A Research On The Transformation Of Pharmaceuticals And Personal Care Products (PPCPs) In Nature Environment

Pharmaceutical and personal care products (PPCPs) are emerging micropollutants, which had received much concern. Previous studies on the environmental fate of PPCPs have mostly focused on content determination, distribution of survey, manual removal and their behaviors in aquatic environments and in the sludge. However, little PPCPs are known about their behavior in nature environment. Sunlight degradation and micro-biological degradation of pharmaceuticals may be of major significance in the natural elimination process. Indomethacin and naproxen were selected as the model compounds to investigate the fate of PPCPs in environment. Results deduced from the present study can help to assess the environmental risks of PPCPs.(1) In this work, solid-phase extraction was used to study the microbial and sunlight (Wuhan, spring) degradation of indometacin in surface water. The effects of different parameters such as water quality, initial concentration, familiar ions (Cl-, HCO3-, NO3-, Fe3+, HA) and coexisting compounds (furazolidone, naproxen) on the photodegradation of indometacin have been studied. The results showed that microbial degradation in East Lake water was significant but neglect in Changjiang River water. When the concentration ranges1-500μg/L, correlation between the degradation rate and concentration exactly filed the exponential function. In addition to HCO3-, familiar ions could promote the degradation. Coexisting compound furazolidone could promote the photodegradation, but naproxen inhibits the photodegradation.(2) The effect of coexisting compounds on the fate of pharmaceuticals under solar irradiation was investigated. Furazolidone with familiar absorption spectrum to NPX was employed to study the effect of photodegradation. The experimental results indicated that the presence of coexist compound with familisr absorption spectrum to NPX could produce obvious effect on the photodegradation of NPX. Besides, the overlapping absorption spectrum to NPX of260nm such as diclofenac sodium, ketoprofen, indometacin, enoxacin and the non-overlapping absorption spectrum ibuprofen and metronidazole were selected to investigate the mechanism of effect. The results showed that the effect depended on the degree of overlapping absorption spectrum between NPX and the coexisting pharmaceuticals. The relationship between the degree of the influence and the ultraviolet absorption spectra of coexisting pharmaceuticals found in this study could give an example in assessing the fate of pharmaceuticals in environmental water.(3) Adsorption and degradation of naproxen and indometacin were investigated in the laboratory using three agricultural soils in China. The results indicated that adsorption of all tested chemicals in soils could be well described with Freundlich equation, and their adsorption affinity (Kf) on soil followed the order of indometacin> naproxen. Generally, higher Kf value was associated with soils which had higher organic matter contents. The competitive adsorption of the two compounds was apparent when they coexisted. Degradation of selected PPCPs in soils generally followed first-order exponential decay kinetics, and the half-lives were different with each other. Coexisting compounds could inhibit the degradation of chemicals. Sterilization generally decreased the degradation rates, which indicated that microbial activity played a significant role in the degradation in soils.