Stable carbon isotope analysis (δ13C values) of polybrominated diphenyl ethers and their UV-transformation products

Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the δ¹³C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in ¹³C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in ¹³C because of more stable bonds between ¹³C and bromine. As a result, the δ¹³C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the δ¹³C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products.     

A rapid isotope ratio analysis protocol for nuclear solid materials using nano-second laser-ablation time-of-flight ICP-MS

The analysis of the isotopic composition of nuclear or non-nuclear solid materials is performed in a variety of fields, e.g., for quality assurance in the production of nuclear fuels, as signatures in forensics, nuclear safeguards, and non-proliferation control, in material characterization, geology, and archeology. We have investigated the capability of laser ablation (New Wave Research, 213 nm) coupled to time-of-flight (TOF) ICP-MS (GBC OptiMass 8000) as a rapid analytical protocol for multi-isotope screening of nuclear and non-nuclear solid samples. This includes natural and non-natural isotopic compositions for elements including Cu, Zr, Mo, Cd, In, Ba, Ta, W, Re, Pt, Pb, and U, in pure metals, alloys, and glasses. Without correcting for mass bias (mass fractionation), an overall precision and accuracy of about 4% (1σ) can be achieved by minimizing the deposited laser power and thus fractionation (mass removal based on thermal properties). The precision and accuracy in combination with literally no or minimized sample preparation enables a rapid isotope screening of solid samples that is of particular interest to support nuclear forensic and safeguard analysis.     

Lead contamination of the Seine River, France: geochemical implications of a historical perspective

Four sediment cores collected in the Seine River basin and dated between 1916 and 2003 were analyzed for lead concentrations and isotopic composition. In all four cores, the measured Pb concentration (up to 460 mg kg⁻¹) lies significantly above the natural background (27-40 mg kg⁻¹), although a significant decrease (down to 75 mg kg⁻¹) was observed during the second half of the 20th century which can be explained by the reduction of lead emissions. The ²⁰⁶Pb/²⁰⁷Pb ratio measured in these samples indicates that the main source of Pb used in the Paris conurbation is characterized by a “Rio Tinto” signature (defined as ²⁰⁶Pb/²⁰⁷Pb = 1.1634 ± 0.0001). A high contribution, up to 25%, from the leaded gasoline (characterized by ²⁰⁶Pb/²⁰⁷Pb = 1.08 ± 0.02) is revealed in the Seine River downstream Paris, indicating that lead from the leaded gasoline is preferentially released to the river.The dominating Pb signature in the Paris conurbation that is currently sampled through incinerators fumes (²⁰⁶Pb/²⁰⁷Pb = 1.1550 ± 0.0005) and waste water treatment plant (²⁰⁶Pb/²⁰⁷Pb = 1.154 ± 0.002), represents a mixture of highly recycled lead from the Rio Tinto mine and lead from leaded gasoline (imprinted by the low ²⁰⁶Pb/²⁰⁷Pb of the Broken Hill mine). This signature is called “urban” rather than “industrial”, because it is clearly distinct from the Pb that is found in areas contaminated by heavy industry, i.e. the heavy industries located on the Oise River which used lead from European ores characterized by high ²⁰⁶Pb/²⁰⁷Pb ratios (∼1.18-1.19) and possibly a minor amount of North American lead (²⁰⁶Pb/²⁰⁷Pb ratios > 1.20). The “urban” signature is also found in a rural area upstream of Paris in the 1970’s. At the Seine River mouth in 2003, Pb with an urban signature represents 70% of the total Pb sediment content, with the 30% remaining corresponding to natural Pb.     

