We examined the impact of the effluent discharged from a freshwater (trout and related species) fish hatchery on the presence of antibiotic-resistant microorganisms in a small stream. There had been no documented use of antibiotics in the hatchery for at least 6 months prior to our study, although a variety of biocides were employed routinely for cleaning. Heterotrophic bacteria and Escherichia coli were isolated from both water column and sediment samples at sites above and below the discharge of the hatchery effluent as well as from the hatchery effluent itself. Randomly chosen isolates (≥96 isolates per site) were tested for their resistance to ampicillin, cephalexin, erythromycin, and tetracycline. Resistance to at least one antibiotic was found in greater than 30% of both the heterotrophic isolates and the E. coli isolates from each of the sites. There were no significant differences among the sites in the proportion of the heterotrophic isolates resistant to any specific antibiotic. The proportion of E. coli isolates resistant to tetracycline in the hatchery effluent and in both the downstream water and sediment samples was significantly higher than in either the upstream water or sediment. These results support the possibility of the hatchery as a source of tetracycline-resistant microorganisms even in the absence of recent use of this antibiotic.

The contamination of soils and waters by dye-containing effluents is of environmental concern. Due to the increasing awareness and concern of the global community over the discharge of synthetic dyes into the environment and their persistence there, much attention has been focused on the remediation of these pollutants. Among the current pollution control technologies, biodegradation of synthetic dyes by different microbes is emerging as an effective and promising approach. The bioremediation potentials of many microbes for synthetic dyes have been demonstrated and those of others to be explored in future. The biodegradation of synthetic dyes is an economic, effective, biofriendly, and environmentally benign process. Bioremediation of xenobiotics including synthetic dyes by different microbes will hopefully prove a green solution to the problem of environmental soil and water pollution in future. This review paper discusses comprehensively the science and arts of biodegradation of synthetic dyes.

The influence of inoculum preparation and cell density on the efficiency of Cr(VI) removal was assessed with two chromate-resistant yeasts, Pichia jadinii M9 and Pichia anomala M10, isolated from textile wastewaters. Batch cultures in yeast nitrogen base (YNB)′ liquid medium (YNB without amino acids and ammonium sulfate plus sucrose and ammonium sulfate) containing 1-mM initial Cr(VI) concentrations revealed that heavy metal removal in both isolates was substantially affected by the inoculation procedure. Inocula with high initial density or pregrown in a nutritionally rich medium (Malt Czapek) were found to be key factors in order to achieve successful Cr(VI) decontamination. In contrast, low-density inocula and/or synthetic media-precultured cells were shown to negatively influence Cr(VI) disappearance, either by increasing the time for complete degradation or by reducing the percentage of heavy metal removed. These results emphasized the relevance of the selection of an appropriate inoculum culture medium and the positive influence of increasing one order of magnitude inoculum cell density in order to achieve successful and rapid Cr(VI) removal. Under these considerations, the selected yeasts, P. jadinii M9 and P. anomala M10, exhibited a remarkable ability to tolerate and completely remove Cr(VI) concentrations up to 1 mM, thus being candidates for potential applications in bioremediation of Cr(VI)-contaminated environments.

The removal of chlorinated benzenes (CBs) from the compartments and from polluted industrial sites is of great public interest for the decontamination of polluted water and for the protection of the environment. Biological degradation could be considered as a feasible process to eliminate these compounds from the environment as soil or groundwater. A research program in progress since the year 2007 was initiated to investigate the capacity of eco-remediation of CB-contaminated groundwater using a pilot-scale subsurface flow constructed wetland. In order to assess the removal efficiency of these compounds and to evaluate the biological activities, column experiments were performed. The fate of three CBs was investigated by feeding spiked tap water through laboratory columns filled with two different solid-state materials: peat and pozzolana. In order to stimulate biological activity, organic matter coming from aged vertical flow constructed wetland was added to the media. Concentrations of CBs in water effluent and in air and biological activities were monitored during 4 months. At the end of the experimental period, CB concentrations in the depth of columns were determined and a mass balance was calculated for the CBs. Removal efficiencies of the laboratory columns were >98% in the peat columns and situated around 87% to 95% in the pozzolana columns, indicating the suitability of the experimental systems for the removal of CBs. Higher effluent CB concentrations from the pozzolana columns were detected. Concentration of CBs in ambient air indicates that volatilization was low. ATP monitoring, reduction of tetrazolium violet, and exopolysaccharide determination indicated considerable biological activity with variations according to column depth and carrier material.

