An assessment of the physicochemical properties and toxicity potential of carwash effluents from professional carwash outlets in Gauteng Province, South Africa

The assessment of the quality of carwash effluents has received scant attention as a potential source of public and environmental health hazard in South Africa as demonstrated by the lack of literature in this subject. The physicochemical quality and potential ramifications of carwash effluents on receiving waterbodies were investigated in this study. Grab effluent samples were collected from six carwash outlets in Gauteng Province of South Africa and analysed for selected physicochemical qualities including biological oxygen demand (BOD), oil and grease, total petroleum hydrocarbons-gasoline range organics (TPH-GRO), pH, dissolved oxygen (DO), total solids (TS) and total dissolved solids (TDS), electrical conductivity (EC), nutrients (nitrates, nitrites and phosphates), anionic surfactants and heavy metals (zinc [Zn], copper [Cu], lead [Pb] and chromium [Cr]). Further, the toxicity potential of the effluent samples was assessed using organisms from four trophic levels ranging from Selenastrum capricornutum (primary producer), Daphnia magna (primary consumer), Poecilia reticulata (secondary-tertiary consumer) and Vibrio fischeri (decomposer). High pollutant levels were observed in all effluents with BOD ranging from 27±2.1 to 650±4.9 mg/l, TDS from 362±8.5 to 686±8.5 mg/l, GRO-TPH from 0.01±0.0 to 7.6±0.2 mg/l, DO from 0.0 to 0.1 mg/l, Zn from 0.79±0.08 to 20±2.12 mg/l, Cu from 0.77±0.03 to 13±0.71 mg/l and oil and grease from 12±2.8 to 43±2.1 mg/l. Ammonium concentrations ranged from 0.4±0.1 to 75±6.4 mg/l; turbidity from 109±0.7 to 4000±29.7 mg/l, anionic surfactants from 1.4±0.1 to 5.8±0.3 mg/l and TPH from < 0.01 to 7.6 mg/l. Toxicity assessment assays resulted in 100% mortality for fish and Daphnia after 96 and 24 h respectively and significant bioluminescence and growth reduction in Vibrio fischeri and algae after 15 min and 72 h respectively. Most of the measured physicochemical parameters were in concentrations above the Environmental Management Agency (EPA) stipulated guidelines. Additionally, the effluents demonstrated acute toxicity against all four test species.UNISA-WiREnvironmental Science

Screening and evaluation of some green algal strains (Chlorophyceae) isolated from freshwater and soda lakes for biofuel production

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Prevalence and characterisation of non-cholerae Vibrio spp. in final effluents of wastewater treatment facilities in two districts of the Eastern Cape Province of South Africa: implications for public health

Vibrios and other enteric pathogens can be found in wastewater effluents of a healthy population. We assessed the prevalence of three non-cholerae vibrios in wastewater effluents of 14 wastewater treatment plants (WWTP) in Chris Hani and Amathole district municipalities in the Eastern Cape Province of South Africa for a period of 12 months. With the exception of WWTP10 where presumptive vibrios were not detected in summer and spring, presumptive vibrios were detected in all seasons in other WWTP effluents. When a sample of 1,000 presumptive Vibrio isolates taken from across all sampling sites were subjected to molecular confirmation for Vibrio, 668 were confirmed to belong to the genus Vibrio, giving a prevalence rate of 66.8 %. Further, molecular characterisation of 300 confirmed Vibrio isolates revealed that 11.6 % (35) were Vibrio parahaemolyticus, 28.6 % (86) were Vibrio fluvialis and 28 % (84) were Vibrio vulnificus while 31.8 % (95) belonged to other Vibrio spp. not assayed for in this study. Antibiogram profiling of the three Vibrio species showed that V. parahaemolyticus was ≥50 % susceptible to 8 of the test antibiotics and ≥50 % resistant to only 5 of the 13 test antibiotics, while V. vulnificus showed a susceptibility profile of ≥50 % to 7 of the test antibiotics and a resistance profile of ≥50 % to 6 of the 13 test antibiotics. V. fluvialis showed ≥50 % resistance to 8 of the 13 antibiotics used while showing ≥50 % susceptibility to only 4 antibiotics used. All three Vibrio species were susceptible to gentamycin, cefuroxime, meropenem and imipenem. Multiple antibiotic resistance patterns were also evident especially against such antibiotics as tetracyclin, polymixin B, penicillin G, sulfamethazole and erythromycin against which all Vibrio species were resistant. These results indicate a significant threat to public health, more so in the Eastern Cape Province of South Africa which is characterised by widespread poverty, with more than a third of the population directly relying on surface water sources for drinking and daily use

