Canadian Water Quality Guidelines Research Articles

Chronic Radium-226 toxicity to and oxidative stress in the aquatic invertebrate Chironomus dilutus.

The mining industry, including uranium mining and milling, is of high importance in Canada. It is, however, important to consider that ore processing can result in the creation of by-products that contain radionuclides such as radium-226 (226Ra). Even with the strict discharge regulations in place, there is limited evidence to suggest that the current Canadian regulatory thresholds for 226Ra are protective for aquatic life. This concern underscores the importance of generating toxicity data for 226Ra, as no federal Canadian water quality guidelines for 226Ra currently exist to safeguard aquatic ecosystems. The potential ecological risks of 226Ra are significant due to its high mobility under typical environmental conditions, long half-life (t1/2 ~ 1,600years), bioaccumulative properties, and similarity to calcium (Ca2+). Considering this, the primary objective of this research was to gather data on the toxicity of 226Ra to the aquatic invertebrate Chironomus dilutus. For this purpose, a partial life cycle experiment was conducted, with larval growth, survival and pupation, and emergence and sex ratio of emerged adults, as the experimental endpoints. In addition, an assessment of oxidative stress as a potential cause of toxicity was performed. These experiments revealed that elevated activity concentrations of 226Ra (25.5Bq/L) can significantly impact the growth of C. dilutus. However, none of the other nonlethal endpoints were significantly affected by 226Ra exposure, and there was no evidence of oxidative stress in exposed C. dilutus. Finally, 226Ra was shown to adsorb onto the silica sand used as a substrate for all experiments and desorbed following acid extraction.

Tracking down pharmaceutical pollution in surface waters of the St. Lawrence River and its major tributaries

A reconnaissance survey was undertaken to evaluate the occurrence and risks of 27 pharmaceuticals and metabolites in the St. Lawrence watershed. Surface water samples were collected over a five-year period (2017–2021) along a 700-km reach of the St. Lawrence River as well as 55 tributary rivers (overall N = 406 samples). Additionally, depth water samples and sediments were collected near a major wastewater effluent. Caffeine, diclofenac, and venlafaxine were the most recurrent substances (detection rates >80 %), and extremely high levels were found near a municipal effluent (e.g., ibuprofen (860 ng/L), hydroxyibuprofen (1800 ng/L) and caffeine (7200 ng/L)). Geographical mapping and statistical analyses indicated that the St. Lawrence River water mass after the Montreal City effluent was significantly more contaminated than the other water masses, and that contamination could extend up to 70 km further downstream. This phenomenon was repeatedly observed over the five years of sampling, confirming that this is not a random trend. A slight increase in contamination was also observed near Quebec City, but concentrations rapidly declined in the estuarine transition zone. Tributaries with the highest pharmaceutical levels (ΣPharmas ∼400–900 ng/L) included the Mascouche, Saint-Régis, and Bertrand rivers, all located in the densely populated Greater Montreal area. When flowrate was factored in, the top five tributaries in terms of mass load (ΣPharmas ∼200–2000 kg/year) were the Des Prairies, Saint-François, Richelieu, Ottawa, and Yamaska rivers. All samples met the Canadian Water Quality Guideline for carbamazepine. Despite the large dilution effect of the St. Lawrence River, a risk quotient approach based on freshwater PNEC values suggested that four compounds (caffeine, carbamazepine, diclofenac, and ibuprofen) could present intermediate to high risks for aquatic organisms in terms of chronic exposure.

