Bodies of water contaminated by cyanobacteria and their neuro- and hepatotoxins have caused environmental and public health issues all over the world. Therefore, determining safe concentrations in water for multiple uses to protect aquatic biota and identify forms of remediation are of broad interest. In this study, we isolated strains of the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii, which produce microcystin (MC) and saxitoxin (STX), respectively. Ecotoxicological tests using suspensions of lysed lyophilizated cells with concentrations of toxins equivalent to those permitted by legislation for potability (1 μg L⁻¹ for MC and 3 μg L⁻¹ for STX) did not result in significant mortality of the model organism, Ceriodaphnia dubia, where as concentrations five times greater resulted in decreased survival for both toxins. However, reproduction was significantly reduced even in the lower concentrations, indicating that the currently permitted standards are not safe for environmental protection. When cyanotoxins were treated with ultrasound, mortalities were no longer significant, independent of concentrations. Although reproduction was still lower in relation to the control, it was significantly higher when compared to the results obtained before ultrasound. Ultrasound has been previously applied to cyanobacteria cell lysis, but this is the first study to investigate the ecotoxicological effects of ultrasound on cyanotoxins. Using new test organisms and different times and potency of sonication will permit the development of more efficient techniques for the remediation of these toxins and the development of more adequate parameters for the protection of aquatic life.

The purpose of this research was to evaluate the biodegradation extent of petroleum hydrocarbons by Phormidium ambiguum strain TISTR 8296 in the presence of inorganic nutrients and heavy metals as co-contaminants. In this context, waste motor oil served as a source of petroleum hydrocarbons. Strain TISTR 8296 grew actively with waste motor oil at 0.5–2.0% (v/v) concentrations and also exhibited good biodegradation potential at this concentration range. Meanwhile, its growth and biodegradation capacity fell down with increasing oil concentration to 3.0 and 4.0%. Strain TISTR 8296 adapted quickly to pH changes, showing good growth ability and biodegradation capability at a pH range of 4.0–9.0 with an acidic pH of 4.0 and 5.0 appearing to decelerate its biodegradation efficiency. The addition of PO₄ ³⁻ and NO₃ ⁻ exerted a strong stimulatory effect on growth and biodegradation efficiency, while a slight promoting effect was observed for NO₂ ⁻. By contrast, amendment of NH₄ ⁺ as well as heavy metals caused a substantial inhibitory effect on growth and biodegradation efficiency with NH₄ ⁺ and Mn(II) appearing to show a weak suppressing effect. GC-MS analyses indicated that strain TISTR 8296 could transform and degrade both aliphatic and aromatic compounds.

In this study, a process has been proposed whereby the sulfide required for autotrophic denitrification is supplied by reducing the sulfate of influent water without the need to add an external sulfide source. The molar ratio of nitrate-to-sulfide was maintained at 1.6. The proposed system was operated continuously for 6 months, including two anoxic and anaerobic reactors with upward flow. The results indicate that the average amount of nitrate declined by 74%. The pH of 7–8 was more effective than a pH of 6 in removing the nitrate. As the hydraulic retention time was prolonged from 1.5 to 3 and was further prolonged to 5 h, the system efficiency was enhanced by removing the nitrate. An alkalinity consumption rate of 1.15 mg (as CaCO₃) per mg of removed NO₃ ⁻-N was achieved. In the effluent water, the increased sulfate was 6.7 mg per mg of removed NO⁻ ₃-N, while the hardness was diminished by 2.85 mg (as CaCO₃).

Cadmium and lead are some of several heavy metals that present a great concern for the environment because even in non-toxic concentrations for plants, their toxicity can affect animals and humans. Three different concentrations of sodium chloride solution were employed as pretreatment agents in order to increase the bioavailability of heavy metals and to analyze the interaction between heavy metals under saline soil conditions. The biomass production presented a remarkable increase for plants grown in soil pretreated with a 0.3 M NaCl solution, whereas the growth curve response of Arabidopsis thaliana in all samples showed a clear alteration compared with the control system. The conclusion was reached that saline solution pretreatment used in soil containing heavy metals produced an apparent stimulation of plant growth. In regards to the uptake of heavy metals by plants, lead and especially cadmium were the most favored metals by NaCl application.

Elevated bacteria concentrations have led to the impairment (e.g., closures of shellfisheries and recreational beaches) of coastal waters. Although many previous studies have suggested that wastewater inputs can lead to elevated fecal indicator bacteria (FIB) concentrations in surface waters, few studies have quantified wastewater-associated FIB exports at the watershed scale. The goal of this study was to estimate bacterial exports at the watershed scale based on wastewater management approach (septic vs. sewer). Six watersheds (three exclusively on septic and three exclusively served by a sewer system) were selected for water quality assessment and comparison. Streams were monitored approximately monthly from August 2011 to June 2012 during baseflow conditions. Additionally, three storms were monitored. Samples were collected in sterile 100-mL bottles and analyzed for Escherichia coli concentrations. Discharge from streams was measured and bacterial exports were estimated by multiplying discharge by E. coli concentration. The results revealed that (1) during baseflow conditions, septic watersheds contained elevated stream discharge and E. coli concentrations and exports as compared to sewer watersheds; (2) warmer months had elevated E. coli watershed exports compared to colder months in both septic and sewer watersheds; and (3) storms significantly increased watershed E. coli exports in both septic and sewer watersheds. Storms significantly increased watershed E. coli exports in both septic and sewered watersheds, but E. coli counts in sewered watersheds were considerably greater likely due to greater impervious surface coverage and or leaky sewer infrastructure. These findings in conjunction with previous studies suggest that septic systems may play a pivotal role in the delivery of FIB to receiving waters, particularly during baseflow conditions.

