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The Nature, Sources, and Environmental Chemistry of Hazardous Wastes
Published in Stanley E. Manahan, Environmental Chemistry, 2022
The environmental movement, effects, and fates of hazardous waste compounds are strongly related to their chemical properties. For example, a toxic heavy metal cationic species, such as Pb2+, may be strongly held by negatively charged soil solids. If the lead is chelated by the chelating EDTA anion, represented Y4−, it becomes much more mobile than PbY2−, an anionic form. Chelation of cobalt(II) and cobalt(III) with nitrilotriacetate anion (Section 2.14) makes the metal much more mobile in mineral strata. Oxidation state can be very important in the movement of hazardous substances. The reduced states of iron and manganese, Fe2+ and Mn2+, respectively, are water soluble and relatively mobile in the hydrosphere and geosphere. However, in their common oxidized states, Fe(III) and Mn(IV), these elements are present as insoluble Fe2O3•xH2O and MnO2, which have virtually no tendency to move. Furthermore, these iron and manganese oxides will sequester heavy metal ions, such as Pb2+ and Cd2+, preventing their movement in the soluble form.
Introduction to Trace Environmental Quantitative Analysis (TEQA)
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
In its broadest sense, environmental chemistry might be considered to include the chemistry of everything outside of the synthetic chemist’s flask. The moment that a chemical substance is released to the environment, its physical-chemical properties may have an enormous impact on ecological systems, including humans. Researchers have identified 51 synthetic chemicals that disrupt the endocrine system. Hormone disrupters include some of the 209 polychlorinated biphenyls (PCBs) and some of the 75 dioxins and 135 furans that have a myriad of documented effects (p. 81).22 The latter half of the 20th century has witnessed more synthetic chemical production than any other period in world history. Between 1940 and 1982, the production of synthetic chemicals increased about 350 times. Billions of pounds of synthetic materials were released into the environment during this period. U.S. production of carbon-based synthetic chemicals topped 435 billion pounds in 1992, or 1,600 pounds per capita (p. 137).22
Risk Assessment
Published in Thomas K.G. Mohr, William H. DiGuiseppi, Janet K. Anderson, James W. Hatton, Jeremy Bishop, Barrie Selcoe, William B. Kappleman, Environmental Investigation and Remediation, 2020
Barrie Selcoe, William B. Kappleman
Certain chemical properties influence environmental fate and transport, and thus ecological exposure and toxicity (risk) potential. Data on several key chemical and physical properties of 1,4-dioxane, and its fate and transport potential in the environment, are discussed in detail in Chapter 3 and found in various review documents (e.g., NICNAS, 1998; USEPA, 1999; ECB, 2002; CCME, 2008; Health Canada, 2010; ATSDR, 2012; USEPA, 2015a; USEPA, 2017; and NAVFAC, 2018). Based on its physical and chemical properties, 1,4-dioxane is characterized by high water solubility (>800,000 mg/L; totally miscible in water), moderate to high vapor pressure (38.1 mm Hg at 25°C), low to moderate Henry's law constant (4.29 to 4.80 × 10−6 atm-m3/mole at 25°C), very low log Kow (-0.10 to -0.49 with a recommended value of −0.39 [USEPA, 1995]), and a very low estimated log Koc of 1.07–1.23.
Low-level pharmaceuticals alter stream biofilm structure and function
Published in Chemistry and Ecology, 2021
Elizabeth M. Stover, Kristin E. Judd
Few studies have explored the ecological disrupting effects of environmentally relevant, non-lethal levels of multiple pharmaceuticals on multiple response variables. We found that low levels of PPCPs have the potential to impact some but not all aspects of the biofilm functions we measured. We observed decreases in Alcanivorax and Halioglobus genera and an increase in the Pseudomonas following treatments, indicating a shift to more drug-tolerant groups, and these shifts in community composition in response to PPCPs may impact bacterial function. Further research is required to determine the specific mechanisms by which various pharmaceuticals impact biofilms and the extent to which these processes may be affected. Even subtle changes in biofilm function may have important cumulative impacts on biogeochemical processes in natural waters. Our study addressed only a small number of the pharmaceuticals and synthetic compounds found in waterways. While individual PPCP contaminants are typically found in low concentrations, they are often detected in combination, forming ‘chemical cocktails’ that have unexpected interactive effects [3–5,32,36,37]. Each contaminant has unique chemical properties that influence its ease of removal, persistence in the environment, biological pathways it impacts, and interactive effects in combination with other contaminants. With the large number of possible pharmaceutical combinations commonly detected in streams, further research on various aspects of ecosystem function and the interactive effects of these combinations in the environment is needed [4,37]. Understanding the ecological impacts of pharmaceutical contaminants in aquatic ecosystems will better inform regulations and remediations for the health of aquatic systems.