good mixing by the Khamaseen winds. The rare earth elements patterns are similar to those of the upper continental crust composition and average shale. Total amount of dust deposited on Jordan during the spring of 2006 is around 0.3 million tons.     

Overexploitation of karst spring as a measure against water scarcity

Water scarcity, especially in the hydrologically critical part of the year, is a problem often present in many cities and regions, particularly in arid and sub-arid areas. Climate change and human water demand compound the problem. This paper discusses a climate change adaptation measure—the possibility of karst spring overexploitation, where there is a siphon-shaped cavity inside the mountain. The pilot area is near the city of Ni?, where a decreasing precipitation trend has already been observed and is expected to continue in the future. The paper also presents some basic information related to the pilot area and undertaken investigations. The project, successfully implemented in 2004, has provided the city of Ni? with an additional amount of 200 l/s of spring water during the most critical part of the year.     

Episodic release of methane bubbles from peatland during spring thaw

Methane (CH(4)) flux into the atmosphere during spring thaw was investigated in a small ombrotrophic peatland (141 degrees 48'E, 43 degrees 19'N, Japan) using the conventional chamber method. More than 50 chamber deployments on top of the snow cover were carried out and continued for more than 165h until the surface snow and underlying ice cover on top of the peat layer had thawed completely. Methane emissions were almost absent in the presence of snow cover. At the very moment the surface ice cover thawed, a large CH(4) flush (>10mgCH(4)m(-2)h(-1)) was recorded, which was on the same order of magnitude as episodic ebullition previously observed in the high-summer. Gas bubbles trapped in the ice layer on top of the waterlogged peat were preliminarily analyzed for the volumetric percentage in the total ice volume and their gas species compositions. Results showed that the bubbles occupied about 3.2% volume and that the mixing ratio of CH(4) in the bubbles was about 20%. The abundance of the bubble-form CH(4) was sufficient to explain the observed episodic CH(4) release during the thaw. Results of this study show that CH(4) emissions during the thaw season have great temporal variability; emission occurs as an episodic release of bubble-form CH(4) stored in the frozen layer. The results also imply the possibility that gas-phase CH(4) plays an important role, not only during the growing season but also in cold-season CH(4) dynamics in northern peatlands.     

Effects of carbaryl on the spring zooplankton communities in ponds

A carbamate insecticide, carbaryl, was applied in spring to concrete ponds to study its effects on zooplankton communities. The population density of Cladocera (Daphnia spp.) was nearly constant before application of the chemical. Carbaryl at 1 ppm killed all zooplankton species, including Chaoborus larvae. After treatment, cladocerans never recovered to their previous level. The relatively rapid recovery of a predator, Chaoborus, seemed to interfere with recovery of the cladoceran populations. The lower water temperature occurring in spring was thought to favour the former because of its influence on growth rates.     

Micropollutant content of Sargassum drifted ashore: arsenic and chlordecone threat assessment and management recommendations for the Caribbean

Environmental Science and Pollution Research - Massive Sargassum beachings occurred since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and...     

Biosorption potential of brown algae,Sargassum polycystum,for the removal of toxic metals,cadmium and zinc

Environmental Science and Pollution Research - In this research work, the biosorption potential of brown algae, Sargassum polycystum, was investigated for the removal of toxic metals, cadmium (Cd)...     

Decomposition of halogenated methanes in oxygen-free gas mixtures by the use of a silent electric discharge

A silent electric discharge was applied to decompose halogenated methanes including CCl4, CHCl3, CFCl3, CF2Cl2 and CF3Cl, in argon-containing gas mixtures. The decompositions of the target compounds were studied in static reactors at a fixed electric field and room temperature. The reaction products were analyzed by FT-IR spectroscopy, gas chromatography and UV spectrophotometry. The results demonstrated, that the radical-type decomposition of chlorofluoromethanes led to products formed by realignment of the halogen atoms. The decomposition of CCl4 was faster than that of the cholorofluoromethanes, and produced perchloroethane and chlorine. CHCl3 exhibited the highest decomposition rate and produced a large variety of products.     

Snow as a contributor to spring flooding in Belarus

Environmental Science and Pollution Research - There are some peculiarities in instrumental observation over snow cover characteristics in Belarus and those of neighboring countries. Maximum snow...     

Antioxidant effect of Sargassum polycystum (Phaeophyceae) against acetaminophen induced changes in hepatic mitochondrial enzymes during toxic hepatitis

The present study was aimed to examine the protective effects of Sargassum polycystum (Phaeophyceae) alcoholic extract on changes in liver mitochondrial enzymes against acetaminophen induced toxic hepatitis in experimental rats. The levels of protein, lipid peroxide, glutathione (GSH) in mitochondrial fraction, superoxide dismutase (SOD) and catalase (CAT) were also determined. The activities of tricarboxylic acid enzymes such as isocitrate dehydrogenase (ICD), alpha-ketoglutarate dehydrogenase (alpha-KGD), succinate dehydrogenase (SD), malate dehydrogenase (MD), NADH dehydrogenase, and cytochrome-c-oxidase were determined in mitochondrial fraction. The rats intoxicated with acetaminophen showed significant elevation in the levels of lipid peroxides with decreased levels of protein, GSH, SOD, CAT and impaired tricarboxylic acid cycle enzyme activities. The prior oral administration of S. polycystum alcoholic extract showed significant diminution in the severity of toxic hepatitis in acetaminophen-induced rats by maintaining the activities of tricarboxylic acid enzymes with concomitant improvement in the hepatic mitochondrial antiperoxidative status when compared with intoxicated animals. The results obtained in the present study indicate that the protective effects of S. polycystum extract may be due to the presence of some active compounds that are inhibitory against the free radicals generated during lipid peroxidation in acetaminophen induced toxic hepatitis.     

Characterization of carbonaceous species in PM2.5 in Xi'an during spring

The characterization of carbonaceous species in PM_2.5 during a spring period in a suburb of Xi'an, China was investigated. PM_2.5 samples were collected on quartz filters and analyzed for organic carbon (OC) and elemental carbon (EC). The thermal optical reflectance method was used. The minimum OC/EC ratio method was used to estimate the concentration of secondary organic carbon (SOC). The distribution of eight carbon fractions was investigated as well. The average mass concentrations of OC and EC were 15.90 and 8.38 μg/m³, respectively. The average OC/EC ratio ranged from 1.16 to 3.16 with an average value of 2.25. This implies the existence of SOC in PM_2.5. The mean SOC concentration was 7.20 μg/m³, accounting for 45.28% of total OC. This result suggests that SOC is a significant component of OC in the suburb of Xi'an. Results from the distribution of eight carbon fractions revealed that emissions from motor vehicle, coal combustion, and road dust were the main source of carbonaceous particles in the sampling period.