The risks of exceeding EU limit values for NO2 concentrations have increased in many European cities, and compliance depends strongly on meteorological conditions. This study focuses on meteorological conditions and their influences on urban background NO2 concentrations in the city of Gothenburg for 1999–2008. The relations between observed NO2 concentrations and meteorological conditions are constructed using two modelling approaches: multiple linear regression and synoptic regression. Both approaches assume no trends in emissions over the study period. The multiple linear regression model is established on observed local meteorological variables. The synoptic-regression model first groups days according to synoptic conditions using Lamb Weather Types and then uses linear regression on each group separately. A model comparison shows that linear regression model and synoptic-regression model perform satisfactory. The synoptic-regression model gives higher explained variance (R 2) against observations during the calibration years (1999–2007), in particular for the morning peak and afternoon–evening peak concentrations, but the improvement in the validation period is weak. The annual mean NO2 variations, and their trends during the study period, were assessed using the synoptic-regression model. The synoptic-regression model is able to explain 54%, 42% and 80% of the annual variability of daily mean, morning peak and afternoon–evening peak NO2 concentrations, respectively. The observed and modelled annual means of the daily mean and morning/afternoon–evening peak NO2 concentrations show decreasing trends from 1999 to 2008. All trends, except the trend in annual-average observed morning peak NO2 are statistically significant. The presence of trends in the modelled NO2 concentrations—even though emissions are assumed to be constant—leads us to conclude that weather and climate alone are responsible for a substantial fraction of the recent declines in observed NO2 concentrations in Gothenburg. Favourable meteorological conditions may have mitigated increases in local NO2 emissions during 1999 to 2008.

The effects of application of biosolids, at four rates, to an alkaline (pH 8.4), neutral (pH 7.0) and acidic (pH 4.0) soil on concentrations of Cu, Zn, Pb, Cd and dissolved organic C in soil solution were measured over a 170-day period in a laboratory incubation study using Rhizon pore water samplers. Applications of biosolids decreased solution pH in the alkaline soil, increased it in the acidic soil and had little effect in the neutral soil. In general, increasing application rates of biosolids progressively increased EC and concentrations of dissolved organic C (DOC), Cu, Zn, and to a lesser extent Cd and Pb, in soil solution. Concentrations of DOC and concentrations of solution Cu, Zn, and to a lesser extent solution Cd and Pb, decreased over the incubation period. In all three soils, concentrations of solution Cu and Zn were closely positively correlated with DOC concentrations and similar positive but weaker correlations were found for solution Cd and Pb. For the alkaline and neutral soils, concentrations of solution Cu, Zn, Cd and Pb were generally negatively correlated with solution pH but for the acidic soil, positive correlations for Cu and Zn were recorded. The percentage reduction in solution Cu and Zn, between 0 and 170 days incubation, increased with increasing rates of biosolids in the acid soil (where biosolids applications increased pH) but the reverse was the case for the alkaline soil (where pH fell following biosolids applications). Greatest percentage reduction in soluble Cu and Zn occurred in the neutral soil which had the greatest BET surface area, clay and organic matter contents and therefore the greatest capacity to adsorb heavy metal cations. It was concluded that solution pH, dissolved organic C and the intrinsic capacity of the soil to remove metals from solution, were the main factors interacting to regulate heavy metal cation solubility in the biosolids-amended soils.

Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil–water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil–water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the feasibility of bioremediation technology, in general, and its applicability for remediating LNAPLs polluted lands under aforesaid environments, in particular.

Phosphorus (P) delivered by urban rainfall–runoff partitions and speciates during the transport process. This study examines transport and speciation of P in rainfall and runoff across 15 wet weather events from a paved source area dominated by biogenic loads and to a lesser degree, anthropogenic loads. The mean and median event-based source area total phosphorus is 3.6 and 3.5 mg/l, respectively. The mean and median event-based source area dissolved fraction (f d) are 0.31 and 0.32 illustrating that P is predominately bound to particulate matter fractions. The majority of events across the monitoring campaign produce a weak mass-limited transport of dissolved phosphorus (DP). With respect to the DP fraction in runoff (pH range of 6.4 to 8.6), the dominant species are orthophosphates (HPO4 −2 and H2PO4 −) which account for more than 90% of DP mass. The order of species predominance is consistently HPO4 −2 ≈ H2PO4 − >> CaHPO4 > MgHPO4. With rainfall pH ranging from 4.2 to 4.9 and a f d ≈ 1.0, H2PO4 − accounts for 95% to 99% of DP in rainfall. Despite the inherent variability of a large dataset (362 samples across 15 events) the speciation of DP is influenced primarily by pH, with a range from 4.2 (rainfall) up to 8.6 (runoff) that results in an order of magnitude change in P species concentration and determines the order between the dominant orthophosphate species. For this source area, the role of alkalinity, dissolved organic carbon and partitioning on DP speciation are minor compared to the influence of pH.

Mining operations are potential sources of airborne metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern USA by climate models may make contaminated atmospheric dust and aerosols increasingly important, with potential deleterious effects on human health and ecology. Fine particulates such as those resulting from smelting operations may disperse more readily into the environment than coarser tailings dust. Fine particles also penetrate more deeply into the human respiratory system and may become more bioavailable due to their high specific surface area. In this work, we report the size-fractionated chemical characterization of atmospheric aerosols sampled over a period of a year near an active mining and smelting site in Arizona. Aerosols were characterized with a ten-stage (0.054 to 18 μm aerodynamic diameter) multiple orifice uniform deposit impactor (MOUDI), a scanning mobility particle sizer (SMPS), and a total suspended particulate collector. The MOUDI results show that arsenic and lead concentrations follow a bimodal distribution, with maxima centered at approximately 0.3 and 7.0 μm diameter. We hypothesize that the sub-micron arsenic and lead are the product of condensation and coagulation of smelting vapors. In the coarse size, contaminants are thought to originate as Aeolian dust from mine tailings and other sources. Observation of ultrafine particle number concentration (SMPS) show the highest readings when the wind comes from the general direction of the smelting operations site.

