Heavy metals in the SPM of air in the environment surrounding a ferro-alloy industrial plant in India

Prices for ferro-alloys have hardened due to the closure of plants in developed countries on account of increasingly stringent pollution control legislation, resulting in a higher cost of production. A ferro-alloy industry with a capacity of 80000 MT per annum was selected to study the nature of pollution. Because of the objectionable nature of polluting air in and around the plant it was located in a rural area where there was no other industry. The area was agriculturally active and there was no effective control system for this plant.The quality of ambient air around the plant site is discussed in this paper along with the meteorological conditions. The maximum concentration of suspended particulate matter (SPM) was 768 µg/NM³ downwind of the plant, minimum 184 µg/NM³, and the average was more than 446 µg/NM³. The presence of heavy metals, viz. Fe, Mn, Cr and Pb, was also assessed. The concentration of Fe was 50 µg/NM³ downwind and 10 µg/NM³ upwind. The concentration of other metals followed a similar trend.     

Matrix diffusion effects in the cleanup of heterogeneous aquifers

Simple mathematical models are developed to account for the rather slow mass transport of nonaqueous phase liquid (NAPL) into aqueous solution in groundwater during flushing operations. The models are based on the assumption that this bottleneck in the process is associated with diffusion in the aqueous phase in the porous medium from the location of the NAPL drops/ganglia in a region of relatively low permeability out into a region of substantially higher permeability, somewhat analogous to diffusion from a block of porous rock into a nearby fracture, where the fracture system overwhelmingly dominates the overall permeability. The models include batch flushing, flushing in a laboratory column, and a one-dimensional model for flushing by means of a single recovery well.     

Trend evaluation of water quality parameters in the Niagara and St. Lawrence Rivers

Physical and chemical (nutrients and major ions) indicators of water quality monitored by Environment Canada between 1977 and 1987 in the Niagara River at Niagara-on-the-Lake and in the St. Lawrence River at Wolfe Island are analyzed for seasonal and annual variations. Parametric methods such as moving averages and linear regression and nonparametric methods (Spearman's rank coefficient) are used to test for the existence of trends in these data. The results indicate that specific conductivity, sodium and chloride have decreased significantly over the period of study. During the same period there is no significant trend for either discharge and nutrients.     

Persistent chlorinated pesticides in fish and cattle fat and their implications for human serum concentrations from the Sene-Gambian region

The concentrations of organochlorine pesticides (OCPs) in fish, shrimps, cattle fat and human serum samples from the Sene-Gambian region were measured using validated analytical methodologies. The results obtained were compared with those of other existing African studies and with data from other developing countries. In fish samples, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and HCB were detected with a frequency of 100%, whereas p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) was detected in eight, heptachlorepoxide in six and endosulfansulfate in five of the nine fish samples. Relatively low concentrations of OCPs were found in cattle and shrimp fat samples. p,p'-DDE and alpha-hexachlorocyclohexane (alpha-HCH) were the most frequently identified. The sum of HCHs ranged from undetected to 13.3 ng g-1 fat, the sum of DDTs from 11.1 to 199.2 ng g-1 fat and the sum of endosulfans from not detected to 49.7 ng g-1 fat in fish and shrimps. In serum samples, alpha-HCH, p,p'-DDE, o,p'-DDT and p,p'-DDT were detected in all 16 pooled serum samples, whereas endosulfansulfate, methoxychlor, mirex, heptachlorepoxide and endrin were detected in 15 samples with most of the concentrations below 10 ng mL-1. The concentrations of OCPs in human serum were given on a serum lipid and whole serum volume basis. The implications for the human diet of these OCP concentrations in serum were investigated by means of biomagnification factors related to the log Kow values of the targeted compounds. The current use of HCH mixtures was suggested to explain the unusually high alpha-HCH concentration. The distribution pattern of these OCPs in humans was also discussed and compared with that in other studies.     

