Chemical cross-linking and the high molecular weight of superabsorbent copolymers (SAPs) are the two main causes of their resistance to biodegradation. However, SAP particles are colonized by microorganisms. For the purposes of this study, the dry technical copolymer of acrylamide and potassium acrylate containing 5.28 % of unpolymerized monomers was wrapped in a geotextile and incubated in unsterile Haplic Luvisol soil as a water absorbing geocomposite. The highest number of soil bacteria that colonized the hydrated SAP and utilized it as the sole carbon and energy source was found after the first month of incubation in soil. It was equal to 7.21–7.49 log₁₀ cfu g⁻¹ of water absorbed by the SAP and decreased by 1.35–1.61 log₁₀ units within the next 8 months. During this time, the initial SAP water holding capacity of 1665.8 g has decreased by 24.40 %. Moreover, the 5 g of SAP dry mass has declined by 31.70 %. Two bacteria, Rhizobium radiobacter 28SG and Bacillus aryabhattai 31SG isolated from the watered SAP were found to be able to biodegrade this SAP in pure cultures. They destroyed 25.07 and 41.85 mg of 300 mg of the technical SAP during the 60-day growth in mineral Burk’s salt medium, and biodegradation activity was equal to 2.95 and 6.72 μg of SAP μg⁻¹ of protein, respectively. B. aryabhattai 31SG and R. radiobacter 28SG were also able to degrade 9.99 and 29.70 mg of 82 mg of the ultra-pure SAP in synthetic root exudate medium during the 30-day growth, respectively.

Cr(VI) adsorption onto a novel fibrous ethylenediamine-functionalized polyethylene/polypropylene (PE/PP-g-PGMA-EDA) nonwoven fabric was investigated in aqueous solutions. The ethylenediamine functionalities were immobilized on the PE/PP nonwoven fabric through the epoxy groups of poly(glycidyl methacrylate) (PGMA) grafted to the fibers via radiation-induced emulsion graft polymerization in aqueous solution. Optimum conditions for grafting and subsequent modification steps were determined. The adsorbents were characterized by FTIR, XPS, and SEM techniques. Cr(VI) adsorption was studied in batch mode as a function of pH, feed concentration, contact time, ionic strength, and coexisting anions. The nonwoven adsorbent exhibited efficient, rapid Cr(VI) removal; high adsorption capacity; and insignificant interference from coexisting ions. Adsorbed Cr(VI) ions were desorbed using 2 M HNO₃ solution, and the adsorption capacity of the nonwoven fabric was retained for four adsorption–desorption cycles. The data for Cr(VI) adsorption on the nonwoven fabric fitted to the Langmuir isotherm model well. The maximum adsorption capacity for the Langmuir isotherm was 178.9 mg Cr(VI)/g polymer at pH 3.00. Graphical Abstract ᅟ

Mine tailings represent a globally significant source of potentially harmful elements (PHEs) to the environment. The management of large volumes of mine tailings represents a major challenge to the mining industry and environmental managers. This field-scale study evaluates the impact of two highly contrasting remediation approaches to the management and stabilisation of mine tailings. The geochemistry of the tailings, overlying amendment layers and vegetation are examined in the light of the different management approaches. Pseudo-total As, Cd and Pb concentrations and solid-state partitioning (speciation), determined via sequential extraction, were established for two Tailings Management Facilities (TMFs) in Ireland subjected to the following: (1) a ‘walk-away’ approach (Silvermines) and (2) application of an amendment layer (Galmoy). PHE concentrations in roots and herbage of grasses growing on the TMFs were also determined. Results identify very different PHE concentration profiles with depth through the TMFs and the impact of remediation approach on concentrations and their potential bioavailability in the rooting zone of grass species. Data also highlight the importance of choice of grass species in remediation approaches and the benefits of relatively shallow-rooting Agrostis capillaris and Festuca rubra varieties. In addition, data from the Galmoy TMF indicate the importance of regional soil geochemistry for interpreting the influence of the PHE geochemistry of capping and amendment layers applied to mine tailings.

