Water Quality Guidelines Research Articles

Effectiveness of the upscaled use of a silver–ceramic (silver ionization) technology to disinfect drinking water in tanks at schools in rural India

ABSTRACT In many low- and middle-income countries, school children consume untreated water that has been pumped into storage tanks. The water is often of poor quality and consumption can cause gastrointestinal illnesses resulting in missed school days, growth stunting, and cognitive impairment. This study deployed a silver–ceramic technology (MadiDrop) to disinfect drinking water in school storage tanks. While silver ionization is effective at the household scale, relatively little research has been conducted on its effectiveness at the community scale. To address this gap, we assessed disinfection via MadiDrop at three schools that serve vulnerable populations in rural India. Tank inflow and treated outflow samples were tested for total coliforms (TCs) and Escherichia coli (EC). TC was significantly reduced overall and in two of three intervention tanks. Compared to the baseline, reductions in TC were significant in all three tanks and overall, while EC reductions were significant overall and in two of three tanks. TC reduction was negatively correlated with silver concentration and tank residence time, and silver concentrations were maintained below the drinking water quality guideline. While the intervention could be considered successful, several barriers and caveats are provided as are study limitations and areas for future research.

Analysis of Heavy Metal Pollution in the Water of the Halda River: A Distinctive Breeding Habitat for Carp Fish in Bangladesh.

The present study aimed to assess the heavy metal concentrations in water from different sampling sites of the Halda River, the only natural breeding ground of Indian major carps. We have analysed the contamination level and seasonal variations of heavy metals (viz. Fe, Cu, Zn, Cr, Cd and Pb). The favourability of the breeding environment was assessed by different contamination indices. Samples were collected from six sampling sites for four different seasons, and the metal concentrations were determined for water samples using Flame atomic absorption spectrophotometer. The obtained order of mean concentrations of heavy metals for four seasons was winter>spring>monsoon>pre-monsoon, and the assessed mean concentrations (mg/L) of heavy metals follow the trend: Fe (9.129)>Pb (0.033)>Zn (0.024)>Cr (0.017)>Cu (0.012)>Cd (0.002). The concentration of Fe was found above the permissible limit set by the World Health Organization (WHO) (Guidelines for Water Quality) and ECR (1997), and the concentrations for Pb were found above the USEPA (2006) limit in all four seasons. Contamination indices (heavy metal pollution Index [HPI] and metal index [MI]) indicate that during winter and monsoon, the river water metal condition is critical (HPI>100) and the sites are moderately as well as slightly (1<MI<2) affected by the studied heavy metals. Contamination indices, such as contamination factors (Cf), degree of contamination (Cdeg) and the pollution load index (PLI), demonstrate the fact that Fe and Pb remarkably contaminated the studied sampling sites. The Pearson correlation matrix and the principal component analysis (PCA) revealed that the studied metals are connected by their sources, which can be geological or anthropogenic. Urgent initiatives need to be taken, and effective strategies must be implemented to control the different sources responsible for the entry of heavy metals into the Halda River water.

Deriving water quality index using site-specific water quality parameter guidelines for real-time water quality stations

ABSTRACT The Newfoundland and Labrador real-time water quality (RTWQ) monitoring program operates a network of surface water monitoring stations, measuring physical water quality parameters in near real time. The network generates vast amounts of data that are too complex for many stakeholders to interpret. While the Canadian Council of Ministers of the Environment water quality index (WQI) has been a valuable tool to simplify and summarize the ambient quality of water, its usage in RTWQ is virtually non-existent. This is largely due to the lack of alignment/congruency between the limited number of parameters from real-time networks and the availability of aquatic water quality guidelines. This paper is the first attempt to outline a method of utilizing real-time water quality data to generate site-specific water quality guidelines using the background concentration method. Using these guidelines, we compute weekly WQI scores for select monitoring stations and examine various influences on the scores, including precipitation. The influence of each parameter on the WQI score is also plotted in the computation of the RTWQ WQI. Comparison is made between the yearly scores of the Canadian Environmental Sustainability Indicators WQI and RTWQ WQI. The paper also discusses the challenges and benefits of using this methodology as well as the sensitivity of WQI scoring at stations with various anthropogenic influences.

