Intermittent wastewater loading, a characteristic of aquaculture operations, undermines the usefulness of treatment wetlands designed using the steady state assumption. Being biological systems, the treatment variability of such wetlands must also be addressed during the design phase. A simulation-optimization model suitable for modeling intermittent pollutant releases and identifying optimal area and wastewater loading patterns for aquaculture operations is integrated with a decision-analytic framework to determine wetland area and release pattern under uncertainty and risk. Wetland area and release patterns corresponding to different decision making priorities were obtained by applying the minimax, maximax, Hurwicz and minimax regret criteria. The developed methodology provides a convenient framework for aquaculture operators and wetland design engineers to consider trade-off between the wetland size (an indicator of construction and opportunity costs) and wastewater loadings (an indicator of operation costs) during the design process. The results can also be used to characterize the risk-attitudes of the aquaculture operators and identify the worth of additional studies (i.e., pilot tests) given their risk-preferences.

A comparison was made of the ability of three different methods to describe the deposition and distribution of chloride from deicing salt in the roadside environment along a highway: direct sampling of airborne deposition (including snow ploughing) in containers; soil sampling and analysis of chloride content in the topsoil; and direct current resistivity measurements. Each method showed a distribution with significant decreasing values with increasing distance from the road. Two transport mechanisms, splash and spray, were identified when describing the airborne deposition. A mathematical model that includes these two transport mechanisms was adopted, and the total amount of airborne deposition on the ground 0–100 m from the road was estimated to approximately 45% of the salt applied on the road. The main part of the chloride spread by air and ploughing ended up within 10 m from the road. The soil sampling and resistivity measurements also showed the highest impact within this distance. The variation in chloride content in the soils reflected a poorer drainage ability of fine-grained soils compared to more coarse-grained soils. The resistivity measurements represented an integrated value of the differences in geology, water content and salinity. The increase in resistivity with distance from road in the topsoil was interpreted to reflect the distribution of chloride from deicing salt.

This study vividly presents results from a seasonal particulate matter measurement campaign conducted at world's largest ship-breaking yard i.e., Alang-Sosiya (Gujarat, India) at six locations and a reference station at Gopnath which is 30 km south of this ship-breaking yard. The collected suspended particulate matter (SPM) 24-h samples were critically analyzed for heavy metals (Pb, Cd, Co, Ni, Cr, Mn, Fe, Cu, Zn). The average concentration of SPM within the ship-breaking yard during the investigation was 287.5 ± 20.4 μg m-³ and at reference station it was 111.13 ± 5.81 μg m-³. These values are found to be in excess of the permitted national standards. The levels of heavy metals at Alang-Sosiya are very high as compared to US EPA and WHO guidelines. The mean concentrations of all metals are in the order: Fe >>Zn >Cu > Mn > Cd >Pb > Co >Ni >Cr. The results on enrichment factors (EF) suggest that most of the metals in the ship-breaking yard exhibit EF values of near or above 100 which must have been comprehensively affected by ship-breaking activities. Metal data was used to evaluate the role of spatial factors on their distribution characteristics. Thereafter, factor analysis was carried out to identify the main components liable for the variance of the data set.

Natural windbreaks have been planted around livestock shelters to improve odour dispersion without substantial knowledge of their best implementation practices. Using three groups of four trained panellists and an odour generator, the objective of the present research was to measure and compare the length of odour plumes (LOP) produced in the field in the absence of, and in the presence of four natural windbreaks exposed to various climatic conditions. During 39 mornings in August, September and December 2003, panellists observed the resulting odour plumes using hedonic tone (HT) as scale and in the afternoon, evaluated the odour concentration (OC) of the odorous air sampled at the generator. By correlating HT with to their corresponding OC, filed HT values were converted into OC units, and 2 OU m⁻³ contours were used to establish LOP. A multiple factor analysis verified the effect significance on LOP of the presence of a windbreak, of windbreak properties and of climatic conditions. While being diluted, OC decreased exponentially with HT as observed by panellists (P < 0.05). Secondly, the windbreaks significantly reduced LOP by 22% as compared to the site without a windbreak. Thirdly, the denser windbreaks had a greater impact on reducing LOP. The LOP of windbreaks with an optical porosity of 0.55 was not significantly different compared to that created in the absence of a windbreak. The wind speed, direction and ambient temperature had a strong influence on LOP while atmospheric stability, windbreak position downwind from the odour source within 60 m and odour emission rate had little impact, based on the analysis of 36 field tests in the presence of a windbreak.

This study assessed the accumulation of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the sediment and biomass of P. australis (Cav.) Trin. ex Steud. in a combined constructed wetland (CW) designed for the treatment of domestic wastewater of 750 population equivalents. The CW consists of two vertical subsurface flow (VSSF) reed beds followed by two horizontal subsurface flow (HSSF) reed beds. The sediment in the VSSF reed bed was contaminated with Cu (201 ± 27 mg kg-¹ DM) and Zn (662 ± 94 mg kg-¹ DM) after 4 years of operation. Concentrations of Cd, Cu, Pb and Zn in the sediment generally decreased along the treatment path of the CW. On the contrary, higher Al, Cr, Fe, Mn and Ni concentrations were observed in the sediment of the inlet area of the HSSF reed bed. Redox conditions were presumably responsible for this observed trend. Metal concentrations in the reed biomass did not show excessive values. Accumulation in the aboveground reed biomass accounted for only 0.5 and 1.4% of, respectively, the Cu and Zn mass load in the influent. The sediment was the main pool for metal accumulation in the CW.

