Adenine nucleotides in snail muscles as one of biomarkers of fluoride toxicity

The aim of this work was to determine the extent of bioaccumulation of fluorides in tissues of Helix aspersa maxima. The toxicity of fluorides administered orally on the energy balance of the snail's foot was investigated based on measurements of concentrations of adenine nucleotides and their metabolism degradation products. Quantitation of fluoride levels was done in soft tissues (foot, hepatopancreas) and shells of mature snails. Qualitative and quantitative analysis of purine compounds was performed in slices of foot from mature snails. Fluoride concentrations in pulverized shells were measured using an ion-selective electrode. Gas chromatography was used to determine fluoride concentrations in soft tissues (hepatopancreas and foot). Purines were measured in foot muscle slices with high-performance liquid chromatography (HPLC). Fluoride levels in soft tissues of the snail cannot serve as an indicator for biomonitoring purposes as no significant accumulation was observed during exposure to maximum allowable concentrations of fluoride in drinking water. Contrary to this, levels of fluoride in the shell rose significantly with this concentration of fluoride in drinking water. The effect of fluorides on energy metabolism of foot muscle was evidenced by elevated AMP levels, increased adenine nucleotide pool and reduced conversion of ADP to ATP. Exposure to rising F(-) concentrations was accompanied by decreasing values of the adenylate energy charge AEC. Determination of AMP or AEC in foot muscle of exposed snails seems to be a useful indicator of fluoride effects on metabolic activity.     

River water quality and pollution sources in the Pearl River Delta, China

Some physicochemical parameters were determined for thirty field water samples collected from different water channels in the Pearl River Delta Economic Zone river system. The analytical results were compared with the environmental quality standards for surface water. Using the SPSS software, statistical analyses were performed to determine the main pollutants of the river water. The main purpose of the present research is to investigate the river water quality and to determine the main pollutants and pollution sources. Furthermore, the research provides some approaches for protecting and improving river water quality. The results indicate that the predominant pollutants are ammonium, phosphorus, and organic compounds. The wastewater discharged from households in urban and rural areas, industrial facilities, and non-point sources from agricultural areas are the main sources of pollution in river water in the Pearl River Delta Economic Zone.     

Arsenic speciation in human hair: a new perspective for epidemiological assessment in chronic arsenicism

The analysis for arsenic in hair is commonly used in epidemiological studies to assess exposure to this toxic element. However, poor correlation between total arsenic concentration in hair and water sources have been found in previous studies. Exclusive determination of endogenous arsenic in the hair, excluding external contamination has become an analytical challenge. Arsenic speciation in hair appears as a new possibility for analytical assessing in As-exposure studies. This study applied a relative simple method for arsenic speciation in human hair based on water extraction and HPLC-HG-ICP-MS. The concentration of arsenic species in human hair was assessed in chronically As(V)-exposed populations from two villages (Esqui?a and Illapata) of the Atacama Desert, Chile. The arsenic concentrations in drinking water are 0.075 and 1.25 mg L(-1), respectively, where As(V) represented between 92 and 99.5% of the total arsenic of the consumed waters. On average, the total arsenic concentrations in hair from individuals of Esqui?a and Illapata were 0.7 and 6.1 microg g(-1), respectively. Four arsenic species, As(III), DMA(V), MMA(V) and As(V), were detected and quantified in the hair extracts. Assuming the found species in extracts represent the species in hair, more than 98% of the total arsenic in hair corresponded to inorganic As. On average, As(III) concentrations in hair were 0.25 and 3.75 microg g(-1) in Esqui?a and Illapata, respectively; while, the As(V) average concentrations were 0.15 and 0.45 microg g(-1) in Esqui?a and Illapata, respectively. Methylated species represent less than 2% of the extracted As (DMA(V)+ MMA(V)) in both populations. As(III) in hair shows the best correlation with chronic exposure to As(V) in comparison to other species and total arsenic. In fact, concentrations of As(total), As(III) and As(V) in hair samples are correlated with the age of the exposed individuals from Illapata (R= 0.65, 0.69, 0.57, respectively) and with the time of residence in this village (R= 0.54, 0.71 and 0.58, respectively).     

