Phytoremediation is a method in which plants, soil microorganisms, amendments, and agronomic techniques interact to enhance contaminant degradation. We hypothesized that bermudagrass (Cynodon dactylon L) and an appropriate amount of N fertilizer would improve remediation of pyrene-contaminated Captina silt loam soil. The soil was contaminated with 0 or 1,000 mg pyrene/kg of soil and amended with urea at pyrene-C:urea-N (C:N) ratios of 4.5:1, 9:1, 18:1, or unamended (36:1). Either zero, one, two, or three bermudagrass sprigs were planted per pot and -33 kPa moisture potential was maintained. Pyrene concentrations, inorganic-N levels, shoot and root parameters, and pyrene degrader microbial numbers were measured following a 100-day greenhouse study. At a C:N ratio of 4.5:1, the presence of plants increased pyrene biodegradation from 31% for the no plant treatment to a mean of 62% for the one, two, and three plant treatments. With no plants and C:N ratios of 4.5:1, 9:1, 18:1, and 36:1, the mean pyrene biodegradation was 31, 52, 77, and 88%, respectively, indicating that increased inorganic-N concentration in the soil reduced pyrene degradation in the treatments without plants. Additionally, none of the one, two, or three plant treatments at any of the C:N ratios were different with a mean pyrene degradation value of 69% after 100 days. Pyrene resulted in reduced shoot and root biomass, root length, and root surface area, but increased root diameter. The pyrene degrading microbial numbers were approximately 10,000-fold higher in the pyrene-contaminated soil compared to the control. At the highest N rate, bermudagrass increased pyrene degradation compared to the no plant treatment, however, in the unvegetated treatment pyrene degradation was reduced with added N.

Although microbially-mediated redox environments can alter the characteristics of soil/sediment organic matter (SOM) and its interactions with persistent hydrophobic organic contaminants (HOCs) bound to soils and sediments, the nature of their effects has not been adequately addressed. In this study, a field soil collected from a manufacturer gas plant site and contaminated historically with creosotes was incubated under aerobic and anoxic/anaerobic conditions along with various amendments (extra carbon and enrichment minerals) for stimulating microbial activities. Anaerobic conditions stimulated significant fractions of bound polycyclic aromatic hydrocarbons (PAHs) encompassing naphthalene through benzo[g,h,i]perylene to be mobilized to the aqueous phase, leaving their aqueous phase concentrations far in excess of solubility (increases in their apparent aqueous phase concentrations by factors as high as 62.8 relative to their initial aqueous phase concentrations). Such effects became more evident for high molecular weight PAHs. Dissolved organic matter exhibiting a high affinity for PAHs was liberated from soils during the anaerobic soil incubations. Feasibility of this concept for field applications was evaluated with a lab-scale continuous flow system composed of an anaerobic soil column followed by an aerobic bioreactor inoculated with PAH-degrading microbes. High quantities of PAHs exceeding their aqueous solubilities were eluted from the anaerobic soil column and those mobilized PAHs were readily bioavailable in the secondary aerobic bioreactor. This study may offer a potential method for cost-effective and performance-efficient ex situ remediation technologies (or in situ if appropriate hydrological control available in the contaminated field site) and risk assessment for the HOC-contaminated soils/sediments.

In the present study, a three-dimensional Eulerian photochemical model was employed to estimate the impact that organic compounds have on tropospheric ozone formation in the Metropolitan Area of São Paulo (MASP). In the year 2000, base case simulations were conducted in two periods: August 22-24 and March 13-15. Based on the pollutant concentrations calculated by the model, the correlation coefficient relative to observations for ozone ranged from 0.91 to 0.93 in both periods. In the simulations employed to evaluate the ozone potential of individual VOCs, as well as the sensitivity of ozone to the VOC/NO x emission ratio, the variation in anthropogenic emissions was estimated at 15% (according to tests performed previously variations of 15% were stable). Although there were significant differences between the two periods, ozone concentrations were found to be much more sensitive to VOCs than to NO x in both periods and throughout the study domain. In addition, considering their individual rates of emission from vehicles, the species/classes that were most important for ozone formation were as follows: aromatics with a kOH > 2 x 10⁴ ppm⁻¹ min⁻¹; olefins with a kOH < 7 x 10⁴ ppm⁻¹ min⁻¹; olefins with a kOH > 7 x 10⁴ ppm⁻¹ min⁻¹; ethene; and formaldehyde, which are the principal species related to the production, transport, storage and combustion of fossil fuels.

