Pollutants, Volume 2, Issue 4 (December 2022) – 9 articles

Neonicotinoid pesticides are one of the most commercialized groups worldwide. Their application in agriculture aims to control pests through a systemic mode of action which is not specific to target species. Our study aimed to evaluate the effects of the insecticide Actara^® [active ingredient thiamethoxam (TMX)] on a non-target species, Girardia tigrina. Therefore, acute and sublethal endpoints, such as mortality, feeding activity, locomotion and behavioral biomarkers were assessed. Actara^® exerted low toxicity towards the planarian Girardia tigrina, showing a 96 h LC₅₀ value of 77.6 mg TMX·L⁻¹ (95% C.I: 74.1–81.2 mg TMX·L⁻¹; R² = 0.85). At the sublethal level, Actara^® exerted no effect on regeneration of photoreceptors and auricles of planarians after 24 and 48 h post-exposure (NOEC > 7.8 mg TMX·L⁻¹). The feeding rate of planarians was significantly increased by Actara^®, but only at the highest tested concentration (LOEC = 7.8 mg TMX·L⁻¹). Planarians showed to be less sensitive to the active ingredient TMX compared to other freshwater species. This might be explained by the presence of a high proportion of sub-types of acetylcholine receptors in planarians, exhibiting low binding affinity sites for TMX, an acetylcholine partial agonist. The comparison between effects induced by Actara^® with the ones caused by other formulations, in planarians, might support our understanding of how other unknown ingredients can modify the uptake, and bioavailability of such substances, as well as the detoxification capacity of planarians, all of which influences toxicity. Full article

The discovery of plastic by humankind is fast becoming a challenge as the end-of-life disposal of plastic continues to be a discourse on the global platform. This discussion results from several findings that the additives in plastic distress both land and marine life by contributing to organic pollutants when the plastic waste is disposed of improperly. With a growing population in sub-Saharan Africa, managing waste generally, and plastic waste, in particular, represents a continuous challenge. With only between 15–25% of its plastic waste recycled, the larger proportion of waste is either burnt openly or disposed of in open spaces or landfills, where the additives pollute the environment. Moreover, some of the waste finds its way into waterways through estuaries into global water networks and continues to cause harm to man through the food chain. This article examines the literature to highlight the environmental and health impact of plastic waste pollution in sub-Saharan Africa, and it proposes mitigation strategies to reduce the critical consequences of plastic waste pollution. Full article

Pollution of water sources is a global issue that primarily affects rural communities that rely on these water sources for domestic purposes on a daily basis. The study’s goal was to determine if the effluent from the Bushbuckridge Municipality’s Waste Water Treatment Works (WWTWs) contributes to the pollution of the Sand River Catchment. The investigation was conducted at two WWTWs, Dwarsloop and Thulamahashe. A questionnaire was used to collect information from participants. Water samples were collected monthly from the treatment plant and Sand River for the determination of physico-chemical parameters and coliform counts. The study found that the WWTWs were the main sources of the pollution of the Sand River Catchment. The WWTWs are confronting unprecedented mechanical and technical challenges. The WWTWs have experienced numerous system failures due to aging systems and pressure on deteriorating facilities, resulting in raw wastewater discharges into catchments. Furthermore, the study revealed that factors such as population growth, poor operation and maintenance of WWTWs, poor budgeting, and a lack of well-trained personnel contributed to WWTW failure. The effluent quality in both WWTWs met the National Water Act of South Africa’s effluent discharge standards for pH (ranged from 6.90 to 9.30), EC (ranged from 20.80 to 87.50 mS/m), ammonia (ranged from 7.22 to 86.80 mg/L as N), nitrate/nitrite (ranged from 0.10 to 0.73 mg/L as N), and ortho-phosphate (ranged from 0.01 to 6.50 mg/L as P). While COD levels in both WWTWs (ranging from 25.00 to 149.00 mg/L) were over the limit during some months of the study period. The study also discovered that E. coli counts were low upstream but high in both the WWTWs point of discharge and downstream for both catchments. The study, therefore, established a connection between wastewater treatment plants and water quality parameters as well as poor water quality linked to the condition of the WWTWs. The study recommends that effective measures be implemented to address the challenges. Full article

