ISSN / EISSN : 1181-8700 / 1208-6053
Published by: Canadian Science Publishing (10.1139)
Total articles ≅ 674
Latest articles in this journal
Environmental Reviews, Volume 29, pp 491-509; https://doi.org/10.1139/er-2021-0001
In the last two decades, several process-based models had been developed to describe the transport and fate of contaminants in subsurface flow constructed wetlands (SSF CWs) under a variety of conditions. These models have become valuable tools to better design, control, and optimize the SSF CW system. Moreover, they can aid investigations on the effects of variables of interest on the system. While excellent review papers on these models have been published, the ability of the existing process-based models to simulate the nitrogen transformations in the SSF CWs have not been highlighted. Consequently, a critical review of the simulation of nitrogen transformation processes is desirable. This paper presents an overview of the available models that are capable of modelling the nitrogen dynamics in the SSF CWs. The existing process-based models can be mainly categorized as process-dedicated models and Gujer matrix models. A process-dedicated model is a feasible tool for design purposes. Meanwhile, the Gujer matrix model delivers valuable insights into scientific studies. In this paper, the existing models are summarized and critically discussed with regards to their capability and practicality in simulating the nitrogen dynamics in SSF CWs. Organic nitrogen, ammonium, and nitrate are the common nitrogen compounds considered in the process-based models of SSF CWs. Meanwhile, nitrite was frequently considered together with nitrate, owing to its low concentration in the effluent of SSF CWs. By comparison, ammonification, nitrification, denitrification, plant uptake, and ammonium adsorption are the typical nitrogen transformation and degradation processes found in the existing models, whereas ammonia volatilization processes are rarely found in the literature. Oxygen and organic matter are the major limiting reactants of nitrogen transformation and degradation processes in the modelling, and other factors such as microbial population, temperature, and pH are also considered. The recommendations and future research directions on the influence of microorganism distribution, resting period, oxygen release, ammonium adsorption, and plants are outlined.
Environmental Reviews, Volume 29, pp 510-528; https://doi.org/10.1139/er-2020-0126
This study is a broad and critical review of the transdisciplinary literature on the construction of culverts and their impacts on stream hydrology and geomorphology as well as on stream habitats and biota. For engineers, a culvert is a structure, usually of the tunnel type, that transfers a stream or open drain under a road, railway line, or other obstacle from one side to the other. In fact, culverts are complex hydraulic structures whose impacts on stream ecosystems must be evaluated and understood before they are designed. The objective of this paper is to analyse and discuss recent knowledge about culvert functioning in terms of their negative effects on the passage of freshwater biota, particularly fish, and on entire stream ecosystems. We present the results of many studies showing that improperly designed culverts are barriers for migrating animals and usually have serious ecological consequences (mainly disturbances to fish life history). We also pay attention to different culvert modification methods that increase their passability for organisms and mitigate the impacts of culverts on the surrounding environment. The other purpose of this review is therefore to emphasize that the integration of the knowledge and professional experience of biologists and ecologists with those of river managers, river engineers, hydraulic engineers, hydrologists, and geomorphologists is necessary to design culverts that preserve the natural properties of streams.
Environmental Reviews; https://doi.org/10.1139/er-2021-0048
Microplastics—plastic particles in the size range of planktonic organisms—have been found in the water columns and sediments of lakes and rivers globally. The number and mass of plastic particles drifting through a river can exceed those of living organisms such as zooplankton and fish larvae. In freshwater sediments, concentrations of microplastics reach the same magnitude as in the world’s most contaminated marine sediments. Such particles are derived from a unique biogeochemical cycle that ultimately influences productivity, biodiversity, and ecosystem functioning. Furthermore, microplastics act as vectors of toxic substances to invertebrates, fishes, herpetofauna, and waterfowl. We contend that the concentration of this distinct particle component is an ecologically significant parameter of inland waterbodies because of its ubiquity, environmental persistence, and interactions with key ecological processes. No environmental field survey that has searched for microplastics has yet failed to detect their presence. Standardized limnological protocols are needed to compare spatio-temporal variation in the concentration of microplastics within and across watersheds. Data obtained from such protocols would facilitate environmental monitoring and inform policy for managing plastic waste; furthermore, they would enable more accurate modeling of contaminant cycling and the development of a global plastic budget that identifies sources, distribution and circulation pathways, reservoir size and retention times.