Evaluating land use impacts on water quality: perspectives for watershed management

Human activities threaten the integrity of watersheds. We aimed to investigate the impact of land use on water quality, adopting a multiscale approach. We collected water samples from twelve streams in Southern Brazil and conducted limnological analyses (physical, chemical, and biological) during the dry season. We used the water quality index based on the quality standards of Canada and Brazil. Land use percentage was measured in two groups (local scale and network scale). Environmental variables were summarized through Principal Component Analysis, and we organized them into Linear Models, integrating the percentage of land use classes and terrain slope in the Multifit formula. Statistical analyses were performed using the R software. Results indicated contamination by lead, chromium, copper, nitrogen, and Escherichia coli in water samples. The Canadian Water Quality Guidelines for the Protection of Aquatic Life resulted in an index ranging from 23.3 to 47.3, compared to the Brazilian Resolution No. 357/2005 for Class 2, which had an index ranging from 47.5 to 100. This disparity is attributed to the more rigorous and sensitive monitoring approach adopted by the Canadian guidelines. Riparian forests which are up to 50 m wide are associated with improved water quality. Agricultural and urban activities were the main contributors to water quality degradation in an area extending up to 1000 m from the watershed. We emphasize the importance of a multiscale approach in watershed management and public policies, considering not only riparian forest preservation, but also human activities throughout the watershed. It is crucial to prioritize science-based environmental public policies and strengthen enforcement to prevent increasingly pronounced environmental collapses. We have identified the urgency to reformulate CONAMA Resolution No. 357/2005 with a more conservationist and ecosystem-oriented approach, as well as to propose modifications to the Brazilian Forest Code, particularly regarding the buffer zones of permanent preservation areas. Thus, this study can provide insights, such as incorporating the “effect scale,” to enhance water resource management in landscapes heavily influenced by human action, contributing to the advancement of future research in freshwater ecosystems.

Assessment of Hg pollution in stream waters and human health risk in areas impacted by mining activities in the Ecuadorian Amazon.

Illegal gold mining activities have contributed to the release and mobilization of Hg and environmental degradation in many parts of the world. This study aims to determine the concentration of Hg in five provinces of the Amazon Region of Ecuador, in addition to assessing the risk to human health of exposed populations, applying deterministic and probabilistic methods. For this purpose, 147 water samples were collected in rivers and streams crossing and/or located near mining areas. As a result, 100% of the samples analyzed exceeded the maximum permissible limit (MPL) according to the water quality criteria for the preservation of aquatic life of the Ecuadorian regulations, while 7% of the samples exceeded the MPL for drinking water. On the other hand, considering the European Environmental Quality Standard (EQS) for surface water bodies, in our study, 100% of the samples exceed the maximum permissible limit (0.07µg/L), and with respect to the Canadian water quality guidelines, 35% of the samples exceed the permissible limit (0.001mg/l) for drinking water, and 100% of the samples exceed the limit for life in water bodies (0.0001mg/l). The risk assessment revealed that the probability of developing adverse health effects from exposure to Hg is below the recommended limits according to the probabilistic assessment; this is in relation to the criterion of residential and recreational use of water resources. However, it was identified that the child population doubles the acceptable systemic risk level according to the results of the deterministic assessment in the residential scenario. This information can be used by decision-makers to implement strategies to reduce Hg contamination and exposure of the population in Ecuadorian Amazonian rivers.

Characterisation of Neonicotinoid Insecticides in the Cocoa-producing Owena River Basin of Nigeria by a QuEChERS Method Coupled to Liquid Chromatography-Tandem Mass Spectrometry

