Volatile chloro‐ and bromocarbons in coastal waters1

• Published in: Limnology and Oceanography
• Main Authors: Helz, George R., Hsu, Rong Y.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1978
• Subjects: Aquatic Science; Oceanography; Back River
• Online Access: http://dx.doi.org/10.4319/lo.1978.23.5.0858; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.1978.23.5.0858; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1978.23.5.0858

Contaminated coastal waters can contain nanomolar levels of C 1 and C 2 halocarbons originating through in situ synthesis from chlorine and through waste discharge. Haloforms are the major volatile products formed from chlorine. In freshwaters, CHCl 3 dominates with lesser amounts of CHBr 3 and the mixed Cl–Br haloforms; however, above about 5 g · kg −1 salinity, CHBr 3 is virtually the only product when typical chlorine doses (10–100 µ M) are used. On a molar basis, >4% conversion of chlorine to haloforms was observed in some experiments. Samples from the Back River estuary (Maryland), which receives effluent from a very large urban wastewater treatment plant, contained CH 2 Cl 2 , CHCl 3 , CCl 4 , CCl 2 = CHCl, and CCl 2 =CCl 2 at concentrations exceeding 1 nM. Even when winter ice cover minimized loss by volatilization, downstream mixing was nonconservative, suggesting that chemical or biological degradation processes occur. Under normal circumstances, however, volatilization followed by chemical degradation in the atmosphere is probably the most important loss mechanism. Data on possible biologic effects of these compounds are critically needed.