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Dissolved organic matter in open-canopy streams is mostly derived from autochthonous sources, but the role of autochthonous DOM to sustain heterotrophic communities has been poorly studied. We compared respiration rates of epiphytic and epipelic biofilms (measured by the Resazurin—Resorufin tracer system) when processing autochthonous and allocthonous DOM sources with different chemical and optical properties. We performed laboratory experiments to determine aerobic respiration rates of epipelic and epiphytic communities in different leachates from autochthonous (macroalgae and emergent and submerged macrophytes) and allochthonous (riparian grasses) DOM sources from a Pampean stream. We also determined dissolved organic carbon and nutrient contents and DOM optical properties of each leachate. We found that epipelon was more heterotrophic and showed a lower respiratory activity than epiphyton, regardless of the type of leachate. Epiphytic respiratory activity was positively associated with DOM of microbial origin with a lower degree of humification (i.e., autochthonous microbial-algal derived materials), while epipelic respiratory activity was related to autochthonous and allochthonous humic-like materials, with higher aromaticity, derived from grasses and macrophytes. This indicates that both autochthonous and allochthonous sources can sustain microbial respiratory activity in the stream, and highlights the role of primary producers in the carbon cycle of open-canopy streams. [ABSTRACT FROM AUTHOR]

Induced heavy metals (HMs) phytoextraction from heavily contaminated soils is challenging, as high HM bioavailability causes phytotoxicity and leaching. This study introduces a novel approach for HM immobilization with biochar (BC) and lignin (LN), and later their controlled mobilization with citric acid (CA) in soil. Conocarpus erectus was grown for 120 days in shooting-range soil (SS) polluted with Pb, Cr, Cd, Ni, and Cu. HM concentrations in parts of the plants, their percentage removal, and leaching from SS were measured. Moreover, plant biochemical parameters such as the contents of chlorophyll a (Chl-a), chlorophyll b (Chl-b), protein, ascorbic acid (AsA), amino acids, and total phenolics, along with biophysical parameters such as relative water content (RWC) and water uptake capacity (WUC), were also inspected. Adding BC, LN, and BC+LN to SS improved biomass, as well as the biophysical and biochemical parameters of plants, while efficiently reducing HM concentrations in plant parts, DTPA extract, and leachates compared to the control (CK). However, the greatest amplifications in plant height (82%), dry weight of root (RDW) (109%), and dry weight of shoot (SDW) (87%), plant health, and soil enzymes were noted with the BC+LN+CA treatment, compared with the CK. Moreover, this treatment resulted in Pb, Cr, Cd, Ni, and Cu removal by 68, 30, 69, 59, and 76% from the SS compared to the CK. Surprisingly, each HM concentration in the leachates with BC+LN+CA was below the critical limits for safer water reuse and agricultural purposes. Initial HM immobilization in HM-polluted soils, followed by their secured mobilization during enhanced phytoextraction, can enhance HM removal and reduce their leaching without compromising plant and soil health. [ABSTRACT FROM AUTHOR]

The pesticide transportation to deeper soil layers can result in groundwater contamination and, consequently, environmental issues. In this research, our objective was to investigate transport efficiency of indoxacaarb using three different soils to understand the leaching potential. The leaching experiments were performed using a 0.01 M calcium chloride solution over five consecutive days. Leachates (water) and soil samples were collected and the residues of indoxacarb were analyzed using gas chromatography mass spectrometry. The method’s accuracy was validated by conducting recovery experiments at levels ranging from 0.01 to 0.1 µg/g. The results showed that 82.67 to 84.00%, 80.67 to 82.70% and 76.68 to 78.70% of the indoxacarb applied was retained in the topsoil layer (0–10 cm) for acid, alkali and neutral soil, respectively. Its low leaching behavior, as evidenced by its retention in the topsoil layer and absence in the leachate, contributes to its limited mobility within the soil profile. The study suggests that indoxacarb has no potential for contaminating groundwater and the soil environment through leaching processes. [ABSTRACT FROM AUTHOR]

Cascade cropping systems (CCS) utilize leachate from a primary crop to grow secondary crops and enhance the efficient use of water and fertilizers in areas with scarce water resources. A preliminary study investigated the effect of melatonin in a cascade cropping system to potentially improve plant tolerance to abiotic stresses. This study aimed to cultivate Salicornia fruticosa in this cropping system to reduce nutrient discharge and assess the impact of exogenous melatonin on Salicornia growth and quality. The CCS included a primary crop of Salicornia grown in an agroindustrial compost or peat. Leachates from these media were used to cultivate the same plant once again in a floating system under four treatments: compost leachate (T1), peat leachate (T2), 100% nutrient solution (NS) (T3), 50% NS (T4) strength. Four concentrations of exogenous melatoninwere applied in foliar spray: 0, 100, 200, and 400 µM. Melatonin application increased yield, with the highest values observed when plants were grown in T1. Water use efficiency was also maximized in T1 and with both 200 and 400 µM melatonin applications. The highest nitrogen use efficiency was achieved in plants grown in peat leachate. The lipid membrane damage was assessed revealing that plants grown in compost leachate exhibited the lowest MDA values regardless of melatonin concentrations. The accumulation of some antinutritional compounds (nitrate, oxalate, and sodium) were the highest in those plants grown in compost leachate. Overall, shoots grown in peat leachate exhibited the best phytochemical profile (total phenol content, total flavonoids, and antioxidant capacity), with peak values in plants treated with 200 µM melatonin. These findings suggest that S. fruticosa can be effectively cultivated using leachate from a previous crop in a floating system and that exogenous melatonin application enhances the yield and nutritional quality of Salicornia shoots. [ABSTRACT FROM AUTHOR]

Aim: The present study examined the leaching and cytotoxicity of bismuth from ProRoot MTA and aimed to identify whether bismuth leaching was affected by the cement base and the immersion regime used. Methodology: The leaching profile of bismuth was examined from ProRoot MTA and compared with hydroxyapatite containing 20% bismuth oxide as well as hydroxyapatite and tricalcium silicate to investigate whether bismuth release changed depending on the cement base. Bismuth leaching was determined after 30 and 180 days of ageing immersed in Dulbecco's modified Eagle's medium (DMEM) using mass spectroscopy (ICP‐MS). The media were either unchanged or regularly replenished. The pH, surface microstructure and phase changes of aged materials were assessed. Wistar rat femoral bone marrow stromal cells (BMSCs) and cutaneous fibroblasts were isolated, cultured and seeded for cell counting (trypan blue live/dead) after exposure to non‐aged, 30‐ and 180‐days‐aged samples in regularly replenished DMEM. Aged DMEM in contact with materials was also used to culture BMSCs to investigate the effect of material leachates on the cells. Gene expression analysis was also carried out after direct exposure of cells to non‐aged materials. Differences between groups were statistically tested at a significance level of 5%. Results: All materials exhibited alterations after immersion in DMEM and this increased with longer exposure times. The bismuth leached from ProRoot MTA as detected by ICP‐MS. Aged ProRoot MTA samples exhibited a black discolouration and surface calcium carbonate deposition. ProRoot MTA influenced cell counts after direct exposure and its 180‐days leachates reduced BMSC viability. After direct BMSC contact with non‐aged ProRoot MTA an upregulation of metallothionein (MT1 and MT2A) expression and down‐regulation of collagen‐1a (Col‐1a) and bone sialoprotein (BSP) expression was identified. Conclusions: Bismuth leaching was observed throughout 180‐days observation period from all materials containing bismuth oxide. This negatively influenced cell viability and gene expression associated with bismuth exposure. This is the first study to report that metallothionein gene expression was influenced by exposure to ProRoot MTA. [ABSTRACT FROM AUTHOR]