Background: Neonicotinoids (hereafter called “neonics”) are systemic insecticides used for the protection of agricultural crops. However, their dispersion in nature has been the subject of global concern due to reports of adverse effects on some living organisms. One of the applications of neonics in Nigeria is to protect the cocoa cash crop. Objective: Previous studies on pesticide-related pollution in Nigeria focused mainly on organochlorines, but research on neonics is sparse, and the knowledge gap needs to be filled. This work aimed at confirming the presence of four neonics, namely, imidacloprid, thiacloprid, acetamiprid, and thiamethoxam, within the Owena River Basin. Methods: Neonics were extracted from cocoa-growing soil, river water, and sediments by a modified QuEChERS method, followed by clean-up of the extractant by dispersive solid phase extraction and analysis by an optimized liquid chromatography/tandem mass spectrometry analytical procedure. The overall performance of these developed methods was then evaluated by set criteria. Results: The Limit of Detection (LOD) and Limit of Quantitation (LOQ) ranged from 0.0005 to 0.002 μg/g and 0.002 to 0.005 μg/g, respectively. The recovery for the four target analytes exceeded 75% across all matrices from laboratory-prepared samples. It was discovered that the average concentrations of three of the four neonics of interest in the individual media were: 10.34 nmol/g in cocoa-producing soil, 1.03 nmol/g in river sediment, and 1.08 nM (1.08 x 10-3 nmol/g) in surface river water. No imidacloprid was identified in any of these three environmental compartments. Conclusion: The concentration of neonics in the river water, i.e., 0.23 µg/L (230 ng/L), is identical to that of the maximum value recommended in the Canadian Water Quality Guidelines for the Protection of Freshwater Aquatic Life.

Water Quality Assessment of Karnaphuli River of Bangladesh Using CCME-WQI Method

Karnaphuli River is one of the largest recipients of industrial effluent among all the rivers in Bangladesh in the last couple of years. The main purpose of this study is to evaluate the suitability of the river water for irrigation, livestock and other uses and to identify the main pollutants affecting the river during its course through the city. Ten Sampling points along with the Karnaphuli river basin was selected for the WQI assessment. The sampling was conducted for a period of one year from May 2021 to April 2022. Canadian Council of Ministers of the Environment (CCME)-(WQI) Water Quality Index was applied for several water quality parameters namely pH, Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Phosphate, Nitrate, Chloride, Total Hardness, Conductivity, Biological Oxygen Demand (BOD), Cd, Cu, Zn, Pb. Irrigation and livestock indices were analyzed based on Canadian Water Quality Guidelines (CWQGs). The study shows that the river water is mostly alkaline and the pH lies between 6.4 -7.8. The DO value varies from 1.8 to 6 ppm and BOD varies from 1.7 to 3.4 ppm. The concentrations of Cu, Cd, Pb and Zn are Cu- (0.108-0.743 ppm), Cd- (0.073-0.281 ppm), Pb- (0.017-0.699 ppm), Zn- (0.012-0.032 ppm) respectively. Based on the index values, the river water quality has been observed as poor and marginal.

Interactive effects of increasing chloride concentration and warming on freshwater plankton communities

AbstractAcross the Northern hemisphere, chloride concentrations in lakes are increasing from decades of road salt use, threatening aquatic ecosystems. Zooplankton are sensitive to increasing chloride but few studies have considered how additional stressors, such as soft water or increasing lake temperatures interact with the negative effects of chloride. To determine the effects of increasing chloride and temperature on freshwater zooplankton and phytoplankton communities, we conducted a mesocosm experiment using 30 concentrations of chloride from ambient levels to 1500 mg L−1, ambient or warmed (+2.7°C) temperatures, and plankton from a softwater lake. We compared the results with current Canadian Water Quality Guidelines (CWQG) for chronic exposure to chloride. Although warming elicited little response, increasing chloride concentrations led to reduced zooplankton biomass and richness, even at concentrations below the CWQG, and an increase in cyanobacteria abundance, suggesting that policies regulating road salt application should be reevaluated to better protect aquatic ecosystems.

Chloride trends in Ontario’s surface and groundwaters

The Ontario Ministry of the Environment, Conservation and Parks leads 11 long-term monitoring programs at over 2,500 surface and groundwater sampling locations across the province that report chloride (Cl−) concentration, some dating back to the 1960s. This study integrates these disparate datasets to provide comprehensive evidence relevant to spatial and temporal Cl− trends in the Laurentian Great Lakes, and Ontario's inland lakes, streams and groundwaters. While the vast majority of historical Cl− data indicate concentrations are well below the chronic exposure Canadian Water Quality Guideline (120 mg L−1), many lake, stream and groundwater sampling locations proximal to roadways or in urbanized areas meet or exceed this guideline, and concentrations in these regional areas are persistently increasing. The current evidence implicates road salting activities for winter safety as a primary contributor to elevated Cl− concentrations, and the trends may be exacerbated with urbanization and population expansion, particularly in southern Ontario.