Urban streams often are a major source of phosphorus (P) to rivers, primarily due to large inputs of sewage effluent. A good example of this is Chicago (Illinois, USA) area streams, which make up most of the flow of the upper Illinois River. Even though streams in this section of the Mississippi River basin are characteristic hard-water systems and exhibit high calcium and carbonate concentrations, the precipitation of Ca–P minerals is minimal and phosphate is not removed from the water column. The objective of this study was to determine the chemical mechanisms controlling P activity in Chicago area streams. Measurement of dissolved ion activities on filtered surface water samples demonstrated that an average of 79% of P in the study streams was dissolved and the remaining was particulate (<0.05 μm and >1.0 μm in diameter, respectively). Neither a P colloidal-size fraction nor a correlation between dissolved and particulate Fe and P was observed. Thermodynamic modeling and SEM-EDS analysis of particulate matter in filter residues indicated that dissolved P may adsorb and co-precipitate on the surface of calcite rather than precipitating in a pure Ca–P mineral phase. Although SEM-EDS results also suggested that P was adsorbed to silicate minerals, organic residues likely dominated the P-containing particulate fraction. Sediment extraction results indicated that organic P was one of two major P components in the stream bottom. The Fe-associated P fraction represented the largest sediment-P fraction, and with little association between Fe and P in the overlying water, dissolved inorganic P may have aided in the authigenic formation of an Fe–P sediment phase. Overall, results suggest that pH combined with Ca and Mg activity are the dominant chemical controls on P chemistry in this P enriched system.

The authors have successfully developed novel efficient and cost-effective sorbent and oxidant for removing mercury from power plant flue gases. These sorbent and oxidant offer great promise for controlling mercury emissions from coal-fired power plants burning a wide range of coals including bituminous, sub-bituminous, and lignite coals. A preliminary analysis from the bench-scale test results shows that this new sorbent will be thermally more stable and cost-effective in comparison with any promoted mercury sorbents currently available in the marketplace. In addition to the sorbent, an excellent elemental mercury (Hg(0)) oxidant has also been developed, and will enable coal-fired power plants equipped with wet scrubbers to simultaneously control their mercury emissions as well as their sulfur oxides emissions. This will work by converting all elemental mercury to an oxidized form which will be removed by the wet scrubber. This will result in significant cost savings for mercury emissions control to the atmosphere, and will help in keeping electric costs low. The sorbent and oxidant will benefit from the utilization of a waste stream from the printed circuit board (PCB) industry, and would thus be environmentally beneficial to both of the utility and electronics industries. The sorbent also demonstrated thermal stability up to 350°C, suggesting a possibility of an application in pulverized coal-fired power plants equipped with hot-side electrostatic precipitators and coal gasification plants.

The odorous air emissions from confined animal feeding operations (CAFOs), such as swine, poultry and dairy farms, are increasingly raising community complaints. Odorous emissions can result in health damages, psychological discomforts and adverse aesthetic effects in the community. However, these emissions are not well characterized up to now due to the lack of legislation, the limitations in sampling and instrumentation techniques, and the complexity of the emissions themselves. This study is aimed at the development of a high volume sampler and sorbent assembly to identify the odor causing compounds from a diary CAFO. The sorbent was custom designed to target the potential compounds that may exist in a dairy farm and was validated in laboratory with a synthetic odor from the swine manure. The actual samples at the diary farm were collected in spring and summer of 2005. The sorbents were solvent extracted and individual odor compounds were identified using GC-MS (gas chromatography-mass spectroscopy). The data obtained indicated that high volume sampling can shorten the sampling time from days to within 4 h. Both volatile organic compounds (VOCs) and volatile fatty acids (VFAs) have been identified from the dairy farm, such as phenol, methylphenol, 4-ethyl phenol, indole, methyl indole, benzyl alcohol, hexanoic acid, valeric acid and iso-valeric acid, together with some nitrogen containing compounds that have not been reported before.