Optimizing the removal of small fish passage barriers

Removing small artificial barriers that hinder upstream migrations of fish is a major problem in riparian habitat restoration. Because of budgetary limitations, it is necessary to prioritize barrier removal and repair decisions. These have usually been based on scoring and ranking procedures, which, although simple to use, can be very inefficient in terms of increasing the amount of accessible instream habitat. We develop a novel decision-making approach, based on integer programming techniques, which optimizes repair and removal decisions. Results show based on real datasets of barrier culverts located in Washington State that scoring and ranking is over 25% below the optimum on average and a full 100% below in the worst case, producing no net habitat gain whatsoever. This is compared to a dynamic programming method that was able to find optimal solutions in less than a second, even for problems with up to several hundred variables, and a heuristic method, which found solutions with less than a 1% average optimality gap in even less time.     

SI-traceable certification of Cu, Cr, Cd and Pb in sediment and fly ash candidate reference materials

Many fields in environmental analytical chemistry deal with very low limits and thresholds as set by governmental legislations or transnational regulations. The need for the accuracy, comparability and traceability of analytical measurements in environmental analytical chemistry has significantly increased and total uncertainties are even asked for by accreditation bodies of environmental laboratories. This paper addresses achieving these goals to guarantee accuracy, quality control, quality assurance or validation of a method by means of certified reference materials. The assessment of analytical results in certified reference materials must be as accurate as possible and every single step has to be fully evaluated. This paper presents the SI-traceable certification of Cu, Cr, Cd and Pb contents in geological and environmentally relevant matrices (three sediments and one fly ash sample). Certification was achieved using isotope dilution (ID) ICPMS as a primary method of measurement. In order to reduce significantly the number of analytical steps and intermediate samples a multiple spiking approach was developed. The full methodology is documented and total uncertainty budgets are calculated for all certified values. A non-element specific sample digestion process was optimised. All wet chemical digestion methods examined resulted in a more or less pronounced amount of precipitate. It is demonstrated that these precipitates originate mainly from secondary formation of fluorides (essentially CaF2) and that their formation takes place after isotopic equilibration. The contribution to the total uncertainty of the final values resulting from the formation of such precipitates was in general < 0.1% for all investigated elements. Other sources of uncertainty scrutinised included the moisture content determination, procedural blank determination, cross-contamination from the different spike materials, correction for spectral interferences, instrumental background and deadtime effects, as well as the use of either certified values or IUPAC data in the IDMS equation. The average elemental content in the sediment samples was 30-130 micrograms g-1 for Pb, 0.5-3 micrograms g-1 for Cd and 50-70 micrograms g-1 for Cu. Cr was measured in one sample and was about 60 micrograms g-1. The concentrations in the fly ash sample were up to 2 orders of magnitude higher. Expanded uncertainty for the investigated elements was about 3% (coverae factor k = 2) except for Cr, (measured by high resolution ICPMS), for which the expanded uncertainty was about 7% (k = 2).     

Using Multiple Antibiotic Resistance and land use characteristics to determine sources of fecal coliform bacterial pollution

Multiple Antibiotic Resistance (MAR) analysis and regression modeling techniques were used to identify surface water areas impacted by fecal pollution from human sources, and to determine the effects of land use on fecal pollution in Murrells Inlet, a small, urbanized, high-salinity estuary located between Myrtle Beach and Georgetown, South Carolina. MAR analysis was performed to identify areas in the estuary that are impacted by human-source fecal pollution. Additionally, regression analysis was performed to determine if an association exists between land use and fecal coliform densities over the ten-year period from 1989 to 1998. Land-use variables were derived using Geographic Information System (GIS) techniques and were used in the regression analysis.MAR analyses were conducted by comparing the frequency and patterns of antibiotic resistance found in Escherichia coli isolates derived from surface water samples and from sewage sources in the Murrells Inlet sewage collection system. The MAR results suggest that the majority of the fecal pollution detected in the Murrells Inlet estuary may be from non-human sources, including fecal coliforms isolated from areas in close proximity to high densities of active septic tanks.A MAR Index, which measures the frequency of antibiotic resistance, was calculated for each of twenty-three water samples and nine sewage samples. The antibiotic resistance pattern comparisons were performed using cluster analysis. Although the MAR indices indicated that several surface water sites had potential human-source contamination, the cluster analysis suggests that only one sampling site had MAR patterns that were similar to those found in the sewage samples. This site was in close proximity to several large pleasure boats as well as a sewage collection system lift station, but was not near areas with active septic tanks. The results of the regression analysis also suggest that sewage sources and rainfall runoff from urbanized areas may contribute to fecal pollution in the estuary.     