Contamination Assessment of Heavy Metals in Sediment Cores from De Montigny Lake around Siscoe-Sullivan Former Mining Sites, Val-d’Or, Canada

Seven sediment cores were collected from De Montigny Lake in order to determine concentrations, and contamination assessment of heavy metals such as Cr, Zn, Ni, Pb, Cu, Co and Cd. The mean concentrations of heavy metals are as follows: 48.3 mg/kg for Cr, 36.4 mg/kg for Zn, 20.6 mg/kg for Ni, 14.7 mg/kg for Pb, 10.2 mg/kg for Cu, 6.7 mg/kg for Co and 0.1 mg/kg for Cd. Based on the sediment quality guidelines, the mean concentration metals such as Cr, Cu and Ni exceeded the US Environmental Protection Agency (USEPA) guideline. However, the concentration of Cr was more than the Canadian Water Quality Guidelines for Protection of Aquatic Life (CCME), and Threshold Effect Level (TEL) guidelines. The metal contamination in the sediments was also evaluated using Enrichment Factor (EF) and geoaccumulation index (Igeo) to assess natural and anthropogenic factors. The results of enrichment factor methods demonstrated that sediments from De Montigny Lake were moderately to high enriched, mainly controlled by through anthropogenic activities. According to Sediment Quality Guidelines (SQGs), the concentrations metals from the core sediment of De Montigny Lake are classified as having moderate impacts with potential adverse biotoxic effects.

Water Quality Index and Environmental Assessment of Rosetta Branch Aquatic System, Nile River, Egypt

This study was carried out on Rosetta branch water and 3 drains (El-Rahawy, El-Soble and El-Gezira) that discharging wastewater into it, to assess the Water Quality Index (WQI) of their waters. This investigation was performed during the period starting from winter 2017 to summer 2018. The mean annual averages of WQI values of Rosetta branch Water were good to poor for irrigation (up to 55) and from poor to very poor for aquatic life (up to 97) at stations exposed to wastewater discharged from drains into water branch. The obtained values of physical and chemical variables of Rosetta branch and drains water were matched with the standard values set by FAO (1994) for irrigation and Canadian Water Quality Guidelines (2011) for aquatic life. The obtained results indicated that the values of examined variables were higher than the recommended standards which affects the environmental live in this area and producing healthy problems. The concentrations of physical and chemical parameter were higher during winter than summer.

Are current tissue-based selenium guidelines and criteria overly protective of freshwater fish populations? A critical review with recommendations.

Several decades after selenium impacts on wild fish populations were observed in freshwater reservoirs receiving fly ash effluents from electric power facilities at Belews Lake and Hyco Reservoir (North Carolina, USA), developments in selenium (Se) toxicology have led to a greater understanding of Se effects on freshwater fish. These latter advancements have allowed regulatory agencies in several jurisdictions to develop tissue-based toxicity benchmarks for the protection of aquatic life. These benchmarks were generally derived from datasets encompassing multiple fish species and designed to protect the most sensitive species (US Environmental Protection Agency [EPA] water quality criteria). Safety factors have been applied in the development of some Canadian guidelines (British Columbia [BC]), resulting in guidelines that appear to be overly conservative. The present study addresses the question, "Are current tissue-based selenium guidelines and criteria overly protective of freshwater fish populations?" A literature review was conducted of studies in which Se was the primary constituent of concern, to compare tissue concentrations and results of fish population metrics and deformity assessment studies with current regulatory thresholds for the protection of aquatic life in the United States and Canada. EPA fish tissue-based Se criteria were found to be protective of fish populations and, at times, overly protective. Canadian water quality guidelines for Se (BC Ministry of Environment and Climate Change Strategy [BCMOECCS], Environment and Climate Change Canada [ECCC]) were consistently found to be overly protective, especially for benchmarks in which safety factors were used to derive those guidelines. In addition to a synthesis of the results of these studies, various limitations of the reviewed studies are discussed, and recommendations for future studies are proposed. Integr Environ Assess Manag 2022;18:622-630. © 2021 SETAC.

Effects of chloride and nutrients on freshwater plankton communities

AbstractIncreasing chloride concentrations threaten freshwater zooplankton. We questioned the protectiveness of the Canadian Water Quality Guideline for chloride because it is based on individual species studied under laboratory conditions and does not account for potential interactive factors, such as nutrient concentration. We exposed plankton communities to 30 chloride concentration increments for 6 weeks, crossed with either ambient or high nutrient treatments. Total zooplankton abundance, biomass, and richness declined with increasing chloride, with losses observed below the Canadian Water Quality Guideline. Nutrients did not affect the impact of chloride on zooplankton. Phytoplankton and protist responses varied by nutrient level. Under low nutrients, phytoplankton and protist abundance, biomass, and richness increased with chloride. Under high nutrients, phytoplankton and protist abundance and biomass were unaffected while richness decreased with chloride. These results indicate that current water quality guidelines do not sufficiently protect plankton and that nutrient context may alter phytoplankton and protist response.

Case Study of a SCAT Survey and Successful Remediation Strategy by Mechanical Mixing of a Fuel Oil Spill into a Mountain Stream

ABSTRACT # 1141233 The cargo of a double-tank truck carrying diesel and gasoline was released directly into a fast-flowing upland stream following an accident on a mountainous section of road in British Columbia (BC), Canada. High concentrations of the product were trapped in the interstitial spaces of coarse (cobble-boulder) sediments during a period of rising water levels. Almost the entire river backshore in the affected area was characterized by steep wooded slopes so that access everywhere was very difficult. These constraints for the SCAT program largely were overcome where direct backshore access was not possible using river rafts, boats (on the reservoir above the dam) and small Unmanned Aerial System (sUASs). Based on the survey results, a 4x4 Spider Walking Excavator equipped with a Universal grab on the hydraulic arm was deployed over a 2.5 km section of river immediately downstream of the accident site over a 9-day period. The grab rotated to mix the sediment or lifted and moved cobbles and boulders along the channel margin and in river bed sediments to release the oil. Swift Water Rescue personnel and river rescue response equipment were positioned with the Spider operations and the SCAT river bank surveys throughout the project, and used to scout river conditions ahead of SCAT rafting operations. Air monitoring was maintained throughout the response during all operations both along river banks as well as in the cab of the Spider while working in the river. A small UAS quadcopter was deployed to monitor the mixing activity in real time where the excavator could operate but ground access was unsafe or physically not possible. Standard SCAT practices were followed to provide the Unified Command (UC) with Shoreline Treatment Recommendation (STR) forms to guide the operations activities and once the treatment criteria were achieved STR Inspection Reports (SIRs) were submitted for approval by the UC. A downstream daily water sampling program monitored for PHs, VOCs and PAHs in the river waters during the mixing operations downstream of the operations area. At no time during the mechanical mixing activities (April 3 – 12) did the results of the analyses exceed Canadian and BC Water Quality Guidelines standards downstream past the confluence with the Salmo River and standards only were exceeded for the first few days of mechanical mixing (April 3 – April 5) during the period that the Spider was working on the upper reaches of the South Salmo.

Nonylphenol, Octylphenol, and Nonylphenol Ethoxylates Dissemination in the Canadian Freshwater Environment.