Fluoride, a common phytotoxic air, water and soil pollutant is commonly released to the environment by a number of industrial processes. Agricultural soils high in fluoride are common due to long term accumulation of fluoride from multi-sources and extensive application of phosphate fertilizers. The effect of sodium fluoride (0, 50,100,150 mM) on growth, pigments content, changes in biochemical parameters, along with fluoride and other ions accumulation was investigated in Salicornia brachiata grown in solution cultures under controlled conditions. With fluoride treatment growth as fresh or dry mass accumulation increased marginally. However, higher concentrations decreased the biomass and shoot tip became blunt; margin of the shoot changed its colour to reddish brown and developed necrotic spots. Photosynthetic pigments (chlorophylls and carotenoids) content decreased, while, anthocyanin content increased significantly with fluoride treatment. Peroxidase (POX), superoxide dismutase (SOD), ATPase and acid phosphate activities were negatively regulated. In addition F-, Na⁺, Mn²⁺ and Fe²⁺ ions concentration increased while, K⁺, Ca²⁺ and Mg²⁺ contents decreased with fluoride treatment. To our knowledge this is the first report on fluoride tolerance in a marshy halophytes using as high as 150 mM concentration and the results suggest that S. brachiata is a moderately fluoride tolerant annual halophyte and may be useful to vegetate the fluoride contaminated marshy lands.

Sediments from 18 different road runoff detention systems, located on the Swedish West Coast, were assessed for their ecological hazard potential. Thirteen of the sites were detention ponds, three were manholes within the same sedimentation construction, and two were detention basins handling wash water from road tunnels. Sediments from all sites were analysed for a range of physico-chemical parameters and contaminants, and screened for acute toxicity using Hyalella azteca (sediment), Daphnia magna (elutriate), and Ceriodaphnia dubia (elutriate) as the test organisms, and for chronic toxicity using C. dubia as the test organism. The benthic fauna of the thirteen detention ponds was also studied. Sediment quality guidelines probable effect levels were exceeded for one or several contaminants at half of the sites, and one third revealed toxicity in some of the bioassays. Most of the detention ponds were dominated by tolerant taxa indicating low biological quality. Relationships between contaminant concentrations, toxicity in bioassays, and benthic fauna were, however, found to be weak. Extractable organic Zn, which was used as a tire wear marker, correlated with Zn, Cu, presumably from brake linings, and W, a common component of tire studs. The highest concentration, which was found in the manholes (14 mg kg⁻¹ ds), corresponds to a tire wear concentration of 11 g kg⁻¹ ds. The results of the present study have shown that traffic related contaminants accumulate in the studied runoff treatment systems, and, therefore, the maintenance of them is crucial in order to prevent contamination of surrounding waters.

While hydrophilic compounds are degraded easily in Trickling bed air biofilters (TBABs), hydrophobic compounds are retarded until biological cultures produce a sufficient RNA or enzyme/protein to utilize this compound. Hydrophobic compounds are not readily bio-available which makes them reluctant to biodegradation as mass transfer between the gas and liquid phases is a rate limiting step. To enhance the destruction of hydrophobic compounds in TBABs, the utilization of surfactant was introduced to increase the solubility which helps overcoming the rate limiting step. The surfactant was used as well to limit the growth of excess biomass ensuring smooth flow through the biofilter bed and preventing short circuits. Two different non-ionic non-toxic surfactants were used in this study: Triton X-100 and Tomadol® 25-7. Two lab-scale controlled TBABs were operated for investigating the performance difference for n-Hexane as an example of hydrophobic volatile organic compound (VOC) with and without the addition of surfactant. Operating conditions in both TBABs were as follows: nutrient feed rate (2L/day), air flowrate (1.4L/min), bed depth (60cm), empty bed retention time (120s), bed material (diatomaceous earth pellets) and room-temperature. The inlet concentration was changed from 50 to 100ppmv. Acclimation period, removal profile along biofilter depth, nitrogen consumption, and CO₂ production were compared under continuous loading operation condition. The optimum concentration of surfactant in the nutrient feed was determined by a batch experiment. The effect of different surfactant concentrations on VOC water solubility with time was studied by considering different VOC concentration sets within the TBAB loading rate range.

An open limestone channel (OLC) was constructed within an existing drain to treat the acidic and metal-rich drainage waters generated from an acid sulfate soil (ASS) catchment. The OLC was constructed downstream of a catchment pump and it consisted of a series of ponds and limestone sections. The accumulation of sediment over the limestone, preventing contact of limestone with acidic water, was the greatest problem impacting the OLC in its first year of operation. The continuous or sporadic operation of the catchment pump (at 120 l/s) was not sufficient to flush sediment from the limestone. The accumulation of large amounts of sediment onto the limestone reduced the amount of alkalinity and calcium released into solution. However, if the sediment is removed by agitating the limestone then an equivalent or greater amount of alkalinity may be added to solution and more metals removed from solution compared to fresh limestone. The coating on the limestone had a high concentration of manganese oxides in addition to slightly lower concentrations of aluminium and iron. Removal of these metals from the water was due to the increase in pH produced by limestone dissolution in addition to sorption reactions of the existing coating which had natural microbial activity.