Establishing the link between urban land cover change and the proliferation of aquatic hyacinth (Eichhornia crassipes) in Harare Metropolitan, Zimbabwe

Urbangrowthisakeyprocessaffectingthefunctioningofnaturalecosystems,andconsequentlythegloballand-surface process. This work aimed at establishing the link between land cover changes around HarareMetropolitancityandtheproliferationofaquatichyacinth(Eichhornia crassipes)inLakeChivero.RemotelysensedLandsatseriesacquiredintheyear1973,1981,1994,1998,2008,2009and2014wasused.Imageclassificationwasimplementedtomaptheassociatedchangesovertimeusingdiscriminantanalysisalgorithm.Derivedthematiclandcovermapsshowedthatagriculturallandincreasedfrom2%in1973toa5%in1981reachingupto30%in2014,whereasthecity'slandareasignificantly(p<0.05)increasedbetween1973and1994.However,waterhyacinthconstantlyincreasedovertime.ThespatialandtemporalresolutionofLandsatimagesdetectedlandcoverchangesandtheproliferationofaquatichyacinth(Eichhorniacrassipes)intheLakeChiveroovertime

Inter-Seasonal Estimation of Grass Water Content Indicators Using Multisource Remotely Sensed Data Metrics and the Cloud-Computing Google Earth Engine Platform

Indicators of grass water content (GWC) have a significant impact on eco-hydrological processes such as evapotranspiration and rainfall interception. Several site-specific factors such as seasonal precipitation, temperature, and topographic variations cause soil and ground moisture content variations, which have significant impacts on GWC. Estimating GWC using multisource data may provide robust and accurate predictions, making it a useful tool for plant water quantification and management at various landscape scales. In this study, Sentinel-2 MSI bands, spectral derivatives combined with topographic and climatic variables, were used to estimate leaf area index (LAI), canopy storage capacity (CSC), canopy water content (CWC) and equivalent water thickness (EWT) as indicators of GWC within the communal grasslands in Vulindlela across wet and dry seasons based on single-year data. The results illustrate that the use of combined spectral and topo-climatic variables, coupled with random forest (RF) in the Google Earth Engine (GEE), improved the prediction accuracies of GWC variables across wet and dry seasons. LAI was optimally estimated in the wet season with an RMSE of 0.03 m2 and R2 of 0.83, comparable to the dry season results, which exhibited an RMSE of 0.04 m2 and R2 of 0.90. Similarly, CSC was estimated with high accuracy in the wet season (RMSE = 0.01 mm and R2 = 0.86) when compared to the RMSE of 0.03 mm and R2 of 0.93 obtained in the dry season. Meanwhile, for CWC, the wet season results show an RMSE of 19.42 g/m2 and R2 of 0.76, which were lower than the accuracy of RMSE = 1.35 g/m2 and R2 = 0.87 obtained in the dry season. Finally, EWT was best estimated in the dry season, yielding a model accuracy of RMSE = 2.01 g/m2 and R2 = 0.91 as compared to the wet season (RMSE = 10.75 g/m2 and R2 = 0.65). CSC was best optimally predicted amongst all GWC variables in both seasons. The optimal variables for estimating these GWC variables included the red-edge, near-infrared region (NIR) and short-wave infrared region (SWIR) bands and spectral derivatives, as well as environmental variables such as rainfall and temperature across both seasons. The use of multisource data improved the prediction accuracies for GWC indicators across both seasons. Such information is crucial for rangeland managers in understanding GWC variations across different seasons as well as different ecological gradients