Biotreatability and kinetics of UASB reactor to mixtures of chlorophenol pollutants

In most natural ecosystems heterotrophic microorganisms encountercomplex mixtures of carbon sources, each of which is present at aconcentration of few micrograms per litre. This study examined the biotreatability and kinetics of an upflow anaerobic sludge blanket (UASB) reactor to complex mixtures of chlorophenols encountered in environmental conditions using on-line and off-line experimental studies. Results indicate that (1) steady-state concentration was quite lower (98.3 mg L^-1) with complex mixture of chlorophenols than steady-state concentration achieved when only 2.4 dichlorophenol (124 mg L^-1) was studied alone on the same reactor; (2) that toxiceffects of chlorophenols increase with increasing concentrationsof toxicant. (Onset of the inhibitory effect occurred at a lowerconcentration in multi-substrate than in single substrate utilization); (3) addition of alternative utilizable substrate can mitigate toxic effects and enhance degradation; (4) the relative concentration of substrate was critical in determiningutilization patterns. HPLC analysis of off-line experimental samples resulted in a steady-state treatment efficiency of68% for COD, 36% for 2-hlorophenol, 40.5% for 4-chlorophenol, 70.7% for 2,4-dichlorophenol, 53.2% for 2,4,6-trichlorophenol and 42% for pentachlorophenol in presence of glucose. Kinetic constant in terms of V _max and K _s were determined. K _s for the five chlorophenols ranged between 0.016 and 0.117 kg m^-3 day^-1 while V _max ranged between 0.056 and 0.244 kg m^-3 day^-1.     

Fuel characteristics and emissions from biomass burning and land-use change in Nigeria

Nigeria is one of the 13 low-latitude countries that have significant biomass burning activities. Biomass burning occurs in moist savanna, dry forests, and forest plantations. Fires in the forest zone are associated with slash-and-burn agriculture; the areal extent of burning is estimated to be 80% of the natural savanna. In forest plantations, close to 100% of litter is burned. Current estimates of emissions from land-use change are based on a 1976 national study and extrapolations from it. The following non-carbon dioxide (CO₂) trace gas emissions were calculated from savanna burning: methane (CH₄), 145 gigagrams (Gg); carbon monoxide (CO), 3831 Gg; nitrous oxide (N₂O), 2 Gg; and nitrogen oxides (NO_x), 49 Gg. Deforestation rates in forests and woodlands are 300 × 10³ ha (kilohectare, or kha) and 200 × kha per year, respectively. Trace gas emissions from deforestation were estimated to be 300 Gg CH₄, 2.4 Gg N₂O, and 24 Gg NO_x. CO₂ emissions from burning, decay of biomass, and long-term emissions from soil totaled 125 561 Gg. These estimates should be viewed as preliminary, because greenhouse gas emission inventories from burning, deforestation, and land-use change require two components: fuel load and emission factors. Fuel load is dependent on the areal extent of various land uses, and the biomass stocking and some of these data in Nigeria are highly uncertain.     

Migration of pollutants in groundwater: I. reduction of numerical dispersion by conformal mapping

The partial differential equations governing the migration of adsorbable pollutants undergoing 2-dimensional flow in saturated aquifers are presented. The analytical solution of these equations is rarely possible, and the use of mesh or grid techniques for numerical integration leads to so-called numerical dispersion, excessive dispersion which is an artifact associated with the numerical method. We discuss here the use of conformal mapping techniques to develop coordinate systems in which numerical dispersion transverse to the direction of flow is eliminated. Some simple illustrations are presented.