Most ammonia (NH₃) emission inventories have been calculated on an annual basis and do not take into account the seasonal variability of emissions that occur as a consequence of climate and agricultural practices that change throughout the year. When used as input to atmospheric transport models to simulate concentration fields, these models therefore fail to capture seasonal variations in ammonia concentration and dry and wet deposition. In this study, seasonal NH₃ emissions from agriculture were modelled on a monthly basis for the year 2000, by incorporating temporal aspects of farming practice. These monthly emissions were then spatially distributed using the AENEID model (Atmospheric Emissions for National Environmental Impacts Determination). The monthly model took the temporal variation in the magnitude of the ammonia emissions, as well as the fine scale (1-km) spatial variation of those temporal changes into account to provide improved outputs at 5-km resolution. The resulting NH₃ emission maps showed a strong seasonal emission pattern, with the highest emissions during springtime (March and April) and the lowest emissions during summer (May to July). This emission pattern was mainly influenced by whether cattle were outside grazing or housed and by the application of manures and fertilizers to the land. When the modelled emissions were compared with measured NH₃ concentrations, the comparison suggested that the modelled emission trend corresponds fairly well with the seasonal trend in the measurements. The remaining discrepancies point to the need to develop functional parametrisations of the interactions with climatic seasonal variation.

A dynamic model of the carbon budget of an oak forest ecosystem that takes into account forest stand age was developed. A numerical experiment was designed to simulate the afforestation process, and a Monte Carlo simulation was performed to determine how parameter uncertainties and environmental variability influence the result. It was found that while the total amount of carbon stored in the ecosystem increases from 1.9 kg C/m² to 4.4 kg C/m² over the following 20 years, the relative standard deviation increases from 9 to 21%. The contribution of varying climate and carbon dioxide parameters to total uncertainty is substantial; for example, the standard deviation at the 10th modeling year for phytomass doubles and the uncertainties of the soil pool and total accumulated carbon increase by a factor of nearly 1.4, while the uncertainty of the litter pool stays almost at the same level.

The effects of harvesting on the long-term mass balances of calcium (Ca), magnesium (Mg) and potassium (K) were evaluated on a regional level in Sweden. A new high-resolution weathering database was used together with estimates of total deposition, losses through harvest and leaching. Estimates were made for pine and spruce separately and for two harvesting intensity scenarios: stem harvesting and whole-tree harvesting. The mass balance calculations showed net losses of Ca and Mg in almost the whole country for both scenarios. The losses were smaller for pine than for spruce. The K balances were mainly positive for pine but negative for spruce. Leaching was a main factor in the mass balances, especially for Ca and Mg. Whole-tree harvesting in spruce forests led to substantially higher net losses of K and Ca than stem harvesting, according to the calculations. In the whole-tree harvesting scenario in spruce forests the estimated yearly net losses of Ca, Mg and K corresponded to at least 5%, 8% and 3% of the pools of exchangeable base cations, respectively, at 25% of the analysed sites. If losses of this magnitude continue the depletion of the pools of Ca, Mg and K may lead to very low base saturation of the soils, possibly accompanied by negative effects on soil fertility, runoff water quality, tree vitality and tree growth within a forest rotation in parts of Sweden. Avoiding whole-tree harvesting can improve the situation substantially for K, but the losses of Ca and Mg will still be significant.

In order to gain insight into the community structure and the biodegradative potential of bacteria residing in a BTEX-contaminated field site, with benzene as main pollutant, an investigation strategy with a variety of cultivation-independent and -dependent approaches was undertaken. Based on 16S ribosomal DNA sequence analysis, sampling stations in the center of the pollution plume were found to be dominated by a bacterial consortium affiliated with various members of the class of Proteobacteria and Firmicutes, including different sporulating and non-sporulating sulfate-reducing bacteria and members of the genus Geobacter. Non-polluted samples retrieved from outside the plume revealed several phylotypes which were also observed in the centre of the plume. Bacterial sequences retrieved from the fringe of the plume were dominated by several genera of beta Proteobacteria subclass which were not associated with other phylotypes obtained in this study. All sampling stations were tested positive for catechol 2,3-dioxygenase genes, indicating the presence of microorganisms with the genetic potential degrading aromatic compounds via the meta-cleavage pathway. The groundwater system at the down-gradient edge of the plume was characterized, in contrast to all other sampling stations in the center and outside the plume, by high numbers of cultivable bacteria and cultivable aerobic benzene and toluene degraders. These findings are also in accordance with the investigations based on fluorescent in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes, suggesting the presence of an actively benzene degrading bacterial community of beta Proteobacteria at the fringe of the pollution plume.

On 1998, a settling pond of a pyrite mine in Aznalcóllar (SW Spain) broke open, spilling some 3.6 × 10⁶ m³ of water and 0.9 × 10⁶ m³ of toxic tailings into the Agrio and Guadiamar river basin 40 km downstream, nearly to Doñana National Park. The soils throughout the basin were studied for arsenic pollution. Almost all the arsenic penetrated the soils in the solid phase (tailings) in variable amounts, mainly as a result of the different soil structure. The chemical oxidation of the tailings was the main cause of the pollution in these soils. A study of the relationships between the main soil characteristics and arsenic extracted with different reagents (water, CaCl₂, acetic acid, oxalic–oxalate and EDTA) indicates a direct relationship with the total arsenic concentration. The highest amount of arsenic was extracted by oxalic–oxalate (24%–36% of the total arsenic), indicating the binding with the iron oxides.