Urban effluent discharges as causes of public and environmental health concerns in South Africa's aquatic milieu

Developing an Approach for Integrating Chemical Analysis and Transcriptional Changes to Assess Contaminants in Water, Sediment, and Fish

Pharmaceuticals in aquatic environments pose threats to aquatic organisms because of their continuous release and potential accumulation. Monitoring methods for these contaminants are inadequate, with targeted analyses falling short in assessing water quality's impact on biota. The present study advocates for integrated strategies combining suspect and targeted chemical analyses with molecular biomarker approaches to better understand the risks posed by complex chemical mixtures to nontarget organisms. The research aimed to integrate chemical analysis and transcriptome changes in fathead minnows to prioritize contaminants, assess their effects, and apply this strategy in Wascana Creek, Canada. Analysis revealed higher pharmaceutical concentrations downstream of a wastewater-treatment plant, with clozapine being the most abundant in fathead minnows, showing notable bioavailability from water and sediment sources. Considering the importance of bioaccumulation factor and biota-sediment accumulation factor in risk assessment, these coefficients were calculated based on field data collected during spring, summer, and fall seasons in 2021. Bioaccumulation was classified as very bioaccumulative with values >5000 L kg-1, suggesting the ability of pharmaceuticals to accumulate in aquatic organisms. The study highlighted the intricate relationship between nutrient availability, water quality, and key pathways affected by pharmaceuticals, personal care products, and rubber components. Prioritization of these chemicals was done through suspect analysis, supported by identifying perturbed pathways (specifically signaling and cellular processes) using transcriptomic analysis in exposed fish. This strategy not only aids in environmental risk assessment but also serves as a practical model for other watersheds, streamlining risk-assessment processes to identify environmental hazards and work toward reducing risks from contaminants of emerging concern. Environ Toxicol Chem 2024;00:1-22. © 2024 SETAC.

A novel approach to identify priority areas for optimal nutrient management in mixed land-use watersheds through nutrient budget assessment

Excessive nutrient supply in agricultural regions has led to various environmental issues, thereby requiring concentrated management owing to its persistent upward trend. Nutrient budgets (NBs), a vital agricultural environmental indicator, are employed for nutrient management in agricultural areas, using data surveyed by administrative agencies. However, the spatial extent of nutrient data for nutrient budgeting is limited by administrative boundaries according to the surveying organization, posing challenges in interpreting spatial patterns at the watershed level. In this study, a novel approach was developed to identify priority nutrient management areas by applying hot spot spatial analysis to watershed-level NBs, considering hydrological characteristics. This method was applied to approximately 850 subwatersheds across the Republic of Korea, where land cover characteristics are complex. Reassessing nutrient budgets at the watershed scale, accounting for overlapping administrative boundary areas and crop cultivation ratios, indicated similar levels between the two methods. Hot spot analysis revealed that watersheds with elevated NBs mirrored the spatial patterns of livestock excreta and cropland. The spatial distribution characteristics of watersheds with high nutrient levels in rivers corresponded with the concentration characteristics of industrial and commercial areas. Therefore, applying watershed-level NBs based on land cover ratios that consider nutrient input characteristics in agricultural regions is deemed appropriate for selecting priority nutrient management areas. Collectively, this study presents a method for selecting nutrient management priority areas by simultaneously considering the spatial characteristics of various environmental factors, such as land cover, livestock excreta, river water quality, and land area-based watershed-specific NBs. The proposed approach, considering mixed land cover characteristics, is anticipated to be valuable for selecting priority management areas in watersheds with diverse pollution sources. Future research is needed to explore nutrient budgets within watersheds, the influence of land use on pollution sources, and their correlation with water quality.