Samples of airborne particulate matter (PM₂.₅) were collected at a site in Lahore, Pakistan from November 2005 to January 2006. A total of 129 samples were collected using an Andersen Reference Ambient Air Sampler 2.5-400 sampler and analyzed for major ions, trace metals, and organic and elemental carbon concentrations. The data set was then analyzed by positive matrix factorization (PMF) to identify the possible sources of the atmospheric PM collected in this urban area. Six factors reproduced the PM₂.₅ sample compositions with meaningful physical interpretation of the resolved factors. The sources included secondary PM, diesel emissions, biomass burning, coal combustion, two-stroke vehicle exhaust, and industrial sources. Diesel and two-stroke vehicles contributed about 36%, biomass burning about 15%, and coal combustion sources around 13% of the PM₂.₅ mass. Nearly two thirds of the PM₂.₅ mass is carbonaceous material. Secondary particles contributed about 30% of PM₂.₅ mass. The conditional probability function (CPF) was then used to help identify likely locations of the sources present in this area. CPF analysis point to the east and northeast, which are directions of urban and industrial areas located across the border near Amritsar, India as the most probable source for high PM₂.₅ concentration from diesel and two-stroke vehicles exhaust in Lahore. Analysis of those days within three different ranges of PM₂.₅ concentration shows that most of the measured high PM₂.₅ mass concentrations were driven by diesel and two-stroke vehicle emissions including the associated primary sulfate. The use of the potential source contribution function (PSCF) to find the source locations of regionally transported particles is inapplicable in situations when high PM₂.₅ concentrations are dominated by local sources and local meteorology.

An exploratory survey of the mercury content of some common California biomass feedstocks shows that the concentrations are well below EPA toxicity levels with representative feedstock concentrations of 20 ppb for rice straw, 28 ppb for wheat straw, and 32 ppb for whole-tree wood chips. The temporal variability for rice straw (17-20 ppb) is near the analytical uncertainty (∼2 ppb). Saline-irrigated feedstock does not contain greatly higher mercury contents (17-38 ppb) compared to normally irrigated feedstock. Water leaching has likewise no detectable effects on mercury mobility, despite an up to 30% increase in the Hg concentrations attributable to mass losses during leaching. Combustion at temperatures of at least 575°C results in complete volatilization of mercury leaving solid ash and slag residuals with mercury contents at or near the lower limit of detection (5 ppb). The mercury strongly concentrated in fly ash can reach concentrations up to 40 times (<1,166 ppb) the corresponding fuel concentrations.

Geography, population growth, and politics combine to make the Gaza Strip a worst-case scenario for water resource planners. Potable water sources are shrinking while at the same time, the proportion of potable water used for irrigation is increasing. To assess whether water from wastewater treatment plants could be safely used for irrigation, this study collected 51 treated wastewater, 51 sludge, 44 soil, 30 alfalfa, and 24 oranges and lemon samples and analyzed the samples for major and trace elements. Both Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP/OES) and X-ray fluorescence (XRF) were used for the determination of Ag, Al, As, B, Ba, Br, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Se, Sr, Zn, Zr, Th, and U in digested and solid samples, respectively. Treated wastewater characteristics showed a very good agreement with the guidelines of many developed countries. Moreover, none of the tested parameters in soil showed concentrations exceeding their corresponding background values. For alfalfa, both ICP/OES and XRF showed Zn concentrations in leaves (36-42 mg/kg, respectively) higher than in root (19-31 mg/kg, respectively). The Cu showed also the same trend as Zn. No significant variation was observed between the concentrations of Cr and Mn in plant parts; concentrations of Co and Pb were two times higher in roots than in leaves and stems. The findings confirm that treated wastewater is safe to use for irrigation in Gaza. Collecting and reclaiming this water can contribute to wise use of each drop of water available.