Investigation of the Organic Solvent Resistance Mechanisms in Rhodococcus and Lysinibacillus Using Several Molecular Forensic Tools

Rhodococcus erythropolis IBB_Po5 (KM405337) and Lysinibacillus xylanilyticus IBB_Po7 (KM405338) showed good tolerance to 5% (v/v) organic solvents (alkanes, aromatics). However, 5% (v/v) alkanes (i.e., cyclohexane, n-hexane, n-decane) were less toxic for R. erythropolis IBB_Po5 and L. xylanilyticus IBB_Po7 cells, compared with 5% (v/v) aromatics (i.e., toluene, o-xylene, ethylbenzene). The high organic solvent tolerance of these two Gram-positive bacteria could be due to the presence in their genome of some catabolic (alkB1, todM, xylM) and trehalose-6-phosphate synthase (otsA1) genes. R. erythropolis IBB_Po5 possesses three catabolic genes (i.e., alkB1, todM, xylM), while L. xylanilyticus IBB_Po7 possesses only one catabolic gene (i.e., alkB1). Numerous adaptations involved in organic solvents tolerance were depicted in R. erythropolis IBB_Po5 and L. xylanilyticus IBB_Po7 cells exposed to 5% (v/v) alkanes and aromatics (i.e., changes in the cell growth rate, membrane permeability, cell morphology, biosurfactant emulsification index, carotenoids profile, DNA fingerprinting). Therefore, microbiological, biochemical, and DNA fingerprinting studies of the bacteria isolated from polluted environments could provide valuable information that may complement or supplement other forensic investigations.     

Lead (Pb) isotopic fingerprinting and its applications in lead pollution studies in China: A review

As the most widely scattered toxic metal in the world, the sources of lead (Pb) observed in contamination investigation are often difficult to identify. This review presents an overview of the principles, analysis, and applications of Pb isotopic fingerprinting in tracing the origins and transport pathways of Pb in the environment. It also summarizes the history and current status of lead pollution in China, and illustrates the power of Pb isotopic fingerprinting with examples of its recent applications in investigating the effectiveness of leaded gasoline phase-out on atmospheric lead pollution, and the sources of Pb found in various environmental media (plants, sediments, and aquatic organisms) in China. The limitations of Pb isotopic fingerprinting technique are discussed and a perspective on its development is also presented. Further methodological developments and more widespread instrument availability are expected to make isotopic fingerprinting one of the key tools in lead pollution investigation.     

Assessment of aerobic biodegradation of lower-chlorinated benzenes in contaminated groundwater using field-derived microcosms and compound-specific carbon isotope fractionation

Biodegradation of lower chlorinated benzenes (tri-, di- and monochlorobenzene) was assessed at a coastal aquifer contaminated with multiple chlorinated aromatic hydrocarbons. Field-derived microcosms, established with groundwater from the source zone and amended with a mixture of lower chlorinated benzenes, evidenced biodegradation of monochlorobenzene (MCB) and 1,4-dichlorobenzene (1,4-DCB) in aerobic microcosms, whereas the addition of lactate in anaerobic microcosms did not enhance anaerobic reductive dechlorination. Aerobic microcosms established with groundwater from the plume consumed several doses of MCB and concomitantly degraded the three isomers of dichlorobenzene with no observable inhibitory effect. In the light of these results, we assessed the applicability of compound stable isotope analysis to monitor a potential aerobic remediation treatment of MCB and 1,4-DCB in this site. The carbon isotopic fractionation factors (ε) obtained from field-derived microcosms were -0.7‰ ± 0.1 ‰ and -1.0‰ ± 0.2 ‰ for MCB and 1,4-DCB, respectively. For 1,4-DCB, the carbon isotope fractionation during aerobic biodegradation was reported for the first time. The weak carbon isotope fractionation values for the aerobic pathway would only allow tracing of in situ degradation in aquifer parts with high extent of biodegradation. However, based on the carbon isotope effects measured in this and previous studies, relatively high carbon isotope shifts (i.e., ∆δ¹³C > 4.0 ‰) of MCB or 1,4-DCB in contaminated groundwater would suggest that their biodegradation is controlled by anaerobic reductive dechlorination.     

浓度层析荧光光谱局部匹配溢油鉴别技术

溢油事故的频繁发生对海洋环境造成极大的影响,建立一种快速、准确、经济的现场溢油检测技术及时对事故作出响应有着重要的意义.针对海洋环境中溢油样品浓度和油源都未知的情况,对于溢油可疑样本,获取其浓度参量同步荧光光谱(concentration-synchronous-matrix fluorescence,CSMF),通过在浓度维度上进行插值处理获取的样品的CSMF浓度层析荧光光谱.而对于肇事溢油样品,无需进行脱水浓缩等预处理,只需取现场样本逐级稀释获取小浓度范围内的CSMF局部谱图,并将之与可疑油样大浓度范围内的CSMF浓度层析荧光光谱进行曲面匹配,利用最小二乘法确定最佳匹配光谱,最佳匹配的可疑油样即满足最近油种符合度,而对应的浓度即为待测样本的初始浓度值.对原油样品集交叉检验的结果,样品的识别准确度为92%.该油种鉴别方法快速,准确,并可以同时实现油种鉴别和单位体积内溢油含量的定量.     

