Influence of bacteria on Pb and Zn speciation, mobility and bioavailability in soil: A laboratory study

A soil column experiment was carried out to investigate the effects of inoculation of bacteria on metal bioavailability, mobility and potential leachability through single chemical extraction, consequential extraction and in situ soil solution extraction technologies. Results showed that bacteria inoculated, including Azotobacter chroococcum, Bacillus megaterium and Bacillus mucilaginosus, may pose both positive and negative impacts on bioavailability and mobility of heavy metals in soil, depending on the chemical nature of the metals. The activities of bacteria led to an increase of water dissolved organic carbon (DOC) concentration and a decrease of pH value, which enhanced metal mobility and bioavailability (e.g. an increase of water-soluble and HOAc-soluble Zn). On the other hand, bacteria could immobilize metals (e.g. a great reduction of water-soluble Pb) due to the adsorption by bacterial cell walls and possible sedimentation reactions with phosphate or other anions produced through bacterial metabolism.     

Use of cattails in treating wastewater from a Pb/Zn mine

This article describes the use of a combined treatment system, which includes an aquatic treatment pond withTypha latifolia Linn. (Typhaceae) as the dominant species and a stabilization pond, to treat the wastewater from a Pn/Zn mine at Shaoguan, Guangdong Province, China. In 1983, it was noted thatT. latifolia bloomed in areas affected by the wastewater emitted from the mine, hence a combined purification system was subsequently built. The influent contained high levels of total suspended solids (4635 mg/liter), chemical oxygen demand (14.5 mg/liter) as well as Pb (1.6 mg/liter) and Zn (1.9 mg/liter). The results of the effluent after treatment showed that the total suspended solids, chemical oxygen demand, Pb, and Zn had been reduced by 99%, 55%, 95%, and 80% respectively. The results of plant tissue analysis indicled thatT. latifolia assimilated significant amounts of Pb and Zn, especially in the root portion. During 1986 several species of algae and fish were present in the pond, usually with a higher density in areas containing lower metal concentrations in the water. Paper was presented in part at the conference “The Use of Constructed Wetlands in Water Pollution Control” held 24–28 September 1990, Cambridge, UK.     

Enantiomer fractions of chiral organochlorine pesticides and polychlorinated biphenyls in standard and certified reference materials

Enantiomeric ratios (ERs) and enantiomeric fractions (EFs) of a number of chiral organochlorine pesticides and PCB atropisomers were measured by chiral gas chromatography/mass spectrometry (GC/MS) in five standard (SRM) and certified (CRM) reference materials: SRM 1588a (organics in cod liver oil), SRM 1945 (organics in whale blubber), Marine Mammal Quality Assurance Exercise Control Material IV (NIST IV, organics in whale blubber), CRM trout, and CRM EC-5 (sediment). Target analytes were cis- and trans-chlordane, heptachlor exo-epoxide, oxychlordane, U82, MC5, MC6, MC7, o,p^′-DDT, and PCB congeners 91, 95, 136, 149, 174, 176, and 183. Measured ERs and EFs are in close agreement with the few literature values reported for some of these analytes in SRMs and CRMs. Chiral PCB ERs and EFs measured by one-dimensional chiral GC/MS were similar to values measured using multidimensional chiral GC/MS. Non-racemic chiral compositions are in agreement with known uptake and biotransformation in the respective environmental matrices. These values should aid in the quality assurance/quality control methodologies for chiral environmental chemistry using standardized reference materials.     

Bibliometric analysis of the research landscape on rice husks gasification (1995–2019)

Environmental Science and Pollution Research - The processing of rice (Oryza sativa L.) generates large quantities of lignocellulosic wastes termed rice husks (RH). Numerous researchers have...     

The geomorphology and ecosystem service economic value baselines of tributary watersheds in Malaysia

Environment, Development and Sustainability - This study presents how a cluster of tributary watersheds was evaluated for geomorphology and ecosystem service economic value baselines. Tributary...     

Health risk assessment of organochlorine pesticides with emphasis on DDTs and HCHs in abandoned agricultural soils

The aim of this study was to evaluate the consequence of changing land use from agriculture land to other use purposes with respect to OCPs non-cancer and cancer risk on human health, based on concentrations of DDTs and HCHs in soils collected from 55 locations representing 12 different land use types. There were no non-cancer risks of DDTs and γ-HCHs on adults and children, and there were very low cancer risks of DDD, o,p'-DDE, DDT, α-HCH, β-HCH, γ-HCH based on their total concentrations in all samples. Nonetheless, there were significant correlations of DDT to its metabolites (DDE and DDD) (r = 0.506 and r = 0.648) and DDE to DDD (r = 0.438) both at p < 0.01. OCP levels should be routinely monitored in different environmental media and food in order to verify whether there is fresh input. Their potential risks on human health should also be assessed.