The aim of this work was to determine the optimum values for the biodegradation process of six abiotic factors considered very influential in this process. The optimisation of a polycyclic aromatic hydrocarbon (naphthalene, phenanthrene and anthracene) biodegradation process was carried out with a degrading bacterial consortium C2PL05. The optimised factors were the molar ratio of carbon/nitrogen/phosphorus (C/N/P), the nitrogen source, the iron source, the iron concentration, the pH and the carbon source. Each factor was optimised applying three different treatments during 168 h, analysing cell density by spectrophotometric absorbance at 600 nm and PAH depletion by HPLC. To determine the optimum values of the factors, an analysis of variance was performed using the cell density increments and biotic degradation constants, calculated for each treatment. The most effective values of each factor were: a C/N/P molar ratio of 100:21:16, NaNO3 as nitrogen source, Fe2(SO4)3 as iron source using a concentration of 0.1 mmol l−1, a pH of 7.0 and a mixture of glucose and PAHs as carbon source. Therefore, high concentrations of nutrients and soluble forms of nitrogen and iron at neutral pH favour the biodegradation. Also, the addition of glucose to PAHs as carbon source increased the number of total microorganism and enhanced PAH biodegradation due to the augmentation of PAH degrader microorganisms. It is also important to underline that the statistical treatment of data and the combined study of the increments of the cell density and the biotic biodegradation constant have facilitated the accurate interpretation of the optimisation results. For an optimum bioremediation process, it is very important to perform these previous bioassays to decrease the process development time and, therefore, the costs.

Nitrogen fertilizers used in agriculture often cause nitrate leaching towards shallow groundwater, especially in lowland areas where the flat topography minimize the surface run off. In order to introduce good agricultural practices that reduce the amount of nitrate entering the groundwater system, it is important to quantify the kinetic control on nitrate attenuation capacity. With this aim, a series of anaerobic batch experiments, consisting of loamy soils and nitrate-contaminated groundwater, were carried out using acetate and natural dissolved organic matter as electron donors. Acetate was chosen because it is the main intermediate species in many biodegradation pathways of organic compounds, and it is a suitable carbon source for denitrification. Sorption of acetate was also determined, fitting a Langmuir isotherm in both natural and artificially depleted organic matter soils. Experiments were performed in quadruplicate to account for the spatial variability of soil parameters. The geochemical code PHREEQC (version 2) was used to simulate kinetic denitrification using Monod equation, equilibrium Langmuir sorption of acetate, and equilibrium reactions of gas and mineral phases (calcite). The reactive modeling results highlighted a rapid acetate and nitrate mineralization rate, suggesting that the main pathway of nitrate attenuation is through denitrification while calcite acted as a buffer for pH. However, in the absence of acetate, the natural content of organic matter did not allow to complete the denitrification process leading to nitrite accumulation. Reactive modeling is thought to be an efficient and robust tool to quantify the complex biogeochemical reactions which can take place in underground environments.

Aquatic risk assessments for fungicides are carried out without information on their toxicity to non-target aquatic fungi. This might cause an underestimation of the toxic effects to the aquatic fungal community. This study focuses on the question whether recently derived concentrations limits for fungicides considered to protect populations of primary producers and (in)vertebrates also do protect the aquatic fungi. A panel of fungal species and Oomycetes was isolated and identified from unpolluted surface waters in the Netherlands. Toxicity tests were used to determine effects of seven fungicides with different modes of actions. For the triazoles epoxiconazole and tebuconazole, the chronic lowest observable effect concentration was lower than the regulatory acceptable concentration based on acute HC5 values.

Limited data on microbial partitioning between the freely suspended and particulate attached phases during transport along overland flow pathways have resulted in high uncertainty in bacterial fate and transport models and the application of these models to watershed management plans. The objectives of this study were to examine differences in attachment between E. coli and enterococci in runoff from plots with highly and sparsely vegetated grassland; investigate relations between flow regime, total suspended solids, and E. coli and enterococci attachment; and identify the particle size categories to which the attached cells were associated. Two rainfall simulations were conducted on large field plots 3 m wide by 18.3 m long with highly and both highly and sparsely vegetated covers and treated with standard cowpats. Results from the first experiment representing pasture with highly vegetated cover indicate that the majority of E. coli and enterococci are transported from the fresh manure source in the unattached state with only 4.8% of E. coli and 13% of enterococci associated with particles. The second experiment which compared partitioning in runoff from both highly and sparsely vegetated covers found lower bacterial attachment rates: the average E. coli percent attached was 0.06% from plots with highly vegetated cover and 2.8% from plots with sparsely vegetated cover while the corresponding values for enterococci were 0.98% and 1.23%, respectively. The findings from this study provide the first set of data on bacterial partitioning in overland flow from large field plots, and results may be helpful for parameterizing water quality models and designing conservation practices.

The current study aimed to compare lindane degradation by pure and mixed cultures of Streptomyces sp. Cell-free extracts were assayed for potentiating dechlorinase activity and, based on these results, consortia of two to six microorganisms were assayed for their growth on and degradation of lindane. Furthermore, the role of bacterial consortia of lindane-degrading strains was examined in lindane decontamination soil assays. Four actinobacteria, previously isolated from a pesticide-contaminated area, were selected because of their tolerance to lindane and their ability to use the pesticide as sole carbon source. These strains as well as Streptomyces sp. M7 and Streptomyces coelicolor A3 were used to study specific dechlorinase activity (SDA) and lindane removal in mixed cultures. Pure cultures presented SDA in the presence of 1.66 mg L-1 lindane as carbon source. SDA was improved by certain mixed cultures until 12 times compared with pure cultures. Mixed cultures with two, three, and four strains showed maximum lindane removal of 46% to 68%, whereas combinations of five and six strains did not efficiently remove the pesticide from the culture medium. The Streptomyces sp. A2, A5, M7, and A11 consortium presented the lowest ratio between residual lindane concentration and SDA and could be a promising tool for lindane biodegradation.