Responses of diatoms and aquatic macroinvertebrates to deposited fine sediment in mesocosm channels as a basis for a new water quality guideline

Water quality guidelines are an important tool for managing environmental pressures on freshwater streams. Currently, there is a lack of guideline values for fine sediment deposition in South Australian and, more broadly, Australian and overseas streams despite the potentially profound impacts of sediment deposition on aquatic communities. We used an outdoor recirculating stream mesocosm to assess the responses of freshwater diatoms and macroinvertebrates to fine sediment burial after six weeks following a pulsed event. Communities were exposed to five treatments of fine sediment deposition (inert sand) with an average depth between 1 and 20 mm, added on top of, and compared to, representative background sediments from a high-quality stream dominated by hard-bottom sediments and detritus. The most pronounced change was between the control and treatment one (1 mm sediment depth). Sediment deposition negatively affected diatom composition, with a decrease in functional diversity but a concurrent increase in taxonomic diversity arising from increased abundances of motile species. For macroinvertebrates, there was a clear negative response in the richness and abundance of the sensitive Ephemeroptera, Plecoptera and Trichoptera insect orders to fine sediment burial, and an associated higher macroinvertebrate drift propensity. This study highlights the importance of incorporating functional and behavioural responses in addition to taxonomic metrics when assessing biotic responses to stressors. This study recommends a new guideline which restricts additional fine sediment deposition to <1 mm in temperate South Australian freshwater streams, particularly those dominated by hard-bottom substrates and, or containing sensitive aquatic taxa. This threshold could act as an interim guideline for these stream types elsewhere in the absence of comparable studies.

Aquatic hazard and risk posed by four pesticides detected in waterways discharging to the Great Barrier Reef, Australia: Part 2. Hazard and risk assessment

Pesticide active ingredients (PAIs) are regularly detected in the rivers, creeks, wetlands, and inshore waterways that discharge to the Great Barrier Reef (GBR) lagoon. Pesticide active ingredients detected above ecologically protective concentrations may pose a hazard and risk to aquatic species. The ability to assess this hazard and risk is reliant on the availability of water quality guidelines, which are only available for a limited number of PAIs detected in GBR catchment waterways. Unendorsed guideline values, known as ecotoxicity threshold values (ETVs) were developed in part one of this study for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. In the current study, the hazard and risk posed by these PAIs was assessed by comparing the ETVs to environmental monitoring data from the Great Barrier Reef Catchment Loads Monitoring Program. Exceedances of the concentrations that should protect 99 % of aquatic species (i.e., PC99) were observed for all four pesticides. Detected concentrations of 4-hydroxychlorothalonil, carbendazim and methoxyfenozide exceeded the PC95 ETV, however no exceedances of the PC95 were observed for dimethoate. The hazard quotient (HQ) method was used to identify high hazard sites across the GBR catchment area. In total, six sites were identified as having concentrations that exceeded the PC95 ETVs. For 4-hydroxychlorothalonil, the risk to aquatic species based on the 95th percentile concentrations ranged from 3 to 13 %, 1 to 8 % for carbendazim and 2 to 8 % for methoxyfenozide. Detected concentrations of carbendazim were two orders of magnitude higher than concentrations that are reported to induce behavioural effects in some fish species. Considering that detected concentrations of three of the four PAIs individually pose a potential risk to aquatic species, their contributions to pesticide mixture toxicity should be further assessed.