A new combined difenoconazole and fluxapyroxad fungicide formulation, as an 11.7 % suspension concentrate (SC), has been introduced as part of a resistance management strategy. The dissipation of difenoconazole and fluxapyroxad applied to apples and the residues remaining in the apples were determined. The 11.7 % SC was sprayed onto apple trees and soil in Beijing, Shandong, and Anhui provinces, China, at an application rate of 118 g a.i. ha⁻¹, then the dissipation of difenoconazole and fluxapyroxad was monitored. The residual difenoconazole and fluxapyroxad concentrations were determined by ultrahigh-performance liquid chromatography tandem mass spectrometry. The difenoconazole half-lives in apples and soil were 6.2–9.5 and 21.0–27.7 days, respectively. The fluxapyroxad half-lives in apples and soil were 9.4–12.6 and 10.3–36.5 days, respectively. Difenoconazole and fluxapyroxad residues in apples and soil after the 11.7 % SC had been sprayed twice and three times, with 10 days between applications, at 78 and 118 g a.i. ha⁻¹ were measured. Representative apple and soil samples were collected after the last treatment, at preharvest intervals of 14, 21, and 28 days. The difenoconazole residue concentrations in apples and soil were 0.002–0.052 and 0.002–0.298 mg kg⁻¹, respectively. The fluxapyroxad residue concentrations in apples and soil were 0.002–0.093 and 0.008–1.219 mg kg⁻¹, respectively. The difenoconazole and fluxapyroxad residue concentrations in apples were lower than the maximum residue limits (0.5 and 0.8 mg kg⁻¹, respectively). An application rate of 78 g a.i. ha⁻¹ is therefore recommended to ensure that treated apples can be considered safe for humans to consume.

Stream biomonitoring tools are largely lacking for many developing countries, resulting in adoption of tools developed from other countries/regions. In many instances, however, the applicability of adopted tools to the new system has not been explicitly evaluated. The objective of this study was to test the applicability of foreign diatom-based water quality assessment indices to streams in Zimbabwe, with the view to highlight challenges being faced in diatom-based biological monitoring in this developing country. The study evaluated the relationship between measured water quality variables and diatom index scores and observed some degree of concordance between water quality variables and diatom index scores emphasising the importance of diatom indices in characterisation and monitoring of stream ecological conditions in developing countries. However, ecological requirements of some diatom species need to be clarified and incorporated in a diatom-based water quality assessment protocol unique to these regions. Resources should be channelled towards tackling challenges associated with diatom-based biological monitoring, principally taxonomic studies, training of skilled labour and acquiring and maintaining the necessary infrastructure. Meanwhile, simpler coarse taxonomy-based rapid bioassessment protocol, which is less time and resource consuming and requires less specialised manpower, can be developed for the country.

Tributyltin (TBT) is a species of organotin compound (OTC), used as antifouling biocide in boat and ship paints to prevents the attachment of marine organism on their hull surfaces. Tributyltin was found to be very toxic to a variety of targeted and non-targeted organisms and has high persistence in sediments even after the total global ban by the International Maritime Organization (IMO) in 2008. Therefore, there is an urgent need to clean up TBT-polluted environments after the global banning due to the significant risks it poses to the human and aquatic organisms for its slow degradation rate. In selecting bioremediation agents, indigenous bacteria were documented to be of great potentials compared to non-indigenous. In this study, comparison was made between a bacterial isolate Klebsiella sp. FIRD 2, isolated from TBT-contaminated surface sediment and Pseudomonas specie isolated from non-TBT-contaminated soil. Previously, we isolated, screened, and identified Klebsiella sp. FIRD 2 as a TBT-resistant bacterium from TBT-contaminated surface sediment of Kong Kong Laut, Johor, Malaysia. The isolate was able to resist TBT up to 1500 μg/L without addition of carbon source in minimal salt medium (MSM). Pseudomonas sp., isolated from non-TBT-contaminated soil was tested in MSM treated with different concentration of TBT. The bacterium did not endure to survive in TBT-treated media without addition of carbon source; thus, the strain has no ability to utilize TBT as source carbon. Growth of Pseudomonas sp. was observed in MSM treated with TBT at concentration of 500 μg/L and 1000 μg/L along with addition of glucose as carbon source. No growth of Pseudomonas sp. was observed in MSM with higher TBT concentration even with additional of carbon source. This study equally endorses the potentials of indigenous bacteria in bioremediation of TBT contamination.