Waste management in large urban centers is one of the main challenges for public administration. Two of the most abundant wastes in cities are waste solid and municipal wastewater (MWW). Their management can be optimized if they are treated together. This work analyzed an anaerobic–aerobic system for the treatment of fruit and vegetable wastes (FVWs) and MWW. Firstly, FVWs were collected and characterized; once in the laboratory, they were placed in a tank with the MWW, aiming at transferring to the water those solids with a particle size below 105 µm; then, they were separated by sieving. The mixture of MWW and FVWs with a particle size below 105 µm was fed into an up-flow anaerobic sludge reactor (UASB); in the latter, dissolved and suspended organic matter was transformed into methane and carbon dioxide. The water that left the UASB was sent to be post-treated in an activated sludge reactor (ASR). The chemical oxygen demand (COD) was used as an evaluation parameter of the anaerobic–aerobic system; a removal efficiency higher than 80% was achieved, whereas it was 60% in the ASR. Another evaluation parameter was methane (CH4) productivity, with an average of 3.0 LCH4 L−1 d−1. VWF leaching achieved an average COD extraction of 7.68 kg∙m−3. The UASB efficiency was on average 70% for the assayed loads (2–8 kg COD·L−1·d−1). The energy potential calculated for the anaerobic–aerobic system was 510.2 kW∙h∙d−1 [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the content and leachability of Sr in ashes obtained through combusting municipal waste in household furnaces. The waste had been collected as a mixed stream and as separate fractions (i.e. furniture, sponges, waste paper, PCV packaging, plastic-coated paper cartons, imitation leather, rubber, textiles and polystyrene). Using single-step chemical extractions, (HCl + HNO3, H2O, 0.01 M CaCl2, 0.1 M CH3COOH), we determined the total content of Sr (TC) and proportions of the following fractions: water-leachable, phytoavailable and easily soluble and bound to carbonates. We also analyzed the effect of reducing pH in the extraction solutions on St leachability from the study material. The study showed that Sr concentration in ash generated from the combustion of conventional fuels, alternative fuels and municipal waste ranged from 114 to 1006 mg/kg. The largest amounts of Sr were found in ash generated from the combustion of alternative fuels (coal pellets 488–1006 mg/kg), conventional fuels (hard coal 430–670 mg/kg) and mixed waste (237–825 mg/kg). The most mobile fraction of Sr (water-leachable) comprised from 1.3% to nearly 91% TC; the phytoavailable fraction and the ion-exchange and carbonate-bound fraction comprised 3–92% TC and 9–72% TC, respectively. We also found that the greatest pH reductions do not always entail the greatest amounts of extracted Sr. A much more significant factor in this respect is the mineral and chemical composition of primary materials, which can buffer changes in pH. The Risk Assessment Code (RAC) values pointed to a varied environmental risk and the highest RAC values (> 70) were found for coal pellets, wood pellets, straw, rubber and plastic containers for mixed oils. [ABSTRACT FROM AUTHOR]

Discarded cigarette waste may leach toxic elements and can contaminate different environments. In this study, the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in cigarette butts (CBs) leachates were determined, and the release rate of these pollutants from three CBs types such as smoked CBs with and without tobacco (SCBs and SFs) and unsmoked filters (USFs) were examined. The mean concentration levels of PCBs compounds were

Geopolymers are inorganic polymers projected as feasible alternatives to Portland cement due to their lower CO2 emissions and high mechanical properties. In recent times, however, their impact on other environmental indices such as abiotic depletion, freshwater toxicity, marine ecotoxicity, terrestrial ecotoxicity, acidification, and human toxicity has become questionable, thus the need to investigate alternative eco-friendly precursors and activators. This work aims to manufacture an eco-efficient geopolymer by utilising biomass ash leachate as an alternative to the conventional alkali silicate solution. The leachate was obtained by soaking the rice husk ash (RHA) in a 10 M concentration of NaOH solution and filtering to obtain a clear solution. The effects of the calcination temperature of the kaolin and the RHA content in the alkaline solution were investigated, and a factorial design of experiments was developed considering three levels of calcination temperature (700°C, 800°C, and 900°C) and five levels of RHA content (0 g, 5 g, 10 g, 15 g, and 20 g). Physical and mechanical tests were performed on the synthesised geopolymer pastes, and chemical analysis was performed using X-ray diffraction and X-ray spectroscopy. The impacts of replacing the synthetic alkali silicates with rice husk ash-based activators were compared. The results showed that the calcination temperature of the kaolin and the content of the RHA both contributed significantly to the flexural and compressive strength at the 0.01 level of significance. A compressive strength of 10.4 MPa was obtained for the MK915 binders, which showed a 100% increase from samples without RHA content. This research proves that utilising RHA-based activators in metakaolin-based geopolymers can be feasible for less critical applications where a very high compressive strength will not be required.

Abstract Microplastics, particles under 5 mm, pervade aquatic environments, notably in Tarragona’s coastal region (NE Iberian Peninsula), hosting a major plastic production complex. To investigate weathering and yellowness impact on plastic pellets toxicity, sea-urchin embryo tests were conducted with pellets from three locations—near the source and at increasing distances. Strikingly, distant samples showed toxicity to invertebrate early stages, contrasting with innocuous results near the production site. Follow-up experiments highlighted the significance of weathering and yellowing in elevated pellet toxicity, with more weathered and colored pellets exhibiting toxicity. This research underscores the overlooked realm of plastic leachate impact on marine organisms while proposes that prolonged exposure of plastic pellets in the environment may lead to toxicity. Despite shedding light on potential chemical sorption as a toxicity source, further investigations are imperative to comprehend weathering, yellowing, and chemical accumulation in plastic particles.

Abstract Invasive alien species are becoming more and more prevalent worldwide, Erigeron bonariensis and Bidens pilosa are two invasive species of Asteraceae in Egypt. To mitigate their detrimental effects and understand their differences in invasiveness, we compared the allelopathic potentials of E. bonariensis and B. pilosa using leachates, decaying residues, and volatilization processes. Notably, the allelopathic variances in leachates were significant, influenced by plant types, concentrations, and response patterns of target plant traits, as indicated by EC50. The relative phytotoxicity of the invasive species decayed residues peaked between 20 and 25 days in the soil, with a positive correlation with concentrations and soil properties. The highest quantities of phenolic acids were chlorogenic acid and caffeic acid reaching (5.41 and 4.39 µg g−1) E. bonariensis and (4.53 and 4.46 µg g−1) B. pilosa, in leachates extracts respectively, while in the soil extract of decayed residues were coumaric acid and ferulic acid measuring (1.66 and 1.67 µg g−1) E. bonariensis and (1.47 and 1.57 µg g−1) B. pilosa, respectively. Using GC/MS analysis, the main volatile components in E. bonariensis were 1, 8 cineole (5.62%), and α-terpinene (5.43%) and iso-Caryophyllene (5.2%) which showed the greatest inhibitory effects. While B. pilosa main constituents were trans-sabinene (5.39%) and Camphene (5.11%), respectively. Finally, the high invasion level displayed from E. bonariensis (0.221) compared with B. pilosa (0.094) which correlated with the stronger allelopathic activities against plant species, and soil properties. Therefore, the allelopathic potentialities of these species are critically relevant to their invasion success.