Novel hybrid treatment for canal water recycling by integrating coagulation, catalytic ozonation, and filtration for agricultural sustainability

This study employed a novel approach, utilizing recycled alumina flocs after coagulation/flocculation (C/F) as a catalyst in catalytic ozonation (CO), along with the auxiliary catalyst sodium zeolite (Na-Z), where alumina produces hydroxyl radicals, and zeolite enhances molecular ozone reactions. This synergistic strategy focuses on treating contaminated canal water, recognizing that the presence of various pollutants can reduce the efficacy of a singular catalyst type. In the current investigation, alum, Na-Z, and rice husk (RH) were applied as a coagulant, catalyst, and filter media in C/F, CO, and filtration processes respectively. Four treatment technologies (C/F, O3, O3/Na-Z, and RHF) were studied independently and in four different combinations (O3–C/F, C/F–O3, C/F–O3/Na-Z, and C/F–O3/Na-Z–RHF) for the first time and their efficacious performance was evaluated. It was revealed that the combination-IV (C/F–O3/Na-Z–RHF) was a more efficient and economical treatment than others. This novel integrated treatment C/F–O3/Na-Z–RHF has remarkable removal efficiency of 99 %, 99 %, 85 %, 93 %, 100 %, 89 %, and 93 % for TSS, turbidity, COD, BOD5, fecal coliforms, cadmium, and copper respectively, under optimized working conditions. Also, treated canal water complied with the studied irrigation water quality guidelines. Notably, this efficient treatment combination halved the treatment time compared to others, potentially reducing the electrical energy demand of 11.45 kWh.m−3 and the overall operational treatment cost of 1.62 USD.m−3. Hence, the application of this efficient hybrid treatment system contributed to recycling canal water for agricultural use, livestock, and pasture watering, playing a crucial role in mitigating the water crisis.

Canadian beach cohort study: protocol of a prospective study to assess the burden of recreational water illness

BackgroundRecreational water activities at beaches are popular among Canadians. However, these activities can increase the risk of recreational water illnesses (RWI) among beachgoers. Few studies have been conducted in Canada to determine the risk of these illnesses. This protocol describes the methodology for a study to determine the risk and burden of RWI due to exposure to fecal pollution at beaches in Canada.MethodsThis study will use a mixed-methods approach, consisting of a prospective cohort study of beachgoers with embedded qualitative research. The cohort study involves recruiting and enrolling participants at public beaches across Canada, ascertaining their water and sand contact exposure status, then following-up after seven days to determine the incidence of acute RWI outcomes. We will test beach water samples each recruitment day for culture-based E. coli, enterococci using rapid molecular methods, and microbial source tracking biomarkers. The study started in 2023 and will continue to 2025 at beaches in British Columbia, Manitoba, Ontario, and Nova Scotia. The target enrollment is 5000 beachgoers. Multilevel logistic regression models will be fitted to examine the relationships between water and sand contact and RWI among beachgoers. We will also examine differences in risks by beachgoer age, gender, and beach location and the influence of fecal indicator bacteria and other water quality parameters on these relationships. Sensitivity analyses will be conducted to examine the impact of various alternative exposure and outcome definitions on these associations. The qualitative research phase will include focus groups with beachgoers and key informant interviews to provide additional contextual insights into the study findings. The study will use an integrated knowledge translation approach.DiscussionInitial implementation of the study at two Toronto, Ontario, beaches in 2023 confirmed that recruitment is feasible and that a high completion rate (80%) can be achieved for the follow-up survey. While recall bias could be a concern for the self-reported RWI outcomes, we will examine the impact of this bias in a negative control analysis. Study findings will inform future recreational water quality guidelines, policies, and risk communication strategies in Canada.

Evaluating seasonal variation in macronutrient levels and their impact on water quality in urban coastal waters: A case study in nutrient management along the North Colombo coast of Sri Lanka

