Passive air sampler as a tool for long-term air pollution monitoring: Part 1. Performance assessment for seasonal and spatial variations

The potential of passive air sampling devices (polyurethane foam disks) to assess the influence of local sources on the quality of the surrounding environment was investigated. DEZA Valasske Mezirici, a coal tar and mixed tar oils processing plant, and Spolana Neratovice, a chemical factory with the history of high production of organochlorinated pesticides (OCPs), were selected as the point sources of PAHs, and OCPs, respectively. Levels of PCBs, OCPs and PAHs were determined for all sampling sites and sampling periods. The study brought useful data about the air concentrations of POPs in the investigated regions. More important, it provided information on the transport and fate of POPs in the vicinity of local sources of contamination useful for the estimation of their influence. Very good capability of passive samplers to reflect temporal and spatial fluctuation in concentrations of persistent organic pollutants in the ambient air was confirmed which makes them applicable for monitoring on the local scale.     

Effects of medetomidine, a novel antifouling agent, on the burrowing bivalve Abra nitida (Müller)

The effects of medetomidine, a novel antifouling candidate, on the burrowing bivalve Abra nitida were studied. The burrowing behaviour, sediment reworking activity and faeces production were assessed after 24 h exposure of A. nitida to sublethal concentrations of medetomidine. Medetomidine caused a significant decrease in the burrowing response and in the sediment reworking activity. The median effective concentrations (EC50) were 430 nM (86 microg/l) and 4.4 nM (0.9 microg/l), respectively. No effects on the faeces production were detected. Although significant effects of medetomidine on A. nitida were registered, a reversibility of the effects was observed when 24 h-exposed animals were incubated in clean seawater and sediment for 24 h. Considerations relating to the future commercialisation of medetomidine for antifouling purposes are discussed.     

State of energy consumption and CO2 emission in Bangladesh

Carbon dioxide (CO2) is one of the most important gases in the atmosphere, and is necessary for sustaining life on Earth. It is also considered to be a major greenhouse gas contributing to global warming and climate change. In this article, energy consumption in Bangladesh is analyzed and estimates are made of CO2 emission from combustion of fossil fuel (coal, gas, petroleum products) for the period 1977 to 1995. International Panel for Climate Change guidelines for national greenhouse gas inventories were used in estimating CO2 emission. An analysis of energy data shows that the consumption of fossil fuels in Bangladesh is growing by more than 5% per year. The proportion of natural gas in total energy consumption is increasing, while that of petroleum products and coal is decreasing. The estimated total CO2 release from all primary fossil fuels used in Bangladesh amounted to 5072 Gigagram (Gg) in 1977, and 14 423 Gg in 1995. The total amounts of CO2 released from petroleum products, natural gas, and coal in the period 1977-1995 were 83 026 Gg (50% of CO2 emission), 72 541 Gg (44% of CO2 emission), and 9545 Gg (6% CO2 emission), respectively. A trend in CO2 emission with projections to 2070 is generated. In 2070, total estimated CO2 emission will be 293 260 Gg with a current growth rate of 6.34% y . CO2 emission from fossil fuels is increasing. Petroleum products contribute the majority of CO2 emission load, and although the use of natural gas is increasing rapidly, its contribution to CO2 emission is less than that of petroleum products. The use of coal as well as CO2 emission from coal is expected to gradually decrease.     

Phytostabilization of a metal contaminated sandy soil. I: Influence of compost and/or inorganic metal immobilizing soil amendments on phytotoxicity and plant availability of metals

In a lysimeter set-up, compost addition to an industrial contaminated soil slightly reduced phytotoxicity to bean seedlings. The "Phytotoxicity Index" (on a scale from 1 to 4) decreased from 3.5 to 2.8. The same treatment also reduced metal accumulation in grasses: mean Zn, Cd and Pb concentrations decreased respectively from 623 to 135, from 6.2 to 1.3 and from 10.7 to <6 mg kg-1 dry weight. When combined with inorganic metal immobilizing amendments, compost had a beneficial effect on plant responses additional to the inorganic amendments alone. Best results were obtained when using compost (C)+cyclonic ashes (CA)+steel shots (SS). The "Phytotoxicity Index" decreased to 1.7, highest diversity of spontaneously colonizing plants occurred, and metal accumulation in grasses reduced to values for uncontaminated soils. Based on the first year evaluation, C+CA+SS showed to be an efficient treatment for amendment assisted phytostabilization of the contaminated Overpelt soil.     