Erythrocyte Recovery in Oreochromis niloticus Fish Exposed to Urban Effluents

Urban activities pollute aquatic ecosystems, and the integrity of organisms such as fish. The use of cytological techniques, such as the analysis of blood cellular integrity using the Micronucleus test, can help detect mutagenic damage as a result to urban effluents exposure. In this context, this study aimed to evaluate the frequency of micronucleus and other nuclear abnormalities in Oreochromis niloticus fish environmentally exposed to urban effluents in relation to their erythrocyte recovery capacity when exposed to clean water (30 and 45 days). The results indicated high copper, dissolved iron, nickel, and thermotolerant coliform levels in the urban stream. There was no difference in the frequency of micronuclei. In contrast, cells with nuclear nuclei, binucleates, kidney-shaped nuclei, notched nuclei, lobed nuclei, and segmented nuclei decreased according to the time the fish were exposed to clean water. When exposed to clean water, we conclude that urban fish recover from genotoxic and cytotoxic damage.

Seasonal monitoring of microbial activity using conventional approaches in a full-scale urban biological wastewater treatment plant

Activated sludge processes contain various groups of microorganisms with different metabolic properties, which are responsible for contaminants removal. Therefore, it is important to elucidate the general structure and functional properties of biomass in activated sludge processes. For this purpose, a full-scale domestic biological wastewater treatment plant in Tunceli (Turkey), Tunceli WWTP (wastewater treatment plant), was monitored to observe seasonal variations in process performance and biomass properties for a year. It was observed that nitrifying bacteria developed abundantly in the rainy and cool spring season as they were suppressed in summer because their large losses took place due to an environment containing high alkalinity values. In September, aerobic heterotrophic, nitrify, denitrify, and anaerobic activities increased. It can be said that the biomass contained young and mature microorganism in this environment in which the sludge volume index (SVI) value increased to 196 mL/g. As a result of the improvement in the structural and functional properties of biomass, the nitrogen removal efficiency reached 99%. Throughout the whole study, the structural improvement observed in biomass was reflected in its removal activity. The amount of biomass and removal activity decreased with the abundance of organic matter in the influent at the period in which biomass was closer to being categorized in the aged sludge class. The results showed that as the lowest mixed liquid suspended solids (MLSS) and mixed liquid volatile suspended solids (MLVSS) values of the year were 530 and 400 mg/L, respectively, in November 2017, MLSS and MLVSS values reached the highest amount (1700 and 1400 mg/L, respectively) in December 2017 when aerobic heterotrophic activity accelerated with a decrease in organic matter level.

In vitro genotoxic and mutagenic effects of water samples from Sapucaia and Esteio streams (Brazil) under the influence of different anthropogenic activities

Pollution of aquatic ecosystems is associated with the discharge of mainly industrial and urban effluents, which may cause damage to public health. This study aims to evaluate the cytotoxic, genotoxic, and mutagenic potential of surface water samples under the influence of different anthropogenic effluents in a human-derived liver cell line (HepG2). Samples were collected in Esteio and Sapucaia streams (Rio Grande do Sul; Brazil), which flow into the Sinos River, a source of water supply for more than one million people. Physicochemical and microbiological analyses were performed as well as an analysis of inorganic elements using the PIXE technique (Particle-Induced X-Ray Emission). The presence of pharmaceutical compounds and caffeine was evaluated by gas chromatography coupled to mass spectrometry. The cytotoxicity, genotoxicity, and mutagenicity of the samples were evaluated in HepG2 cells by cell viability assays, alkaline Comet Assay and Cytokinesis-block micronucleus (CBMN) assay. We verified alterations in the physicochemical and microbiological parameters and detected caffeine, diethyltoluamide, and different inorganic elements that corresponded to elements from domestic and industrial effluents and agricultural runoff. Although the samples in the concentration used were not cytotoxic, water samples from all sites induced DNA damage. However, it is difficult to attribute these damages to a specific substance since the factors are a complex mixture of different compounds. Despite this, it is observed that both urban and industrial contributions had a similar effect in the cells evaluated. Such results demonstrate the need to perform biomonitoring of surface waters under anthropogenic influence, especially those that flow into rivers that are a source of public supply water. We also highlight the need for research into emerging pollutants in these aquatic environments.