Macronutrients are vital for sustaining marine food webs and primary production. However, their overabundance through riverine inflows and untreated wastewater discharges causes adverse ecological changes, especially in developing countries, necessitating effective nutrient management for ecosystem preservation. We assessed macronutrient enrichment and dispersion patterns in the north Colombo coast of Sri Lanka, an urban estuary stressed by untreated wastewater discharge from sewer channels and macronutrients from the Kelani River. Maximum concentrations of NO3−−N, total dissolved nitrogen, PO43−−P and total dissolved phosphorus were 0.085, 0.74, 0.70, and 0.79 mg/L, respectively, while the dissolved oxygen levels and temperature ranged from 6.42 to 8.62 mg/L and from 28.1 to 30.8 0C during January 2023. The estuary was a nitrogen-limited ecosystem, with the Kelani River being the primary source of NO3−−N. Although nutrient levels were within water quality guidelines, understanding how pollutants disperse during a catastrophic discharge is crucial for risk management. Simulated dispersion patterns using Delft3D revealed that NO3−−N and other solutes introduced through the Kelani River accumulate near the breakwaters of the Colombo harbor complex during the Northeast monsoon, primarily due to seasonal wave and wind conditions. The accumulation of the limiting nutrient increased the risk of eutrophication and harmful algal blooms by non-indigenous toxic algae species introduced by untreated ballast water disposal. The findings elucidate the critical role of breakwaters in retaining solutes and emphasize the influence of morphological, climatic, and topographical factors on dispersion patterns in coastal ecosystems. The study provides an example for developing countries to integrate cost-effective monitoring technologies and numerical modelling into coastal management, facilitating data-driven decision making for effective environmental management.

Practical estimation and use of natural background concentrations in surface waters for nickel in Europe.

Estimates of ambient background concentrations in surface waters, referred to as natural background concentrations (NBCs) in European guidance documents, may be an important factor in determining whether a monitoring site meets the legally binding Environmental Quality Standard (EQS) when assessing naturally occurring substances. Here, we focus on utilizing routine regulatory surface water monitoring data to provide risk assessors and environmental practitioners with a transparent, implementable, repeatable, and resource-effective approach to estimate NBCs. The methodology does not use additional environmental sampling beyond that which is routine or require advanced statistical methods, or the incorporation of highly specialist, and not always readily accessible, local knowledge. It determines both whether a site is suitable for NBC assessment as well as the identification of suitable surrogate sites and local NBCs using 11 criteria: six for identifying if a site is suitable for NBC correction, and five for identifying suitable surrogate sites for local NBC values. The criteria consider both the extent of any EQS exceedance, after accounting for bioavailability in line with the European guidance and potential anthropogenic impacts at the site, and can be applied in a simple sequential procedure. The method has been applied to derive NBCs for nickel on three case-study countries-Cyprus, France, and Spain-to determine its useability and impact on compliance. The methodology presented addresses a gap in the current guidance regarding the practical and consistent implementation of NBCs and could be applied to other naturally occurring substances in an EQS or Water Quality Guideline compliance assessment process. Integr Environ Assess Manag 2024;00:1-14. © 2024 WCA Environment Ltd and NiPERA Inc. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Potential of ecological water treatment elements to reduce pollution of river water used for urban agriculture in Addis Ababa, Ethiopia

Cities in developing countries, such as Addis Ababa, face enormous challenges as a result of high demand for food and clean water, as well as the generation of large amounts of urban waste that is discharged into natural water bodies, contaminating rivers, lakes, and other freshwater bodies used in urban agriculture. Farmers in Addis Ababa and nearby areas use polluted irrigation water diverted from the highly contaminated Little and Great Akaki rivers. The study aimed to assess how well a floating treatment wetland with vetiver grass could reduce irrigation water pollution at the Mekanisa-Gofa-Lafto Cooperative (MGLC) farm in Addis Ababa, Ethiopia. Additionally, the study sought to provide design recommendations that could be implemented at the farmer level. The irrigation water underwent a 7-day treatment using a Vetiver grass floating treatment wetland. A field test was also conducted to evaluate the effectiveness of the floating treatment wetland in reducing pollutants at the study site. The results showed that the floating treatment wetland was able to reduce the Biochemical Oxygen Demand (BOD) (73.68%), Chemical Oxygen Demand (COD) (73.92%), Acidity/Basicity (pH) (0.39%), Chloride (Cl−) (43.12%), Total Hardness (66.56%) and Total Suspended Solid (TSS) (96.21%) values, approaching the recommended irrigation water quality guideline values within 3 days. In contrast, there was an increase in Electro Conductivity (EC) (22.2%) and Sodium (Na) (15.2%) concentrations, which exceeded the recommended values, due to evapotranspiration or the entry of the surrounding soil into the irrigation water of the study site.