Metal concentrations in edible mushrooms following municipal sludge application on forest land

In the context of biosolids utilisation in forestry, effects of sludge application on mushroom metal concentration were studied in six sites of maritime pine forests in the South-West of France. Municipal sludge were applied at a rate of 6 T dry matter per hectare. Edible mushrooms were collected two years after sludge application. As, Cd, Cu, Hg, Pb, Se and Zn concentrations were determined. Results showed a high variability for trace element concentrations in mushrooms collected from control areas. No significant correlation was found between soil parameters (pH and trace elements concentrations) and mushroom trace element concentrations. Even if the concentration of trace metals increased in the soils, sludge application did not affect As, Cu, Se and Zn concentrations in carpophores but slightly increased Cd, Pb and Hg concentrations on some sites. This effect is dependent on sludge type and sites.     

Effects of initial saturation on properties modification and displacement of tetrachloroethene with aqueous isobutanol

Packed column experiments were conducted to study effects of initial saturation of tetrachloroethene (PCE) in the range of 1.0-14% pore volume (PV) on mobilization and downward migration of the non-aqueous phase liquid (NAPL) product upon contact with aqueous isobutanol ( approximately 10 vol.%). This study focused on the consequences of swelling beyond residual saturation. Columns were packed with mixtures of neat PCE, water and glass beads and waterflooded to establish a desired homogeneous residual saturation, and then flooded with aqueous isobutanol under controlled hydraulic conditions. Results showed a critical saturation of approximately 8% PV for these packed column experimental conditions. At low initial PCE saturations (<8% PV), experimental results showed reduced risk of NAPL-product migration upon contact with aqueous isobutanol. At higher initial PCE saturations (>8% PV), results showed NAPL-product mobilization and downward migration which was attributed to interfacial tension (IFT) reduction, swelling of the NAPL-product, and reduced density modification. Packed column results were compared with good agreement to theoretical predictions of NAPL-product mobilization using the total trapping number, N(T). In addition to the packed column study, preliminary batch experiments were conducted to study the effects of PCE volumetric fraction in the range of 0.5-20% on density, viscosity, and IFT modification as a function of time following contact with aqueous isobutanol ( approximately 10 vol.%). Modified NAPL-product fluid properties approached equilibrium within approximately 2 h of contact for density and viscosity. IFT reduction occurred immediately as expected. Measured fluid properties were compared with good agreement to theoretical equilibrium predictions based on UNIQUAC. Overall, this study demonstrates the importance of initial DNAPL saturation, and the associated risk of downward NAPL-product migration, in applying alcohol flooding for remediation of DNAPL contaminated ground water sites.     

Ammonium, nitrate and nitrite nitrogen and nitrate reductase enzyme activity in groundnut (Arachis hypogaea L.) fields after diazinon, imidacloprid and lindane treatments

Impacts of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate), imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] and lindane (1,2,3,4,5.6-hexachlorocyclohexane) treatments on ammonium, nitrate, and nitrite nitrogen and nitrate reductase enzyme activities were determined in groundnut (Arachis hypogaea L.) field for three consecutive years (1997 to 1999). Diazinon was applied for both seed- and soil-treatments but imidacloprid and lindane were used for seed treatments only at recommended rates. Diazinon residues persisted for 60 days in both the cases. Average half-lives (t1/2) of diazinon were found 29.3 and 34.8 days respectively in seed and soil treatments. In diazinon seed treatment, NH4(+), NO3(-), and NO2(-) nitrogen and nitrate reductase activity were not affected. Whereas, diazinon soil treatment indicated significant increase in NH4(+)-N in a 1-day sample, which continued until 90 days. Some declines in NO3(-)N were found from 15 to 60 days. Along with this decline, significant increases in NO2(-)N and nitrate reductase activity were found between 1 and 30 days. Imidacloprid and lindane persisted for 90 and 120 days with average half-lives (t1/2) of 40.9 and 53.3 days, respectively. Within 90 days, imidacloprid residues lost by 73.17% to 82.49% while such losses for lindane residues were found 78.19% to 79.86 % within 120 days. In imidacloprid seed-treated field, stimulation of NO3(-)N and the decline in NH4+NO2(-)-N and nitrate reductase enzyme activity were observed between 15 to 90 days. However, lindane seed treatment indicated significant increases in NH4(+)-N, NO2(-)-N and nitrate reductase activity and some adverse effects on NO3(-)N between 15 and 90 days.     