Environmental Reviews, Volume 29, pp 340-353; https://doi.org/10.1139/er-2020-0118
Atmospheric dry and wet deposition of particulate matter controls its lifetime in air and contributes to the environmental burden of toxic pollutants and thus has important implications on human and ecosystem health. This synthesis review focuses on atmospheric wet deposition of particulate elements and analyzed their scavenging ratios (i.e., ratio of concentration in precipitation to that in ambient air), solubility, and wet deposition flux measurements based on published studies in the literature, aiming to gather updated knowledge that can be used for modeling their wet deposition. Our analysis finds that scavenging ratios of a specific element have a narrow range. Overall, elemental scavenging ratios for snow are approximately three times higher than those for rain. Elements that are bound to coarse (PM2.5–10) particles have larger scavenging ratios than those bound to fine (PM2.5) particles, except for Fe and Si. Solubility of elements in rainwater ranges from 8% (Fe) to 94% (Ca). Solubility is moderately correlated with scavenging ratio, possibly explaining the lower scavenging ratios of Fe and Si compared with other elements with similar fine fractions. Data collected from North America, Europe, the Middle East, and Asia show that the wet fluxes of Al and Fe are orders of magnitude greater than those of routinely monitored anthropogenic elements (Zn, Pb, Cu, Ni, Cd, Cr). Wet deposition fluxes of particulate elements in the Middle East exceed those in other regions, likely due to regional transport of dust and soil resuspension. Fluxes from all regions are a factor of two to three times greater in industrialized and urban locations than in rural and remote locations because of industrial, vehicular, and soil and mineral dust emissions. Dry deposition fluxes are usually greater than wet deposition fluxes, although to varying degrees according to co-located measurements. Based on the relationships between scavenging ratio and the elemental PM2.5 fraction under rain and snow conditions, we derived regression equations for estimating scavenging ratios of particulate elements for which measurements are limited. Such knowledge and data improve the quantification of atmospheric deposition fluxes for an expanded list of metals and metalloids and the understanding of pathways contributing to ecological risk.
Environmental Reviews, Volume 29, pp 378-390; https://doi.org/10.1139/er-2020-0108
River ice is an important hydraulic and hydrological component of many rivers in the high northern latitudes of the world. It controls the hydraulic characteristics of streamflow, affects the geomorphology of channels, and can cause flooding due to ice-jam formation during ice-cover freeze-up and breakup periods. In recent decades, climate change has considerably altered ice regimes, affecting the severity of ice-jam flooding. Although many approaches have been developed to model river ice regimes and the severity of ice-jam flooding, appropriate methods that account for the impacts of future climate on ice-jam flooding have not been well established. Therefore, the main goals of this study are to review current knowledge regarding climate change impacts on river ice processes and to assess current modelling capabilities to determine the severity of ice jams under future climatic conditions. Finally, a conceptual river ice-jam modelling approach is presented for incorporating climate change impacts on ice jams.
Environmental Reviews, Volume 29, pp 391-400; https://doi.org/10.1139/er-2020-0058
The Chinese government has made a strong effort to solve pollution problems in the Taihu Basin, and scholars have also paid close attention to these issues. Based on 2094 valid studies on the Taihu Basin obtained from the Web of Science (WoS) core database from 1998 to 2019, this study conducted a systematic review of research and development trends using bibliometric methods. The results reveal that academic achievement has increased rapidly in recent years, especially after a severe blue-green algae bloom event in Taihu Lake in 2007. Taihu Basin related studies are becoming more interdisciplinary in nature with an integration of knowledge. The Chinese Academies of Sciences and universities in eastern China play key roles in academic output. Although hotspots of environmental topics vary at different time periods, the eutrophication issue at Taihu Lake has long been a focus. Eutrophication studies on Taihu Lake have evolved from “general causes of eutrophication” to “more detailed causes of eutrophication” to “long-term monitoring and management of water quality” to “risk assessment”. Future trends in Taihu Basin research should continue to emphasize risk assessment and long-term management. This bibliometric review presents a comprehensive analysis of Taihu Lake related research, which can provide important insights into the potential direction for future studies.
Environmental Reviews, Volume 29, pp 415-429; https://doi.org/10.1139/er-2020-0105
Air pollution is one of the major problems caused by urban growth, and both industrial and automobile emissions have been the main causes of air quality deterioration in cities since the beginning of the 20th century. Atmospheric pollution is the largest single environmental risk for health, causing about 7 million human deaths per year. On a global scale, developing countries are major contributors to air pollution due to their rising economies, with rapid industrial and population growth combined with poor emission controls. In South America, there are five megacities (Bogotá, Buenos Aires, Lima, Rio de Janeiro, and São Paulo) with over 10 million people potentially contributing to wide-ranging environmental consequences. Atmospheric particulate matter (APM) plays a leading role in the transport of trace metals and metalloids through the atmosphere and are chemical markers of air quality. The presence of these pollutants in APM has a detrimental effect on both air quality and human health. In this review, we provide an integrated assessment of hazardous metals and metalloids in the fine and coarse APM fractions, focusing on the South American megacities. We identified the current state of research for Ba, Cd, Cr, Cu, Mo, Ni, Pb, Pd, Pt, Rh, Sb, Sn, V, and Zn and summarized the findings in the 21st century. The findings of this review highlight that despite the phasing out of leaded gasoline, Pb continues to be a metal pollutant with one of the highest atmospheric emission rates, mainly due to vehicular pollution. The megacities from Brazil and Argentina were, by far, those with the highest number of studies performed; however, updated research is needed for the five megacities, including specific studies on fine and ultrafine particulate matter fractions as these pose serious human health issues. Urban agglomerations denoted sustained increases of most metals over time that is indicative of deteriorating air quality. Nickel and Cd concentrations in megacities from Argentina, Brazil, and Colombia, as well as Pb in one study from Colombia, were found to have exceeded international air quality guidelines.