Correction: sibanda et al. application of drone technologies in surface water resources monitoring and assessment: a systematic review of progress, challenges, and opportunities in the global south. drones 2021, 5, 84

In the original publication [1], “Fahad Alawadi. Detection of surface algal blooms using the newly developed algorithm surface algal bloom index (SABI)”, “Proc. SPIE 7825, Remote Sensing of the Ocean, Sea Ice, and Large Water Regions 2010, 782506 (18 October 2010); https://doi.org/10.1117/12.862096” [2] was not cited. The citation has now been inserted in “3.5. The Role of Drone Data Derived Vegetation Indices and Machine Algorithms in Remote Sensing Water Quality and Quantity” as reference [60] and should read: “Numerous vegetation indices were derived from drone remotely sensed data for characterizing surface water quality and quantity. The most widely used sections of the electromagnetic spectrum in detecting water quality parameters were the visible section (blue and green) and the NIR wavebands. In this regard, vegetation indices such as the red and near-infrared (NIR), Surface Algal Bloom Index (SABI) [60], two-band algorithm (2BDA) [26], NDVI, and Green NDV [33], as well as band combinations and differencing such as (R+NIR/G) were used mostly in characterizing chlorophyll content as well as TSS

Assessment of the physicochemical and microbiological qualities of Tyume River in Amathole District in the Eastern Cape Province, South Africa

