Final answer:
It is true that volatile organic compounds in groundwater can be detected by the gases they emit. This is because many VOCs turn into vapors or gases that can be easily identified. Specifically, BTEX compounds and other organic pollutants such as pesticides and PAHs can be monitored this way.
Step-by-step explanation:
The statement that volatile organic compounds (VOCs) as contaminants in groundwater can be detected by the gases they emit is true. VOCs are carbon-containing chemicals that easily become vapors or gases. Due to their volatile nature, many VOCs can indeed be identified by the gases they emit, especially when they are present in groundwater. Examples of VOCs include BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) which are found in gasoline and some industrial solvents like tetrachloroethylene (PCE) and trichloroethylene (TCE) that were used in dry cleaning and metal degreasing.
Organic pollutants such as pesticides and polycyclic aromatic hydrocarbons (PAHs) are also found in groundwater. Naphthalene is a notable PAH due to its solubility and mobility in groundwater systems, and benzo(a)pyrene is recognized for its toxicity. The detection of these VOCs is crucial for protecting drinking water sources and avoiding potential health hazards.
Techniques for detecting VOCs in groundwater involve analyzing the gases above the water surface or sub-surface in soil vapor, which can indicate the presence of these compounds in the groundwater. Additionally, there are concerns over groundwater contamination from hydraulic fracturing, also known as fracking, where VOCs may be introduced from both the petroleum resource and the fracking fluid.