Environmental models are frequently used within regulatory and policy frameworks to estimate environmental metrics that are difficult or impossible to physically measure. As important decision tools, the uncertainty associated with the model outputs should impact their use in informing regulatory decisions and scientific inferences. In this paper, we present a case study illustrating a process for dealing with a key issue in the use and application of air quality models, the additional error in annual mean aggregations resulting from imputation of missing data from model data sets. The case study is based on the US Environmental Protection Agency’s Multi-layer Model, which estimates the hourly dry deposition velocity of air pollutants based on hourly measurements of meteorology and site characteristics. A simulation was implemented to evaluate the effect of substituting historical hour-specific average values for missing model deposition velocity predictions on annual mean aggregations. Sensitivity studies were performed to test the effects of different missing data patterns and evaluate the relative impact of the substitution procedure on annual mean SO2 deposition velocity estimates. The substitution procedure was shown to result generally in long-term unbiased estimates of the annual mean and contributed less than 20% additional error to the estimate even when all data were missing. Consequently, it may be possible to use the historical record of deposition velocities to provide reasonably accurate and unbiased annual estimates of deposition velocities for years without meteorological measurements.

The capability of environmental microorganisms to biodegrade simazine—an active substance of 2-chloro-s-triazine herbicides (pesticide waste since 2007)—was assessed. An enormous metabolic potential of microorganisms impels to explore the possibilities of using them as an alternative way for thermal and chemical methods of utilization. First, the biotope rich in microorganisms resistant to simazine was examined. Only the higher dose of simazine (100 mg/l) had an actual influence on quantity of bacteria and environmental fungi incubated on substrate with simazine. Most simazine-resistant bacteria populated activated sludge and biohumus (vermicompost); the biggest strain of resistant fungi was found in floral soil and risosphere soil of maize. Compost and biohumus were the sources of microorganisms which biodegraded simazine, though either of them was the dominant considering the quantity of simazine-resistant microorganisms. In both cases of periodic culture (microorganisms from biohumus and compost), nearly 100% of simazine (50 mg/l) was degraded (within 8 days). After the repeated enrichment culture with simazine, the rate of its degradation highly accelerated, and just after 24 h, the significant decrease of simazine (20% in compost and 80% in biohumus) was noted. Although a dozen attempts of isolating various strains responsible for biodegradation of simazine from compost and biohumus were performed, only the strain identified as Arthrobacter urefaciens (NC) was obtained, and it biodegraded simazine with almost 100% efficiency (within 4 days).

Hexavalent chromium is a heavy metal used in a variety of industrial applications which is highly toxic to humans, animals, plants and microorganisms. Moreover, it is a well-established human carcinogen by the inhalation route of exposure and a possible human carcinogen by the oral route of exposure. Therefore, it should be removed from contaminated waters. Its reduction to trivalent chromium can be beneficial because a more mobile and more toxic chromium species is converted to a less mobile and less toxic form. During the last two decades, there has been important interest in using zero-valent iron (ZVI) as a Cr(VI)-reducing agent. A considerable volume of research has been carried out in order to investigate the mechanism and kinetics of Cr(VI) reduction with ZVI, as well as the influence of various parameters controlling the reduction efficiency. Therefore, the purpose of this review was to provide updated information regarding the developments and innovative approaches in the use of ZVI for the treatment of Cr(VI)-polluted waters.

The destination of sewage sludge is a problem faced by sewage treatment plants (STPs). Many alternatives have been sought, such as the application of sewage sludge in degraded soils and in agriculture as fertilizer. However, due to the risk of contamination with pathogens and/or metals, the use of sludge should be done cautiously. By the habits that diplopods present, they have been considered good environmental indicators for soil analysis. In this study, animals from the Rhinocricus padbergi species were exposed to two sewage sludge samples from two STPs in the São Paulo State, for different periods. The midgut of the animals were removed and histologically processed and subjected to histochemical tests. It was detected the following tissular responses: clusters of haemocytes through the cells of the fat body layer, increase in the quantity of intracellular granules in the cells of the fat body layer, increase in the release of secretion vesicles of the intestinal epithelium, and intense vacuolization of the cytoplasm of epithelial cells. The results suggest the presence of toxic substances to the studied species in both sludge samples used.

Antimony (Sb) pollution in the downstream farmland soil of the Sb mine area has been of a great environmental concern to the local residents. However, effects of Sb on the growth and physiology of crops are still not well known. In the present study, Sb uptake and its effect on growth, antioxidant defense system, and photosynthesis of maize (Zea mays) were investigated. Our results demonstrated that accumulation of Sb in the maize increased with increasing Sb level in the soil. Sb could be easily translocated from root to shoot with a translocation coefficient over 2.05. Plant growth and biomass were reduced due to Sb pollution. Under Sb stress, the activities of peroxidase (POD), superoxide dismutases (SOD), and catalase (CAT) responded differently. The activities of POD and SOD were inhibited when the soil Sb concentration was higher than 50 mg kg−1. CAT activity showed an increasing trend with increasing soil Sb concentration. Chlorophyll synthesis and the maximum photochemical efficiency (F V/F M) were also inhibited significantly under stress of high-level Sb in soil.