How does the citizens' choice of water use actions based on their empirical knowledge affect the water quality in a rural community of the Philippines?

This research assessed water quality, based on the purpose of water consumption, in households in the municipality of Barbaza, the Province of Antique, Philippines, according to the national water quality guidelines. The effects of the empirical/traditional water use actions taken by local people on the quality of the water they use were investigated through a descriptive study using water quality measurements. Most of the drinking water in the community did not meet the required standards of pH, total dissolved solids (TDS), or coliform. Tap water and well water samples generally met the pH and TDS standards. However, Escherichia coli (E. coli) and coliform were detected, and nitrogen pollution in well water was also confirmed. Local practices, such as using old clothes as filters for well pumps, increased the coliform concentration from 0-10 CFU/mL to too numerous to count (TNTC) levels of more than 100 CFU/mL. Storing well water in a bucket also affected both E. coli and coliform concentrations. Such empirical/traditional water use actions create a high risk of exposing local people to harmful microorganisms. This research integrated citizen science into the methodology for local water management, which could assist governors, practitioners, and citizens, particularly in Southeast Asia, where strong community relationships exist.

Assessment of the Impact of Coal Mining on Water Resources in Middelburg, Mpumalanga Province, South Africa: Using Different Water Quality Indices

The objective of this study was to assess the water quality status of the surface water and groundwater resources in the Middelburg area, South Africa. The assessment was addressed using combined water quality indices, investigating selected chemical parameters over four different seasons for a period of five years from 2017 to 2021. A combination of the Canadian Council of Ministers of the Environment water quality index and the comprehensive pollution index was used to analyze the water quality status of surface water and groundwater of the town of Middelburg, situated near coal mining activities in Mpumalanga, South Africa. The combination of the indices indicated that some surface water monitoring sites ranged between poor to fair water quality. Groundwater monitoring points also showed a poor to fair ranking. The comprehensive pollution index confirmed that some sites showed very poor water quality in the summer seasons, exceeding expected limits for the period 2017 to 2021. The principal component analysis further showed that both surface water and groundwater sites had high levels of contamination with increased chemical parameters. The results were compared against the different water quality guidelines. In an extensive monitoring program, water management systems must be properly implemented to mitigate impacts on water resources.

Toxicity of rare earth elements (REEs) to marine organisms: Using species sensitivity distributions to establish water quality guidelines for protecting marine life

A lack of chronic rare earth element (REE) toxicity data for marine organisms has impeded the establishment of numerical REE water quality benchmarks (e.g., guidelines) to protect marine life and assess ecological risk. This study determined the chronic no (significant) effect concentrations (N(S)ECs) and median-effect concentrations (EC50s) of eight key REEs (yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), gadolinium (Gd), dysprosium (Dy) and lutetium (Lu)) for 30 coastal marine organisms (encompassing 22 phyla and five trophic levels from temperate and tropical habitats). Organisms with calcifying life stages were most vulnerable to REEs, which competitively inhibit calcium uptake. The most sensitive organism was a sea urchin, with N(S)ECs ranging from 0.64 μg/L for Y to 1.9 μg/L for La and Pr, and EC50s ranging from 4.3 μg/L for Y to 14.4 μg/L for Pr. Conversely, the least sensitive organism was a cyanobacterium, with N(S)ECs ranging from 121 μg/L for Y to 469 μg/L for Pr, and EC50s ranging from 889 μg/L for Y to 3000 μg/L for Pr. Median sensitivity varied 215-fold across all organisms. The two-fold difference in median toxicity (μmol/L EC50) among REEs (Y ∼ Gd > Lu ∼ Nd ∼ Dy ∼ Ce > La ∼ Pr) was attributed to offset differences in binding affinity (log K) to cell surface receptors and the percentage of free metal ion (REE3+) in the test waters. The toxicity (EC50) of the remaining REEs (samarium, europium, terbium, holmium, thulium and ytterbium) was predicted using a combination of physicochemical data and measured EC50s for the eight tested REEs, with good agreement between predicted and measured EC50s for selected organisms. Numerical REE water quality guidelines to protect marine life were established using species sensitivity distributions (e.g., for 95 % species protection, values ranged from 1.1 μg/L for Y to 3.0 μg/L for La, Pr or Lu).