Abstract Upon entering the environment, the surface properties of pristine plastics are rapidly altered due to interactions with exogenous biomolecules, contaminants, and even microbiota, which ultimately alter their ecological impacts. When present in biological fluids or high protein environments, micro(nano)plastics bind with proteins, which form a protein corona around the particle. Although a significant body of literature exists on protein corona formation on nanomaterials, less is known about how the physiochemical properties of microplastics may influence protein corona formation. This study utilises quantitative proteomics to quantify protein binding to pristine and leached microplastics. Pristine polyethylene (PE) beads (50 and 500 μm), polyamide (PA) fibres (100 μm), polyethylene terephthalate fibres (500 μm), and fragments (

This paper demonstrates that ash composites, comprising fly ash and polyurethane, can be used to develop value-added products that exhibit an effective decrease in the leaching of coal ash inorganics to less than one-third of the Environmental Protection Agency (EPA)'s maximum contaminant level (MCL) when soaked in a water circulation system for 14 months. Furthermore, the composite blocks remain safe even with ruptured surfaces. The concept of encapsulating fly ash within ash composites by using a polar polymer to bind the fine inorganic particles, mimicking how nature does it in the original unburned coal, ensures the safety of the composite. The ash composites can be formulated to have designed mechanical, fire, and electrical properties by controlling the formulation and the density. The properties of typical density composites were produced, measured, and compared with commercial materials. This paper also demonstrates that ash composite technology can be extended to coal ash stored in ponds. Finally, a typical electric utility box cover was designed, fabricated, and test validated. The box cover has less than one-half the weight of the original box cover for the same design limits. Finally, the benefits of this ash-composite technology for product manufacturers, society, and ash producers are summarized. [ABSTRACT FROM AUTHOR]

Invasive alien species are becoming more and more prevalent worldwide, Erigeron bonariensis and Bidens pilosa are two invasive species of Asteraceae in Egypt. To mitigate their detrimental effects and understand their differences in invasiveness, we compared the allelopathic potentials of E. bonariensis and B. pilosa using leachates, decaying residues, and volatilization processes. Notably, the allelopathic variances in leachates were significant, influenced by plant types, concentrations, and response patterns of target plant traits, as indicated by EC50. The relative phytotoxicity of the invasive species decayed residues peaked between 20 and 25 days in the soil, with a positive correlation with concentrations and soil properties. The highest quantities of phenolic acids were chlorogenic acid and caffeic acid reaching (5.41 and 4.39 µg g−1) E. bonariensis and (4.53 and 4.46 µg g−1) B. pilosa, in leachates extracts respectively, while in the soil extract of decayed residues were coumaric acid and ferulic acid measuring (1.66 and 1.67 µg g−1) E. bonariensis and (1.47 and 1.57 µg g−1) B. pilosa, respectively. Using GC/MS analysis, the main volatile components in E. bonariensis were 1, 8 cineole (5.62%), and α-terpinene (5.43%) and iso-Caryophyllene (5.2%) which showed the greatest inhibitory effects. While B. pilosa main constituents were trans-sabinene (5.39%) and Camphene (5.11%), respectively. Finally, the high invasion level displayed from E. bonariensis (0.221) compared with B. pilosa (0.094) which correlated with the stronger allelopathic activities against plant species, and soil properties. Therefore, the allelopathic potentialities of these species are critically relevant to their invasion success. [ABSTRACT FROM AUTHOR]

Upon entering the environment, the surface properties of pristine plastics are rapidly altered due to interactions with exogenous biomolecules, contaminants, and even microbiota, which ultimately alter their ecological impacts. When present in biological fluids or high protein environments, micro(nano)plastics bind with proteins, which form a protein corona around the particle. Although a significant body of literature exists on protein corona formation on nanomaterials, less is known about how the physiochemical properties of microplastics may influence protein corona formation. This study utilises quantitative proteomics to quantify protein binding to pristine and leached microplastics. Pristine polyethylene (PE) beads (50 and 500 μm), polyamide (PA) fibres (100 μm), polyethylene terephthalate fibres (500 μm), and fragments (< 300 μm), as well as pristine and leached textile microfibres comprised of PET, recycled PET, PA or cotton were incubated for 24 h in bovine serum albumin solution (2 mg mL−1) to form a protein corona. Protein adsorption to microplastics was dependant on particle surface area to volume ratio but only when additives were absent. For environmentally relevant textile microfibres, cotton microfibres adsorbed significantly more protein than synthetic microfibres. Fourteen-day aqueous leaching increased the zeta potential of all microfibres. However, only PA fibres adsorbed significantly higher protein on the leached fibres compared to their pristine counterparts. Overall, the presence of chemical additives in microplastics strongly influenced protein corona formation, and this phenomenon should be incorporated into routine microplastic toxicity assessment. [ABSTRACT FROM AUTHOR]

The potential of the most prevalent weeds should be characterized biologically and chemically in infected soil and crops for sustainable agriculture. Therefore, the allelopathic potential of Avena fatua L. and Lolium temulentum L. weeds were compared via leachates, root exudates, decayed residues in soil, and the decomposition in water pathways. Chemical measurements were taken on wheat (Triticum aestivum L.), and soil decomposed solution. Based on EC50, the allelopathic effect of leachates were higher in aboveground parts than in subterranean parts, influenced by plant parts and concentrations. The root exudates show EC50 by 655.9 μg. ml−1 for A. fatua and 625.66 μg. ml−1 for L. temulentumin the seedling biomass fresh weights of T. aestivum. The systematic inhibition by decayed residues was affected by plant types, concentration, and time and correlated with soil parameters and crop performance. The decomposition rate was higher under aerobic conditions than anaerobic conditions, with the inhibition pattern showing the reverse trend. These finding highlight the importance of environmental conditions in mediating allelopathic effects. The highest quantities of phenolic acids determined by LC-ES/MS in decomposed solutions were citric acid, with concentrations of 7.71 and 13.31 μg/ml in A. fatua under aerobic conditions, and coumaric acid, with concentrations of 9.21 and 16.99 μg/ml in L. temulentum under aerobic conditions. The allelopathic potentials of A. fatua and L. temulentum may play a crucial role in T. aestivum crop growth and soil parameters. In general weed residues can suppress crop growth and negatively affect soil parameters based on their quantity and type, therefore they should be managed carefully for sustainable crop production.