Spatial and seasonal variations of endocrine disrupting compounds in water and sediment samples of Markman Canal and Swartkops River Estuary, South Africa and their ecological risk assessment

The presence of pharmaceuticals in surface water and sediment has sparked up a global concern, as they could cause harm to human health. In this study, we investigated five pharmaceuticals (caffeine, carbamazepine, sulfamethoxazole, testosterone, and trimethoprim) in surface water and sediment samples from Swartkops River Estuary and Markman Stormwater Canal, in the Eastern Cape Province, South Africa. Ultra-Performance Liquid Chromatography (UPLC) systems coupled with a hyphenated quadrupole-time-of-flight mass spectrometry (QTOF-MS) was used for the analysis. Of the five pharmaceuticals investigated, three were detected in sediment samples at concentrations ranging from BDL - 23.86 μg/kg (dw). Caffeine and sulfamethoxazole were below the detection limit. The finding of this current study suggests that Markman and Motherwell's stormwater canals were potential contributors to pollution in Swartkops River Estuary. Ecotoxicity risk assessment indicated that trimethoprim and carbamazepine could constitute potential risk to aquatic organisms in Markman Canal and Swartkops Estuary, suggesting the need for proper control measure to prevent the pollution from toxicants in aquatic resources.

Biodiversity and Sediment Contamination in Wet Stormwater Ponds Depending on Design and Catchment Characteristics

Stormwater ponds are a common way to handle stormwater and are used to retain pollutants through sedimentation. The ponds resemble small natural lakes and will be colonized by flora and fauna. How design with respect to age, ratio between wet volume and reduced catchment area and land use influences the retention and how biodiversity is affected was examined. Age and ratio were determined in 135 and 59 ponds, respectively, and 12 of these ponds were selected for studies of dry weight (DW), organic matter (OM), total phosphorus (TP) and aluminum (Al), zinc (Zn), copper (Cu), chromium (Cr), cadmium (Cd) and lead (Pb) in the sediment. Invertebrate biodiversity was determined by Shannon–Wiener index (H’) and Pielou Evenness (J). DW, OM, TP and metals in the sediment close to the outlet of the ponds were influenced by pond age and the volume/area ratio whereas the sediment in the inlet area was more affected by the catchment type. Biodiversity increased with increasing ratio, while age had no effect on the sediment biodiversity but some effect on the water phase biodiversity. Biodiversity decreased with higher OM and TP and tend to decrease with increasing metal content. Higher volume/area ratio results in less sediment accumulation which improves the biodiversity. More pollutants are accumulating with age, which negatively affects the biodiversity. In conclusion, pond ratio, catchment type and, to some extent, age effect the load of contaminants in the sediment and the pond biodiversity. Proper design and management are recommended as a mitigating measure.

Machine learning approach identifies water sample source based on microbial abundance

Water quality can change along a river system due to differences in adjacent land use patterns and discharge sources. These variations can induce rapid responses of the aquatic microbial community, which may be an indicator of water quality characteristics. In the current study, we used a random forest model to predict water sample sources from three different river ecosystems along a gradient of anthropogenic disturbance (i.e., less disturbed mountainous area, wastewater discharged urban area, and pesticide and fertilizer applied agricultural area) based on environmental physicochemical indices (PCIs), microbiological indices (MBIs), and their combination. Results showed that among the PCI-based models, using conventional water quality indices as inputs provided markedly better prediction of water sample source than using pharmaceutical and personal care products (PPCPs), and much better prediction than using polycyclic aromatic hydrocarbons (PAHs) and substituted PAHs (SPAHs). Among the MBI-based models, using the abundances of the top 30 bacteria combined with pathogenic antibiotic resistant bacteria (PARB) as inputs achieved the lowest median out-of-bag error rate (9.9%) and increased median kappa coefficient (0.8694), while adding fungal inputs reduced the kappa coefficient. The model based on the top 30 bacteria still showed an advantage compared with models based on PCIs or the combination of PCIs and MBIs. With improvement in sequencing technology and increase in data availability in the future, the proposed method provides an economical, rapid, and reliable way in which to identify water sample sources based on abundance data of microbial communities.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal-oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