Modelling the extra and intracellular uptake and discharge of heavy metals in Fontinalis antipyretica transplanted along a heavy metal and pH contamination gradient

Samples of the aquatic bryophyte Fontinalis antipyretica Hedw. were transplanted to different sites with the aim of characterizing the kinetics of the uptake and discharge of heavy metals in the extra and intracellular compartments. The accumulation of metals in extracellular compartments, characterized by an initial rapid accumulation, then a gradual slowing down over time, fitted perfectly to a Michaelis-Menten model. The discharge of metals from the same compartment followed an inverse linear model or an inverse Michaelis-Menten model, depending on the metal. In intracellular sites both uptake and discharge occurred more slowly and progressively, following a linear model. We also observed that the acidity of the environment greatly affected metal accumulation in extracellular sites, even when the metals were present at relatively high concentrations, whereas the uptake of metals within cells was much less affected by pH.     

The combined use of chemical and biochemical markers to assess water quality along the Ebro River

Carp (Cyprinus carpio) and barbel (Barbus graellsii) were collected from five sites along the Ebro River. The study was designed to assess levels of persistent organic pollutants and metals bioaccumulated by fish, and some biochemical responses (cytochrome P450 system, phase II activities, and metallothioneins) against those pollutants. The highest levels of PCBs and DDTs were detected in carp from industrialised areas, which also showed high levels of mercury and cadmium in the liver, and high levels of nonylphenol in bile. Significant alterations in some biochemical markers were observed and associated to combined exposure to pollutants. The activity 7-ethoxyresorufin O-deethylase ranged from 69 pmol/min/mg protein in carp from the reference site to 415 pmol/min/mg protein in those from polluted sites. Carp from the Ebro Delta, an agricultural area, had depressed acetylcholinesterase in muscle tissue. Metallothionein concentrations were positively correlated with copper residues, but no significant differences among sampling points were observed.     

Increased thyroid volume and frequency of thyroid disorders signs in schoolchildren from nitrate polluted area

Thyroid volume (ThV) and echogenicity by ultrasound were estimated in 324 schoolchildren (aged between 10 and 13-years) from high nitrate area (HNA) located in agricultural lowland with high nitrate drinking water supply (51-274 mg/l) from shallow wells. The data were compared to children of the same age from low nitrate area (LNA) consisting of 168 children from the neighboring area with very low nitrate (< 2 mg/l) drinking water and of 596 children from the city of Kosice located in a vicinity of LNA and also supplied by low nitrate water. Blood samples were obtained from 315 willing children from HNA and 109 children from LNA and the levels of thyrotropin (TSH), total thyroxine (TT4), free triiodothyronine (FT3) and thyroperoxidase antibodies (anti-TPO) in serum were determined. ThV (mean +/- SE) in 10-year (5.10 +/- 0.14 ml) and 13-year (5.97 +/- 0.11 ml) old children from HNA was significantly higher than that in two groups of respective age from LNA, 4.58 +/- 0.17 (p < 0.02) and 5.23 +/- 0.15 ml (p < 0.05), and from the city of Kosice, 4.77 +/- 0.10 ml (p < 0.05) and 4.87 +/- 0.1 0ml (p < 0.0001). The frequency of hypoechogenicity in HNA was also significantly higher than that in pooled LNA plus Kosice, 13.7% vs. 4.7% (p < 0.01) in 10-year and 10.6% vs. 5.7% (p < 0.03) in 13-year, respectively. The frequency of TSH level in the range of subclinical hypothyroidism (> 4.0 mU/l) in pooled age groups from HNA was 13/324 (4.0%) and that of positive anti-TPO was 8/324 (2.5%), while no case of either increased TSH or positive anti-TPO was found in 109 children from LNA. Finally, no differences in the levels of TT4 and FT3 were found between HNA and LNA. It was concluded that long-term exposure to high nitrate intake by drinking water and home made meals from local products results in increased thyroid volume and increased frequency of signs of subclinical thyroid disorders (thyroid hypoechogenicity by ultrasound, increased TSH level and positive anti-TPO).