Response of a grassland ecosystem to air pollutants. VI. The chemical climate: concentrations and potential flux densities of relevant criteria pollutants

Of the so-called criteria air pollutants, ozone (O3) and sulfur dioxide (SO2) are relevant to agriculture due to their known toxic (O3, SO2) and fertilizing (SO2) potentials. A proper entity to describe pollutant doses in dose-response relationships is the cumulative flux density absorbed by the respective receptor systems. For nutrient budgets the whole ecosystem acts as receptor; for toxicological considerations, stomatal uptake has to be considered primarily. In Central Europe, the atmospheric inputs of oxidized S (SO2, SO3(2-) and SO4(2-)) have declined from the past, and at present are generally below the nutrient requirements of agroecosystems. In contrast, the phytotoxic potential of O3 has increased during the last decade. Pollutant absorbed doses and weighted concentrations were used to describe the risk potential. It could be shown that these two differ significantly.     

Risk assessment approach for untreated wastewater using the QUAL2E water quality model

This paper presents a novel approach for assessing the risk of consumer product ingredients in surface waters that receive untreated wastewater. The approach utilizes the water quality simulation model QUAL2E for predicting the impact caused by conventional pollutants, as well as the exposure concentration of consumer product ingredients. This approach invokes an impact zone concept whereby the receiving water can be thought of as a natural wastewater treatment system. After the river has recovered via self-purification, the ecosystem is then assessed by traditional risk assessment methods. This approach was validated using data collected from the Balatuin River, which is located in the Philippines. Results from this study support the use of QUAL2E for assessing the risk of consumer product ingredients in riverine systems receiving untreated wastewater.     

Determination of metoxuron and 3-chloro-4-methoxyaniline via direct derivatization with heptafluorobutyric anhydride and GC-ECD

The phenylurea herbicide metoxuron and its main metabolite, 3-chloro-4-methoxyaniline, can be determined rapidly in aqueous samples via extraction, derivatization with heptafluorobutyric anhydride (HFBA), washing with an aqueous bufferof pH 8, and analysis by capillary GC with electron capture detection. Linear calibration curves are obtained over two orders of magnitude, and the detection limit for the HFB derivatives is about 0.5 pg. The method has successfully been applied to several types of water samples.     

Long-term sampling method for polychlorinated dibenzofurans (PCDFs) and dibenzo(p)dioxins (PCDDs) in flue gas of combustion facilities

A long-term sampling method for PCDF/D in emissions from combustion facilities is presented. The sampling of PCDF/D was performed over a four week period. The results are compared to results of four one-week measurements.     

Effects of an industrial effluent on plant colonization and on the germination and post-germinative growth of seeds of terrestrial and aquatic plant species

Major oil sands industrial companies are located in the Athabasca Oil Sands Deposit in northeastern Alberta, Canada. During the process used to extract light crude oil (via hot water digestion and flotation), gypsum is usually added to produce consolidated tails (CT) and CT release water. The vast volumes of process-treated waters (effluent) are held within large dyked tailings ponds. Toward testing viable options for reclamation, various hummock-wetlands systems have been constructed; in addition, natural wetlands (inhabited by obligate wetland plant species) have become established as a result of seeping of the effluents held within the large dyked ponds. Vegetation surveys conducted on and around the industrial site revealed that the constructed wetlands associated with the dyke drainage (effluent treated with phosphorous) and consolidated tails (CT; effluent treated with gypsum) had low biodiversity and were not invaded by many aquatic plants. Although the natural wetland was also not invaded by many aquatic species, it was found to be as diverse as the reference wetlands (i.e. off-site wetlands not exposed to the effluents). Exposure to oil sands effluents had an inhibitory effect on the germination (percent and/or rate) of several plant species (tomato, clover, wheat, rye, pea, reed canary grass, loblolly pine); clover and tomato seed germination were most affected. Two treatments in particular (effluents from the natural on-site wetland and the CT constructed wetland), delayed germination, and also led to reduced fresh weight of seedlings of tomato, wheat, clover and loblolly pine. The osmolarities of the effluents associated with the natural on-site wetland and CT constructed wetland were 712 and 728 mOs/kg, respectively; substituting these effluents with solutions of polyethylene glycol of the same osmotic potentials had a greater inhibitory effect on germination rate. The negative effects of the effluents on seed germination may account for the paucity of aquatic species that invaded the oil sands impacted wetlands. This factor will also be critical in determining the long-term feasibility of hummock-wetland systems.     

Analysis of the long-term behavior of solute transport with nonlinear equilibrium sorption using breakthrough curves and temporal moments

We analyzed the long-term behavior of breakthrough curves (BTCs) and temporal moments of a solute subjected to Freundlich equilibrium sorption (s = kc(n)). For one-dimensional transport in a homogeneous porous medium, we derived a power-law relation between travel time, tau, and solute displacement, chi, with the exponent being equal to the Freundlich n exponent. The mean solute velocity, derived from the first time moment, was found to change as tau(n-1). For n values larger than 0.66, the second time moment could be related to c chi(2/n), where c is a constant. An approach based on the use of a critical concentration was developed to estimate the presence of the asymptotic regime in the tail of the BTC. This approach was tested successfully using numerical case studies. One-dimensional numerical simulations with varying values of k, n and initial mass were run to verify the closed form analytical expressions for the large time behavior of temporal moments and the tailing part of breakthrough curves. Good agreement between the slope of the tailing part of log-log transformed BTCs and the predicted slope using asymptotic theory was found. Asymptotic theory in general underestimated the magnitude of the concentration in the tail. The quality of the estimated concentrations in the tail improved for small values of the dispersivity. Experimental BTCs of uranin and benazolin were analyzed in combination with sorption/desorption batch experiments using asymptotic theory. A good agreement between the value of n parameter derived from desorption experiment with benazolin and the value of the n parameter derived from the tail of the BTC was found.     

Oxidant stress, antioxidants and nitric oxide in traffic police of Hyderabad, India

Exposure to environmental pollutants is known to be harmful to health, in general, and to lungs in particular. In this respect, traffic police are at particular risk due to the nature of their job, since they are exposed to emissions from the vehicles. Here, we show that in the traffic police of Hyderabad city, India, the plasma levels of lipid peroxides are high, whereas the concentrations of the nitric oxide are low. In addition, the levels of various antioxidants in the RBC lysate such as catalase, superoxide dismutase and glutathione peroxidase were found to be low with no significant alteration in plasma ceruloplasmin levels. These results suggest that exposure to air pollutants, a major portion of which is due to emissions from the vehicles, can increase oxidant stress, decrease the levels of antioxidants and nitric oxide. This imbalance in the oxidant/antioxidant system may lead to lung damage and is likely to cause respiratory problems in individuals exposed to air pollution.