In Mexican waters, there is no a formal and well-established monitoring program of harmful algal blooms (HAB) events. Until now, most of the work has been focused on the characterization of organisms present in certain communities. Therefore, the development of new techniques for the rapid detection of HAB species is necessary. Capillary electrophoresis finger print technique (CE-SSCP) is a fingerprinting technique based on the identification of different conformers dependent of its base composition. This technique, coupled with capillary electrophoresis, has been used to compare and identify different conformers. The aim of this study was to determine if CE-SSCP analysis of ribosomal RNA (rRNA) gene fragments could be used for a rapid identification of toxic and harmful HAB species to improve monitoring activities along the coasts of Baja California Sur, Mexico.Three different highly variable regions of the 18S and 28S rRNA genes were chosen and their suitability for the discrimination of different dinoflagellate species was assessed by CE-SSCP.The CE-SSCP results obtained for the LSU D7 fragment has demonstrated that this technique with this gene region could be useful for the identification of the ten dinoflagellates species of different genera.We have shown that this method can be used to discriminate species and the next step will be to apply it to natural samples to achieve our goal of molecular monitoring for toxic algae in Mexican waters. This strategy will offer an option to improve an early warning system of HAB events for coastal BCS, allowing the possible implementation of mitigation strategies. A monitoring program of HAB species using molecular methods will permit the analysis of several samples in a short period of time, without the pressure of counting with a taxonomic expert in phytoplankton taxonomy.

The electrochemical abatement of the drug ibuprofen (2-(4-isobutylphenyl)propionic acid) from aqueous solution has been carried out by anodic oxidation. The electrolyses have been performed at constant current using a small, undivided cell equipped with a Pt or thin-film boron-doped diamond (BDD) anode and a carbon-felt cathode. The results have shown that ibuprofen has been destroyed under all the conditions tested, following pseudo-first-order kinetics; however, BDD enables higher removal rates than Pt, because the former produces greater quantity of •OH. Using BDD anode, the pseudo-first-order rate constant increased with applied current and when NaCl replaced Na₂SO₄ as supporting electrolyte, while it is almost unaffected by ibuprofen concentration. Mineralization of ibuprofen aqueous solutions was followed by total organic carbon (TOC) measurements. After 8 h of electrolysis, TOC removal varied from 91 % to 96 % applying a current in the range of 50–500 mA. The reaction by-products were quantified by chromatographic techniques, and in particular, aliphatic acids (oxalic, glyoxylic, formic, acetic, and pyruvic) have been the main intermediates formed during the electrolyses. The absolute rate constant for the oxidative degradation of ibuprofen have also been determined, by competition kinetic method, as 6.41 × 10⁹ M⁻¹ s⁻¹.

Plant cell walls may play an important role in the uptake and accumulation of heavy metals. This study was undertaken to obtain a better understanding of the role of the root cell walls (RCW) and their subfractions on adsorption of cadmium (Cd) in a promising woody phytoremediation species, Salix jiangsuensis J172. In order to examine how Cd binding was affected by pectin and hemicellulose, RCW were isolated and sequentially fractioned by removing pectin (RCW1), partial removal of hemicellulose (RCW2), and complete removal of hemicellulose (RCW3). The RCW and fractions were characterized by Fourier transform infrared spectroscopy, which suggested decomposition of hemicellulose and a decline in nitrogen content following cell wall isolation and fractionation. The adsorption affinity of Cd increased gradually following the sequential extraction of root cells, suggesting that hemicellulose negatively impacted Cd adsorption, while pectin and cellulose enhanced Cd adsorption. Cd adsorption dynamics and isotherms could be best described by the pseudo-second-order (R > 0.99) and Freundlich (R > 0.97) models, respectively. Thermodynamic properties (∆G, ∆H, and ∆S), determined using the van’t Hoff equation, indicated that while Cd adsorption was endothermic, and spontaneous for RCW2 and RCW3, adsorption was not spontaneous for the root, RCW, and RCW1. The results provide evidence for the importance of the root cell walls in the adsorption of Cd by willow roots.

