Section Number : 9 . 2 . 2 Background Chapter : 4 Reference Number : 14 Title : " Volatilization , Off - Site Deposition and Dissipation of DCPA in the Field " in Journal of Environmental Quality

A once widely used nematicide that is now banned, 1,2dibromokhloropropane (DBCP), persists in groundwaters and is a significant pOlluUnt in some water supplier. A study was conducted to determine whether a means for the biodegradation of this persistent compound could be devised. DBCP was not converted to organic products, halide, or CO, in unamended samples of soil, subsoil materiel, or groundwaters in 60 d, and no microorganism could be isolated that was able to use the compound as a C source for growth. However, cell suspensionsof Pseudomonas pufida and of baeteria grown in solutions containing chlorinated fatty acids or 3-chloro-l-propanol comerabolird DBCP in the presence of 0, with the formationof halide but not Co t . Psrudomonupurida had the greatest activity. DBCP was also converted aerobically to organic products and CO, by soil suspensions incubated with methane. The compound was also converted anaerobically to organie producU but not CO, in suspensions of soil, but no anaerobic eansformation was obsewed in samples of groundwater or aquifer solids. We suggest that biological treatment may be used as a means to destroy this pollutant. HE NEMATICIDE 1,2-dibromo-3-chloropropaneT (DBCP) persists in %reasin which it was used asa pesticide. In California, DBCP is a frequent contam-inant in wells, the concentrations usually ranging be-tween 0. l and 9.9 pg/L (Cardoza et al., 1985; Peopleset al., 1980). Similarly, DBCP at concentrations of0.02to 20 ag/L has been detected in groundwaters in Ha-waii, Arizona, South Carolina, and Maryland (Cohen R.A. Bloom and M.Alexander, Inst. for Comparative and Environ.Toxicology and Dep. ofsoil. Crop, and Atmospheric Sciences. Cor-nell Univ.. Ithaca. NY 14853.Received 7 Feb. 1990. 'Correspondingauthor. Published inJ. Environ. Qual. 19722-726 (1990).et al., 1984). Although this nematicide has b w s ,banned for most uses since 1978 because of eviof human toxicity (USEPA, 1977), its presence in I:..-table waters at concentrations that exceed rsruhtn:!standards poses a risk to human health. In xik:it!w~.to its presence in aquifers below or near fields 'U k:;it was used to control nematodes. the compcund :\still being detected at sites near which it was m:Ki:-factured, and the costs for remediation of the arrn aiiestimated 10 be exceedingly high (Shabecoff. I Y S S i .The loss of DBCP from soils by volatilizatior! 31icifield applications can be substantial (Saltzman 2ndKliger, 1979), but once the chemical reaches d e c p rsoil horizons and groundwaters, the loss by vaialili-zation is probably not significant (Hodges and LCX1974). The compound appears to be resistant IO a b i o ~ : ~degradation, and the half-life of DBCP under sun&tions prevailing in many groundwaters of thc US-! I \estimated to exceed I14 yr (Burlinson et al.. 19821. 1:.the other hand, some evidence exists that DBCI: ni.:>be subject to microbial transformation. Thus. C a wand Belser (1968) demonstrated reductive dehalo;-::-ation of DBCP in soil suspensions supplemented w:jglycerol. although they could not isolate a pure cuI:u:.or demonstrate dehalogenase activity in the absen:of soil. Nongrowing cultures of Pseudotnorras .PI(Lamand Vilker, 1987) and a strain of Flarobarirrr:!"(Castro and Bartnicki, 1968) have been shown I@ d:'-halogenate DBCP.Because of the widespread occurrence of grotlllt'.waters contaminated with the compound. its thrcni !'health, and the high cost of site remediation. 8 S I C ? 'was undertaken to determine factors that contra; 1':-microbial transformation of DBCP. This informallll:'should prove useful in devising a field technolog! :,