Drainage filters using porous granular material constitute new innovative technologies for remediating phosphorus (P) from agricultural tile drainage water. In drainage filters where convective velocities are often high, we hypothesize that intragranular diffusion may affect solute transport depending on filter characteristics and flow rate. This was investigated for six drainage filter materials (Leca, Filtralite-P®, granulated limestone, crushed seashells, calcined diatomite earth (CDE), and a poorly ordered Fe oxide aggregate (CFH)) conducting a tritium (³H₂O) tracer experiment at low (0.26 cm h⁻¹), medium (23 cm h⁻¹), and high (41 cm h⁻¹) flux densities. The filter materials differed widely with respect to grain-size distribution (D ₅₀ from 1.6 to 3.3 mm), uniformity coefficient (1.7 to 2.2), particle density (1.75 to 2.76 g cm⁻³), bulk density (0.34 to 1.46 g cm⁻³), and water-filled porosity (0.39 to 0.73 cm³ cm⁻³). Measurements of specific surface area (SSA) included both SSABET and SSAEGME to ensure inclusion of the intragranular microporosity, not accounted by N₂-BET. SSA varied widely across methods and allowed the differentiation of filters according to the significance of the intragranular porosity. Tritium transport varied from approximately equilibrium transport at all flow rates in Leca, Filtralite-P®, and limestone, to progressive non-equilibrium transport as flow rate increased in Seashells, CDE, and CFH. In general, the filter materials were highly variable in hydro-physical properties. Filters with (approximately) equilibrium transport were, however, all characterized by low specific surface areas. The non-equilibrium transport was explained by an intragranular diffusion in filters with larger specific surface area (Seashells, CDE, and CFH).

dithiocarbamate-graphene oxide (GO) was prepared by simple method through reactions between poly3-aminopropyltriethoxysilane functionalized GO (PAS-GO) and CS₂. DTC-GO can capture Cu²⁺ and Cd²⁺ effectively to generate stable structures and then remove them from aqueous solutions. The properties of the DTC-GO are characterized by Fourier transform infrared spectroscopy (FTIR). The adsorption capacity for heavy metal ions of DTC-GO was evaluated by the removal of Cu²⁺ and Cd²⁺ from aqueous solution. The effect of several factors, including the pH, contact time, and temperature, was investigated by batch experiment. The results show that the DTC-GO exhibits excellent adsorption capacity for Cu²⁺ and Cd²⁺. The adsorption kinetics study indicates that the adsorption kinetics of Cu²⁺and Cd²⁺ all could be well described by pseudo-second-order kinetic model. The adsorption isotherm was investigated by Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models, and the adsorption process was well described by the Langmuir model. The effect of temperature shows that the process of DTC-GO for Cu²⁺ and Cd²⁺ is an endothermic process. The results indicated that the DTC-GO can be used as one of the promising candidate adsorbents with enhanced removal capacity for the adsorption of Cu²⁺ and Cd²⁺.

Biomixtures comprise the active part of biopurification systems (BPS) for the removal of pesticide-containing wastewater from agricultural origin. Considering that biomixtures contain an important amount of lignocellulosic substrates, their bioaugmentation with degrading ligninolytic fungi represents a promising way to improve BPS. The fungus Trametes versicolor was employed for the bioaugmentation of rice husk-compost-soil (GCS) biomixtures in order to optimize the removal of the highly toxic insecticide/nematicide carbofuran (CFN). Composition of biomixtures has not been optimized before, and usually, a volumetric composition of 50:25:25 (lignocellulosic substrate:humic component:soil) is employed. Optimization of the biomixture composition was performed with a central composite design, using the volumetric content of rice husk (pre-colonized by the fungus) and the volumetric ratio compost/soil as design variables. Performance of biomixtures was comprehensively assayed considering CFN removal, the production of toxic transformation products (3-hydroxycarbofuran/3-ketocarbofuran), the ability to mineralize [¹⁴C]carbofuran, and the residual toxicity in the matrix. According to the models, the optimal volumetric composition of the GCS biomixture is 30:43:27, which maximizes removal and mineralization rate, and minimizes the accumulation of transformation products. Results support the value of assessing new biomixture formulations according to the target pesticide in order to obtain their optimal performance, before their use in BPS.

The study of the time series from the township of Campo Grande in the State of Mato Grosso do Sul (from January 2004 to 31 December 2010) is presented. Various statistical methods were used for the data analysis. Using robust statistics, very pronounced skewness of the ozone volume part distribution during each month of the year was obtained. The variability in data is the largest during a month of September. The average annual values have asymmetrical distribution of the ozone volume fraction. Within the measured period, these averages are between 15 and 20 ppb. Particularly pronounced ozone distribution asymmetry throughout the year 2007 could be explained by observing meteorological parameters. Principal component analysis (PCA) presented here clearly shows that air temperature and wind speed are contributing factors in ozone formation, while relative humidity and atmospheric pressure cause the decrease in the ozone volume fraction in the air. Further, the hierarchical cluster analysis (CA) was performed for meteorological and ozone data using the Ward’s methods. The correlation between ozone and the effective temperature index (TEv) showed a development of the ozone with high temperature of air. From the Pearson’s correlation coefficients, it is clear that the relative humidity and the air temperature have a negative effect on respiratory system, causing respiratory illnesses.