Characterization of land-based sources of pollution in Jobos Bay,Puerto Rico: status of heavy metal concentration in bed sediment

As part of an assessment of land-based sources of pollution in Jobos Bay, Puerto Rico, sediment samples were collected at 43 sites to characterize concentrations of a suite of pollutants, including metals. Fifteen major and trace metals (Ag, Al, As, Cd, Cr, Cu, Fe, Hg, Mn Ni, Pb, Sb, Se, Sn, and Zn) were measured along with total organic carbon and grain size in surficial sediments. For most metals, maximum concentrations were seen in the eastern bay; however, values were still within concentration ranges found in other estuarine systems. In contrast, silver was higher in the western region. In general, metal distribution in the bay was positively correlated with grain size. Additionally, correlations between Al and other metals suggest natural sources for metals. The data presented here suggest that, although the Jobos Bay watershed contains both urban centers along with industrial and agricultural developments, anthropogenic inputs of metals may be negligible.     

A novel liquid-liquid extraction for the determination of naphthalene by GC-MS with deuterated anthracene as internal standard

Polycyclic aromatic hydrocarbons are known for their carcinogenic and mutagenic effects on human health. This therefore calls for the regulation of their concentrations in air, water, and soil. Naphthalene as the simplest in structure of the polycyclic aromatic hydrocarbons is mainly used as a starter material for other chemicals but also has impacts on human health. A method is therefore proposed for the determination of naphthalene in water samples by gas chromatography mass spectrometry after liquid-liquid extraction. The extraction method was optimized to improve the extraction output, thereby lowering the limit of detection. The limits of detection and quantification obtained for naphthalene were 4.4 and 14.6 ng mL^?1, respectively. Deuterated anthracene was used as internal standard to enhance the precision of the method, for which a relative standard deviation of 4.3% was obtained. The percent recovery of naphthalene obtained from tap water was ranged between 93.8 and 102.2.     

Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano

Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure from llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-l reactors at a temperature of 25 degrees C with 30 days of hydraulic retention time (HRT) and an organic loading rate (OLR) of 1.8kgVSm(-3)d(-1). Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process.     

Hydrogeochemical comparison and effects of overlapping redox zones on groundwater arsenic near the Western (Bhagirathi sub-basin, India) and Eastern (Meghna sub-basin, Bangladesh) margins of the Bengal Basin

Although arsenic (As) contamination of groundwater in the Bengal Basin has received wide attention over the past decade, comparative studies of hydrogeochemistry in geologically different sub-basins within the basin have been lacking. Groundwater samples were collected from sub-basins in the western margin (River Bhagirathi sub-basin, Nadia, India; 90 samples) and eastern margin (River Meghna sub-basin; Brahmanbaria, Bangladesh; 35 samples) of the Bengal Basin. Groundwater in the western site (Nadia) has mostly Ca-HCO(3) water while that in the eastern site (Brahmanbaria) is much more variable consisting of at least six different facies. The two sites show differences in major and minor solute trends indicating varying pathways of hydrogeochemical evolution However, both sites have similar reducing, postoxic environments (p(e): +5 to -2) with high concentrations of dissolved organic carbon, indicating dominantly metal-reducing processes and similarity in As mobilization mechanism. The trends of various redox-sensitive solutes (e.g. As, CH(4), Fe, Mn, NO(3)(-), NH(4)(+), SO(4)(2-)) indicate overlapping redox zones, leading to partial redox equilibrium conditions where As, once liberated from source minerals, would tend to remain in solution because of the complex interplay among the electron acceptors.     

The Effect of an Ergonomic Intervention on Musculoskeletal,Psychosocial and Visual Strain of VDT Entry Work: Organization and Methodology of the International Study

This special issue of the International Journal of Occupational Safety and Ergonomics (JOSE) reports the results from an extensive multinational and multidisciplinary collaborative investigation of the impacts on visual display terminal (VDT) work of musculoskeletal, visual, ergonomic, and psychosocial factors. For brevity, this effort has been referred to as the MEPS project (musculoskeletal—eyestrain—psychosocial—stress). This paper lays out the basic methodological structure of the study. The study was conducted in 4 countries utilizing VDT data entry workers as the primary subject population. A battery of objective and subject assessment measures, including muscle load, visual function, physical and visual strain, postural, ergonomic and psychosocial factors, were assessed at 3 different points in time. A pre-test was given prior to an ergonomic intervention. Two post-tests were given 1 month and 1 year after the ergonomic intervention.     

Organophosphates in aircraft cabin and cockpit air--method development and measurements of contaminants

Methods for measurements and the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils among flying personnel in the aviation industry are described. Different sampling methods were applied, including active within-day methods for OPs and VOCs, newly developed passive long-term sample methods (deposition of OPs to wipe surface areas and to activated charcoal cloths), and measurements of OPs in high-efficiency particulate air (HEPA) recirculation filters (n = 6). In total, 95 and 72 within-day OP and VOC samples, respectively, have been collected during 47 flights in six different models of turbine jet engine, propeller and helicopter aircrafts (n = 40). In general, the OP air levels from the within-day samples were low. The most relevant OP in this regard originating from turbine and engine oils, tricresyl phosphate (TCP), was detected in only 4% of the samples (min-max 相似文献   

Oxidation of sulphite originating from flue gas desulphurization waste in soil

The rate of catalyzed oxidation of sulphite originating from flue gas desulphurization (FGD) waste was studied under varying conditions. The pH dependence was examined in aqueous solution at the pH range of 5 to 8, the effect of soil moisture was studied in sieved soil of different moisture contents, and the oxidation of sulphite to a soil as FGD waste, was measured at different depths in a field experiment. The experiments that the half-lives of sulphite in aqueous solution were between 0.5 and 2 hours and that the oxidation rate was highest at the lowest pH. In sieved soil the half-lives of sulphite were in the range of 3 to 20 days with the oxidation rate at the highest moisture content, indication that oxygen availability was the limiting factor. The slowest decrease of the sulphite concentration was found at a soil depth of 8–10 cm which was the where the highest background concentration of sulphite was found in control plots, too.Environmental Geochemistry and Health, 1988,10(1), 26–30     

Report: waste refinery in the municipality of Bor?s.

This paper briefly describes waste treatment trends in Sweden and describes an example of state-of-the-art treatment in a local integrated waste treatment system (Bor?s). The focus is on treatment of household waste, to illustrate what can be done to establish a sustainable waste treatment system with high recovery of materials and energy. The various processes have resulted in a low amount of landfilled household waste, and high proportions of recovered energy and materials. Heat, electricity, vehicle fuel and fertilizers, metals and construction materials are recovered from the local waste in Bor?s, with less than 4% of domestic waste being sent to landfill.