Relevance. Geoelectrical resistivity technology (GRT), together with geological data, was employed to delineate the hydrokinetic characteristics, protective capacity, and groundwater potential of a soughtafter housing development in Southern Nigeria. Aim. The GRT utilized Schlumberger’s 1-D vertical electrical resistivity sounding (VES) and 2-D electrical resistivity tomography (ERT) techniques. Methods. The primary and secondary geoelectric indices were combined with existing geological data to calculate hydrodynamic parameter maps of the shallowest aquifer unit. These maps are crucial for effectively managing the unconfined aquifer system beneath, which is extensively utilized in the area. The study area’s saturation dynamics were determined by analyzing total porosity (ranging from 0.282 to 0.691), specific yield (ranging from 0.040 to 0.107), field capacity/specific retention (ranging from 0.242 to 0.623), and storage-dependent drainability efficiency (ranging from 7.6% to 40.5%). The results indicated that the area experiences the most effective release of pore water when the drainability efficiency, which is reliant on storage, exceeds 21%. The range of potential index parameters, including transmissivity (57.4–4339.2 m2/day), transverse resistance/aquifer potential scale (453.6–152,756.5 Ωm2), permeability (91.7–7269.7 mD), and hydraulic conductivity (57.4–4339.2 m/day), exhibited favorable potential but limited to moderate protection, as indicated by the longitudinal conductance index (0.004–0.6218 Siemens). Given the strong preference of many people to live in this rapidly growing and competitive housing estate, it is important to establish effective waste disposal systems to prevent the leakage and infiltration of harmful substances, such as leachates and other organic/inorganic waste, into the vulnerable underground water sources that provide water for various purposes.

Cascade cropping systems (CCS) utilize leachate from a primary crop to grow secondary crops and enhance the efficient use of water and fertilizers in areas with scarce water resources. A preliminary study investigated the effect of melatonin in a cascade cropping system to potentially improve plant tolerance to abiotic stresses. This study aimed to cultivate Salicornia fruticosa in this cropping system to reduce nutrient discharge and assess the impact of exogenous melatonin on Salicornia growth and quality. The CCS included a primary crop of Salicornia grown in an agro-industrial compost or peat. Leachates from these media were used to cultivate the same plant once again in a floating system under four treatments: compost leachate (T1), peat leachate (T2), 100% nutrient solution (NS) (T3), 50% NS (T4) strength. Four concentrations of exogenous melatonin were applied in foliar spray: 0, 100, 200, and 400 µM. Melatonin application increased yield, with the highest values observed when plants were grown in T1. Water use efficiency was also maximized in T1 and with both 200 and 400 µM melatonin applications. The highest nitrogen use efficiency was achieved in plants grown in peat leachate. The lipid membrane damage was assessed revealing that plants grown in compost leachate exhibited the lowest MDA values regardless of melatonin concentrations. The accumulation of some antinutritional compounds (nitrate, oxalate, and sodium) were the highest in those plants grown in compost leachate. Overall, shoots grown in peat leachate exhibited the best phytochemical profile (total phenol content, total flavonoids, and antioxidant capacity), with peak values in plants treated with 200 µM melatonin. These findings suggest that S. fruticosa can be effectively cultivated using leachate from a previous crop in a floating system and that exogenous melatonin application enhances the yield and nutritional quality of Salicornia shoots.

The Sargassum phenomenon is currently affecting the Caribbean in several ways; one of them is the increase of greenhouse gases due to the decomposition process of this macroalgae; these processes also produce large amounts of pollutant leachates, in which several microbial communities are involved. To understand these processes, we conducted a 150-day study on the Sargassum spp environmental degradation under outdoor conditions, during which leachates were collected at 0, 30, 90, and 150 days. Subsequently, a metagenomic study of the microorganisms found in the leachates was carried out, in which changes in the microbial community were observed over time. The results showed that anaerobic bacterial genera such as Thermofilum and Methanopyrus were predominant at the beginning of this study (0 and 30 days), degrading sugars of sulfur polymers such as fucoidan, but throughout the experiment, the microbial communities were changed also, with the genera Fischerella and Dolichospermum being the most predominant at days 90 and 150, respectively. A principal component analysis (PCA) indicated, with 94% variance, that genera were positively correlated at 30 and 90 days, but not with initial populations, indicating changes in community structure due to sargassum degradation were present. Finally, at 150 days, the leachate volume decreased by almost 50% and there was a higher abundance of the genera Desulfobacter and Dolichospemum. This is the first work carried out to understand the degradation of Sargassum spp, which will serve, together with other works, to understand and provide a solution to this serious environmental problem in the Caribbean. [ABSTRACT FROM AUTHOR]

Some wastes from the paper pulp production process are still sent to a controlled waste landfill. These materials can constitute alternative resources for constructing road pavements. The study aimed to characterize and explore the sustainable application of two inorganic wastes resulting from the paper pulp process, the dregs (green liquor wastes) and the grits (slaker wastes), in the production of bituminous mixtures by the analysis of samples prepared with 5 and 10% of dregs and 5 and 10% of grits on the baseline reference bituminous mixture AC 14 surf 35/50. Some relevant mechanical properties of the blends were assessed based on Marshall compression, sensitivity to water and wheel-tracking tests. Additionally, water poured on the loose asphalt and compacted slabs' surface was analysed to determine the portion of harmful chemical compounds leached from the asphalt material. The results show that using dregs presented some technical limitations related to mechanical performance and that the incorporation of grits has an acceptable mechanical behaviour. Moreover, the study shows that the measured leachate resulting from water flow in a reference asphalt mixture and the blends with grits are insignificant. It can be concluded that using grits in asphalt mixtures is a promising technique regarding mechanical behaviour and environmental impacts that need further studies. [ABSTRACT FROM AUTHOR]

The recovery of gold by adsorption using activated carbon from sodium cyanide and thiourea leached solutions are reported in this study. The leached solutions were obtained under real operating conditions from the beneficiation plant “Paz Borja”, Machala-Ecuador. Calgon Carbon DG-11 6X12 type, widely used in the local metallurgical industry was used as adsorbent material. The operational parameters varied during the adsorption process experiments included the concentration of leaching agent, agitation speed, dose of activated carbon and initial concentration of gold. The control parameters included density, percentage of solid, pH, temperature, and solution potential. The obtained results were adjusted to mass transfer model by diffusion through the interface and the Freundlich model for the equilibrium isotherms. The analysis of the results indicates a higher adsorption rate of the gold di-cyanide complex on activated carbon compared to gold-thiourea complexes.

Abstract The research was carried out to assess the concentration and distribution of heavy metals in groundwater from selected automobile workshops in Ozoro metropolis, a busy university town, in the Niger Delta region of Nigeria. The major activities carried out in the sampled automobile workshops include vehicle maintenance, painting, panel beating and fabrication. Nine (9) groundwater samples from the automobile workshops and one control sample 2 km away from the influence area were analyzed. Heavy metal concentration, contamination factor, and pollution loading indices were investigated using geostatistical modeling and statistical analysis tools. Heavy metal concentrations in the various samples were determined in accordance with the Association of Official Agricultural Chemists (AOAC) International guidelines. Findings obtained from the study revealed that the groundwater was affected by leachates from the automobile workshops, as the heavy metal levels in the groundwater from the sampling sites were considerably higher than the reference point. The concentration ranges (mg/L) of the heavy metals were Cd (0.0217–0.0412), Cr (0.0643–0.0901), Cu (0.0599–0.0803), Fe (0.3118–0.4171), and Pb (0.1423–0.1781). The spatial distribution maps showed that the metals spread unevenly across the study area. The pollution indices revealed that groundwater from the sampling sites is moderately polluted with heavy metals and the trend of the pollution load index (PLI) is Cd > Ni > Cu > Mn > Pb > Zn > Fe. Comparing the results with those of international regulatory bodies, the groundwater from the study area was found to still be within the approved range for potable water. However, there is evidence of slight contamination due to the activities of the automobile workshops. This may call for minor treatment before usage, regular monitoring and ensuring that the artisans comply with relevant regulations in their operations.