Longitudinal Surveillance of Antibiotic Resistance in Escherichia coli and Enterococcus spp. from a Wastewater Treatment Plant and Its Associated Waters in KwaZulu-Natal, South Africa

We assessed the prevalence, distribution, and antibiotic resistance patterns of Escherichia coli and Enterococcus spp. isolated from raw and treated wastewater of a major wastewater treatment plant (WWTP) in KwaZulu-Natal, South Africa and the receiving river water upstream and downstream from the WWTP discharge point. Escherichia coli and enterococci were isolated and counted using the Colilert^®-18 Quanti-Tray^® 2000 and Enterolert^®-18 Quanti-Tray 2000 systems, respectively. A total of 580 quantitative PCR-confirmed E. coli and 579 enterococci were randomly chosen from positive samples and tested for in vitro antibiotic susceptibility using the disk diffusion assay against 20 and 16 antibiotics, respectively. The removal success of the bacterial species through the treatment procedure at the WWTP was expressed as log removal values (LRVs). Most E. coli were susceptible to meropenem (94.8%) and piperacillin-tazobactam (92.9%), with most Enterococcus susceptible to ampicillin (97.8%) and vancomycin (96.7%). In total, 376 (64.8%) E. coli and 468 (80.8%) Enterococcus isolates showed multidrug resistance (MDR). A total of 42.4% (246/580) E. coli and 65.1% (377/579) enterococci isolates had multiple antibiotic resistance indices >0.2. The LRV for E. coli ranged from 2.97 to 3.99, and for enterococci the range was observed from 1.83 to 3.98. A high proportion of MDR E. coli and enterococci were present at all sampled sites, indicating insufficient removal during wastewater treatment. There is a need to appraise the public health risks associated with bacterial contamination of environmental waters arising from such WWTPs to protect the health of users of the receiving water bodies.

Rare earth elements (REE) in the urban wastewater of Cotonou (Benin, West Africa)

The rare earth element (REE) contamination of urban wastewater, which was collected from open sewers and the inlet of a wastewater treatment plant in Cotonou (Benin), was assessed. The drinking water distributed to the inhabitants of Cotonou and water samples from private wells were also analyzed. The sampling occurred between October and December 2016 and the samples were analyzed by ICP-MS. Although the only magnetic resonance imaging facility in Cotonou opened in November 2016, pollution by anthropogenic gadolinium (Gd), which is included in phase contrast agents, was observed: there was 30-620 times more Gd in wastewater samples than in drinking and well water samples. Europium was another REE presenting positive anomalies. It is hypothetized than the europium came from the leachates of solid waste piles in the street. In the absence of any wastewater treatment, the REEs found in the wastewater are spread to the aquatic environment. It would be interesting to monitor the wastewater REEs over the long term. So far, the aquifers used for water provision have not been polluted by the anthropogenic REEs.

Investigating Industrial Effluent Impact on Municipal Wastewater Treatment Plant in Vaal, South Africa

Industrial effluents with high concentrations of toxic heavy metals are of great concern because of their persistence and non-degradability. However, poor operation and maintenance of wastewater treatment infrastructure is a great concern in South Africa. In this study, physico-chemical parameters and heavy metals (HMs) concentration of wastewater from five different industries, Leeuwkuil wastewater treatment plant (WWTP) inflow and effluent, and Vaal River water samples were monitored between January and September 2017, to investigate the correlation between heavy metal pollution and the location of industries and ascertain the effectiveness of the municipal WWTP. Physico-chemical variables such as pH, biological oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), total dissolved solids (TDS) and electrical conductivity (EC) exhibited both temporal and spatial variations with the values significantly higher in the industrial samples. Inductively coupled plasma optical emission spectrometry (ICP-OES) results also showed that aluminium (Al), copper (Cu), lead (Pb) and zinc (Zn) were significantly higher in industrial effluents (p < 0.05), with only Zn and Al exhibiting significant seasonal variability. Statistical correlation analysis revealed a poor correlation between physicochemical parameters and the HMs compositional quality of wastewater. However, toxic HMs (Zn, Cu and Pb) concentrations in treated wastewater from WWTP were above the permissible limits. Although the WWTP was effective in maintaining most of the wastewater parameters within South African Green drop Standards, the higher Cu, Zn, Pb and COD in its final effluent is a concern in terms of Vaal river health and biological diversity. Therefore, we recommend continuous monitoring and maintenance of the WWTPs infrastructure in the study area.