Environmental Reviews, Volume 29, pp 329-339; https://doi.org/10.1139/er-2020-0122
The National Pollutant Release Inventory (NPRI), which has been collecting and disseminating pollutant data since 1994, is Canada’s legislated, publicly accessible inventory of pollutant releases (to air, water, and land), disposals, and transfers (for treatment, recycling, or energy recovery). The public availability of NPRI data is a key program output, initially driven by the community-right-to-know movement and now also compelled by the need to support a myriad of environmental science and policy efforts at various scales. Twenty-five years after the inception of the NPRI, this scoping review of peer-reviewed literature (up to 2019) was undertaken to better understand the nature and extent of uptake of NPRI information by researchers, namely, who are using it and how. The findings show that NPRI use in peer-reviewed research has increased steadily since 1997. NPRI information is implicated in 225 scholarly journal articles between 1994 and 2019. The main users are from the Government of Canada and Canadian universities, though many users from diverse backgrounds beyond these categories and beyond Canada were also noted. Researchers were primarily leveraging NPRI data on pollutants released to air, the focus of which was most often on the criteria air contaminants and metals (mercury). Less popular were data on water releases, land releases, and disposal data, while there were no examples of researchers using data on transfers. Seven prominent themes arose pertaining to the area(s) of interest of studies that use NPRI information, including geospatial analyses, environmental monitoring, predictive modelling, industrial sectors, other pollutant inventories, human health outcomes, and policy or program analysis. Several other study themes were also noted relating to socioeconomic issues, waste treatment and remediation, climate change, indigenous groups, and biomonitoring. Future opportunities to increase NPRI use in research in general, and in understudied areas in particular, as well as to increase the use of underutilized NPRI variables, remain.
Environmental Reviews, Volume 29, pp 401-414; https://doi.org/10.1139/er-2020-0063
Catchment urbanization is widely recognised as a primary driver of stream degradation by increasing stormwater runoff, which causes major changes to key ecosystem processes. Reinstating the “natural” hydrogeomorphic conditions is central in designing successful, self-sustaining restoration actions; however, addressing urban stream degradation by re-establishing the hydrogeomorphic conditions remains a challenge, and comparatively limited measurable progress has been observed, particularly in achieving ecological objectives. This review articulates that stream restoration goals might be better achieved when management measures take a broader approach that considers anticipated hydraulic condition effects that liaise relationships between flow and ecology. The study argues that fluvial systems are characterised by complex and dynamic ecosystem processes primarily governed by the hydraulic conditions (e.g., velocity, depth, shear stress); thus, as the practice of addressing urban stream restoration becomes increasingly common, it is critical to explore and understand the anticipated response of the hydraulic conditions. It describes how hydraulic regime consideration provides further opportunity for a holistic approach to urban stream management given their capacity to account for multiple ecological and geomorphic objectives. This review suggests that developing suitable flow–biota–ecosystem processes nexus is critical to addressing urban stream degradation, and hydraulic consideration in restoration actions provides an important step towards that. It discusses opportunities to evolve management actions to achieve restoration goals by highlighting how the management of the two key levers (addressing altered flow regime and morphology) to improve the hydraulic conditions can help to address the urban stream disturbance.
Environmental Reviews, Volume 29, pp 354-377; https://doi.org/10.1139/er-2020-0115
The development of rare earth element (REE) production in Canada could generate significant economic benefits but also poses serious potential risks to the environment. Rare earth elements have been widely used in modern life and industries and are even indispensable in some crucial advanced technologies (e.g., permanent magnets). Increasing demand and the current United States – China trade tensions provide a commercial economic development opportunity for Canada, which has rich resources of REEs, to develop its own sector. However, environmental and health issues caused by REE production are challenges that Canada has to face given that significant environmental impacts have been reported elsewhere (e.g., China). Little literature is available on the potential environmental risks associated with the development of REE production in Canada. It is important to know what environmental issues, particularly those generated by REEs themselves, may happen in Canada in the future. Therefore, three major aspects are evaluated and summarized from multidisciplinary perspectives in this paper: (1) a general conceptual model of the transport of REEs as a group in the environment is established; (2) toxicity levels, biochemical mechanisms, and physiological effects of REEs on different organisms are reviewed, and case-studies from existing REE mining areas are briefly highlighted; and (3) considering specific environmental condition and risk factors, environmental risks that Canada may face in future REE developments are identified and discussed. This review concludes with macro-identification of potential environmental risks associated with the development of REE production in Canada considering both human and ecological health. We note that ingestion, inhalation, and dermal exposure for workers and surrounding residents (including potentially Indigenous communities) and subarctic and arctic climate conditions could increase the risks to human and ecological health in future REE production development in Canada. Finally, future research directions are proposed that could be applied to both Canadian and other geographical contexts.