Distribution pattern of ambient cadmium in wetland ponds distributed along an industrial complex

Water and sediment samples collected from 18 wetland ponds within and outside industrial areas were examined for cadmium concentration and water quality parameters during the period of January to July 1996. The Cd contents in gill, liver, mantle and shell of freshwater mussel (Lamellidens marginalis) as well as leaves and roots of water hyacinth Eichhornia those occurred in these ponds were also estimated. Cd concentration ranged from 0.006 to 0.7025 mg/l in water and from 7 to 77 microg/gdw in sediments of all the ponds investigated. The amount of Cd occurring in water and sediment was much higher in concentrations in the ponds located in Captain Bheri and Mudiali farm close to industrial areas, compared to remaining ponds located outside the industrial belt. Lamellidens marginalis procured from Mudiali and Captain Bheri ponds showed regardless of size, tissue and season of collection significantly higher Cd concentration than did those from other ponds. Likewise, tissue Cd in Eichhornia collected from Mudiali pond was as high as 125-152 microg/gdw in root and 21-63 microg/gdw in leaves compared to 40-108 microg/gdw in root and 9-43 microg/gdw in leaves in the remaining ponds. Seasonal variability of Cd was clear-cut; the concentration was relatively higher in water and sediment in all ponds during summer than during monsoon season or winter. Size-wise, smaller groups showed the highest concentrations of Cd in all tissues of Lamellidens compared with medium and large size groups. Concentration factor for all tissues of Lamellidens regardless of size and season, was inversely proportional with the ambient Cd concentrations. Concentration factor estimated for all tissues in all ponds and all seasons was in the order: liver>gill>shell>mantle. As all ponds located outside the industrial belt showed Cd concentrations ranging from 0.006 to 0.049 mg/l, it is suggested that these wetlands do not pose serious risk to the environment.     

Dual-domain solute transfer and transport processes: evaluation in batch and transport experiments

Soil macropore networks establish a dual-domain transport scenario in which water and solutes are preferentially channeled through soil macropores while slowly diffusing into and out of the bulk soil matrix. The influence of macropore networks on intra-ped solute diffusion and preferential transport in a soil typical of subsurface-drained croplands in the Midwestern United States was studied in batch- and column-scale experiments. In the batch diffusion studies with soil aggregates, the estimated diffusion radius (length) of the soil aggregates corresponded to the half-spacing of the aggregate fissures, suggesting that the intra-ped fissures reduced the diffusion impedance and preferentially allowed solutes to diffuse into the soil matrix. In the column-scale solute transport experiments, the average diffusion radius (estimated from HYDRUS-2D simulations and a first-order diffusive transfer term) was nearly double that of the batch-scale study. This increase may be attributed to a loss of pore continuity and a compounding of the small diffusion impedance through macropores at the larger scale. The column-scale solute transport experiments also suggest that two preferential networks exist in the soil. At and near soil saturation, a primary network of large macropores (possibly root channels and earthworm burrows) dominate advective transport, causing a high degree of physical and sorption nonequilibrium and simultaneous breakthrough of a nonreactive (bromide) and a reactive (alachlor) solute. As the saturation level decreases, the primary network drains, while transport through smaller macropores (possibly intra-ped features) continues, resulting in a reduced degree of nonequilibrium and separation in the breakthrough curves of bromide and alachlor.     

Mechanism of Cd（II） adsorption by macrofungus Pleurotus platypus

The mechanism of Cd(II) uptake by the dead biomass of macrofungus Pleurotus platypus was investigated using di erent chemical and instrumental techniques. Sequential removal of cell wall components of the biosorbent revealed that structural polysaccharides play a predominant role in the biosorption of Cd(II). The adsorption kinetics fitted well with the pseudo second-order model suggested that the adsorption of Cd(II) on P. platypus involved a chemisorption process. Transmission electron microscopy of the cadmium exposed biomass confirmed the deposition of the metal mainly in the cell wall. Fourier transform infrared spectroscopic analysis of the metal loaded biosorbent confirmed the participation of –OH, –NH and C–O–C groups in the uptake of Cd(II). Energy dispersive X-ray analysis of the biosorbent before and after metal uptake revealed that the main mechanism of adsorption was ion-exchange. The e ectiveness of CaCl2 in the desorption of cadmium perhaps suggested the exchange of Ca2+ with Cd(II).     

Microbial diversity,community composition and metabolic potential in hydrocarbon contaminated oily sludge: prospects for in situ bioremediation