Atmospheric deposition of silver and thallium since 12 370 14C years BP recorded by a Swiss peat bog profile, and comparison with lead and cadmium

A peat core from an ombrotrophic bog in Switzerland provides the first complete, long-term record (14 500 years) of atmospheric Ag and Tl deposition. The lack of enrichment of Ag and Tl in the basal peat layer shows that mineral dissolution in the underlying sediments has not contributed measurably to the Ag and Tl inventories in the peat column, and that Ag and Tl were supplied exclusively by atmospheric deposition. The temporal and spatial distribution of modern peaks in Ag and Tl concentrations are similar to those of Pb which is known to be immobile in peat profiles. Silver and Tl, therefore, are effectively immobile in the peat bog also, allowing an atmospheric deposition chronology to be reconstructed. Silver concentrations vary by up to 114x and Tl up to 241x. While Holocene climate change and land use history can explain the variation in metal concentrations and enrichment factors (EF) in ancient peats (i.e. pre-dating the Roman Period), anthropogenic sources have to be invoked to explain the very high EF values (up to 123 in the case of Ag and 12 in the case of Tl) in peat samples since the middle of the 19th Century. The "natural background" EF of Tl in ancient peats is remarkably close to unity, indicating a lack of significant enrichment of this element in atmospheric aerosols due to chemical weathering of crustal rocks. Silver, on the other hand, shows a pronounced enrichment from 8030 to 5230 (14)C years BP (12x compared to crustal rocks); this may be due to weathering phenomena or biological processes, both of which are driven by climate. Even compared to the natural enrichment of Ag during the mid-Holocene, however, the enrichments of Ag and Tl in modern peats from the Industrial Period are at least an order of magnitude greater. The Pb/Ag and Tl/Ag ratios show that Pb and Tl are preferentially released, compared to Ag, during smelting of argentiferous Pb ores mined during the Roman and Medieval Periods.     

The distribution of molybdenum in the tissues of wild ducks

The Mo contents and the relations between Mo and Cu or Crcontents were investigated in the organs of Japanese wild ducks(spotbill duck, pintail, wigeon, scaup and tufted duck). Thehighest Mo content in kidney and liver of the dabbling duckswere more than 30 g g^-1 dry weight (g g^-1 d.wt.), though that of diving ducks were less than 11 gg^-1 d. wt. The contents were lower in the ducks migratingwithin Japan, Eurasia and North America than those in the birdsmigrating between Japan and Eurasia. The contents of liver inall species were more than 50 and less than 5 g g^-1 d.wt. for Cu and Cr, respectively. Significant correlations werefound between Mo and both elements in pintail and scaup, and Moand Cr in tufted duck. These results suggest that thecontamination of wild ducks reflects the reproductive area, andnot the collected area. Mo contents closely correlated with theCu and/or Cr contaminations.     

Microbiological characteristics in a zero-valent iron reactive barrier

Zero-valent iron (Fe⁰)-based permeable reactive barriertreatment has been generating great interest for passivegroundwater remediation, yet few studies have paid particularattention to the microbial activity and characteristics withinand in the vicinity of the Fe⁰-barrier matrix. The presentstudy was undertaken to evaluate the microbial population andcommunity composition in the reducing zone of influence byFe⁰ corrosion in the barrier at the Oak Ridge Y-12 Plantsite. Both phospholipid fatty acids and DNA analyses were usedto determine the total microbial population and microbialfunctional groups, including sulfate-reducing bacteria,denitrifying bacteria, and methanogens, in groundwater andsoil/iron core samples. A diverse microbial community wasidentified in the strongly reducing Fe⁰ environment despitea relatively high pH condition within the Fe⁰ barrier (up topH 10). In comparison with those found in the backgroundsoil/groundwater samples, the enhanced microbial populationranged from 1 to 3 orders of magnitude and appeared to increase from upgradient of the barrier to downgradient soil. Inaddition, microbial community composition appeared to change overtime, and the bacterial types of microorganismsincreased consistently as the barrier aged. DNA analysisindicated the presence of sulfate-reducing and denitrifyingbacteria in the barrier and its surrounding soil. However, theactivity of methanogens was found to be relatively low,presumably as a result of the competition by sulfate/metal-reducing bacteria and denitrifying bacteria because of the unlimited availability of sulfate and nitrate in the site groundwater. Results of this study provide evidenceof a diverse microbial population within and in the vicinity ofthe iron barrier, although the important roles of microbial activity, either beneficially or detrimentally, on the longevityand enduring efficiency of the Fe⁰ barriers are yet to be evaluated.     