The Impact of Sewage Water Overflow (SWO): An Analysis of Zandspruit River in Cosmo City, Johannesburg, South Africa

Cosmo City, situated in Johannesburg, Gauteng, has been experiencing sewage water overflows (SWO) for several years, and this raises concerns about the water quality of Zandspruit River. The study aimed to investigate the impacts of SWO on the Zandspruit River, and the perceptions of the community towards SWO. Water samples were collected from three sampling sites of Zandspruit River. Some water quality parameters were measured in the field using a multi-parameter water quality meter while other parameters were analyzed at a SANAS accredited laboratory. Results were compared with South African water quality guidelines and most water quality parameters were within permissible set standards. However, COD, E. coli and turbidity were above permissible set standards which indicates a highly polluted river. Furthermore, we assessed perceptions of the Cosmo City community towards SWO through questionnaires. The community ascribed the main causes of SWOs to population growth, blocked, and broken sewers. This study revealed that SWO around Cosmo City has a negative impact on the quality of river water and poses health risks. The combined evidence from both the experimental analysis and the community perception survey underscores the urgent need for effective management strategies to address the negative environmental and human health implications of SWO in the Zandspruit River. By integrating these findings and considering the broader implications of pollution on both the ecosystem and community well-being, policymakers and stakeholders can work towards implementing sustainable solutions to mitigate the risks associated with sewage water overflows.

Ecotoxicity threshold values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide in fresh and marine waters: Part 1. Derivation of threshold values

Pesticide active ingredients are frequently detected in the rivers, creeks, wetlands, estuaries, and marine waters of the Great Barrier Reef (GBR) region and are one of the main contributors to poor water quality. Pesticide concentrations detected in the environment through water quality monitoring programs can be compared against estimates of ecologically “safe” concentrations (i.e., water quality guidelines) to assess the potential hazard and risk posed to aquatic ecosystems. Water quality guidelines are also required to estimate the aquatic risk posed by pesticide mixtures, which is used for the Reef 2050 Water Quality Improvement Plan pesticide target. Seventy-four pesticide active ingredients and their degradates are frequently detected in GBR catchment waterways, however many do not have water quality guidelines in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The current study derives ecotoxicity threshold values (ETVs) as unendorsed guideline values for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. The proposed ETVs have been derived using species sensitivity distributions, as recommended in the Australian and New Zealand nationally endorsed method for deriving water quality guidelines for aquatic ecosystem protection. Four ETVs were derived for each chemical with values that should theoretically protect 99, 95, 90 and 80 % of species (i.e., PC99, PC95, PC90, PC80, respectively). The PC99 and PC95 values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide were 0.49 μg/L and 4 μg/L, 0.029 μg/L and 0.45 μg/L, 0.11 μg/L and 5.8 μg/L and 0.19 μg/L and 2 μg/L, respectively. The ETVs will be used in an ecological hazard and risk assessment across GBR waterways in part two of this study. The ETVs can also be used to assess potential risk across Australia and internationally where monitoring data are available.