This research encompassed an 8-month investigation to evaluate the biological treatment of complex landfill leachates. The primary objectives were the removal of organic and nitrogen compounds, as well as the mitigation of H2S and VOC emissions. Biological treatment was conducted within a sequencing batch reactor (SBR), incorporating aerobic, anaerobic, and anoxic stages. The results indicate that biological treatment is indeed effective in eliminating biodegradable organic matter, with an average removal rate of 84.5% for BOD5, 42.7% for COD, and 40.9% for TOC. Nonetheless, it is imperative to integrate supplementary processes to enhance organic removal. It is worth noting that biological nitrification proved inadequate for sufficiently reducing elevated ammonia concentrations, achieving only a 23.2% reduction. In controlled laboratory conditions, the utilization of chemical precipitation, employing either MgO+H3PO4 or MgCl2.6 H2O+Na2HPO4.7 H2O in an equimolar ratio of Mg:NH4:PO4, exhibited substantial ammonia removal rates of 76.8 ± 6.4% and 80.7 ± 4.5%, respectively. Additionally, the incorporation of an anoxic stage in reactor operation demonstrated its effectiveness in achieving proficient denitrification, with an 80% removal rate for nitrates present in the raw leachates. These findings underscore the potential for optimizing the efficiency of biological leachate treatment processes through strategic modifications and the integration of additional treatment steps.

We investigated the allelopathic effects of A. philoxeroides stem on E. crassipes and found reduction in plant height (32 to 61 %), number of leaves (13 to 38 %), number of branches (20 to 43%) and fresh weight (63 to 73 %). The E. crassipes plants got dried in cisterns treated with A. philoxeroides. The allelochemicals present in A. philoxeroides plants were inhibitory to water hyacinth. The allelopathic leachate of A. philoxeroides caused maximum decrease in growth of E. crassipes, due to presence of alkaloids and phenols. In control, there were no detrimental effects on growth of E. crassipes. [ABSTRACT FROM AUTHOR]

Surface water, groundwater, and soil are all heavily polluted by leachates from landfill. In underdeveloped countries, many of these are not treated due to the high costs of implementing wastewater treatment plants. In Colombia, there are few sanitary landfills that comply with the standards for leachate discharge to nearby water sources. In this work, the potential use of activated rice husk biochar for the removal of polypollutants associated with leachates (metals and microorganisms) has been studied. For this, rice husk residues have been used in a pyrolysis process in a fixed-bed reactor. This biochar has been activated through a physicochemical process, with which the surface area has been improved with KOH activation. Batch adsorption experiments were carried out to evaluate the removal of metals and microbes. Metal removal was determined using an ICP-EOS analysis, while the total microorganisms were calculated using the UFC g−1 colony count. It has been found that during three cycles, biochar achieves a high percentage of removal of microorganisms (up to 100% in four of the five cycles evaluated) and metals (<95% cycle 1, <80% cycle 2, and <65% cycle 3). On the other hand, with respect to the toxicity tests, a percentage >50% has been found up to the cycle 3. In compliance with the regulations, up to the fourth cycle, this is complied with, in terms of contaminant removal efficiencies, but after cycle 5, there is a loss in efficiency. [ABSTRACT FROM AUTHOR]

Marble is one of the materials most susceptible to copper leaching, resulting in easily identifiable turquoise stains on the marble. This problem is particularly relevant when we are talking about marble structures of heritage value. For this reason, conservators look for cleaning materials that are specific to the structure to be treated without damaging the original surface. Materials such as agar have been studied for a long time. Agar creates a controlled water release system that adapts to the needs of conservators who seek the greatest possible cleanliness without damaging the material to be treated. To improve the cleaning, chelating agents such as EDTA are added to the agar composition. However, the microbiological growth and the damage it produces to the original material are disadvantages to take into account. In order to solve these problems, other natural materials with cleaning potential such as kudzu and konjac gels were studied in combination with other chelating agents such as citrate, oxalate, and gluconic acid. For the characterization and evaluation of copper cleaning, various analytical techniques were used, including Raman spectroscopy, colorimetry, X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). In this study, both konjac and kudzu emerged as promising alternatives to agar, revealing distinctive features such as simplified preparation methods and inherent antimicrobial properties. The EDTA chelator was found to be the most harmful for marble surfaces, as it extracted a greater amount of calcium from the marble during application of the gels doped with it. Citrate and gluconic acid have been identified as a promising substitute to prepare doped gels for the removal of copper stains. These compounds exhibit comparable or potentially superior cleaning capabilities than EDTA, with no negative side effects. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes such as TiO2/UV heterogeneous photocatalysis are suitable treatment methods for wastewater with high pollutant loads such as landfill leachates. Optimizing the variables that influence the process is a fundamental aspect. However, in this regard, experimental conditions are limited in terms of resources and time, which is why modeling allows obtaining a general understanding of the phenomenon from a set of experimental data. This work sought to model the photocatalytic process via multivariate polynomial regression, considering variables such as the catalyst concentration, the pH level, and the accumulated energy concerning the percentage of degradation in terms of dissolved organic carbon (DOC). The implemented fitting method resulted in a third-degree polynomial with an R2 of 0,8652, concluding that the model and its conclusions are valid. Moreover, with greater degrees, the model curve overfitted, even with better R2. DOC abatement showed a negative correlation with pH and the catalyst dose, while an opposite trend was observed for the accumulated energy. The model predictions allow inferring that, at low catalyst doses and medium and high pH levels, it is possible to find maximum degradations at low cumulative energies.

Polyethylene terephthalate-based glitters (PET glitters) are a potential source of primary microplastics in the environment. However, the bioeffects of PET glitters and the associated leachates remain largely unknown. In this study, we investigated the individual and combined toxicity of five colors (silver, black, red, green, and blue) of PET glitters and their corresponding leachates on the cellular responses of Desmodesmus sp. The results indicated that the photosynthesis of Desmodesmus sp. could be partly affected by PET glitters through the shading effect, but not that of growth. Conversely, the leachates of red and green PET glitters significantly inhibited the growth of the microalga, suggesting a higher risk associated with additives leached from these colors of PET glitters. Furthermore, the adverse effects of the co-occurrence of PET glitters and leachates were closely related to oxidative stress responses in the microalgal cells, along with a color effect, which could be mainly attributed to variations in the composition and abundance of toxic additives in different colors of PET glitters. Overall, our findings provide insights into the ecological risks posed by glitters in aquatic environments and emphasize the importance of considering color factors in assessing microplastics toxicity. [ABSTRACT FROM AUTHOR]