水中Mg~(2+)的测试管快速测定

研制了一种测定水中Mg2 + 的测试管 ,测定范围为 0 .5mg/L～ 2 .0mg/L。该测试管适用于现场应急监测 ,具有快速、简便、抗干扰能力强和价格低廉等特点     

Multivariate analysis of the bioaccumulation of polychlorinated biphenyls (PCBs) in the marine pelagic food web from the southern part of the Baltic Sea,Poland

The concentration, pattern, bioaccumulation and biomagnification features of many chlorobiphenyl congeners including non- and mono-ortho chlorine substituted members have been determined in a pelagic food chain including mixed phyto- and zooplankton, herring (Clupea harengus), harbour porpoise (Phocoena phocoena) and black cormorants (Phalacrocorax carbo sinensis) collected from the southern part of the Baltic Proper. TCDD (tetrachlorodibenzo-p-dioxin) toxic equivalents (TEQs) in plankton, herring, harbour porpoise and cormorants were 0.42, 5.3, 79 and 2,700 pg g(-1) lipid weight, respectively. Concentrations of total polychlorinated biphenyls (PCBs) in plankton, herring, harbour porpoise and cormorants were 1.9, 120, 8700 and 2,100 ng g(-1) wet weight (210, 1,300, 10,000 and 42,000 ng g(-1) lipid weight) respectively. Herring, harbour porpoise and black cormorant apparently bioaccumulate many PCBs found in their food, and the values of the bioaccumulation factors (BAFs) for PCBs were approximately 10 in herring, 35 in harbour porpoise and up to 300 in breast muscle of cormorants. Harbour porpoise clearly is able to metabolize the most toxic non-ortho PCBs (no. 77, 126 and 169) and a few mono-ortho PCBs (no. 114, 123 and 156), while all non- and mono-ortho PCBs are bioaccumulated by herring. Penta-, hexa- and hepta-CBs were the dominatant homologue classes both in the muscle tissue and liver. PCB congeners nos. 201, 209, 172/192, 194 and 195 were characterized by the largest BAFs (between 100 and 300). Principal component analysis has been used to analyse the interdependences and differences in the CB congener accumulation patterns between the components of the investigated pelagic food web.     

Development of a diffusive sampling method for determination of methyl isocyanate in air

A diffusive sampling method for determination of methyl isocyanate in air has been developed. A glass fibre filter impregnated with 1-(2-methoxyphenyl)piperazine in a commercially available diffusive sampling device was used to collect methyl isocyanate and the derivative formed was analysed with LC-MS/MS. The sampling rate was determined to be 15.6 ml min(-1), with a relative standard deviation of 7.3%. The sampler was validated for sampling periods from 15 min to 8 h, for relative humidities from 20% to 80% and for concentrations from I to 46 microg m(-3). A field validation was also made and the diffusive sampling results showed no difference compared to a pumped reference method. The impregnated filters have to be stored apart from the diffusive sampler housing and loaded into the sampler prior to each sampling.     

Speciation of iron in river water using a specific catalytic determination and size fractionation

A comprehensive speciation scheme was proposed for the speciation of iron in river water (0.45 microm filtrate). The speciation was based on the catalytic determination of reactive iron as Fe3+ and Fe(III)Li/(3 -in)+, where i = 1 or 2 for a unidentate and i = 1 for a bidentate ligand, Ln-. The scheme incudes size fractionation and acid decomposition of the sample and determination of the coexisting species. The proposed scheme was applied to natural and artificial samples and acidified preparations of these. Resulting fractionation patterns of reactive and unreactive iron and of coexisting humic acid were useful for the characterization of iron species in the natural samples. The reactive iron in the molecular weight (Mr) > or = 10(4) fraction was associated with humic iron aggregates and estimated as iron complexed with them. The unreactive iron in this fraction dissociated in 0.1 M HCI and was estimated as iron in the aggregates of iron(III) hydroxide (s) and humic iron. From the fractionation results of the artificial sample, the reactive and unreactive iron in the Mr < 10(3) fraction may be formed by complexing simple anions like F- and C2O4(2-) at their naturally-occurring concentration levels. The fractionation results also suggested that humic acid and Si contributed to the formation of reactive and unreactive iron in the Mr > or = 10(4) fraction.