Pyrene is a dominant PAH in urban environments. It can combine with airborne particulates and accumulate on plant leaves. To investigate pyrene’s biodegradation potential, this study initially monitored the abundance of airborne and phyllosphere bacteria. The number of airborne pyrene-degrading bacteria ranged from 22 to 152 CFU m⁻³ air, and more bacteria were found in the proximity of the ornamental plant swath than along the roadside. Pyrene-degrading bacteria averaged 5 × 10⁴ CFU g⁻¹ on the leaves of all tested plant species and accounted for approximately 7% of the total population. Four pyrene-degrading bacteria were isolated from I. coccinea to use as model phyllosphere bacteria. To increase the bioavailability of pyrene, a lipopeptide biosurfactant was applied. Kocuria sp. IC3 showed the highest pyrene degradation in the medium containing biosurfactant. The removal of deposited pyrene at 30 μg g⁻¹ leaf was monitored in a glass chamber containing I. coccinea twigs. After 14 days, leaves containing both Kocuria sp. IC3 and 0.1× CMC biosurfactant showed 100% pyrene removal with the most abundant bacteria. The system with biosurfactant alone also enhanced the activities of phyllosphere bacteria with 94% pyrene removal. Consequently, the bioremediation of deposited pyrene could be achieved by spraying biosurfactant on ornamental shrubs.

Microplastics (MPs) in sediments from the complex lagoon-channel of Bizerte were investigated, for the first time, to evaluate the occurrence and abundance of MPs in Tunisia. After density separation in saline solution, MPs were counted by a stereomicroscope. The number of MPs was at the range of 3–18 items/g sediment (3000–18,000 items/kg dry sediment) and the most contaminated site was of Menzel Abderrahmane (MA) followed by Carrier Bay (CB), Menzel Jemil (MJ) and Channel of Bizerte (C). The MPs gathered during the survey varied in size from 0.3 to 5 mm, and appear in a variety of shapes and colours. The dominant shape was fibre (88.88% in MA, 91.00% in CB, 82.35% in C and 21.05% in MJ). The rest of MPs are fragments whilst no micro beads were found. Colours are clear, white, blue, green, red and black. Cities discharges, fishing activity and industrial production sites are the most likely sources of MPs. This first work provides original data on the presence of MPs that determines their bioavailability to organisms as seafood, and then possibly transfers of to human. The high MP concentrations registered in the complex lagoon-channel of Bizerte suggest that this site is a hotspot for MP pollution and there is an urgency to understand their origins and effects on marine life. The results will provide useful background information for further investigations.

A stable and efficient Fe₂O₃/expanded perlite (Fe₂O₃-Ep) composite catalyst was synthesized by a simple hydrothermal method for degradation of refractory contaminants in heterogeneous photo-Fenton system. X-ray diffraction and FT-IR analyses confirmed the presence of the Fe₂O₃ in the synthesized catalyst. The catalytic activity of the Fe₂O₃-Ep catalyst was evaluated by the degradation of rhodamine B (RhB, 5 mg/L) and metronidazole (MET, 5 mg/L) in the presence of H₂O₂ under visible light irradiation. The Fe₂O₃-Ep catalyst exhibited high efficiency for degradation of RhB at a wide pH range from 2 to 10 and showed excellent catalytic property for decomposition of MET as well. The degradation ratio of RhB was achieved 99%, and the removal ratio of COD was 62% within 90 min at the best experimental conditions (0.5 g/L of Fe₂O₃-Ep catalyst, 2 mL/L of H₂O₂). Furthermore, iron leaching of the Fe₂O₃-Ep catalyst during the catalytic degradation reaction was negligible and the catalyst still exhibited high catalytic activity and stability after five cycles. These results show that the catalyst can be used as a highly efficient heterogeneous photo-Fenton catalyst for the degradation of non-biodegradable refractory pollutants in water.

Cities in developing countries encounter rapid waves of social transformation and economic development where the environment is mostly a neglected aspect. The Katari watershed encompasses mining areas, El Alto city (one of the fastest growing urban areas in South America and the biggest in the Altiplano) as well as agricultural areas. Its outlet is Cohana Bay, one of the most polluted areas of Lake Titicaca. Here we propose an integrative approach (hydrological, physicochemical, chemical and bacterial data) to understand the pollution problem of this developing area, in which a variety of anthropogenic activities takes place. Both mining and urban areas appear to be sources of metal pollution. Nutrient and bacterial contaminations are mainly related to urban and industrial discharges. These situations have impacts in the basin from the mining area down to Cohana Bay of Lake Titicaca. Pollutant concentration patterns are highly influenced by seasonal hydrology variations. The poor quality of surface waters in the basin represents a risk for human and animal populations, as well as for the quality of aquifers located underneath El Alto city.

Influence of edaphic factors and metal content on diversity of Trichoderma species at 14 different soil sampling locations, on two depths, was examined. Forty-one Trichoderma isolates from 14 sampling sites were determined as nine species based on their internal transcribed spacer (ITS) sequences. Our results indicate that weakly alkaline soils are rich sources of Trichoderma strains. Also, higher contents of available K and P are connected with higher Trichoderma diversity. Increased metal content in soil was not inhibiting factor for Trichoderma species occurrence. Relationship between these factors was confirmed by locally weighted sequential smoothing (LOESS) nonparametric smoothing analysis. Trichoderma strain (Szeged Microbiology Collection (SZMC) 22669) from soil with concentrations of Cr and Ni above remediation values should be tested for its potential for bioremediation of these metals in polluted soils.