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The biodegradation of nitrilotriacetic acid (NTA), a synthetic replacement detergent builder, in the estuarine environment was examined by using a laboratory estuarine simulation. Two interdependent microcosms were used; each of five vessels was equilibrated with a saline gradient between 1.30 and 17.17%o, with the final vessel subsequently being increased to a maximum salinity of 31.6%o. Each microcosm was seeded simultaneously with heterotrophic bacteria from both fresh and saline sources. Viable counts demonstrated the ability of each microcosm to sustain a mixed heterotrophic bacterial community throughout the range of salinities for 183 days after a stabilization period. Isolation studies demonstrated that both systems contained four bacterial species, representatives of the genera Vibrio and Flavobacterium and members of the coryneform group and the family Enterobacteriaceae. Total bacterial numbers and species diversity decreased with increased salinity. NTA was administered at low and high concentrations, one concentration to each microcosm, initially with the least amount of saline. Removal of both concentrations of NTA occurred and was attributed to biodegradation after a period of bacterial acclimatization. Subsequent dosing of NTA to vessels of higher salinity demonstrated that biodegradation was incomplete at observed mean salinities of >9.18%o at low influent NTA concentrations and >5.08f%r at high influent NTA concentrations. Therefore, acclimatization was dose dependent. It was concluded that NTA acclimatization at the higher salinities ceased because of salinity stress-induced failure of NTA catabolism and not the disappearance of a particular bacterial species.

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Three components of environmental tobacco smoke, namely, carbon monoxide, particulate matter and nicotine were monitored over 30 minute intervals in travel, work, home and leisure situations. Around 3,000 sets of measurements were made with approximately equal numbers in smoking and non-smoking environments. Mean concentrations of these components were calculated for the total study as well as for different regions, situations and locations. Although some slight regional variations were evident, most differences were associated with the type of location sampled. Carbon monoxide levels were not significantly different between non-smoking and smoking environments for each of the four types of situation, whereas particulate matter and nicotine were higher where smoking occurred.