The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant Tyume River water samples were collected monthly, over a 12-month period starting from August 2010 and ending in July 2011, and transported on ice to the Applied and Environmental Microbiology Research Group (AEMREG) Laboratory at the University of Fort Hare, Alice for analyses within 6 h of collection. Electrical conductivity (EC), total dissolved solids (TDS), temperature, pH and dissolved oxygen (DO) of water samples were determined in situ using a multi-parameter ion-specific meter. Concentrations of orthophosphate and total nitrogen (nitrate + nitrite) were determined by standard photometric methods. Total coliforms (TC), faecal coliforms (FC) and enterococci were determined by the membrane filtration method. Viruses in water samples were concentrated using the adsorption-elution method, followed by extraction of viral nucleic acids and purification done using commercially available kits. The concentrations of human enteric viruses in the river-water samples were estimated using quantitative PCR. RNA viruses were quantified in a two-step protocol where RNA was first transcribed into cDNA in a separate reverse-transcription step. Adenovirus species and serotypes were simultaneously detected using serotype-specific multiplex PCR. Norovirus genogroups GI and GII were detected by semi-nested PCR. The risk of infection associated with recreational and domestic use of the water was also estimated. Biochemical oxygen demand (BOD) levels fell within the stipulated BOD guideline of 10 mg/ℓ for surface waters where full contact use is allowed and ≤ 30 mg/ℓ where public access is prohibited, restricted, or infrequent. DO concentrations generally ranged between 7.47 mg/ℓ and 10.42 mg/ℓ, well within the target water quality requirements. The temperature regime ranged between 6°C and 28°C and for most sampling sites, the temperature regimes were within the acceptable limit of no risk (≤ 25°C) for domestic water uses in South Africa. EC ranged between 47 μS/cm and 408 μS/cm well within the South African target water quality EC guideline of 700 μS/cm though it was observed to increase as the river flowed through settlements. The pH in the period beginning September 2010 through to January 2011 was consistently below pH 9, but from February 2011 to June 2011 the pH significantly increased to between pH 10 and pH 11 at most sampling sites. Unpolluted waters normally show a pH of between 6.5 and 8.5. Most of the pH values observed in this study lie between pH 8.5 and pH 10.8 levels which are not far off from the upper level guideline of pH 9.0 for domestic use. Turbidity ranged between 6 NTU and 281 and fell short of the target water quality range (0 NTU to 1 NTU) of no risk for domestic water uses in South Africa. Monthly TDS values and EC values showed direct proportionality. TDS concentrations at all sites fell within the acceptable guideline of 0 mg/ℓ to 450 mg/ℓ of TDS for domestic use. Nutrient profiles were as follows: nitrate (0.18 mg/ℓ to 4.21 mg/ℓ); nitrite (0.02 mg/ℓ to 2.35 mg/ℓ); and orthophosphate (0.06 mg/ℓ to 2.72 mg/ℓ). The bacteriological qualities of the water were poor, exceeding the guideline of 200 CFU/100 mℓ and 33 CFU/100 mℓ for FC and enterococci respectively, for recreational water. FC counts also exceeded the 1 000 CFU/100 mℓ guideline for water used in fresh produce irrigation. Generally, higher counts of TC, FC and enterococci were recorded at the sampling sites located at the lower reaches of the river compared to the upper reaches. Adenovirus was detected in 31percent of the river samples in concentrations ranging between 1.0×100 genome copies/ℓ and 8.49×104 genome copies/ℓ. Serotyping showed the presence of species C adenovirus serotypes 1, 2, 6 and 7, and species F adenovirus serotype 41. The prevalence of norovirus was 4percent while rotavirus was detected in 4percent of river samples in concentrations ranging between 9×100 genome copies/ℓ and 5.64×103 genome copies/ℓ. Hepatitis A virus was detected in 13percent of river samples in concentrations ranging between1.67×103 and 1.64×104 genome copies/ℓ while enteroviruses were not detected. Detection of enteric viruses was inversely correlated to temperature. Risk analysis showed that both hepatitis A virus and adenovirus presented significantly higher risk of infection values compared to rotavirus in the case of ingestion of 10 mℓ or 100 mℓ of water from Tyume River while enteroviruses did not present any significant risk of infection. Tyume River water samples also did not conform to the US Environmental Protection Agency (US EPA) bacterial criteria of 200 CFU/100 mℓ faecal coliforms and 33 CFU/100 mℓ enterococci for bathing waters. Whereas the physicochemical parameters showed that Tyume River water was relatively clean, the bacteriological water quality was poor. Most of the microbiological contamination observed in this study (especially FIBs) can be blamed on inadequate sanitary infrastructure as we observed that open defecation is commonplace in this catchment, which also serves as a conduit for effluent discharges from wastewater-treatment facilities. Enteric viruses were detected along the course of the river in a sporadic pattern, generally not related to natural hydrological cycles and so we conclude that the presence of enteric viruses in the river is suggestive of the dynamics of the same in the host population. Even though the proportion of infective viruses was estimated in this study, fact remains that there is considerable risk of infection posed by the use of raw surface water for either domestic or recreational use. This study further confirmed the lack of correlation between faecal indicator bacteria and enteric virus occurrence in environmental waters, showing that assaying for enteric viruses in environmental waters remains the best method for determining the health risks associated with the use of faecally contaminated water.Thesis (PhD) -- Faculty of Science and Agriculture, 201

A Systematic Review of UAV Applications for Mapping Neglected and Underutilised Crop Species’ Spatial Distribution and Health

Timely, accurate spatial information on the health of neglected and underutilised crop species (NUS) is critical for optimising their production and food and nutrition in developing countries. Unmanned aerial vehicles (UAVs) equipped with multispectral sensors have significantly advanced remote sensing, enabling the provision of near-real-time data for crop analysis at the plot level in small, fragmented croplands where NUS are often grown. The objective of this study was to systematically review the literature on the remote sensing (RS) of the spatial distribution and health of NUS, evaluating the progress, opportunities, challenges, and associated research gaps. This study systematically reviewed 171 peer-reviewed articles from Google Scholar, Scopus, and Web of Science using the PRISMA approach. The findings of this study showed that the United States (n = 18) and China (n = 17) were the primary study locations, with some contributions from the Global South, including southern Africa. The observed NUS crop attributes included crop yield, growth, leaf area index (LAI), above-ground biomass (AGB), and chlorophyll content. Only 29% of studies explored stomatal conductance and the spatial distribution of NUS. Twenty-one studies employed satellite-borne sensors, while only eighteen utilised UAV-borne sensors in conjunction with machine learning (ML), multivariate, and generic GIS classification techniques for mapping the spatial extent and health of NUS. The use of UAVs in mapping NUS is progressing slowly, particularly in the Global South, due to exorbitant purchasing and operational costs, as well as restrictive regulations. Subsequently, research efforts must be directed toward combining ML techniques and UAV-acquired data to monitor NUS’ spatial distribution and health to provide necessary information for optimising food production in smallholder croplands in the Global South

