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.

Fluoride (F) is an air pollutant that causes phytotoxicity. Besides the importance of this, losses of agricultural crops in the vicinity of F polluting industries in Brazil have been recently reported. Injuries caused to plant leaf cell structures by excess F are not well characterized. However, this may contribute to understanding the ways in which plant physiological and biochemical processes are altered. A study evaluated the effects of the atmospheric F on leaf characteristics and growth of young trees of sweet orange and coffee exposed to low (0.04 mol L−1) or high (0.16 mol L−1) doses of HF nebulized in closed chamber for 28 days plus a control treatment not exposed. Gladiolus and ryegrass were used as bioindicators in the experiment to monitor F exposure levels. Fluoride concentration and dry mass of leaves were evaluated. Leaf anatomy was observed under light and electron microscopy. High F concentrations (~180 mg kg−1) were found in leaves of plants exposed at the highest dose of HF. Visual symptoms of F toxicity in leaves of citrus and coffee were observed. Analyses of plant tissue provided evidence that F caused degeneration of cell wall and cytoplasm and disorganization of bundle sheath, which were more evident in Gladiolus and coffee. Minor changes were observed for sweet orange and ryegrass. Increase on individual stomatal area was also marked for the Gladiolus and coffee, and which were characterized by occurrence of opened ostioles. The increased F absorption by leaves and changes at the structural and ultrastructural level of leaf tissues correlated with reduced plant growth.

Measurements of number size distributions of submicron aerosols have been performed at the Eastern part of Mediterranean as part of an extensive measurement campaign to study photo-oxidants and aerosols (SUB-AERO Project). The measurements were made at the Finokalia station on the island of Crete (Greece) and onboard the research vessel “Aegaeon”. Two campaigns were performed during July 2000 and January 2001 using two scanning mobility particle sizers. The particle distributions measured in the range between 7.8 < d p < 327 nm during the summer measurements and between 7.5 < d p < 316 nm during the winter measurements, where d p is the mobility particle diameter. The concentration of ultrafine particles (7.5 < d p < 30 nm) was higher during the winter period and varied mainly between 5 × 10¹ and 2 × 10³ cm⁻³ with concentration peak values for this mode exceeding 1 × 10⁴ cm⁻³. During the summer campaign, an average number concentration of 1 × 10² cm⁻³ at Finokalia and about 5 × 10¹ cm⁻³ aboard the “Aegaeon” vessel was measured. An average concentration of 1 × 10³ cm⁻³ was measured for the particles in the size range between 30 and 100 nm, whereas in the size range 100-300 nm, the measured concentration ranged between 1 × 10² and 5 × 10³ cm⁻³. Diurnal patterns in number concentrations were observed in connection with the transport of air masses and local sources. During the winter period, three nucleation events were observed in connection with the appearance of a particle mode at 20 nm.

Soil, olive leaves, and fruits, were sampled from an olive grove 200 ha, irrigated with treated municipal wastewater (TMWW), located at Al-Tafilah wastewater processing plant (WWPP), Jordan. Similar samples were also taken from plants not irrigated with TMWW (Control). The heavy metal and essential nutrients were determined in all samples, and the data were statistically processed. The following were found: Much smaller quantities of heavy metals than essential elements were accumulated in the leaves and fruits, the accumulation being independent of the TMWW heavy metal concentration, suggesting a selective uptake of the metals by the olive plants. Also the elemental interactions, which occurred in the olive fruits, contributed mainly essential nutrients and secondarily heavy metals. The trend of heavy metal transfer from soil to olive fruits, and leaves, was almost the same, showing a consistency of transfer.

A bacterial water quality model (BWQM) was developed and used to evaluate the impacts of cattle farming and climate change on the stream fecal coliform pollution in the Salmon River watershed in south-central British Columbia, Canada. The accuracy of the model simulation was evaluated using the Nash-Sutcliffe coefficient of efficiency (COE). The BWQM simulated the observed field data well, with the values of the COE ranging from 0.76 to 0.78 for the stream flow, from 0.55 to 0.60 for the fecal coliform (FC) concentration, and from 0.85 to 0.89 for the FC loading. The BWQM captured more than 79%, 66%, and 90% variation of the daily stream flow, FC concentration, and FC loading, respectively. The BWQM predicts that between 70% and 80% of the FC were transferred from the cattle farm to the Salmon River through the snowmelt-caused surface runoff during late winter and early spring, with the balance 20% to 30% coming from the soil-lateral flow and the groundwater return flow. The model also indicates that the stream FC concentration is sensitive to the distance of the cattle farm to the Salmon River. The model scenario analysis reveals that the climate change, at an assumed 1°C increment of daily air temperature, results in an increase in the stream FC concentration in the spring, fall, and winter, but there is also a decrease in the summer. The increased air temperature also changes the seasonal pattern of the stream FC concentration. Rainfall can reduce the stream FC concentration and mitigate the impact of the increased air temperature on the stream FC concentration as long as it does not result in a surface runoff or flooding event.

Mining activities generate spoils and effluents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremediation. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Aviniéres tailing basins (up to 160,000 mg kg–1 Zn, 90,000 mg kg–1 Pb, 9,700 mg kg–1 of As and 245 mg kg–1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal-tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg–1. These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas.