Search Results (65)

Climate and land-use changes are major drivers of hydrological and water quality dynamics in the Great Lakes Basin. This study investigates recent changes in climate, land use, runoff, and total phosphorus (TP) loading in selected illustrative watersheds within the Canadian Lake Erie Basin and Canadian Lake Ontario Basin during 2009–2022. Results suggest that recent warming and hydroclimatic variability have altered hydrological regimes in southern Ontario, including higher winter temperatures and shifts in seasonal runoff. Land-use changes, including the expansion of row crops and urban areas, have further influenced watershed responses. Variations in TP loading were associated with changes in hydroclimatic conditions and land use. These findings highlight the increasing importance of event-driven nutrient transport under changing hydroclimatic conditions and support adaptive watershed management approaches accounting for seasonal runoff variability and event-driven nutrient transport. This study provides insight into the combined impacts of climate and land-use changes on hydrology and nutrient loading in southern Ontario watersheds. The analysis results enhance understanding of water quality dynamics in the Great Lakes region and support the development of more effective, adaptive, and integrated watershed management strategies under future climate and land-use changes. Full article

All eastern hemlock-dominated forests in Ontario could be gone by 2075 given current trends, which demands rapid assessment to locate these endangered ecosystems. To date, however, neither the Canadian or Ontario governments have developed field assessment protocols or minimum standards for identifying old-growth forests that provide density and biomass estimates for the primary features of these forests. This study focused on the Catchacoma Forest, Canada’s largest eastern hemlock forest, and represents a first step towards establishing minimum standards for old-growth eastern hemlock forests in the Great Lakes-St. Lawrence Forest region. Rectangular plots were systematically placed along evenly spaced east–west transects at a 2% sampling intensity for the 181 ha study area and assessed for mother trees (MTs) and cut stumps. By a factor of 15X, the method developed was more efficient for covering larger areas compared to randomly placed and intensively sampled plots typically used for long-term ecological studies. Mean integrity (stumps/ha) was 0.006/ha and mean MT density was 149/ha with a range of 0–533/ha. Four MT forest types were identified including: eastern hemlock-dominant (47%; 194 MT/ha), white pine-dominant (26%; 123 MT/ha), other MT species-dominant (9%; 169 MT/ha), and eastern hemlock–white pine co-dominant (8%; 133/ha). MTs were absent from roughly 10% of the study area. Full article

Plastic microbeads, widely incorporated into personal care and cleansing products, have emerged as a pervasive contaminant in freshwater systems, including in North America. Historical estimates indicate that North American consumers alone contributed trillions of microbeads daily to municipal wastewater, with global usage reaching quadrillions per day. Regulatory actions in 2017 in Canada and the USA to ban microbeads in personal care products appear to have greatly reduced microbead contamination levels, including a decrease in microbead proportion from 2 to 5% to 0.003%, and an 86% reduction in PE microbead discharge from wastewater treatment plants. Yet these particles still persist in the environment due to their resistance to degradation and continued release from unregulated sources, including industrial abrasives and certain cleaning agents. Studies across the Great Lakes, one of the world’s largest freshwater systems, have documented widespread microbead contamination in surface waters, sediments, and shorelines, highlighting their persistence and accumulation. This review synthesizes findings from key studies conducted between 2013 and 2017 to establish a pre-ban baseline of microbead distribution in the Great Lakes, and presents new data collected from 2018 to 2021 as a post-ban contamination assessment. The review emphasizes the unique challenges posed by microbeads within the broader context of microplastic pollution. We also hope that this paper underscores the critical role of polymer chemists and engineers in developing innovative materials and removal strategies to mitigate future contamination. Full article

Methane (CH₄) is a potent greenhouse gas with a significant impact on short- and medium-term climate forcing, and its atmospheric concentration has been increasing rapidly in recent decades. This study aims to analyze spatio-temporal patterns of atmospheric methane concentrations between 2019 and 2025, focusing on comparisons between regions characterized by high and low emission intensities. Level-3 XCH₄ data from the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite were used, which were aggregated into seasonal and annual composites. High-emission regions, such as the Mekong Delta, Nile Delta, Eastern Uttar Pradesh and Bihar, Central Thailand, Lake Victoria Basin, and Eastern Arkansas, were contrasted with low-emission areas including Patagonia, the Mongolian Steppe, Northern Scandinavia, the Australian Outback, the Sahara Desert, and the Canadian Shield. The results show that high-emission regions exhibit substantially higher seasonal amplitude in XCH₄ concentrations, with an average seasonal variation of approximately 30.00 ppb, compared to 17.39 ppb in low-emission regions. Methane concentrations generally peaked at the end of the year (Q4) and reached their lowest levels during the first half of the year (Q1 or Q2), particularly in agriculturally dominated regions. Principal component and cluster analyses further confirmed a strong spatial differentiation between high- and low-emission regions based on both temporal trends and seasonal behavior. These findings demonstrate the potential of satellite remote sensing to monitor regional methane dynamics and highlight the need for targeted mitigation strategies in major agricultural and wetland zones. Full article

The water quality in lakes and reservoirs is crucial for maintaining ecological balance and ensuring public health. This research focuses on the water quality evaluation of Garaši Reservoir in Serbia, a vital source of drinking water for surrounding communities. We systematically analyzed three profiles (A1, B1, and C1) at various depths ranging from 50 cm to 1500 cm between 2021 and 2023. The study employed the Serbian Water Quality Index (SWQI) and the Canadian Water Quality Index (CWQI) to evaluate the water quality. The findings revealed significant spatial and depth-dependent differences. Higher concentrations of Aluminum (Al), Mercury (Hg) and Manganese (Mn), influenced by the inflow from the Velika Bukulja River, resulted in reduced overall water quality and suitability for drinking water. Dissolved Oxygen levels decreased with depth, indicating thermal stratification and nearly anoxic conditions, which are harmful to aquatic life. Some shallow areas exhibited poor water quality for recreational use due to high pH and metal concentrations. The study underscores the necessity of continuous and comprehensive monitoring to identify pollution sources and implement mitigation measures. Such efforts are essential to protect biodiversity and ensure the sustainable management of water resources in lakes and reservoirs. Full article

This study evaluates the performance of the ICESat-2 ATL13 altimetry product for estimating water levels in 182 Canadian lakes by integrating satellite-derived observations with in situ gauge measurements and applying spatial filtering using the HydroLAKES dataset. The analysis compares ATL13-derived lake surface elevations with hydrometric data from national monitoring stations, providing a robust framework for assessing measurement accuracy. Statistical metrics—including root mean square error (RMSE), mean absolute error (MAE), and mean bias error (MBE)—are employed to quantify discrepancies between the datasets. Importantly, the application of HydroLAKES-based filtering reduces the mean RMSE from 1.53 m to 1.40 m, and the further exclusion of high-error lakes lowers it to 0.96 m. Larger and deeper lakes exhibit lower error margins, while smaller lakes with complex shorelines show greater variability. Regression analysis confirms the excellent agreement between satellite and gauge measurements (R² = 0.9999; Pearson’s r = 0.9999, n = 182 lakes, p < 0.0001). Temporal trends reveal declining water levels in 134 lakes and increasing levels in 48 lakes from 2018 to 2024, potentially reflecting climatic variability and human influence. These findings highlight the potential utility of ICESat-2 ATL13 altimetry for large-scale inland water monitoring when combined with spatial filtering techniques such as HydroLAKES. Full article

Per- and polyfluoroalkyl substances (PFAS) are increasingly detected in remote environments. This review aims to provide a comprehensive overview of the types and concentrations of PFAS found in the air, water, soil, sediments, ice, and precipitation across different remote environments globally. Most of the recent studies on PFAS remote occurrence have been conducted for the Arctic, the Antarctica, and the remote regions of China. Elevated perfluorooctane sulfonate (PFOS) in Meretta and Resolute Lakes reflects the impact of local sources like airports, while PFAS in lakes located in remote regions such as East Antarctica and the Canadian High Arctic suggest atmospheric deposition as a primary PFAS input. Long-chain PFAS (≥C7) accumulate in sediments, while short-chain PFAS remain in water, as shown in Hulun Lake. Oceanic PFAS are concentrated in surface waters, driven by atmospheric deposition, with PFOA and PFOS dominating across oceans due to current emissions and legacy contamination. Coastal areas display higher PFAS levels from local sources. Arctic sediment analysis highlights atmospheric deposition and ocean transport as significant PFAS contributors. PFAS in Antarctic coastal areas suggest local biological input, notably from penguins. The Tibetan Plateau and Arctic atmospheric data confirm long-range transport, with linear PFAS favoring gaseous states, while branched PFAS are more likely to associate with particulates. Climatic factors like the Indian monsoon and temperature fluctuations affect PFAS deposition. Short-chain PFAS are prevalent in snowpacks, serving as temporary reservoirs. Mountainous regions, such as the Tibetan Plateau, act as cold traps, accumulating PFAS from atmospheric precursors. Future studies should focus on identifying and quantifying primary sources of PFAS. Full article

Lake Kotokel, the largest lake on the eastern shore of Lake Baikal, has historically served as an important fishery and recreational resource. However, it underwent an ecological crisis and a Haff disease outbreak in 2008–2009. Hydraulic engineering interventions were subsequently implemented, and the lake was closed to tourism and fishing for an extended period. This study provides the first comprehensive analysis of Lake Kotokel’s water level fluctuations from 1985 to 2022 and evaluates hydrochemical data collected between 2015 and 2024. A comparative assessment of the seasonal variability in Lake Kotokel’s condition during 2023–2024 and 2008–2009 was conducted using various water quality indices, including the Russian Specific Combinatorial Water Pollution Index (SCWPI) and Basic Anthropogenic Load Index (ALI), as well as the international National Sanitation Foundation Water Quality Index (NSF-WQI) and Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI). Trophic state indices, such as Carlson’s Trophic State Index (CTSI) and the Trophic Index (TRIX), were also applied. The analysis revealed a seasonal decline in water quality, transitioning from pure (“excellent”) and “light eutrophic” index classifications in spring to polluted (“marginal”) and “hypertrophic” index classifications in summer and autumn. This study demonstrated that a combination of unfavorable factors, including significant lake-level fluctuations, prolonged high temperatures during the vegetative period, and the discharge of fracture-vein waters, led to a sharp decline in water quality and an increase in the lake’s trophic status. Elevated levels of iron, manganese, COD, pH, and ammonium detected in water samples in 2024, alongside incidents of fry mortality in spring and summer and intense algal blooms, raise concerns as they may signal a potential recurrence of Haff disease in the lake. Full article

Eutrophication in Canadian lakes degrades water quality, disrupts ecosystems, and poses health risks due to potential development of harmful algal blooms. It also economically impacts the general public, industries like recreational and commercial fishing, and tourism. Analysis of a 140-year core record from Utikuma Lake, northern Alberta, revealed the processes behind the lake’s current hypereutrophic conditions. End-member modeling analysis (EMMA) of the sediment grain size data identified catchment runoff linked to specific sedimentological processes. ITRAX X-ray fluorescence (XRF) elements/ratios were analyzed to assess changes in precipitation, weathering, and catchment runoff and to document changes in lake productivity over time. Five end members (EMs) were identified and linked to five distinct erosional and sedimentary processes, including moderate and severe precipitation events, warm and cool spring freshet, and anthropogenic catchment disturbances. Cluster analysis of EMMA and XRF data identified five distinct depositional periods from the late 19th century to the present, distinguished by characteristic rates of productivity, rainfall, weathering, and runoff linked to natural and anthropogenic drivers. The most significant transition in the record occurred in 1996, marked by an abrupt increase in both biological productivity and catchment runoff, leading to the hypereutrophic conditions that persist to the present. This limnological shift was primarily triggered by a sudden discharge from a decommissioned sewage treatment lagoon into the lake. Spectral and wavelet analysis confirmed the influence of the Arctic Oscillation, El Niño Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation on runoff processes in Utikuma Lake’s catchment. Full article

With increasing pressure on freshwater resources in developing countries due to population growth, further research and potential interventions are crucial. Lake Tana, located in the headwaters of the Blue Nile, serves as a critical example of these precious freshwater resources. This study evaluated the water quality of Lake Tana for both ecological health and drinking purposes using the Arithmetic Weighted Water Quality Index (AW WQI) and the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). Samples were collected from 20 lake sampling stations four times between July 2018 and June 2019 to calculate the two water quality indices using ten measured parameters. The average annual AW WQI ranged from good to very poor for ecological health and very poor to unsuitable for drinking water. The CCME WQI categorized Lake Tana’s water quality as poor to fair for both uses. According to the water quality indices, the water quality was most impacted by turbidity, dissolved oxygen, ammonium, and phosphorus. However, except for ammonium, these factors were immaterial for lake management because the lake was nitrogen-limited, and the turbidity resulted from sediment stirred up by waves from the lake bottom, which cannot be managed easily. Dissolved oxygen is related to turbidity. Moreover, the WQIs did not identify two pesticides in the lake that negatively affected the fish. Thus, WQI indices may document water quality changes over time. Therefore, in addition to a favorable economic and political climate, improving lake water management requires insights from experts, the scientific literature, and possibly additional monitoring in addition to what is provided by the WQIS. Full article

Cyanobacteria (blue-green algae) are a diverse group of prokaryotic microorganisms that impact global biogeochemical cycles. Under eutrophic conditions, cyanobacterial species can produce cyanotoxins, resulting in harmful algal blooms (cHABs) that degrade water quality and result in economic and recreational losses. The Laurentian Great Lakes, a key global freshwater source, are increasingly affected by these blooms. To understand the underlying mechanisms in cHAB formation, we investigated microcystin levels, cyanotoxin genes/transcripts, and taxonomic/microcystin metabarcoding across three sampling locations in the Canadian Great Lakes region, including Hamilton Harbour, Bay of Quinte, and Three Mile Lake (Muskoka), to observe the regional and longitudinal cyanobacterial dynamics. The results revealed a positive correlation between microcystin levels, the occurrence of cyanobacterial taxonomic/cyanotoxin molecular markers, and the relative widespread abundance of specific dominant cyanobacterial taxa, including Planktothrix, Microcystis, and Dolichospermum. The Cyanobium genus was not observed in Hamilton Harbor samples during late summer (August to September), while it was consistently observed in the Three Mile Lake and Bay of Quinte samples. Notably, Dolichospermum and saxitoxin genes were predominantly higher in Three Mile Lake (an inland lake), suggesting site-specific characteristics influencing saxitoxin production. Additionally, among the potential microcystin producers, in addition to Microcystis, Hamilton Harbour and Bay of Quinte samples showed consistent presence of less dominant microcystin-producing taxa, including Phormidium and Dolichospermum. This study highlights the complexity of cHAB formation and the variability in cyanotoxin production in specific environments. The findings highlight regional and site-specific factors that can influence cyanobacterial taxonomic and molecular profiles, necessitating the integration of advanced molecular technologies for effective monitoring and targeted management strategies. Full article

The data from thirty-one climate stations in the Canadian Prairie provinces of Alberta, Saskatchewan, and Manitoba are analyzed using a number of day-to-day thermal variability metrics. These are used to classify each climate station location using a decision tree developed previously. This is the first application of the decision tree to identify stations as having rural, urban, peri-urban, marine, island, airport, or mountain climates. Of the thirty-one, eighteen were identified as peri-urban, with fourteen of these being airports; six were identified as marine or island; four were identified as rural; one as urban was identified; and two were identified as mountain. The two climate stations at Churchill, Manitoba, located near the shores of Hudson Bay, were initially identified as peri-urban. This was re-assessed after adjusting the number of “winter” months used in the metric for identifying marine and island climates (which, for all other analyses, excluded only December, January, and February). For Churchill, to match the sea ice season, the months of November, March, April, and May were also excluded. Then, a strong marine signal was found for both stations. There is a potential to use these thermal metrics to create a sea ice climatology in Hudson Bay, particularly for pre-satellite reconnaissance (1971). Lake Louise and Banff, Alberta, are the first mountain stations to be identified as such outside of British Columbia. Five airport/non-airport pairs are examined to explore the difference between an airport site and a local site uninfluenced by the airport. In two cases, the expected outcome was not realized through the decision tree analysis. Both Jasper and Edmonton Stony Plain were classified as peri-urban. These two locations illustrated the influence of proximity to large highways. In both cases the expected outcome was replaced by peri-urban, reflective of the localized impact of the major highway. This was illustrated in both cases using a time series of the peri-urban metric before and after major highway development, which had statistically significant differences. This speaks to the importance of setting climate stations appropriately away from confounding influences. It also suggests additional metrics to assess the environmental consistency of climate time series. Full article

Most Andean lakes and lagoons are used as reservoirs to manage hydropower generation and cropland irrigation, which, in turn, alters river flow patterns through processes of storage and discharge. The Carhuacocha and Vichecocha lagoons, fed by glaciers, are important aquatic ecosystems regulated by dams. These dams increase the flow of the Mantaro River during the dry season, supporting both energy production and irrigation for croplands. Water quality in the Carhuacocha and Vichecocha lagoons was assessed between storage and discharge events by using the Canadian Council of Ministers of the Environment Water Quality Index (CCME _WQI) and multivariate statistical methods. The quality of both lagoons is excellent during the storage period; however, it decreases when they are discharged during the dry season. The most sensitive parameters are pH, dissolved oxygen (DO), and biochemical oxygen demand (BOD). This paper details the changes in water quality in the Carhuacocha and Vichecocha lagoons during storage and discharge events. Full article

The Sea of Azov, an inland shelf sea bounding Ukraine and Russia, experiences the effects of ongoing and legacy pollution. One of the main contaminants of concern is the heavy metal mercury (Hg), which is emitted from the regional coal industry, former Hg refineries, and the historic use of mercury-containing pesticides. The aquatic biome acts both as a major sink and source in this cycle, thus meriting an examination of its environmental fate. This study collated existing Hg data for the SoA and the adjacent region to estimate current Hg influxes and cycling in the ecosystem. The mercury-specific model “Hg Environmental Ratios Multimedia Ecosystem Sources” (HERMES), originally developed for Canadian freshwater lakes, was used to estimate anthropogenic emissions to the sea and regional atmospheric Hg concentrations. The computed water and sediment concentrations (6.8 ng/L and 55.7 ng/g dw, respectively) approximate the reported literature values. The ongoing military conflict will increase environmental pollution in the region, thus further intensifying the existing (legacy) anthropogenic pressures. The results of this study provide a first insight into the environmental Hg cycle of the Sea of Azov ecosystem and underline the need for further emission control and remediation efforts to safeguard environmental quality. Full article

Common bloom-forming cyanobacteria produce complex strain-specific mixtures of secondary metabolites. The beneficial and toxic properties of these metabolite mixtures have attracted both research and public health interest. The advancement of mass spectrometry-based platforms and metabolomics data processing has accelerated the identification of new metabolites and feature dereplication from microbial sources. The objective of this study was to use metabolomics data processing to decipher the intracellular cyanopeptide diversity of six Planktothrix strains collected from Canadian lakes. Data-dependent acquisition experiments were used to collect a non-targeted high-resolution mass spectrometry dataset. Principal component analysis and factor loadings were used to visualize cyanopeptide variation between strains and identified features contributing to the observed variation. GNPS molecular networking was subsequently used to show the diversity of cyanopeptides produced by the Planktothrix strains. Each strain produced a unique mixture of cyanopeptides, and a total of 225 cyanopeptides were detected. Planktothrix sp. CPCC 735 produced the most (n = 68) cyanopeptides, and P. rubescens CPCC 732 produced the fewest (n = 27). Microcystins and anabaenopeptins were detected from all strains. Cyanopeptolins, microviridins and aeruginosins were detected from five, four and two strains, respectively. Cyanopeptolin (n = 80) and anabaenopeptin (n = 61) diversity was the greatest, whereas microcystins (n = 21) were the least diverse. Interestingly, three of the P. rubescens strains had different cyanopeptide profiles, despite being collected from the same lake at the same time. This study highlights the diversity of cyanopeptides produced by Planktothrix and further hints at the underestimated cyanopeptide diversity from subpopulations of chemotypic cyanobacteria in freshwater lakes. Full article