The role of anion in the impact of tetraethylammonium salts on soil phosphatase activities

Quaternary ammonium salts (QAS) are increasingly commonly used in the chemical industry. The diverse usage of these compounds results in high possibility of their penetration to the environment. The aim of this study was to compare the effect of three salts with tetraethylammonium cation with different anions such as chloride [TEA][Cl], bromide [TEA][Br], and iodine [TEA][I] on the activity of phosphatases in loamy sand. Organic carbon and total nitrogen content in the soil were 8.71 and 0.97 g·kg-1, respectively. The salts were applied to soil at doses of 0, 0.05, 0.50, and 5.00 mmol·kg-1. The samples were adjusted to 60% maximum water holding capacity, and they were incubated at a temperature of 20°C. Activities of acid phosphomonoesterase, alkaline phopshomonoesterase, phosphotriesterase, and inorganic pyrophosphatase were assayed on day 1, 7, 14, 28, 56, and 112. The obtained results demonstrated that the presence of [TEA] in the soil at the low dose (0.05 mmol·kg-1) may stimulate the activity of soil phosphatases. Higher doses of the soil had mostly inhibitory effect on phosphatases activity. Among the determined enzymes, phosphomonoesterases were the most sensitive to salts containing [TEA] cation. A considerable contribution of the anion type on the formation of activity of the determined enzymes of phosphorus compound changes. The strongest effect characterized tetraethylammonium bromide [TEA][Br].