The present study was carried out near an industrial area with a high-density urban population and large-scale agricultural activities. These anthropogenic activities lead to groundwater pollution and depletion of the water table. This study attempted to classify pollution sources and hydrochemical facies that help to ensure the suitability of water for agriculture and drinking. Irrigation suitability indexes, water quality index (WQI), principal component analysis (PCA), and hierarchical cluster analysis (HCA) were applied to twenty-six groundwater samples that were analysed during May 2018 for major cations and anion concentrations. The results revealed that the mechanism of groundwater chemistry has been controlled by the evaporation process with the dominance of hydrochemical facies viz., Ca-Mg-HCO_3, Na-K-Cl-SO_4, Ca-Mg-Cl, and Na-K-HCO₃. The mean dominant concentration for cations is in the order of Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ while anions are HCO₃⁻ > SO₄⁻ > Cl⁻ > NO₃⁻ > CO₃²⁻ > F⁻. Irrigation suitability indexes indicated that groundwater in the study area is high in saline and low to medium alkali hazards due to industrial activities. The PCA and HCA also recognized that most of the variations are elucidated by anthropogenic processes, predominantly due to excessive population, industrial emissions, and agricultural activities. Further, the WQI of the study area suggested that 15% of the samples were unsuitable, 69% poor, and the remaining 16% only suitable for drinking purposes. The present article helps to understand the suitability and hydrochemical processes of groundwater for irrigation and drinking, which will help policymakers in water supply planning and management. Full article

Compound-specific isotopic analysis (CSIA) and geochemical modeling were applied to evaluate the effectiveness of an 800 m-long sequential in situ bioremediation (ISB) system in Northern Italy. The system was created for the clean-up of a polluted aquifer affected by chloroethenes. A hydraulically upgradient anaerobic (AN)-biobarrier-stimulated reductive dichlorination (RD) of higher chloroethenes (PCE, TCE) and a downgradient aerobic (AE)-biobarrier-stimulated oxidation (OX) of lower chloroethenes (DCE, VC) were proposed. Carbon CSIA and concentration data were collected for PCE, TCE, cis-DCE and VC and interpreted using a reactive transport model that was able to simulate isotopic fractionation. The analysis suggested that the combination of CSIA and modeling was critical to evaluate the efficiency of sequential ISBs for the remediation of chloroethenes. It was found that the sequential ISB could reduce the PCE, TCE and cis-DCE concentrations by >99% and VC concentrations by >84% along the flow path. First-order RD degradation rate constants ($k_{RD}$) increased by 30 times (from $k_{RD}$= 0.2–0.3 y⁻¹ up to $k_{RD}$ = 6.5 y⁻¹) downgradient of the AN barrier. For cis-DCE and VC, the AE barrier had a fundamental role to enhance OX. First-order OX degradation rate constants ($k_{OX}$) ranged between $k_{OX}$= 0.7–155 y⁻¹ for cis-DCE and $k_{OX }$= 1.7–12.6 y⁻¹ for VC. Full article

One of the main reasons for air pollution is industrial plants releasing huge amounts of air pollutants in the form of gas emissions. The different chemical pollutants and their corresponding levels present in these emissions, and their proximity to the industrial source, have serious effects on the nearby ecosystems. Some of the industrial nuisances include noise, smoke, dirt, dust, odor and noxious gases, which have to be minimized (if possible, eliminated), especially if the location is desired to be used as a community site. When choosing locations at which to build either new industrial plants or new community sites, software can be used to assess both the short-term and long-term concentration profiles of the various detrimental air pollutants. In this study, the AERMOD model was used to find an optimal location to build a new plant in Toledo, Ohio, USA. Simulations were performed to study the pollutant emissions and their dispersion patterns for four different geographic locations situated away from an existing plant in this region. The AERMOD model, along with the IRAP-h View model, which is approved by the US Environmental Protection Agency (EPA), has been successfully used to assess the fate and transport of pollutants from the proposed new industrial plants. The hazard quotients from the analysis of the results for these four different geographic locations were assessed. The highest total non-cancer hazard indices of 18.7 and 13.2 were obtained for fisher adult and fisher child, respectively, in one of the four locations. The acute inhalation quotient risk was less than the target hazard index of 0.25 for all the four locations. With respect to the concentrations of several chemicals of potential concern (COPC), such as soil, produce, beef, chicken, milk and pork, the fourth location (farthest east) recorded the minimum range values compared to the other three locations. Full article