Cultivable bacterial diversity, physicochemical profiles, and toxicity determination of car wash effluents

Carwash effluents contain potentially toxic chemical and microbiological pollutants which may pose public health and ecotoxicological threats if directly discharged into surface waters. This work was aimed at determining the microbiological, physicochemical, and toxicological parameters of carwash effluents. Toxicity assays were determined using whole effluent toxicity (WET) using Danio rerio and Daphnia pulex. For microbiological analysis, sample aliquots were spread plated onto R2A Agar for the isolation of heterotrophic bacteria followed by DNA extraction from axenic cultures for sequencing analysis. The pH of effluent samples lay in the alkaline range, and ranged from pH 7 to pH 10. Sample salinity ranged from 0.2 to 0.3 g/Kg. Electrical conductivity values ranged from 274 to 554 μS/cm. Concentrations of Co, Pb, and Ni were < 1 mg/L in all samples while the concentrations of Cu ranged from 0.94 to 3.8 mg/L and Zn from 1.15 to 3 mg/L. Oil and grease concentrations ranged from 5 to 24 mg/L. The concentrations of TPH-GRO were low at < 1 mg/L in all samples. All the carwash effluents were categorised as acutely toxic, with ≥ 75% mortality recorded for both test organisms within the first 24 h of exposure to the test solutions. Heterotrophic bacteria counts ranged from 2800 to 4600 CFU/100 ml. Sequencing analysis revealed that 57% of the isolates were closely related to Aeromonas species, with 43% closely related to Pseudomonas species. We conclude that carwash effluents are veritable sources of microbiological contaminants and potentially toxic chemical pollutants of public health and ecotoxicological concern.

Prevalence and diversity of blaTEM, blaSHV and blaCTX-M variants among multidrug resistant Klebsiella spp. from an urban riverine environment in India

In the present study, we have investigated prevalence and diversity of ESBL genes among Klebsiella isolates obtained from highly polluted stretch of river Yamuna, India. Phenotypic screenings of 116 Klebsiella isolates revealed ~30% were positive for ESBL production. Antibiotic profiling showed multidrug resistance phenotype among 90% isolates. Prevalence of blaTEM, blaSHV and blaCTX-M genes were found to be 57, 54 and 48% respectively. Furthermore, we identified eight variants of blaSHV (SHV-1, SHV-11, SHV-27, SHV-28, SHV-38, SHV-61, SHV-144, SHV-148), three each of blaTEM (TEM-1, TEM-116, TEM-206) and blaCTX-M (CTX-M-15, CTX-M-55, CTX-M-188) among Klebsiella spp. Co-occurrence of blaTEM, blaSHV and blaCTX-M (any two or all three) was observed among 45% Klebsiella isolates. Occurrence of blaCTX-M-188 and blaTEM-206 in environmental isolates of K. pneumoniae has not been reported earlier. Identification of blaTEM-206, blaSHV-27 and blaSHV-144 from Klebsiella spp. and blaTEM-116 from K. quasipneumoniae and K. variicola is the first report from India.