Nonylphenol, octylphenol, and nonylphenol ethoxylates are manmade compounds that are only discharged in the environment due to anthropogenic activities. The objectives of this study were to determine the current concentrations of these substances in the Canadian freshwater environment and to determine if past regulatory actions were beneficial to the environment. Freshwater samples (n = 241) were collected and analysed for 4-nonylphenols (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), and octylphenols at 35 sites in Canada from 2014 to 2019 with individual compound concentrations ranging from 1.29 to 477.22ng/L. In addition, 18-65% of the samples were reported to be under the laboratory detection limit, depending on the compound. Sampling sites were categorised into five groups based on the dominant activities present upstream in their watersheds: mixed use sites; municipal waste water treatment plant (MWWTP)-associated sites; textile mill-associated sites; urban; and reference sites. All four compounds in the study were detected more frequently in urban and MWWTP-associated sites than at other locations. Additionally, there is a statistically significant (p < 0.05) downward temporal trend in NP concentrations in Canadian surface waters from 2014 to 2019. There were no exceedances of the Canadian Water Quality Guideline of 1000ng/L.

Categorizing the influences of two large seabird colonies on island freshwater ecosystems in the Northwest Atlantic Ocean

Seabird colonies influence ecosystems by releasing high concentrations of nutrients, metals, and contaminants via their wastes. Here, we examined seven lentic waterbodies impacted by two major colonies of Leach’s Storm-petrel (Hydrobates leucorhous), six from Baccalieu Island, Newfoundland and Labrador with ~ 1.95 million breeding pairs, and another from Grand Colombier Island, St. Pierre and Miquelon with ~ 200,000 breeding pairs. In comparison to nearby study sites not influenced by seabirds, we recorded more acidic pH, elevated specific conductance, and higher concentrations of dissolved organic carbon, total nitrogen, and total phosphorus in the seabird-influenced sites. The storm-petrels also significantly increased the metal concentrations of Co, Cu, Fe, Li, Nb, Ni, Sn, Sr, and Ti relative to reference sites. In the most highly affected ponds, the concentrations of Cd, Cu, and Fe exceeded Canadian Water Quality Guidelines for the Protection of Aquatic Life, implicating seabirds as biovectors of environmental contamination. Together, our data highlight the importance of seabirds, and likely other colonial organisms, as influential vectors that can strongly impact aquatic ecosystem chemistry and biota.

Persistent and carcinogenic polycyclic aromatic hydrocarbons in the north-western coastal marine environment of India

The carcinogenic and endocrine-disrupting PAHs were investigated in surface water of the north-western creeks of India. The concentrations of ΣPAHs were found to vary in the range of 114.32-347.04 μg L-1, (mean 224.78 ± 8.85 μg L-1), out of which 49.12% contribution is due to ΣC-PAHs. The assessment of toxicity and biological risk arising due to individual C-PAHs was made by calculating their toxic equivalent quantity. The level of individual C-PAHs was reported exceeding the final chronic values, Canadian water quality guideline values and Netherlands maximum permissible concentration values set for the protection of aquatic life. The mean BaP concentration (10.32 ± 2.75 μg L-1) was above the European Directive 2008/105/EC Environmental Quality Standards (EQS) value; while the sum of BkF + BbF (26.76 μg L-1) and BghiP + InP (19.59 μg L-1) were significantly higher than that set by the EQS. The results of the present study will help in understanding the global distribution and fate of PAHs which is required for implementing the necessary steps towards mitigation of the ecotoxicological risk arising due to the existence of such contaminants in the aquatic environment across the world.

Pesticides in Surface Waters in Argentina Monitored Using Polar Organic Chemical Integrative Samplers.

Polar Organic Chemical Integrative Samplers (POCIS) were deployed in two watersheds in Córdoba province and one watershed in Buenos Aires province in Argentina. The fungicides, tebuconazole, carbendazim and azoxystrobin, and the herbicides, atrazine, dicamba and 2,4-D were detected in POCIS deployed in each of the three watersheds. Estimated time weighted average concentrations of atrazine were greater than 2µg/L at the outflow of Brava Lake in Buenos Aires province, and this concentration exceeds the Canadian water quality guideline for protection of aquatic life. The concentrations of all other pesticides were less than 400ng/L. The distribution of pesticides detected in surface waters indicated that the sources were runoff from agricultural and urban lands and discharges from wastewater treatment plants.