The research and interest towards the use of constructed floating wetlands for (waste)water treatment is emerging as more treatment opportunities are marked out, and the technique is applied more often. To evaluate the effect of a floating macrophyte mat and the influence of temperature and season on physico-chemical changes and removal, two constructed floating wetlands (CFWs), including a floating macrophyte mat, and a control, without emergent vegetation, were built. Raw domestic wastewater from a wastewater treatment plant was added on day 0. Removal of total nitrogen, NH₄-N, NO₃-N, P, chemical oxygen demand (COD), total organic carbon and heavy metals (Cu, Fe, Mn, Ni, Pb and Zn) was studied during 17 batch-fed testing periods with a retention time of 11 days (February-March 2007 and August 2007-September 2008). In general, the CFWs performed better than the control. Average removal efficiencies for NH₄-N, total nitrogen, P and COD were respectively 35%, 42%, 22% and 53% for the CFWs, and 3%, 15%, 6% and 33% for the control. The pH was significantly lower in the CFWs (7.08 ± 0.21) than in the control (7.48 ± 0.26) after 11 days. The removal efficiencies of NH₄-N, total nitrogen and COD were significantly higher in the CFWs as the presence of the floating macrophyte mat influenced positively their removal. Total nitrogen, NH₄-N and P removal was significantly influenced by temperature with the highest removal between 5°C and 15°C. At lower and higher temperatures, removal relapsed. In general, temperature seemed to be the steering factor rather than season. The presence of the floating macrophyte mat restrained the increase of the water temperature when air temperature was >15°C. Although the mat hampered oxygen diffusion from the air towards the water column, the redox potential measured in the rootmat was higher than the value obtained in the control at the same depth, indicating that the release of oxygen from the roots could stimulate oxygen consuming reactions within the root mat, and root oxygen release was higher than oxygen diffusion from the air.

Pollutant concentrations and loads returned to the lower Murray River (South Australia) from flood-irrigated agriculture were monitored over a period of 2 years at six locations. This monitoring programme was designed to provide a baseline prior to environmental improvements being undertaken to reduce pollutant loads returned to the river. Pollutant (Escherichia coli, total nitrogen, oxidised nitrogen, total phosphorus, filtered reactive phosphorus and total organic carbon) concentrations were significantly (p < 0.01) higher in the drainage water than the river water and increased during the irrigation season. Salt concentrations were also significantly (p < 0.01) higher in the drainage water than the river inflow water but decreased during the irrigation season because of dilution of the saline groundwater inputs. Pollutant loads exported to the river were significantly higher (p < 0.01-0.05) during the irrigation season for all water quality parameters except oxidised nitrogen. Levels of oxidised nitrogen, filtered reactive phosphorus and E. coli increased in the river downstream of the where the agricultural pollutant inputs begin. Load calculations indicated that this increased water pollution is likely due to the pollutant contributions from the flood-irrigated areas and biogeochemical processing of dissolved nutrients in the river.

A monitoring program of particulate matter was conducted at eight sampling sites in four highly industrialized cities (Shenyang, Anshan, Fushun, and Jinzhou) of Liaoning Province in Northeast China to identify the major potential sources of ambient PM₂.₅. A total of 814 PM₂.₅ and PM₂.₅₋₁₀ samples were collected between 2004 and 2005. All PM samples were collected simultaneously in four cities and analyzed gravimetrically for mass concentrations. A sum of 16 elemental species concentrations in the PM samples were determined using inductively coupled plasma atomic emission spectroscopy. Annual means of PM₂.₅ concentrations ranged from 65.0 to 222.0 μg m⁻³ in all the eight sampling sites, and the spatial and seasonal variations were discussed. Enrichment factors were calculated, and Cr, Cu, Zn, As, Cd, and Pb will be pollution-derived elements. Site-to-site comparisons of PM₂.₅ species in each city were examined using coefficient of divergence, revealing that the two sites in each city are similar in elemental species. Principle component analysis was used for preliminary source analysis of PM₂.₅. Three or four factors in each city were isolated, and similar sources (crustal source, coal combustion, vehicle exhaust, iron making, or some other metallurgical activities) were identified at four cities.