China 
Africa 
Explore chapters and articles related to this topic
Nature's Response to Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Other VOC compounds, such as benzene, toluene, ethyl benzene, and xylenes (BTEX), are not typically as persistent in the environment and have been known to biodegrade in a few months to years if conditions are favorable (Rogers 1995; USEPA 1996a). The VOC compound MTBE is persistent in the environment. Its relatively high solubility in water and low sorptive properties compared to other common VOC contaminants have resulted in significant MTBE-contaminated groundwater supplies at many urban locations throughout the United States (USGS 2006a). The trihalomethane VOCs include chloroform, bromoform, bromodichloro-methane, and dibromochloromethane. These compounds have been detected in the groundwater of many US aquifers (USGS 2006a). Trihalomethanes have high relative vapor pressures and commonly evaporate quickly when in contact with the atmosphere. Therefore, exposure to trihalomethanes is of special concern during showering and washing (ATSDR 1997a, 2005a). They degrade by photolysis when exposed to direct sunlight and can also be degraded by microorganisms (ATSDR 1997a, 2005a).
Chemistry of Contaminants
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Other VOC compounds, such as benzene, toluene, ethyl benzene, and xylenes (BTEX), are not typically as persistent in the environment, especially in air, and have been known to degrade in a few hours to a few months to years if conditions are favorable (Rogers 2020; USEPA 1996a). The VOC compound MTBE is persistent in the environment. Its relatively high solubility in water and low adsorptive properties compared to other common VOC contaminants have resulted in significant MTBE-contaminated groundwater supplies at many urban locations throughout the United States (USGS 2006a). The trihalomethane VOCs include chloroform, bromoform, bromodichloro-methane, and dibromochloromethane. Trihalomethanes have high relative vapor pressures and commonly evaporate quickly when in contact with the atmosphere. They degrade by photolysis when exposed to direct sunlight and can also be degraded by microorganisms (ATSDR 1997a, 2005b).
Organic Compounds in Raw and Finished Waters
Published in Samuel D. Faust, Osman M. Aly, Chemistry of Water Treatment, 2018
The reports cited above undoubtedly prompted the U.S. Environmental Protection Agency to conduct a nationwide survey of “the concentration and potential effects of certain organic chemicals in drinking water.”7 This resulted in a National Organics Reconnaissance Survey (NORS) for chloroform, dibromochloromethane, bromodichloromethane, and bromoform (the trihalomethane (THM) and carbon tetrachloride in 80 surface and groundwater supplies throughout the United States. (See Figure 2.1.) In general, these five compounds were not detected in all of the raw waters. However, many finished waters contained one or more of the four THMs. Consequently, it was concluded that their occurrence was caused by chlorination practices, and their concentrations were related to the organic content of the raw water. When detected, the THMs were present at less than 4.0 μg/L in the raw water.
Species-specific interaction of trihalomethane (THM) precursors in a scaled-up distribution network using response surface methodology (RSM)
Published in Environmental Technology, 2018
Sajida Rasheed, Imran Hashmi, Jong. K. Kim, Qizhi Zhou, Luiza C. Campos
A water distribution network (DN) acts as a large chemical and biological reactor where numerous reactions take place. Chlorination of drinking water containing natural organic matter (NOM), mainly humic substances, leads to disinfection of by-products’ formation [1,2] such as total trihalomethane (TTHM), that is, chloroform (CHCl3), bromodichloromethane (BDCM) (CHCl2Br), dibromochloromethane (DBCM) (CHClBr2) and bromoform (BF) (CHBr3). The later three brominated trihalomethanes (Br-THMs) are produced by reaction of hypo-bromite with humic acid (HA) [3]. Hassani et al. [4] showed that higher TTHM concentrations formed within DN, while El-Shafey et al. [5] reported that 45% of TTHMs were formed in treatment plant; the rest formed in pipelines. The carcinogenic and non-carcinogenic health effects showed an association between ingestion of chlorinated water and esophagus, pancreas, urinary tract, stomach, colon and rectal cancers and reproductive/developmental anomalies in laboratory animals [6–9]. Therefore, recommended TTHM concentration in drinking water is set to be ≤80 µg/L by World Health Organization (WHO) [10]. This has led to the monitoring of their presence in drinking water for regulatory compliance, health risk assessment, epidemiological evaluation and water quality control purposes so measures may be taken to minimize or eliminate their presence. Moreover, as bromide ion concentration is not lowered by conventional drinking water treatment processes [11], the effect of Br− concentration on trihalomethane formation potential is an important area of study.