An AMS method for measurement of Radium-226 in drinking water

Radium-226 is a naturally occurring radionuclide resulting from the radioactive decay of 238U. The aquifers used for drinking water may contribute to the source of 226Ra in water supplies. To accommodate the needs of 226Ra assessments, we developed a new, rapid and sensitive method for measuring 226Ra in drinking waters utilizing Accelerator Mass Spectrometry (AMS). 226Ra was co-precipitated with BaBeF4, which is known for its insoluble attribute and high stability. Mixed with a large excess amount of PbF2 and compressed into a copper target holder, such sputter targets have adequate electrical and thermal conductivity in the Cs+ sputter ion source used in AMS. Due to the difficulty to obtain a suitable Ra isotope for measurement normalization, we performed an external calibration with 226Ra alone, covering the final co-precipitation and measurement steps. A good linearity was attained in the dilution series with an external error of 5%. The detection limit of this method was 3 fg (∼0.1 mBq) in an AMS-ready target at present, using a low Cs+ sputter ion flux that produced >0.02 226Ra3+ ion counts per second (CPS) per fg. With this BaBeF4 co-precipitation method, we performed a rapid survey of 226Ra concentration in local tap water and several bottled waters. The results suggested that the 226Ra concentrations in all the tested samples were less than the limit set by the Canadian water quality guidelines.

Concentrations of heavy metals in water from the Southern coast of Vietnam

Concentrations of heavy metals (As, Cd, Pb and Hg) in water collected from seven coastal provinces between December 2012 and December 2015 were evaluated. The average total concentrations (μg/L) of As, Cd, Pb and Hg in water ranged from 2.90 to 6.38, &lt; 0.039 to 0.322, 4.26 to 10.5 and &lt; 0.01 to 0.118, respectively. The average concentrations (μg/L) of As, Pb and Hg in suspended particulate matters (SPM) ranged from 0.392 to 7.32, 0.365 to 18.7 and &lt; 0.01 to 0.038, respectively, whereas Cd concentrations were not detected in most of SPM samples. There were positive linear relationships between concentrations of heavy metals in water and SPM, except for Cd. The results showed that the concentrations of metals analyzed in water remained below quality guidelines for the protection of aquatic life recommended by the international and Vietnamese organizations. However, As levels in 2/103 and 5/103 of water samples exceeded the QCVN 10:2015/BTNMT for maximum permitted level using for aquaculture and aquatic life protection (20 μg/L) and the Canadian water quality guidelines for the protection of aquatic life (12.5 μg/L), respectively.

Pesticides related to land use in watersheds of the Great Lakes basin

In this study, we evaluated the distribution and concentrations of a range of neonicotinoid insecticides (NNIs) and other insecticides, fungicides, biocides and selected herbicides in watersheds that drain into the lower Great Lakes in Ontario, Canada. Polar Organic Chemical Integrative Samplers (POCIS) were deployed in 18 watersheds during late May to late June of 2016. Grab samples were also collected in 7 of these watersheds. There was generally good agreement between the time-weighted average concentrations of pesticides estimated from the POCIS and the concentrations detected in grab samples. The NNIs, thiamethoxam, clothianidin and imidacloprid, were present in several watersheds at concentrations that exceeded the Canadian Water Quality Guideline for imidacloprid of 0.23 μg/L. The new generation insecticides, flonicamid and flupyradifurone were also detected in some watersheds, which is the first report of these pesticides in the peer-reviewed literature. Atrazine, 2,4-D, dicamba, carbendazim, thiophanate methyl and several azole-based fungicides were also widely detected. Discriminant Function Analysis (DFA) indicated that a high proportion (i.e. >80%) of the watersheds could be discriminated from each other on the basis of the pattern of pesticides detected in surface waters, and the proportion of field crops in the watershed.