Legacy sites used for petroleum storage and refining exist in various parts of the world, and many contain soils with very viscous petroleum hydrocarbons produced by poor historical practices and many decades of weathering, especially in tropical and subtropical climates. This contamination causes land-use restrictions and may threaten natural resources and living organisms. The possibility of re-valorization of such a weathered hydrocarbon residue (WHR) was investigated for road-base (dense asphaltic mixture), considering site restrictions (re-use only on-site, construction possibilities, volume of residue, sandy soil). Fifty different mixtures were prepared in an iterative process to (1) use the maximum amount of WHR possible, (2) use the minimum amount of gravel possible, (3) meet the main national construction criteria for medium-traffic roadways, and (4) avoid leachate contamination of subsoil and groundwater. The ideal asphaltic mixture achieved was composed of 16.7% hydrocarbon residue, 60.17% sand (from the site), 20.00% commercial gravel and 3.13% Portland cement (filler). It met construction criteria (≥ 700 Kgf, 2–4 mm flux, according to the Marshall protocol) and had 3.39 mg/L of total petroleum hydrocarbons in TCLP-leachates, which were also non-toxic (filter-paper earthworm bioassay). Thus, the exploitation of a very WHR was shown to be an alternative to replace conventional asphaltic mixtures (thus providing another option for revalorization instead of landfill disposal or alternative treatment). Also demonstrated was the value of very WHRs, which may be present in old refineries, for asphalt production without using additives to strengthen the binding characteristics. [ABSTRACT FROM AUTHOR]

The research was carried out to assess the concentration and distribution of heavy metals in groundwater from selected automobile workshops in Ozoro metropolis, a busy university town, in the Niger Delta region of Nigeria. The major activities carried out in the sampled automobile workshops include vehicle maintenance, painting, panel beating and fabrication. Nine (9) groundwater samples from the automobile workshops and one control sample 2 km away from the influence area were analyzed. Heavy metal concentration, contamination factor, and pollution loading indices were investigated using geostatistical modeling and statistical analysis tools. Heavy metal concentrations in the various samples were determined in accordance with the Association of Official Agricultural Chemists (AOAC) International guidelines. Findings obtained from the study revealed that the groundwater was affected by leachates from the automobile workshops, as the heavy metal levels in the groundwater from the sampling sites were considerably higher than the reference point. The concentration ranges (mg/L) of the heavy metals were Cd (0.0217–0.0412), Cr (0.0643–0.0901), Cu (0.0599–0.0803), Fe (0.3118–0.4171), and Pb (0.1423–0.1781). The spatial distribution maps showed that the metals spread unevenly across the study area. The pollution indices revealed that groundwater from the sampling sites is moderately polluted with heavy metals and the trend of the pollution load index (PLI) is Cd > Ni > Cu > Mn > Pb > Zn > Fe. Comparing the results with those of international regulatory bodies, the groundwater from the study area was found to still be within the approved range for potable water. However, there is evidence of slight contamination due to the activities of the automobile workshops. This may call for minor treatment before usage, regular monitoring and ensuring that the artisans comply with relevant regulations in their operations. Highlights: • Effects of automobile workshop activities on Ozoro community groundwater were evaluated. • Findings revealed the groundwater was affected by leachates from the workshop activities. • Cd, Cr, Cu, Fe and Pb level varied from 0.0643–0.0901 mg/L, 0.0599–0.0803 mg/L, 0.0217–0.0412 mg/L, 0.3118–0.4171 mg/L and 0.1423–0.1781 mg/L, respectively. • Spatial distribution maps depicted that the metals spread unevenly across the community. • Trend of the water Pollution Load Index (PLI) is Cd > Ce > Ni > Cu > Mn > Pb > Zn > Fe. [ABSTRACT FROM AUTHOR]

Okra (Abelmoschus esculentus L.) and string bean (Vigna unguiculata L.) are vegetables that provide important nutrients in the human diet. The use of vermicompost leachates could be nutritional alternatives for these crops, which allow reducing the dependence on chemical fertilizers and the impact on the environment. The objective of the work was to evaluate the response of both vegetables to dilutions 1/10 and 1/20 (v:v) of bovine manure leachate mixed with leucaena or moringa, giving rise to four treatments and one control, replicated three times and distributed according to completely randomized design. The treatments were bovine-leucaena leachate (LBL 1/10 and 1/20), bovine-moringa leachate (LBM 1/10 and 1/20) and the control (without application). The first application of the product was by imbibition of the seeds of both crops for 30' and foliar spraying every 15 days. Some growth and yield indicators were evaluated in both crops. The results indicate that the application of LBL 1/10 showed increases in all the variables evaluated in okra, reaching a yield of 44.7 t ha-1 while in string bean, the LBM 1/20 offers better results for all the variables studied, with a yield of 32.4 t ha-1. [ABSTRACT FROM AUTHOR]

Leachate reuse is a helpful tool that contributes to the sustainability of agricultural systems, but it requires previous disinfection. Hydrogen peroxide can be found among the disinfectants frequently applied in ecological production systems. Moreover, it can improve the oxygenation of the root system. The objective of this work was to study its effect on C. fruticosa plants fertigated with leachates. A split-plot design with six treatments, three without an H2O2 supply (S0) and three with an H2O2 supply dosage at 2% (SH2O2), was arranged: raw leachate from C. lanatus (L100), raw leachate from C. lanatus diluted with tap water until EC of 2.5 dS m−1 (LWD), and raw leachate from C. lanatus diluted with standard nutrient solution until EC of 2.5 dS m−1 (LNSD). The results produced data about the evolution of the nutrient and leachate solutions throughout the cultivation period. Morphological (height, leaf number, leaf area, total fresh weight, relative water status, and dry weight) and physiological (chlorophyll a, chlorophyll b, carotenoids, chlorophyll a+b, and proline) parameters were studied to reveal the plant response. The efficiency of nutrient utilization was higher with the LWD treatment, and water and nitrogen utilization efficiency decreased under the H2O2 supply. In conclusion, the reuse of diluted leachate is advised for nutritionally undemanding crops, such as C. fruticosa; moreover, the H2O2 supply improved tolerance to salinity and enhanced root growth and Red-Green-Blue (RGB) values. [ABSTRACT FROM AUTHOR]

Landfills are used in Saudi Arabia to dispose industrial and domestic wastes. The absence of effective management leads to pollution of the groundwater sources. This research focuses on the impact of landfills on soil and groundwater pollutions in Rabigh city in Saudi Arabia. The analysis involved 14 groundwater and 17 soil samples. The permissible limits were based on Saudi General Authority for Meteorology and Environmental Protection (GAMEP) while the Canadian Council of Ministers of the Environment (CCME) standards for the soil. The cations exceeding the standard were Na+, Ca2+, and Mg2 + while the anions were SO42-, Cl-, HCO3-, and NO3-respectively. Total dissolve solids (TDS) distribution indicated high salinity near landfills. Two hydrogeochemical type facies were identified NaCl and CaCl2. The highest concentrations of heavy metals, As, Cu, Co, Cr, Mn, Al, and Fe, were estimated as 0.059, 0.261, 0.640, 2.96, 3.30, 4.75, and 1170 mg/l respectively. They were below the permissible limits. The pH of the soil ranged from 7 to 9.6 suggesting strongly alkaline soil, due to the occurrence of Sodium Carbonate or Sodium Bicarbonate. The distribution of soil pH indicates the highest value is far upstream landfills. The Chromium and Nickel in the soil exceeds the permitted limit. [ABSTRACT FROM AUTHOR]