Solar reclamation of wastewater effluent polluted with bisphenols, phthalates and parabens by photocatalytic treatment with TiO2/Na2S2O8 at pilot plant scale

Investigations of anthropogenic contaminants in fresh- and wastewater have shown a wide variety of undesirable organic compounds such as Endocrine Disruptors (EDs). As a result, wastewater treatments using innovative technologies to remove those organic compounds are required. In this paper, the photodegradation of six EDs in wastewater at pilot plant scale is reported. The EDs were bisphenol A, bisphenol B, diamyl phthalate, butyl benzylphthalate, methylparaben and ethylparaben. Commercial TiO₂ nanopowders (P25, Alfa Aesar and Kronos vlp 7000) were used as photocatalysts. The operating variables (type and loading catalyst, effect of electron acceptor and pH) were previously optimized under laboratory conditions. The results show that the use of TiO₂ alongside an electron acceptor like Na₂S₂O₈ strongly enhances the degradation rate of the studied compounds compared with photolytic tests, especially P25. The oxidation rates of the EDs at pilot plant scale were calculated following the disappearance of the target compound as a function of fluence (H). The ED degradation followed a pseudo-first order kinetics in all cases. In our experimental conditions, the half-fluence (H₅₀) varied from 79 to 173 J cm^-2 (photolytic test), 10-117 J cm^-2 (TiO₂ vlp 7000) and 3-58 J cm^-2 (TiO₂ P25), for bisphenol B and butyl benzylphthalate, respectively. It is concluded that solar photocatalysis using the tandem TiO₂/Na₂S₂O₈ can be considered as an environmental-friendly tool for water detoxification and a sustainable technology for environmental remediation, especially in the Mediterranean Basin, where many places receive more than 3000 h of sunshine per year. Although the cost depends on the nature of the pollutant, the treatment cost was estimate to be about 150 € m^-3 for photocatalytic treatment with TiO₂ P25.

Photocatalytic oxidation of six endocrine disruptor chemicals in wastewater using ZnO at pilot plant scale under natural sunlight

Endocrine disruptors (EDs) are xenobiotics that interfere with the synthesis, secretion, transport, binding, action, and elimination of the natural hormones. In this paper, the photodegradation of six EDs in municipal wastewater treatment plant effluents at pilot plant scale is reported. The EDs were bisphenol A, bisphenol B, diamyl phthalate, butyl benzylphthalate, methyl p-hydroxybenzoate, and ethyl 4-hydroxybenzoate. ZnO as photocatalyst in tandem with Na₂S₂O₈ as electron acceptor under natural sunlight were used. The process was previously optimized under laboratory conditions through a photoreactor under artificial UVA irradiation studying the role of some key operating parameters (catalyst loading, effect of electron acceptor, and pH). Results carried out at pilot plant scale show that addition of ZnO in tandem with Na₂S₂O₈ strongly enhances degradation rates compared with photolytic test. At the end of the irradiation time (240 min), the remaining amounts of EDs ranged from 24% (butyl benzylphthalate) to 0% (< LOQ bisphenol B). The degradation rates were in the order: bisphenols > parabens > phthalates. After the photoperiod, 83% of the initial dissolved organic carbon was removed and toxicity decreased to acceptable values (11% inhibition to Vibrio fisheri). The photodegradation process was found to follow pseudo-first-order kinetic model with DT₅₀ ranging from 5 min (bisphenol B) to 102 min (butyl benzylphthalate). Thereby, photocatalytic oxidation using ZnO is an area of environmental interest for the treatment of polluted water, particularly relevant for Mediterranean countries, where solar irradiation is highly available.

Integrating microbial biomass, composition and function to discern the level of anthropogenic activity in a river ecosystem

Anthropogenic activities (e.g., wastewater discharge and pesticide and fertilizer use) have considerable impact on the biotic properties of natural aquatic ecosystems, especially the microbial community and function. Microbes can respond to anthropogenic activities and are thus potential indicators of activity levels. Several reports have documented the impacts of anthropogenic activities on the variations in the microbial community, but the direct use of microbial community indices to discern anthropogenic activity levels remains limited. Here, we integrated flow cytometry, 16S rRNA sequencing, and natural organic matter metabolism determination to investigate microbial biomass, composition, and function in three areas along a gradient of anthropogenic disturbance (less-disturbed mountainous area, wastewater-discharge urban area, and pesticide and fertilizer used agricultural area) in a river ecosystem. Multiple statistical methods were used to explore the causal relationships between changes in environmental factors and microbial variation. Results showed that anthropogenic activities (e.g., wastewater discharge, pesticide and fertilizer use) facilitated bacterial production, affected dominant species distribution, and accelerated natural organic matter (NOM) metabolic rate by microbes. After screening the possible factors influencing the microbial community, we determined that cyanobacterial concentration could be a diagnostic indicator of nutrient levels. We also developed a NOM metabolic index to quantitatively reflect the holistic influence of nutrients and xenobiotics.