Characterizing leaf nutrients of wetland plants and agricultural crops with nonparametric approach using Sentinel-2 imagery data

In arid environments of the world, particularly in sub-Saharan Africa and Asia, floodplain wetlands are a valuable agricultural resource. However, the water reticulation role by wetlands and crop production can negatively impact wetland plants. Knowledge on the foliar biochemical elements of wetland plants enhances understanding of the impacts of agricultural practices in wetlands. This study thus used Sentinel-2 multispectral data to predict seasonal variations in the concentrations of nine foliar biochemical elements in plant leaves of key floodplain wetland vegetation types and crops in the uMfolozi floodplain system (UFS). Nutrient concentrations in different floodplain plant species were estimated using Sentinel-2 multispectral data derived vegetation indices in concert with the random forest regression. The results showed a mean R2 of 0.87 and 0.86 for the dry winter and wet summer seasons, respectively. However, copper, sulphur, and magnesium were poorly correlated (R2 ≤ 0.5) with vegetation indices during the summer season. The average % relative root mean square errors (RMSE’s) for seasonal nutrient estimation accuracies for crops and wetland vegetation were 15.2 % and 26.8%, respectively. There was a significant difference in nutrient concentrations between the two plant types, (R2 = 0.94 (crops), R2 = 0.84 (vegetation). The red-edge position 1 (REP1) and the normalised difference vegetation index (NDVI) were the best nutrient predictors. These results demonstrate the usefulness of Sentinel-2 imagery and random forests regression in predicting seasonal, nutrient concentrations as well as the accumulation of chemicals in wetland vegetation and crops.Department of Higher Education, Science and Technology and Agricultural Research Council.http://www.mdpi.com/journal/remotesensingpm2022Geography, Geoinformatics and Meteorolog

High prevalence of cisplatin-induced ototoxicity in Cape Town, South Africa

Background. Cisplatin is administered as the first-line treatment of soft-tissue cancers. It has a reported cure rate of up to 85%, but is associated with a high incidence of ototoxicity, characterised by irreversible bilateral hearing loss and affecting 23 - 50% of adults who receive the drug.Objectives. To determine the incidence of cisplatin-induced ototoxicity at Groote Schuur Hospital (GSH), Cape Town, South Africa.Methods. A retrospective cross-sectional study of cisplatin-receiving cancer patients attending GSH between January 2006 and August 2011.Results. A total of 377 patients were recorded as receiving cisplatin therapy during the study period. A 300% increase in new cisplatin-receiving patients receiving audiological monitoring was observed between 2006 and 2010. However, only patients with all clinical data as well as baseline and follow-up audiometric analyses were investigated. One hundred and seven such patients were identified, 55.1% of whom developed cisplatin-induced ototoxicity while receiving high-dose (≥60 mg/m2) cisplatin treatment. Higher cumulative cisplatin dosages were associated with development of significant hearing loss (p=0.027). The odds of developing cisplatin-induced hearing loss were elevated for patients with head and neck tumours and lymphoma (p=0.0465 and p=0.0563, respectively) and were significantly lower for those with reproductive cancers (p=0.0371).Conclusion. Comprehensive audiological monitoring should be available for every patient during cisplatin treatment to minimise the development of disabling hearing loss