Metal contamination in shallow wells through solid waste leaching is a serious environmental problem with contribution to global cancer cases. This paper evaluated the health risks of metals in shallow wells around dumpsites in the Abeokuta metropolis, Nigeria. Five dumpsites were purposively selected to sample twenty-five shallow wells. In situ and laboratory analyses for physico-chemical parameters, copper, lead, cadmium, iron, and chromium were conducted following the APHA standard procedure. Carcinogenic and non-carcinogenic risks for oral and dermal routes were evaluated for adult males and females, children, and infants. Findings revealed that all wells were acidic (pH = 5.82–6.48), with Fe and Cd concentrations above the established limits. The wells around Obada, Obantoko, and Saje dumpsites had high EC (up to 1200 µS/cm), Cu, and Pb concentrations above the permissible limits. Non-carcinogenic risks for oral ingestion were significant for all age groups (hazard index: HI > 1), and the significance level across dumping areas increased in the order: Saje > Obantoko > Obada > Idi-aba > Lafenwa. All wells assessed in Saje and Obantoko recorded significant HI of dermal exposure for children and infants. Cancer risks were significant for all age groups (CR > 1.0E − 04), and metal contributions followed: Cd > Cr > Pb. The overall trend of significant risks for non-carcinogenic and carcinogenic via oral and dermal routes is in the order of infant > children > adult female > adult male. This suggests that groundwater users within the studied areas may experience diverse illnesses or cancer in their lifetime, particularly children and infants. [ABSTRACT FROM AUTHOR]

Phosphogypsum (PG) is a reject of the phosphoric acid production process in phosphate fertilizer industries. The process results in the production of relatively large quantities of PG that it might cause serious environmental and human health concerns. The data of a laboratory investigation of PG are presented here. Lab-scale experiments with lysimeters were conducted in order to simulate and examine the environmental characteristics and the temporal behavior of PG leachates in terms of physicochemical characteristics and chemical composition. Based on the results, leachates from already deposited for many years PG or its mixture with marble powder, seemed to have better pH and conductivity values and lower elemental concentrations compared to leachates from freshly disposed PG. However, the leachates characteristics improve and stabilize in both cases after four days of irrigation or of 1080–1240 mm of rain. Most major elements were found to have minimal leachability, and the material satisfied the environmental limits for its disposal at landfills for inert and non-hazardous wastes. [ABSTRACT FROM AUTHOR]

Landfill leachates are highly contaminated liquids and complex to treat. Two of the processes which are promising for the treatment are the advanced oxidation and adsorption methods. With the combination of the Fenton and adsorption methods, practically all the organic load of leachates can be removed; however, this combination of processes is limited due to the soon clogging of adsorbent material, which leads to high operation costs. In the present work, the results of the regeneration of clogged activated carbon are shown after the application of the Fenton/adsorption process in leachates. This research consisted of four stages: sampling and leachate characterization, clogging of the carbon through the Fenton/adsorption process, carbon regeneration through the oxidative Fenton process, and lastly, evaluation of regenerated carbon adsorption through jar and column tests. In the experiments, HCl 3 M was used, and different concentration of hydrogen peroxide (0.15 M, 0.2 M, 0.25 M) were tested at different times (16 h and 30 h). The activated carbon regeneration through the Fenton process and the optimal peroxide dosage was 0.15 M for 16 h. The regeneration efficiency was obtained from comparing the adsorption efficiency between regenerated and virgin carbon, reaching 98.27% and can be applied up to 4 times without losing regeneration efficiency. These results prove that it is possible to restore the clogged activated carbon adsorption capacity during the Fenton/adsorption process. [ABSTRACT FROM AUTHOR]

The effect of solid waste dumpsites leachate on groundwater quality of Yelwa Kagadama Bauchi, in Bauchi State, Nigeria was evaluated using appropriate standard techniques. The parameters determined included nitrite, magnesium, total alkalinity, sulphate, calcium, phosphate, temperature, TDS, conductivity, pH, colour and turbidity. It was discovered that the wells have high level of colour ranges from 0 to 85 which shows that well I 25, well II 60 and well IV 85 did not falls within the standard compared to WHO and NSDWQ standard of 5.00, but other parameters are within the NSDWQ standard. Hence such water should be treated by employing some measures such as applying alum and disinfectant before use which will help to reduce pollutants, but majorly an improved water supply to the study area will go a long way to correct the unhealthy condition. The pH ranges from 6.33 to 7.79 indicating toxic pollution, turbidity was between 0, 1, 8, 12 and 29 NTU respectively and the concentration of nitrite ranges from 0.010 to 0.008 mg/l which falls within the standard, calcium ranges from 83 to 166 mg/l which does not fall within the standard, which shows the presence of hardness in water. The implication is that forming lather with soap. The results show that all but some of the well was strongly polluted but will require certain levels of treatment before use. Also casing of the wells is of critical importance in addition to siting dump site at reasonable distances from wells, sorting, and adoption of clean technology to prevent further contamination of ground water flow are recommended. [ABSTRACT FROM AUTHOR]

Municipal solid waste landfills leachate can cause serious environmental issues for groundwater quality. Therefore, the application of environmental tracing methods to identify groundwater contamination by municipal solid waste landfills leachate is significant. Hydrogeochemical evaluations to trace municipal solid waste landfills leachate are usually carried out. The study was carried out at a landfill in central Italy (Umbria). Samples of leachate and groundwater have been analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrogeochemical nature. Parameters like pH, Temperature (T), Electrical Conductivity (EC), redox potential (Eh) and Chemical Oxygen Demand (COD) were also measured in situ using digital instruments. Hydrogeochemical data (Na+, K+, Mg2+, Ca2+, SO42−, HCO3−, Cl−, NO3−), ionic ratios and geochemical correlations were used to confirm the processes that govern the chemistry of the spring water and to identify leachate contamination phenomena. In fact, the main geochemical diagrams (Langelier-Ludwig, Piper, Schoeller) confirm the leachate contamination in a groundwater sample. In particular, the Piper diagram shows that a sample is in Na+ – Cl- – HCO3- mixing zone, indicating a possible influence of the leachate on groundwater chemistry. As a matter of fact, some correlations between major elements, such as Cl- versus Na+ and Cl- versus HCO3-, confirm that the leachate in this study area is highly enriched in Cl- and HCO3- due to wastes dissolution and degradation processes. Further, the assessment of K+/Mg2+ ratio also confirms the presence of a sample heavily impacted from leachate contamination. These results indicate that also one basic hydrogeochemical study can be useful for fingerprinting the leachate pollution for groundwater samples.