Changes in Sediment Sources following Wildfire in Mountainous Terrain: A Paired–Catchment Approach,British Columbia,Canada

This paper describes a study examining the potential of mineral magnetic, geochemical and organic properties to determine if a 2003 wildfire in a catchment in British Columbia, Canada, caused a change in the sources of the suspended sediment transported in the channel relative to a nearby unburnt (reference) catchment. The results show that some of the properties offer the potential to determine sediment sources in the unburnt catchment. However, the 2003 wildfire modified the concentrations of some properties and this can either compromise or enhance their ability as tracers in the burnt catchment. At present, the source tracing results are inconclusive. This has implications for the use of certain properties as fingerprints and raises important issues about approaches to sediment source identification.     

Slow Growth and Lack of Recovery in Overfished Holothurians on the Great Barrier Reef: Evidence from DNA Fingerprints and Repeated Large-Scale Surveys

Abstract:  Commercially fished holothurians have important functions in nutrient recycling, which increases the benthic productivity of coral reef ecosystems. Thus, removal of these animals through fishing may reduce the overall productivity of affected coral reefs. To investigate the potential for recovery of overfished holothurian (  Holothuria nobilis ) stocks on the Great Barrier Reef (GBR), we (1) conducted field surveys on 23 reefs after fishery closure, (2) modeled total virgin biomass and compared it with the total amount fished, and (3) estimated individual growth rates with a DNA fingerprinting technique. Two years after fishery closure, no recovery of H. nobilis stocks on reefs previously open to fishing was observed. Densities on reefs protected from fishing since the onset of the fishery in the mid 1980s remained about four times higher than on fished reefs. Based on density estimates and geographic information system data on the habitat area of each reef, we calculated that the virgin biomass (in the main fished area between 12° and 19°S) was about 5500 t and is now about 2500 t. The reduction is on the same order of magnitude as the total amount fished until 1999 (approximately 2500 t). The DNA analysis of repeated samples on three locations indicated high recapture rates of fingerprinted and released individuals of H. nobilis . Fitting growth curves with Francis's growth function indicated that medium-sized individuals (1 kg) grew 35–533 g /year, whereas large animals (2.5 kg) consistently shrank. Small animals (<500 g) were rarely observed. In combination, these data indicate that production of H. nobilis stocks is very low, presumably with low mortality, low recruitment, and slow individual growth rates. Consistent with anecdotal evidence, recovery of H. nobilis stocks on the GBR may take several decades, and we suggest a highly conservative management plan to protect both the stocks and the ecosystem.     

Copulation behavior and paternity in the chaffinch

Summary We investigated two aspects of sperm competition in a wild population of chaffinches Fringilla coelebs: copulation behavior and genetic parentage determined by DNA fingerprinting. Pairs copulated at a high rate before laying, peaking at 4.4 copulation attempts per hour on day –3 relative to laying, with an average of 207 copulation attempts (83 behaviorally successful) per clutch. Extra-pair copulation attempts (n = 20) made up 7.8% of all copulation attempts that females were involved in. The rate at which pairs copulated was lower during egg-laying, but there was no evidence that this was due to the male of the pair timing copulations to coincide with an insemination window; it was more likely due to the fact that females solicited copulations at a lower rate. Both sexes solicited copulations but males solicited mainly extra-pair copulations. DNA fingerprinting showed that 17.0% of chicks (n = 47) in 23% of broods (n = 13) were fathered by a male other than the one paired to their mother. There was no evidence of intraspecific brood parasitism. In three cases where we were able to identify the father of extra-pair offspring it proved to be a neighboring male.Correspondence to: B.C. Sheldon