Practical Application of Aptamer-Based Biosensors in Detection of Low Molecular Weight Pollutants in Water Sources

Water pollution has become one of the leading causes of human health problems. Low molecular weight pollutants, even at trace concentrations in water sources, have aroused global attention due to their toxicity after long-time exposure. There is an increased demand for appropriate methods to detect these pollutants in aquatic systems. Aptamers, single-stranded DNA or RNA, have high affinity and specificity to each of their target molecule, similar to antigen-antibody interaction. Aptamers can be selected using a method called Systematic Evolution of Ligands by EXponential enrichment (SELEX). Recent years we have witnessed great progress in developing aptamer selection and aptamer-based sensors for low molecular weight pollutants in water sources, such as tap water, seawater, lake water, river water, as well as wastewater and its effluents. This review provides an overview of aptamer-based methods as a novel approach for detecting low molecular weight pollutants in water sources.

Mucociliary transport, differential white blood cells, and cyto-genotoxicity in peripheral erythrocytes in fish from a polluted urban pond

The present study evaluated the water quality of a polluted pond through the analysis of in vitro mucociliary transport, hematological parameters, and biomarkers of cyto-genotoxicity in the Nile tilapia (Oreochromis niloticus). Blood and mucus samples were collected from ten specimens from the polluted pond and from ten specimens from a control area. The fish were anesthetized with 3% benzocaine, mucus was collected directly from the gills, and blood was drawn from the caudal artery. Blood smears were stained using the May-Grünwald Giemsa process for the differential leukocyte counts and to determine the frequency of leukocytes, thrombocytes, erythroblasts, micronuclei, and nuclear abnormalities. The results revealed low transportability in vitro, a high percentage of monocytes and eosinophils, and increased frequency of leukocytes and nuclear abnormalities in fish from the polluted pond. However, the frequency of thrombocytes and erythroblasts and the percentage of lymphocytes and neutrophils were significantly lower. It is possible to conclude that changes in fish are due to poor water quality and that these non-destructive biomarkers can be used for the biomonitoring of aquatic environments vulnerable to contamination.

Ecotoxicological water assessment of an estuarine river from the Brazilian Northeast, potentially affected by industrial wastewater discharge

Water pollution generated by industrial effluents discharge is a threat to the maintenance of aquatic ecosystems and human development. The Jundiai River estuarine, located in Northeast Brazil, receives an industrial pretreated effluent load from the city of Macaíba/RN/Brazil. The present study aimed to assess the water quality of this water reservoir through i) physicochemical characterization, ii) quantification of metal concentration and iii) by an ecotoxicological assessment carried out using Mysidopsis juniae and Pomacea lineata. The study was performed throughout the period comprising May to September 2014. Physicochemical variables such as chloride, total solids and electrical conductivity presented values in the waste discharge point, significantly different with those located out of the waste releasing point. Apart from that, metal concentration showed variable behavior throughout the monitored period. Levels of Al, Fe, Cu, Cd, Cr, Ni, Pb and Ag were over the considered guidelines. Both natural and anthropogenic sources seem to be involved in the resulting environmental scenario. A reduction in the fecundity rate (using Mysidopsis juniae) along with an increase in mortality rate (in both species) was observed ratifying the presence of toxic substances in this water reservoir. Moreover, a correlation analysis stated an association of the aforementioned toxicological effects with the delivery of industrial waste products. The ecotoxicological assessment performed highlighted the presence of toxic substance/s in water from the Jundiai River. Especially as a consequence of industrial activity, a fact that might threaten the bioma and, therefore, the human health of the population settled in the studied region.