Magnetic structure of polluted soil profiles from Eastern Ukraine

Our study concerned magnetic properties of soil profiles taken from polluted regions of Eastern Ukraine around the industrial centres Krivyj Rig, Mariupol and Komsomolsk. Soils represent chernozem and podzoluvisol. The low-field magnetic susceptibility shows enhancement in the topsoil caused by contamination by coarse-grain magnetite connected with industrial pollution. Magnetic mineralogy was determined by means of thermal demagnetisation of SIRM, monitoring of susceptibility changes during warming from ?196°C to room temperature and heating to 700°C, and Mössbauer analysis. Granulometry of magnetic particles was investigated by determination of hysteresis parameters, susceptibility, M _s , SIRM and ARM ratios and frequency dependence of susceptibility. The chemical parameters, namely pH, organic carbon and iron content in different pedogenic and lithogenic minerals, measured for particular horizons determined pedogenic characteristic of soil profiles. Our study showed that differences in magnetic parameters of non-polluted and polluted soil profiles are not limited to the topsoil, but reach deep layers of the parent material. Industrial pollution promotes formation of the so-called “pedogenic” SP and SD particles in these layers.     

Preliminary health risk assessment for polybrominated diphenyl ethers and polybrominated dibenzo-p-dioxins/furans in seafood from Guangzhou and Zhoushan, China

Dietary intake is one of the important routes of human exposure to brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs). The use of PBDEs may also result in exposure to polybrominated dibenzo-p-dioxins and dibenzofurans (PBDDs/DFs), as these compounds are impurities in technical mixtures of BFRs and can also be formed unintentionally by the same processes that generate chlorinated dioxins. This study determined the concentrations of polybrominated compounds in common seafood in Guangzhou and Zhoushan, and assessed the health risks of these chemicals via consumption of contaminated seafood. Seafood samples (fish, bivalves, shrimp, crab, and cephalopods) purchased from local markets in 2003 and 2004 were analyzed for PBDEs and PBDDs/DFs. The highest concentration of total PBDEs (46.3 ng g⁻¹ lipid wt.) was detected in fish from Guangzhou, in which BDEs 47 and 209 were the two predominant congeners. The total daily intakes of PBDEs, PBDDs, and PBDFs were, 946, 6.39, and 6.54 pg kg⁻¹ body weight (bw) in Guangzhou, and 489, 4.99, and 7.65 pg kg⁻¹ bw in Zhoushan, respectively. The hazard ratios for PBDDs and PBDFs were both greater than unity, indicating that these compounds may pose some health risks to the local population.     

A late paleo-Indian/Early archaic water well in Mexico—Possible oldest water-Management feature in the new world

A filled prehistoric water well discovered at the village of San Marcos Necoxtla, Puebla, Mexico, may be the oldest directly dated water-management feature in the Americas. The ∼10 m stratigraphic section exposed at this remarkable site records 18,000+ yr of deposition, erosion, water-table and hydrochemical fluctuations, and ≥10,000 yr of continual occupation. Temporal control is afforded by a multicomponent cultural chronology and radiocarbon assays by conventional and experimental techniques. The ∼10 m wide, ∼5 m deep well was excavated, utilized, maintained, and filled with cultural material between <9863 and ≫5950 yr B.P., a span of ≪3913 yr. Ages of other reported Late Pleistocene(?) to Middle Holocene wells in the New World are based on indirect or questionable dating, or are ≤6600 yr. Because of its age and continuity of occupation, the San Marcos Necoxtla well site may help define the nature of the peopling of the Americas and the advent of New World agriculture. © 1996 John Wiley & Sons, Inc.     

Examining the Extraction Efficiency of Petroleum-Derived Dissolved Organic Matter in Contaminated Groundwater Plumes

The extraction efficiency of petroleum-derived dissolved organic matter (DOM) was examined for groundwater samples from an aquifer contaminated with crude oil. Five different types of extraction techniques were investigated to determine which method is best suited for the analysis of potentially toxic petroleum-derived DOM. The five types were a liquid-liquid extraction (LLE) with dichloromethane (DCM) and total petroleum hydrocarbons-diesel range (TPH_d) with DCM (EPA method 3510C), and three solid-phase extraction (SPE) stationary phases that are routinely used for extraction of polar analytes from water. For the LLE and TPH_d, that is selective for nonpolar compounds, the extraction efficiency of petroleum-derived DOM decreased downgradient as the petroleum-derived DOM becomes increasingly polar due to biodegradation. In contrast, the average extraction efficiency by the SPE methods was greater than 65% across the gradient. The results showed that SPE is more efficient for extracting petroleum-derived DOM at hydrocarbon-contaminated sites. The use of a method with greater extraction efficiency for partially oxidized hydrocarbons may prove useful in determining relationships between their composition and structure and potential for risks to human health or the environment.     

Central Asian aridification during the late Eocene to early Miocene inferred from preliminary study of shallow marine-eolian sedimentary rocks from northeastern Tajik Basin

The tempo-spatial development of the Cenozoic Asian aridification across the Eocene-Oligocene and its controlling factors are important scientific topics in Earth Sciences, which are pertinent to regional and global tectonic and climatic events. However, sedimentary rocks preserving the record of aridification during this time from central Asia (ACA) are rare. Here we present a preliminary analysis of sedimentary facies of the lower Paleogene in the northeastern Tajik Basin, which reveals that: the lower part of the studied section is dominated by shallow marine deposits of the Paratethys, the middle part is typical of alternations of eolian dune and fluvial deposits, the upper part is represented by eolian loess-sandy loess (L&SL) like facies, and the top exhibits alternations of fluvial-lacustrine and loess like facies. Based on a chronological framework derived from preliminary magnetostratigraphy, published U-Pb dating of a volcanic ash, and regional litho-stratigraphic correlations, we determine that eolian and L&SL facies accumulated in the northeastern Tajik Basin during the Late Eocene and through most of the Oligocene. These sedimentary units indicate that semi-arid to arid environments of ACA had developed at least since the late Eocene. This initial aridification is closely linked to the westward retreat of the Paratethys that was likely driven by a combination of tectonic activity and sea level changes.     

Crude Oil Metabolites in Groundwater at Two Spill Sites

Two groundwater plumes in north central Minnesota with residual crude oil sources have 20 to 50 mg/L of nonvolatile dissolved organic carbon (NVDOC). These values are over 10 times higher than benzene and two to three times higher than Diesel Range Organics in the same wells. On the basis of previous work, most of the NVDOC consists of partial transformation products from the crude oil. Monitoring data from 1988 to 2015 at one of the sites located near Bemidji, MN show that the plume of metabolites is expanding toward a lakeshore located 335 m from the source zone. Other mass balance studies of the site have demonstrated that the plume expansion is driven by the combined effect of continued presence of the residual crude oil source and depletion of the electron accepting capacity of solid phase iron oxide and hydroxides on the aquifer sediments. These plumes of metabolites are not covered by regulatory monitoring and reporting requirements in Minnesota and other states. Yet, a review of toxicology studies indicates that polar metabolites of crude oil may pose a risk to aquatic and mammalian species. Together the results suggest that at sites where residual sources are present, monitoring of NVDOC may be warranted to evaluate the fates of plumes of hydrocarbon transformation products.