Pseudomonas sp. AKS2 isolated from soil degrades polyethylene succinate (PES) efficiently in the laboratory. However, this organism may not be able to degrade PES with similar efficiency in a natural habitat. Since in situ remediation is preferred for the effective removal of recalcitrant materials like plastic, in the current study, bioaugmentation potential of this organism was investigated. To investigate the potential of the AKS2 strain to bioaugment the PES-contaminated soil, a microcosm-based study was carried out wherein naturally attenuated, biostimulated, and AKS2-inoculated (bioaugmented) soil samples were examined for their ability to degrade PES. The results showed better degradation of PES by bioaugmented soil than other microcosms. Consistent with it, a higher number of PES-degrading organisms were found in the bioaugmented microcosm. The bioaugmented microcosm also exhibited a higher level of average well color development in BiOLOG ECO plate assay than the other two. The corresponding Shannon–Weaver index and Gini coefficient revealed a higher soil microbial diversity of bioaugmented microcosm than the others. This was further supported by community-level physiological profile of three different microcosms wherein we have observed better utilization of different carbon sources by bioaugmented microcosms. Collectively, these results demonstrate that bioaugmentation of PES-contaminated soil with AKS2 not only enhances polymer degradation but also increases microbial diversity. Bioaugmentation of soil with AKS2 enhances PES degradation without causing damage to soil ecology. Thus, Pseudomonas sp. AKS2 has the potential to be implemented as a useful tool for in situ bioremediation of PES.

Filter-feeding bivalves have been used extensively as an indicator of ecosystem condition and in management of estuarine environments. The current study aimed to determine whether sedimentary metals could predict metal concentrations in tissue of filter-feeding mussels (Mytilus galloprovincialis) and to identify areas of the estuary where mussel consumption posed a human health risk. Mussel tissue Cu and Zn concentrations (wet weight) were below guideline values for human consumption in all parts of the waterway, whereas Pb tissue concentrations exceed these guidelines (2.0 μg g(-1) wet weight) in the upper reaches of some embayments of the estuary. Concentrations of Cu and Pb in the fine fraction (<62.5 μm) of bottom sediment reasonably predicted concentrations (dry weight) of these metals in mussel tissue (r (2) = 0.460 and p = 0.001 and r (2) = 0.669 and p < 0.0001, respectively) as these materials are resuspendable and available to filter-feeding estuarine animals, whereas total sediment and mussel tissue were poorly related. Lead concentrations (>350 μg g(-1)) in fine sediments indicated areas of this estuary where human health was at risk due to high tissue concentrations of this metal. These results give encouragement for the use of the metal concentration in fine sediments as an indicator of estuarine condition and risk to human health in this waterway. Mussels were distributed in all parts of the estuary, even in areas where metal concentrations exceeded sediment quality guidelines.

Water in lakes and reservoirs accumulate phosphorous (P) from both internal and external loads. The external P load (EPL) coming from the watershed is considered to be the main cause of eutrophication of water bodies, and control strategies therefore focus on its reduction. However, algae blooms and anoxic conditions often continue even after EPL have been controlled, being the internal P load (IPL) originating from the sediment the main sources of P. To assess the efficiency of the adsorbent Phoslock (a modified bentonite) in controlling P concentrations in water and immobilize releasable P in sediments, mesocosm trials were carried out in a eutrophied reservoir and a model was described and applied that determines the amount of adsorbent and the application frequency necessary to control P concentrations in a eutrophied reservoir. The mesocosm trials confirm that Phoslock reduced P concentrations to or below the limits that define water in mesotrophic state, in approximately 2 weeks. The modeling results suggest that periodic reapplications of the adsorbent are required, unless EPL is reduced by 36 %, which allows the P concentrations in the water column to be constant. Such reduction in EPL would allow future applications of the adsorbent to be required only for control of IPL. The developed model allows planning remediation actions by determining quantities and frequencies for application of adsorbents for P control in eutrophied lakes and reservoirs.

The objective of this study was to develop a bioremediation strategy for cadmium (Cd) and carbendazim co-contaminated soil using a hyperaccumulator plant (Sedum alfredii) combined with carbendazim-degrading bacterial strains (Bacillus subtilis, Paracoccus sp., Flavobacterium and Pseudomonas sp.). A pot experiment was conducted under greenhouse conditions for 180 days with S. alfredii and/or carbendazim-degrading strains grown in soil artificially polluted with two levels of contaminants (low level, 1 mg kg⁻¹ Cd and 21 mg kg⁻¹ carbendazim; high level, 6 mg kg⁻¹ Cd and 117 mg kg⁻¹ carbendazim). Cd removal efficiencies were 32.3–35.1 % and 7.8–8.2 % for the low and high contaminant level, respectively. Inoculation with carbendazim-degrading bacterial strains significantly (P < 0.05) increased Cd removal efficiencies at the low level. The carbendazim removal efficiencies increased by 32.1–42.5 % by the association of S. alfredii with carbendazim-degrading bacterial strains, as compared to control, regardless of contaminant level. Cultivation with S. alfredii and inoculation of carbendazim-degrading bacterial strains increased soil microbial biomass, dehydrogenase activities and microbial diversities by 46.2–121.3 %, 64.2–143.4 %, and 2.4–24.7 %, respectively. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis revealed that S. alfredii stimulated the activities of Flavobacteria and Bradyrhizobiaceae. The association of S. alfredii with carbendazim-degrading bacterial strains enhanced the degradation of carbendazim by changing microbial activity and community structure in the soil. The results demonstrated that association of S. alfredii with carbendazim-degrading bacterial strains is promising for remediation of Cd and carbendazim co-contaminated soil.