Horizontal-flow constructed wetlands by phytoremediation using vetiver grass, common reed, and canna lily as tertiary wastewater treatment for the reduction of pollutant concentrations of ammonia, phosphates, and nitrates

Abstract The discharge of untreated wastewater into rivers and water bodies poses significant environmental and public health risks. High concentrations of contaminants like heavy metals and pharmaceuticals disrupt rivers, exacerbating waterborne diseases, and leading to unsafe water in the Philippines. This study proposed the use of horizontal-flow constructed wetlands as a tertiary treatment method utilizing the plants: vetiver grass, common reed, and canna lily, to reduce pollutant concentrations in wastewater. This is to ensure compliance with water quality guidelines and general effluent standards under the Class SB Category, water suitable for fishery, tourist zones, and recreational activities. The research investigated the efficiency of phytoremediation beds in removing pollutants from wastewater under fixed hydraulic retention times. The efficiency of reducing pollutants and adsorption isotherms (Freundlich and Langmuir) were calculated to analyze the results of the sampling. Phytoremediation bed 1 demonstra ted efficient ammonia removal by 64.64%. Phytoremediation bed 2 was proficient in reducing nitrates at 83.85%, while phytoremediation bed 3 effectively reduced phosphate to an average of 26.26%, achieved after a 6-hour retention time. In addition, Freundlich adsorption isotherm was observable in most parameters in phytoremediation bed 1 such as ammonia as nitrogen, TDS, COD, and DO. Phytoremediation bed 3 exhibited the same adsorption isotherm on ammonia as nitrogen. Conclusively, the phytoremediation system met the Department of Environment and Natural Resources - Updated Water Quality Guidelines and General Effluent Standard (GES) for all parameters tested.

Water quality dynamics and underlying controls in the Halton Region, Ontario.

We assessed the hydrochemistry of 15 watersheds in the Halton Region, southern Ontario, in high resolution (n > 500 samples across n > 40 streams) to characterize water quality dynamics and governing controls on major and trace element concentrations in this rapidly urbanizing region. In 2022, major water quality parameters were generally in line with historic monitoring data yet significantly different across catchments, e.g., in specific conductance, turbidity, phosphate and chloride, and trace element concentrations. Distinct hydrochemical signatures were observed between urban and rural creeks, with urban stream sections and sites near the river mouths close to Lake Ontario having consistently higher chloride (up to 700mg/L) and occasional enrichment in nutrients levels (up to 8 and 20mg/L phosphate and nitrate, respectively). Particularly upper reaches exhibited hydrochemical signatures that were reflective of the catchment surface lithologies, for instance through higher dissolved Ca to Mg ratios. Unlike for chloride and phosphate, provincial water quality guidelines for trace elements and heavy metals were seldom surpassed (on < 10 occasions for copper, zinc, cadmium, and uranium). Concentrations of other trace elements (e.g., platinum group elements or rare earth elements) were expectedly low (< 0.3µg/L) but showed spatiotemporal concentration patterns and concentration-discharge dynamics different from those of the major water quality parameters. Our results help improve the understanding of surface water conditions within Halton's regional Natural Heritage Systems and demonstrate how enhanced environmental monitoring can deliver actionable information for watershed decision-making.

Selenium bioaccumulation in Daphnia pulexvia aqueous and dietary exposure.

Pit lakes are currently being investigated as a way to store and reclaim waste materials in the Alberta Oil Sands (AOS) region, Canada. Lake Miwasin (LM) is a pilot-scale pit lake consisting of treated fine tailings overlayed with oil sands process-affected water (OSPW) blended with fresh surface water. In October 2021, the surface water contained a mean concentration of 1.33 ± 0.04µg/L dissolved selenium (Se), slightly above the Canadian Council of Ministers of Environment water quality guideline for long-term protection of aquatic life (1µg Se/L). This study assessed the bioaccumulation of Se by the cladoceran Daphnia pulex under laboratory conditions through both aqueous and dietary exposure routes for comparison to field-collected specimens. In 12-day semi-static tests, lab-cultured D.pulex were exposed to water, and algae grown in media spiked with selenate. Results showed that Se bioaccumulation by lab-cultured D. pulex increased in all exposure treatments from days 5 to 12, with maximum Se concentrations of 3.08-3.47µg/g dry weight (dw) observed within the exposure range tested. Interestingly, lower Se bioaccumulation concentrations (1.26-1.58µg/g dw) were observed in the highest dissolved Se and dietary Se treatments, suggesting potential internal regulatory mechanisms. In addition, native D. pulex (LM) collected from Lake Miwasin and cultured in-house were exposed in 8-day semi-static tests to Lake Miwasin surface water and algae cultured in Lake Miwasin surface water. Selenium bioaccumulation in native D. pulex (LM) ranged from 2.00 to 2.04µg/g dw at day 8 and was not significantly different (p > 0.05) compared to Se concentrations in D. pulex collected from Lake Miwasin (2.15 ± 0.28µg/g) in summer 2022.