Background: The cephalosporins class is among the most widely used group of antimicrobials worldwide. Antibiotics, together with other drugs and personal care products, make up a group of emerging contaminants. The effects of exposure to this group of chemical contaminants on non-target organisms are not well understood, as they are still poorly studied. Therefore, this study evaluated the phytotoxicity of five cephalosporins in Lactuca sativa. Methods: Lettuce seeds were exposed to different concentrations of antibiotics (25 to 500 mg/L) for 5 days in the dark. After this period, the germination percentage and the wet and dry weights were recorded. Results: The highest tested concentration (500 mg/L) inhibited the germination of lettuce seeds (p < 0.05); there was a decrease in dry weight when exposed to a first-generation cephalosporin (p < 0.05). Additionally, there was a significantly negative influence (p < 0.05) on the fresh weight, especially in the group that evaluated the exposure of seeds to 25 mg/L of Cefepime. Conclusions: We emphasize that there is no record of environmental concentrations of cephalosporins in soil, and therefore, we can indicate that it is possible to have environmental damage resulting from the inappropriate and constant disposal of cephalosporins in the environment. Full article

Soil structure is an important key in the bioremediation process; for instance, clay soils tend to have high absorption of pollutants and low rates of bioremediation due to their high plasticity and oxygen restrictions. This work assesses seven different treatments for contaminated clay soil using lime, silica nanoparticles, and both components in combination. After a three-month treatment, the variation of the soil granulometry, pH, porosity, cation exchange capacity (CEC), humidity, organic matter, respirometry, and humic acids were measured in order to evaluate the improvements regarding soil structure. Furthermore, total petroleum hydrocarbon (TPH), polycyclic aromatic hydrocarbons (PAHs) and heavy metals were monitored before and after the treatments. The combined treatment using lime and nanosilica presented the best results, reducing the percentage of clays from 61% to 5% and showing a relationship between improved of soil structure and the reduction of pollutants, with a 35% removal for TPHs being the highest obtained with the seven treatments. Full article

Lake Victoria (L. Victoria) is the largest African tropical and freshwater lake, with one of the highest pollution levels, globally. It is shared among Uganda, Kenya and Tanzania, but it is drained only by the river Nile, the longest river in Africa. Though environmental studies have been conducted in the lake, investigations of the heavy metals (HMs) contamination of sediments from fish landing sites and ports on the Ugandan portion of L. Victoria are limited. In this study, sediments of an urban, industrial and fish landing site (Port Bell) on L. Victoria, Uganda was investigated to establish its HMs pollution levels and potential health risks to humans and ecosystems. Sediment samples were collected in triplicate (n = 9) from three different points of Port Bell, digested and analyzed using atomic absorption spectrometry for the presence of these HMs: copper (Cu), lead (Pb), cadmium (Cd) and chromium (Cr). The average daily dose through dermal contact and hazard quotient (HQ) were calculated to assess the health risk that is associated with dredging works (lake sand mining). Four geochemical enrichment indices: contamination factor (CF), geo-accumulation index (I_geo), pollution load index (PLI) and potential ecological risk (PERI) were used to quantify the contamination of the HMs in the sediments. The results showed that the mean HM content of the samples ranged from: 6.111 ± 0.01 to 7.111 ± 0.002 mg/kg for Cu; from 40.222 ± 0.003 to 44.212 ± 0.002 mg/kg for Pb; from 0.352 ± 0.007 to 0.522 ± 0.010 mg/kg for Cr; from 3.002 ± 0.002 to 3.453 ± 0.003 mg/kg for Cd. Health risk assessments indicated that there are no discernible non-carcinogenic health risks that could arise from the dredging works that are conducted in the study area as the indices were all below one. The contamination factors that were obtained suggest that Cd has reached a state of severe enrichment in the sediments (CF > 6). An assessment using I_geo established that the sediments were not contaminated with regards to Cu and Cr, but they exhibited low-to-median and median contamination with respect to Pb and Cd, respectively. Though the pollution load indices show that the contamination levels raise no serious concerns, the potential ecological risk indices show that there is considerable pollution of the Port Bell sediments, particularly with regard to Cd. Upon examination using multivariate statistical analyses, Cd and Cr showed a strong correlation which alluded to their introduction from anthropogenic sources. Based on the sedimentary HMs concentrations and the environmental indices that are employed in this study, it is recommended that the spatial variations in the concentrations of the HMs in water, sediments and biota should be monitored. Full article