Studies on the effect of Bladex and Etazine on bacterial indices of pollution
The effect of the triazine herbicides Etazine and Bladex on coliform and fecal streptococci groups was studied in Nile river water, Nile water seeded with sewage, and autoclaved Nile water. The results indicate the fecal streptococci were able to persist and multiply in Nile water containing Bladex or Etazine and seeded with sewage. The successive addition of Bladex and Etazine (up to 10 mg/liter) increased its degradation rate and had no inhibitory effect on the bacterial parameters.
Studies on the persistence of some carbamate insecticides in the aquatic environment—I. Hydrolysis of sevin, baygon, pyrolan and dimetilan in waters
Abstract This paper describes the analysis and rates of hydrolysis of the monoalkyl carbamate insecticides Sevin and Baygon, and the dialkyl carbamates Pyrolan and Dimetilan in aqueous media. The rates of hydrolysis with different hydroxylion concentrations were measured. Second order rate constants for Sevin, Baygon, Pyrolan and Dimetilan at 20°C were found to be 2.04 x 102, 3.04 x 10, 7.0 x 10−1 and 3.4 x 10−3 1. mol−1 min−1, respectively, indicating that the dialkyl carbamates were more stable to alkaline hydrolysis than the monoalkyl carbamates. The rates of hydrolysis at different pH values, ranging from 4.0 to 10.0, were also studied. All the compounds were stable to hydrolysis within the acidic pH range. However, measurable hydrolysis was observed at pH 7.0 and 8.0 for sevin and baygon, respectively, and the rates of hydrolysis increased with the rise of the pH value. At pH 8.0 about 99 per cent of sevin was hydrolyzed in 9 days while baygon reached the same level of hydrolysis after 107 days. Pyrolan and Dimetilan, on the other hand, were stable towards hydrolysis within the investigated pH range. The effect of temperature on the rates of hydrolysis was also investigated. This study shows that the persistence of the carbamate pesticides in natural waters is greatly influenced by the pH value and temperature of the aquatic environment.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.