Potential Hazards of Polycyclic Aromatic Hydrocarbons in Great Lakes Tributaries Using Water Column and Porewater Passive Samplers and Sediment Equilibrium Partitioning.

The potential for polycyclic aromatic hydrocarbon (PAH)-related effects in benthic organisms is commonly estimated from organic carbon-normalized sediment concentrations based on equilibrium partitioning (EqP). Although this approach is useful for screening purposes, it may overestimate PAH bioavailability by orders of magnitude in some sediments, leading to inflated exposure estimates and potentially unnecessary remediation costs. Recently, passive samplers have been shown to provide an accurate assessment of the freely dissolved concentrations of PAHs, and thus their bioavailability and possible biological effects, in sediment porewater and overlying surface water. We used polyethylene passive sampling devices (PEDs) to measure freely dissolved porewater and water column PAH concentrations at 55 Great Lakes (USA/Canada) tributary locations. The potential for PAH-related biological effects using PED concentrations were estimated with multiple approaches by applying EqP, water quality guidelines, and pathway-based biological activity based on in vitro bioassay results from ToxCast. Results based on the PED-based exposure estimates were compared with EqP-derived exposure estimates for concurrently collected sediment samples. The results indicate a potential overestimation of bioavailable PAH concentrations by up to 960-fold using the EqP-based method compared with measurements using PEDs. Even so, PED-based exposure estimates indicate a high potential for PAH-related biological effects at 14 locations. Our findings provide an updated, weight-of-evidence-based site prioritization to help guide possible future monitoring and mitigation efforts. Environ Toxicol Chem 2024;43:1509-1523. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Evaluation of River and Groundwater Quality in the Mzimvubu to Tsitsikamma Water Management Area (WMA7)

This paper assessed and evaluated the river and groundwater quality of five major catchments in the Mzimvubu to Tsitsikamma Water Management Area (WMA7). The river assessment and evaluation considered the present state maximum, minimum and mean seasonal values of physiochemical parameters (EC, NO3 + NO2, Cl, pH, NH4-N, PO4-P and Mg). The study was able to successfully make use of statistical analysis and a water quality index in order to explain seven-year trends and the present state of all five catchments within the study area. The statistical analysis results showed that water quality parameters such as PO4, NH4 and NO3 + NO2 were not complying with the South African Water Quality Guidelines (SAWQG) limits, suggesting that the study area was impacted by anthropogenic activities such as agriculture, sewage works, etc. The application of WQI showed that the Gamtoos catchment was in a good water quality state (49.71) while the other four catchments were in a poor to very poor state, according to the WQI classification. Based on the groundwater quality assessment, the physicochemical parameters (NH4, EC, Ca, NO3 + NO2, pH, Na, Cl, Mg, F, K, SO4 and CaCO3) were selected and the main parameters of concern were EC (salinity), NO3 + NO2 and SO4. However, groundwater assessment revealed that groundwater quality was chemically suitable for drinking purposes in most parts of the study area. Therefore, the study recommended resource-directed measures to improve surface and groundwater resource protection, especially in areas where surface and groundwater quality for other uses remains a challenge. Further, strong water resource compliance monitoring and enforcement to control water resource pollution sources is critical.