What is Environmental Chemistry?
Written by Dr. Shainaz Landge, Assistant Professor of Chemistry at Georgia Southern University Environmental Science is a multidisciplinary field that can include chemical, physical and biological sciences working together to study and find effective solutions for environmental problems.1 There are multiple branches of environmental sciences2
Common quality measurements targeting environmental chemistry include Dissolved Oxygen (DO), pH, temperature, conductivity, clarity and salinity. In water quality monitoring, DO is essential for aquatic organisms, plants, and bacteria to survive. It is measured in parts per million (ppm) or mg/L. The water temperature has a strong influence (inverse relationship) on DO. At lower temperatures, there are higher dissolved oxygen levels.4 Fluctuations in dissolved oxygen can impact the health of a water way by disrupting plant growth, macroinvertebrates, and bacteria. To measure dissolved oxygen environmental chemists needs to fix the water sample and use titration study. The pH test (acidity measure) is one of the most critical indicators for water health. It measures the Hydrogen ion (H+) concentration in the water. Generally, solutions below 7.0 are acidic in nature and above 7.0 are basic. pH can be influenced by a variety of conditions including both man-made (agriculture) and environmental (hurricanes). To meet the Georgia state standards, the pH should be in the range of 6.0 to 8.5. Temperature is an important factor for aquatic life, and state standards suggest that it should be less than 32.2 oC (90 oF). Small, measured, seasonal changes are manageable by aquatic species, but a sudden change of degree or two can create shock or stress in aquatic species. The cold-shock,5 which results from the rapid decrease in water temperature, can bring number of physiological and behavioral changes in species, which can lead to death. In order to get accurate readings on other chemical reactions in water, chemists must know what is happening to the water temperature first. Conductivity is the measure of the ability of water to pass an electric current. It can be affected by the amounts of nutrients or ions present in the water. Conductivity is easily measured by chemists by analyzing the concentrations of different ions in the water, however this can be time consuming so most often use conductivity probes /meters. Temperature significantly affects conductivity. Higher temperatures will have higher conductivity levels, as it will help to dissociate the ions present in the water. Common ions that conduct electrical currents in water are sodium, chloride, calcium, and magnesium. Salinity is the concentration of dissolved salts in water, and it severely affects the plant and animal life. This particular study is important when dealing with ocean water, where the salinity of average ocean water is 35 parts per thousand (ppt). Salinity affects conductivity as well and will increase with higher levels of salt in the water. Because aquatic species are adapted to certain levels of salinity, changes can adversely affect them. Clarity, as the name suggests, is the clearness of the water and is affected by the suspended particles and algae in the water. Water with lower clarity will limit the amount of sunlight needed for photosynthesis resulting in the potential of suffocation of aquatic organisms. Clarity is usually measured with the naked eye and on a scale. Other measurements, which can be studied, are presence of nutrients (nitrates and phosphates) and heavy metal contamination.6 Nutrients such as nitrates are found in the water from fertilizers or animals waste (sewage) and phosphates are generally found in water from soaps, fertilizer etc. An excess of nutrients can lead to environmental impacts such as algal blooms and decreased dissolved oxygen levels. Heavy metal contamination from lead, zinc, cadmium, or mercury can occur through mining, manufacturing or use of synthetic products such as pesticides, paints, industrial waste, or domestic sludge in water bodies.7 Other quantitative research measurements can be conducted by instruments such as Gas Chromatography-Mass Spectrometry (GC-MS), High Performance Liquid Chromatography (HPLC), Atomic Absorption Spectra (AAS), and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). These are generally used to detect metal ion concentrations as well as anion and cation concentrations and their distributions.8 While we often think of water health as a biological construct, it is easy to see why chemists are invaluable partners when it comes to monitoring and studying water ways. It is not just important to know how to collect the data but also the process and what the outcomes mean in terms of overall health, causes of rising or falling chemical fluctuations, and how to conduct further testing to nuisance out potential issues. By studying the chemical reactions in the environment, chemists contribute to the monitoring of our waterways. References:
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June 2019
CategoriesSupported by the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine under the Grant Agreement: 20000G9576
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