With the use of cost-effective natural materials, biosorption is considered as an ecological tool that is applied worldwide for the remediation of pollution. In this study, we proposed Lemna gibba biomass (LGB), a lignocellulosic sorbent material, for the removal of two textile dyes, Direct Red 89 (DR-89) and Reactive Green 12 (RG-12). These azo dyes commonly used in dying operations of natural and synthetic fibres are the most important pollutants produced in textile industry effluents. For this purpose, batch biosorption experiments were carried out to assess the efficacy of LGB on dye treatment by evaluating the effect of contact time, biomass dosage, and initial dye concentration. The results indicated that the bioremoval efficiency of 5 mg L⁻¹ DR-89 and RG-12 reached approximately 100 % after 20 min of the exposure time; however, the maximum biosorption of 50 mg L⁻¹ DR-89 and 15 mg L⁻¹ RG-12 was determined to be about 60 and 47 %, respectively. Fourier transform infrared spectroscopy used to explain the sorption mechanism showed that the functional groups of carboxylic acid and hydroxyl played a major role in the retention of these pollutants on the biomass surface. The modelling results using Freundlich, Langmuir, Temkin, Elovich, and Dubini Radushkevich (D-R) isotherms demonstrated that the DR-89 biosorption process was better described with the Langmuir theory (R ² = 0.992) while the RG-12 biosorption process fitted well by the D-R isotherm equation (R ² = 0.988). The maximum biosorption capacity was found to be 20.0 and 115.5 mg g⁻¹ for DR-89 and RG-12, respectively, showing a higher ability of duckweed biomass for the bioremoval of the green dye. The thermodynamic study showed that the dye biosorption was a spontaneous and endothermic process. The efficacy of using duckweed biomass for the bioremoval of the two dyes was limited to concentrations ≤50 mg L⁻¹, indicating that L. gibba biomass may be suitable in the refining step of textile effluent treatment.

Presently, many pharmaceuticals are listed as emerging contaminants since they are considered to be great potential threats to environmental ecosystems. These contaminants, thus, present significant research interest due to their extensive use and their physicochemical and toxicological properties. This review discusses a whole range of findings that address various aspects of the usage, occurrence, and potentially environmental risks of pharmaceuticals released from various anthropogenic sources, with emphasis on the aquatic systems in Vietnam. The published information and collected data on the usage and occurrence of antibiotics and synthetic hormone in effluents and aquatic systems of Vietnam is reported. This is followed by a potential ecological risk assessment of these pollutants. The extensive use of antibiotics and synthetic hormones in Vietnam could cause the discharge and accumulation of these contaminants in the aquatic systems and potentially poses serious risks for ecosystems. Vietnam is known to have extensively used antibiotics and synthetic hormones, so these contaminants are inevitably detected in aquatic systems. Thus, an appropriate monitoring program of these contaminants is urgently needed in order to mitigate their negative effects and protect the ecosystems.

The aim of this study was to examine the effects of replacement of phosphoric acid with nitric or acetic acid, and replacement of NaOH with KOH, as cleaning agents in dairy factories, on the effects that irrigation of dairy factory effluent (DFE) has on the soil–plant system. A 16-week greenhouse study was carried out in which the effects of addition of synthetic dairy factory effluent containing (a) milk residues alone or milk residues plus (b) H₃PO₄/NaOH, (c) H₃PO₄/HNO₃/NaOH or (d) CH₃COOH/KOH, on soil’s chemical, physical and microbial properties and perennial ryegrass growth and nutrient uptake were investigated. The cumulative effect of DFE addition was to increase exchangeable Na, K, Ca, Mg, exchangeable sodium percentage, microbial biomass C and N and basal respiration in the soil. Dry matter yields of ryegrass were increased by additions of DFE other than that containing CH₃COOH. Plant uptake of P, Ca and Mg was in the same order as their inputs in DFE but for Na; inputs were an order of magnitude greater than plant uptake. Replacement of NaOH by KOH resulted in increased accumulation of exchangeable K. The effects of added NaOH and KOH on promoting breakdown of soil aggregates during wet sieving (and formation of a < 0.25 mm size class) were similar. Replacement of H₂PO₄ by HNO₃ is a viable but CH₃COOH appears to have detrimental effects on plant growth. Replacement of NaOH by KOH lowers the likelihood of phytotoxic effects of Na, but K and Na have similar effects on disaggregation.