Among the most extensively used compounds for the pest control in Argentinean crops is the organochlorine endosulfan. The sublethal effects of the commercial endosulfan formulation on hematology and lipid peroxidation (LPO) of the neotropical fish Prochilodus lineatus were investigated. Firstly, we calculated acute toxicity (LC50) in order to define sublethal concentrations (0, 1.2, and 2.4 μg L−1). Hematological and oxidative stress responses were assessed at 24, 48, and 96 h. Endosulfan exposure significantly diminished the hemoglobin concentration, mean cell hemoglobin, and total plasma protein and increased white blood cells count and plasma glucose after 96 h. Exposed fish showed an alteration of the differential leukocytes count, evidenced by more thrombocytes and monocytes and less lymphocytes and neutrophils. Endosulfan increased LPO levels in intestine, liver, and brain in both sublethal concentrations. The present results suggest that endosulfan produces biochemical and physiological alterations, including immunological disorders, and it is a good inductor of oxidative stress in P. lineatus.

Critical loads of nitrogen (N) from atmospheric deposition were determined for alpine lake ecosystems in the western US using fossil diatom assemblages in lake sediment cores. Changes in diatom species over the last century were indicative of N enrichment in two areas, the eastern Sierra Nevada, starting between 1960 and 1965, and the Greater Yellowstone Ecosystem, starting in 1980. In contrast, no changes in diatom community structure were apparent in lakes of Glacier National Park. To determine critical N loads that elicited these community changes, we modeled wet nitrogen deposition rates for the period in which diatom shifts first occurred in each area using deposition data spanning from 1980 to 2007. We determined a critical load of 1.4 kg N ha−1 year−1 wet N deposition to elicit key nutrient enrichment effects on diatom communities in both the eastern Sierra Nevada and the Greater Yellowstone Ecosystem.

Pot culture experiments were conducted to study the remediation potentials of a newly found accumulator Kalimeris integrifolia Turcz. ex DC. under different cadmium (Cd) concentrations with same fertilizer level, as well as the same Cd dose under different fertilizer doses. At medium (100 g/kg) chicken manure level, Cd concentrations in roots, stems, leaves, inflorescences, and shoots of K. integrifolia grown in the soils contaminated with 2.5, 5, 10, and 25 mg/kg Cd significantly decreased (p < 0.05) in average by 23.8%, 29.9%, 24.0%, 30.1%, and 38.6%, respectively, when compared to those of the pots without addition of chicken manure. In contrast, the medium urea amendment level (1 g/kg) showed no effect on the bioaccumulated Cd concentrations of K. integrifolia regardless of the spiked Cd doses. However, Cd extraction capacities (micrograms per pot) of K. integrifolia shoots were significantly increased (p < 0.05) due to the gain in biomass (more than one- to twofolds) by the soil fertilizing effect of urea and chicken manure. Particularly, Cd extraction capacities (micrograms per pot) of K. integrifolia shoots amended by urea were higher than that of chicken manure. Under the condition of 25 mg/kg Cd addition, shoot biomasses of K. integrifolia were significantly increased (p < 0.05) with the amendment of chicken manure (50, 100, and 200 g/kg) and urea (0.5, 1, and 2 g/kg). As a result, the Cd extraction capacities (micrograms per pot) were increased in treatments even though soil extractable Cd concentrations were significantly decreased (p < 0.05) by amendment with chicken manure and maintained by urea addition. For practical application concerns, chicken manure is better used as phytostabilization amendment owing to its reducing role to extractable heavy metal in soil, and urea is better for phytoextraction.

This paper is a review of the available literature on the main features of 11 of the most widely adopted oxygenated additives to base gasoline and diesel, focusing particularly on the emissions from the oxygenates considered as additives. The oxygenated additives studied are methyl tert-butyl ether, ethyl tertiary butyl ether, tert-amyl ethyl ether, tertiary amyl methyl ether, isopropyl ether, dimethyl carbonate, dimethoxymethane, dibutyl ether, diglycol methyl ether, diethyl carbonate, and 2-methoxyethyl acetate.

The Diep River is a major freshwater ecosystem in the Western Cape, South Africa. Although it is surrounded by many sources of metal pollution, the actual metal levels in this river system are unknown. Wetland plants are known to accumulate metals and may possibly be used as biomonitors of metal contamination in a river system. One such species, the sedge Bolboschoenus maritimus, is found in abundance along the banks of this river. The aim of this study was to investigate and monitor the degree of metal contamination in the water and sediments of the lower Diep River, as well as to study the seasonal accumulation and distribution of metals in B. maritimus, and the use thereof as biomonitor species. Two sampling sites were used: one site above the wetland section of the river, receiving runoff mainly from agricultural lands (site 1), and one site close to the river mouth (site 2), exposed to several possible pollution sources. Water, sediment, and plant (root, leaf and stem) samples were collected seasonally for 1 year and analyzed for Al, Zn, Cu, and Fe. There was greater bioaccumulation of metals by plants at site 2, due to greater bioavailability of metals. B. maritimus was shown to be a root accumulator of metals. Seasonal fluctuations in root, stem, and leaf metal concentrations did not follow seasonal sediment concentration patterns. However, using B. maritimus as test species did provide valuable additional information to sediment and water analyses. More extensive research is needed to conclude whether this species is an effective biomonitor in the lower Diep River environment.