The effect of dissolved natural organic matter on adsorption of phenolic compounds on suspended sediments.

Phenolic compounds have caused different degrees of negative impacts in aquatic environment. Amino acids, humic acids and carbohydrates are the three dominant types of dissolved natural organic matter (DNOM) in natural water bodies. In this research, the influences of dissolved natural organic matter (DNOM) on the adsorption behaviors of phenol, 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) in Weihe River suspended sediment were studied by using DL-alanine, fulvic acid and glucose as the representatives of the three types of DNOM. The results of batch adsorption experiments showed that, without DNOM, Langmuir and Freundlich had good fitting effects on the three phenolic compounds and their maximum adsorption capacities were 21.580, 27.768 and 24.758 mg/kg respectively. The presence of amino acids increased adsorption capacities of the phenol and TCP on suspended sediments by approximately 13.84% and 11.56% respectively. The existence of fulvic acid and glucose positively affected the adsorption of phenol, DCP and TCP on suspended sediment. The isothermal adsorption in the coexistence of different DNOM were more consistent with the nonlinear adsorption. Other influence factors including pH, ionic strength and temperature can influence the adsorption behavior to different extents. The impact of dissolved natural organic matter (DNOM) on adsorption should be fully considered when mastering environmental migration and transformation behaviors of phenolic compounds in water-sediments environment.

Phenolic compounds in water, suspended particulate matter and sediment from Weihe River in Northwest China.

The distribution and ecological risks of 11 phenolic compounds were studied in Weihe River, Northwest China. The concentrations of phenolic compounds were determined by ultra-high performance liquid chromatography (UPLC). The total concentration of 11 phenolic compounds (∑PC11) ranged from 0.06 to 14.12 µg/L with an average of 5.22 µg/L in water, from 0.92 to 34,885 µg/g with an average of 4,446 µg/g in suspended particulate matter (SPM), and from 3.54 to 34.09 µg/g with an average of 11.09 µg/g in sediment. For individual phenolic compound, the mean concentration of pentachlorophenol was the highest in water (2.65 µg/L) and in SPM (3,865 µg/g), while in sediment the mean concentration of 2,4,6-trichlorophenol was the highest (3.05 µg/g). The total concentration of 5 chlorophenols (∑CP5) was significantly higher than that of 6 non-chlorophenols (∑NCP6) in all three studied compartments. The phenolic compounds in Weihe River were at moderate levels in water and at high levels in sediment. The ecological risk assessment results indicated that phenolic compounds exhibited a high ecological risk in Weihe River water. In most sites, the distribution coefficient (Kd) (SPM) was much higher than Kd (sediment), which probably suggested fresh phenolic compounds input in Weihe River.