Abstract The concentrations of heavy metals and health risks associated with the consumption of domestic water sources around a dumpsite in Enugu (southeastern Nigeria) were assessed by atomic absorption spectrophotometry and multivariate analysis. The results showed the dumpsite leachate mean pH value of 4.1, Mn+ of 11.4 µg/l, Fe3+ 4.1 µg/l, Cd+ 0.3, As+ 6.03 µg/l, Pb+ 2.47 µg/l, Ni+ 14.13 µg/l, and Cr3+ 1.48. The groundwater and surface water samples had mean heavy metal values as follows: Mn+ 5.23 and 0.75 µg/l, Fe3+ 1.49 and 0.15 µg/l, Cd+ 0.08 and 0.10 µg/l, As+ 1.90 and 0.15 µg/l, Pb+ 1.01 and 0.35 µg/l, Ni+ 0.37 and 0.05 µg/l, and Cr3+ 0.03 and 0.05 µg/l, respectively. Comparison with maximum permissible limits indicated that the mean heavy metal concentrations of the tested samples were lower than the limits for drinking water, except for Mn+, As+, and Pb + , which were marginal above recommended limits. Principal component analysis results showed two principal components with the first principal component having high loadings of Mn+, Fe3+, As+, Pb+, Ni+, and Cr3+, which are statistically correlated. Probable sources of these contaminants include automobile parts and tools, batteries and electrical appliances and electronics heaped at the dumpsite. Analysis of variance results indicates a significant difference in datasets between and within each and both water sources. Human health risk assessment indices indicated that the water sources are moderate to highly polluted and could pose both non-carcinogenic and carcinogenic threats when consumed untreated, with children being more exposed than adults.

The effect of solid waste dumpsites leachate on groundwater quality of Yelwa Kagadama Bauchi, in Bauchi State, Nigeria was evaluated using appropriate standard techniques. The parameters determined included nitrite, magnesium, total alkalinity, sulphate, calcium, phosphate, temperature, TDS, conductivity, pH, colour and turbidity. It was discovered that the wells have high level of colour ranges from 0 to 85 which shows that well I 25, well II 60 and well IV 85 did not falls within the standard compared to WHO and NSDWQ standard of 5.00, but other parameters are within the NSDWQ standard. Hence such water should be treated by employing some measures such as applying alum and disinfectant before use which will help to reduce pollutants, but majorly an improved water supply to the study area will go a long way to correct the unhealthy condition. The pH ranges from 6.33 to 7.79 indicating toxic pollution, turbidity was between 0, 1, 8, 12 and 29 NTU respectively and the concentration of nitrite ranges from 0.010 to 0.008 mg/l which falls within the standard, calcium ranges from 83 to 166 mg/l which does not fall within the standard, which shows the presence of hardness in water. The implication is that forming lather with soap. The results show that all but some of the well was strongly polluted but will require certain levels of treatment before use. Also casing of the wells is of critical importance in addition to siting dump site at reasonable distances from wells, sorting, and adoption of clean technology to prevent further contamination of ground water flow are recommended.

Regular monitoring of the chemical status of water bodies remains crucial in countries where data on chemical fingerprints that can assist in environmental policy is still limited. The current study focused on the concentrations of 14 metals and their sources in two important South African rivers that pass through various rural areas and two semi-urban towns in the province of the Eastern Cape. Most of the essential metals were within the South African guidelines for domestic water use except for selenium and iron which reached the concentrations of 131 and 712 µg L−1 that exceed the guideline values of 20 and 200 µg L−1, respectively. Cadmium and lead were above the South African Water Quality Guidelines and World Health Organization limits of 3 and 10 µg L−1, attaining the highest concentrations of 35 and 34 µg L−1, respectively. The impact of the wastewater treatment plant effluent and the municipal dumpsite leachates on metal ion concentrations in the rivers was observed for some metals. The metals source was related to deterioration of galvanized corrugated steel sheets from scrap yards and dwellings made-out of galvanized corrugated sheets, as well as agricultural activities and natural geological processes. An overview of the current water quality status of the two rivers may serve as a basis for sink-oriented pollutant fingerprinting toward sustainable water sources for communities. [ABSTRACT FROM AUTHOR]

Hydrostatic level sampling, geo-referencing and Geographic Information System were employed to delineate the major groundwater recharge/discharge zones, the groundwater flow direction and the groundwater divides in Ado-Ekiti metropolis with the objective of groundwater resource protection. Static water level measurements were made from 108 hand - dug wells evenly distributed on a regional basis. The latitudes, longitudes and elevations above mean sea level of the well points were measured using the Global Positioning System. A mean value of 5.84 ± 2.35 m above mean sea level was observed for the depths to the static water level with a mean value of 408.27 ± 46.06 m above mean sea level for the groundwater head. The contour maps obtained enabled the delineation of the major groundwater recharge / discharge zones, the groundwater flow direction and the groundwater divides with the regional tendency of the underground flow approximately lying along the Northwest - Southeast direction and groundwater divides along the South - Eastern/South - Western axes of the Central portion. Strict environmental ethics must be enforced around the groundwater recharge / discharge zones and flow directions in order to avoid groundwater contamination. [ABSTRACT FROM AUTHOR]

Abstract In Ecuador, a country with several active volcanoes and with four eruptions in the last decade in the continental arc, it is very likely that high-voltage transmission lines cross volcanic hazard zones on their routes. Here, we quantify the impact of fresh volcanic ash from the hydromagmatic Cotopaxi-2015 and the magmatic Tungurahua-2016 eruptions on the dielectric characteristics of ANSI 52–3 suspension insulators made of porcelain and glass, under moist conditions. The experiments include two methodologies to measure the performance of the insulators in real-time: the minimum insulator flashover voltage (FOVmin) and the dielectric loss factor angle. Both allow quantifying i) the critical voltage that the insulators can withstand prior to flashover occurrence and, ii) the strong fluctuating behavior that the insulators undergo in an ashy environment. Based on six contamination scenarios, we found that there is a higher chance of flashover if the insulators are completely blanketed (top and bottom) even with a fine ash layer (1 mm), than if they are covered just at the top. Our results further show that the ash of Cotopaxi-2015 eruption has a higher chance of leading to insulator failure because of its higher conductivity (i.e. higher leachate content) than that of Tungurahua-2016. Additionally, we identify two critical voltages prior to electrical flashover on the insulators of 28.25 kV and 17.01 kV for the 230 kV and 138 kV Ecuadorian transmission lines, respectively. Finally, we present a simple impact evaluation for the main Ecuadorian transmission lines based on the outcomes of this research and the official volcanic hazard maps for Cotopaxi and Tungurahua volcanoes.

The environmental fate and risks associated with tire wear particles (TWPs) are closely linked to their biogeochemical behaviors. However, reviews that focus on TWPs from this perspective remain scarce, hindering our understanding of their environmental fate and cascading effects on ecosystems. In this review, we summarize the existing knowledge on TWPs by addressing five key areas: (i) the generation and size-dependent distribution of TWPs; (ii) the release and transformation of TWP-leachates; (iii) methodologies for the quantification of TWPs; (iv) the toxicity of TWPs; and (v) interactions of TWPs with other environmental processes. It has been established that the size distribution of TWPs significantly influences their transport and occurrence in different matrices, leading to the release and transformation of specific TWP-chemicals that can be toxic to organisms. By highlighting the challenges and knowledge gaps in this field, we propose critical issues that need to be addressed to enhance the risk assessment of TWPs. This review aims to provide a comprehensive framework for evaluating the environmental behavior of TWPs. [Display omitted] • Size distribution of TWPs significantly influences their fate in different matrices. • Quantification methods using markers for TWP quantification is still under developing. • DPG, PPDs, and PPD-quinones are ubiquitous TWP-chemicals in the environment. • Toxicological mechanisms of TWP-leachates at molecular level remain largely unknown. [ABSTRACT FROM AUTHOR]