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Water Chemistry
Published in Mary K. Theodore, Louis Theodore, Introduction to Environmental Management, 2021
Mary K. Theodore, Louis Theodore
Water chemistry deals with the fundamental chemical properties of water itself, the chemical properties of other constituents that dissolve in water, and the countless chemical reactions that take place in water. The field of natural water chemistry is concerned principally with reactions that occur in relatively dilute solutions (low concentrations), although some natural waters have rather high solute concentrations [1]. During a chemical reaction, tiny subatomic particles (e.g., electrons) and atoms (e.g., hydrogen) are transferred, shared, and exchanged. When a chemical reaction occurs in water, these changes require transport through the water medium. Water is not passive in these chemical reactions. Instead, it plays an active role, constantly making and breaking chemical bonds, thereby facilitating chemical change.
Water Chemistry
Published in Louis Theodore, R. Ryan Dupont, Water Resource Management Issues, 2019
Louis Theodore, R. Ryan Dupont
Water chemistry deals with the fundamental chemical properties of water itself, the chemical properties of other constituents that dissolve in water, and the countless chemical reactions that take place in water. The field of natural water chemistry is concerned principally with reactions that occur in relatively dilute solution (low concentrations), although some natural waters have rather high solute concentrations (Hem 1970). During a chemical reaction, tiny subatomic particles (e.g., electrons) and atoms (e.g., hydrogen) are transferred, shared, and exchanged. When a chemical reaction occurs in water, these changes require transport through the water medium. Water is not passive in these chemical reactions. Instead, it plays an active role, constantly making and breaking chemical bonds, thereby facilitating chemical change.
Ecotoxicology of Nanoparticles
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
Modern approaches to material risk assessment is to validate and prescribe methodologies and test matrices; however, as has been shown, this may not be effective in providing a true picture of the toxicity of the material in a specific location. The changes in water chemistry are significant and have been shown to have an effect on bioavailability and levels of toxicity. This is evident from trends in ecotoxicological assessments of ENMs to now include testing in natural river water in specific geographical regions (Zeng et al., 2018).
Synoptic snapshots: monitoring lake water quality over 4 decades in an urbanizing region
Published in Lake and Reservoir Management, 2023
C. Doucet, L. Johnston, A. Hiscock, T. Bermarija, M. Hammond, B. Holmes, T. Smith, B. Lalonde, D. Parent, C. Deacoff, R. Scott, J. Kurek, R. Jamieson
Surface waters are vulnerable to degradation by human activities, including the introduction of contaminants and impacts resulting from urban development, agriculture, and resource extraction (Howell et al. 2012, Ren et al. 2014). Vegetation removal and increased impervious surface coverage affect surface water runoff, increasing delivery of contaminants of both natural and anthropogenic origin to freshwater systems (Hall et al. 1999). Contaminants also reach surface waters through atmospheric transport of industrial emissions, and directly, in the form of wastewater effluent and stormwater inputs. Increases in major ions, nutrients, trace elements, and pH are often detected in waterbodies near urban areas (Howell et al. 2012, Ren et al. 2014, Dugan et al. 2017, Scott et al. 2019). Changes in water chemistry affect the functioning of aquatic systems, including their productivity, community structure, and biodiversity, and may also disrupt physical processes such as thermal stratification and mixing regimes (Novotny and Stefan 2012, Dugan et al. 2017).
How appropriate are Canadian Water Quality Guidelines for protecting freshwater aquatic life from toxic chemicals in naturally-discharging groundwater?
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2019
James W. Roy, Patricia L. Gillis, Lee Grapentine, Greg Bickerton
Compared to surface waters, groundwaters typically have high ionic strength (major ions) and metal concentrations, often low dissolved oxygen levels, and typically lower amounts of dissolved organic carbon (DOC) (especially humic/fulvic acids). This is important because water chemistry can significantly affect the bioavailability and thus the toxicity of contaminants, especially inorganic compounds. Indeed, CWQGs for several metals (e.g., Cu, Cd, Ni, Pb) account for water composition and others (e.g., Al, NH4) account for pH, illustrating the importance of geochemical conditions in assessing risk. Furthermore, other jurisdictions (United States (EPA, 2007) and the European Union (EU) (EU 2013)) have adopted the use of software approaches, such as the Biotic Ligand Model (BLM) (Paquin et al., 2002), that derive site-specific guideline values for various metals. Detailed site water composition including pH, alkalinity, DOC (% humic acid) and concentrations of major ions are input into the BLM, to account for both ameliorating (e.g. DOC) or toxicity-enhancing (e.g. ion-dilute waters) factors that influence the concentration of the free metal ion (i.e. the form known to cause toxicity) available to interact with aquatic organisms. Canada is currently considering use of a BLM-type approach for some metal CWQGs (e.g. copper).