Microbial community composition and metabolic potential have been explored in petroleum-hydrocarbon-contaminated sludge of an oil storage facility. Culture-independent clone library-based 16S rRNA gene analyses revealed that the bacterial community within the sludge was dominated by the members of β-Proteobacteria (35 %), followed by Firmicutes (13 %), δ-Proteobacteria (11 %), Bacteroidetes (10 %), Acidobacteria (6 %), α-Proteobacteria (3 %), Lentisphaerae (2 %), Spirochaetes (2 %), and unclassified bacteria (5 %), whereas the archaeal community was composed of Thermoprotei (54 %), Methanocellales (33 %), Methanosarcinales/Methanosaeta (8 %) and Methanoculleus (1 %) members. Methyl coenzyme M reductase A (mcrA) gene (a functional biomarker) analyses also revealed predominance of hydrogenotrophic, methanogenic Archaea (Methanocellales, Methanobacteriales and Methanoculleus members) over acetoclastic methanogens (Methanosarcinales members). In order to explore the cultivable bacterial population, a total of 28 resident strains were identified and characterized in terms of their physiological and metabolic capabilities. Most of these could be taxonomically affiliated to the members of the genera Bacillus, Paenibacillus, Micrococcus, Brachybacterium, Aerococcus, and Zimmermannella, while two strains were identified as Pseudomonas and Pseudoxanthomonas. Metabolic profiling exhibited that majority of these isolates were capable of growing in presence of a variety of petroleum hydrocarbons as sole source of carbon, tolerating different heavy metals at higher concentrations (≥1 mM) and producing biosurfactant during growth. Many strains could grow under a wide range of pH, temperature, or salinity as well as under anaerobic conditions in the presence of different electron acceptors and donors in the growth medium. Correlation between the isolates and their metabolic properties was estimated by the unweighted pair group method with arithmetic mean (UPGMA) analysis. Overall observation indicated the presence of diverse groups of microorganisms including hydrocarbonoclastic, nitrate reducing, sulphate reducing, fermentative, syntrophic, methanogenic and methane-oxidizing bacteria and Archaea within the sludge community, which can be exploited for in situ bioremediation of the oily sludge.     

Applicability of sustainable urban drainage systems: an evaluation by multi-criteria analysis

Urban flooding has become more serious and worldwide in recent years, especially in the big cities of developing countries. This study uses a multi-criteria analysis (MCA) approach to evaluate the applicability of sustainable urban drainage systems (SUDS), a flood control measure, in the central part of Ho Chi Minh City, Vietnam. The output of the personal computer storm water management model along with interviews with 140 households was used to assess the efficacy and acceptability of four SUDS alternatives: rainwater harvesting, green roof, urban green space and pervious pavement. On technical performance, green roof was the best alternative, followed by pervious pavement, urban green space and rainwater harvesting. Results of the social survey, however, diverged largely from the results of the technical assessments. In particular, people generally prefer public SUDS such as urban green space and pervious pavements to household solutions. With respect to the MCA, we applied four different procedures: Borda count, pair-wise voting, range of value and analytic hierarchy process. Despite some differences, the integrated results from MCA largely agree that urban green space is the most favourable type of SUDS, followed by green roof, pervious pavement and rainwater harvesting.     

Environmental factors affecting thyroid function of wild sea bass (Dicentrarchuslabrax) from European coasts

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. We here applied a multi-level approach of thyroid function assessment in 87 wild sea bass collected near several estuaries: namely the Scheldt, the Seine, the Loire, the Charente and the Gironde. Thyroxine (T₄) and triiodothyronine (T₃) concentrations in muscle were analyzed by radioimmunoassay. The activity of hepatic enzymes involved in extrathyroidal pathways of thyroid hormone metabolism, viz. deiodination, glucuronidation and sulfatation were analyzed. Last, follicle diameter and epithelial cell heights were measured. We observed changes that are predicted to lead to an increased conversion of T₄-T₃ and lowered thyroid hormone excretion. The changes in the metabolic pathways of thyroid hormones can be interpreted as a pathway to maintain thyroid hormone homeostasis. From all compounds tested, the higher chlorinated PCBs seemed to be the most implicated in this perturbation.     

Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Abstract

The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture.

A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20–100%).     

Diclofenac disposition in Indian cow and goat with reference to Gyps vulture population declines

Gyps vultures across India are declining rapidly and the NSAID diclofenac has been shown to be the major cause. Vultures scavenge livestock carcasses that have been treated with diclofenac within the days preceding death. We present data on diclofenac disposition in Indian cow and goat, and field data on the prevalence of diclofenac in carcases in the environment. In the disposition experiment, animals were treated with a single intramuscular injection of diclofenac at 1000 microg kg-1 bw. In cow, diclofenac was detectable in liver, kidney and intestine up to 71 h post-treatment; in plasma, half-life was 12.2 h. In goat, tissue residues were undetectable after 26 h. Prevalence of diclofenac in liver from 36 dead livestock collected in the field was 13.9%. Data suggest that diclofenac residues in Indian cow and goat are short-lived, but diclofenac prevalence in carcasses available to vultures may still be very high.     

Additional danger of arsenic exposure through inhalation from burning of cow dung cakes laced with arsenic as a fuel in arsenic affected villages in Ganga-Meghna-Brahmaputra plain

In arsenic contaminated areas of the Ganga-Meghna-Brahmaputra (GMB) plain (area 569,749 sq. km; population over 500 million) where traditionally cow dung cake is used as a fuel in unventilated ovens for cooking purposes, people are simply exposed to 1859.2 ng arsenic per day through direct inhalation, of which 464.8 ng could be absorbed in respiratory tract.     

Chlorine emission during the chlorination of water – case study

This paper deals with the incident of the excessive use of chlorine and leakage of unused chlorine from an industrial chlorination cistern and the lesson learned.