Effect of Sorption on Mineralization of Low Concentrations of Aromatic Compounds in Lake Water Samples

Abstract

Montmorillonite-benzylamine complexes were formed immediately upon addition of 20 pg to 20 μg of amine per ml of suspensions containing the clay. The extent of amine sorbed was a linear function of equilibrium amine concentration in lake water. Increases in the clay concentration decreased the percentage of the organic compound that was mineralized at amine levels of 20 pg to 200 ng, but not at 20 μg/ml. A larger percentage of the chemical was released from the complex during mineralization in the presence of high clay concentrations than in the presence of low clay concentrations. The rates of desorption and mineralization increased linearly with benzylamine levels up to 200 ng/ml. Montmorillonite did not enhance mineralization rates at amine levels of 200 ng/ml or lower, but it was stimulatory at 20 μg/ml. Except at high amine and clay concentrations, mineralization was more rapid than desorption during the early periods of decomposition when the amine concentration in solution was relatively high. However, relative to the microbial demand, desorption was more rapid during later periods of decomposition when the amine level in solution was very low. Mineralization of benzoate was not usually affected by montmorillonite, kaolinite, or glass beads. More than 90% of the carbon from benzylamine and benzoate was often mineralized when the substrate concentration was 250 ng/ml or less. After incubation of the chemical in lake water, none of the radioactivity from benzylamine was in the particulate fraction containing natural sediment and microbial cells. The data indicate that clay may have a significant effect on the microbial decomposition of low concentrations of certain organic compounds.

Mineralization of erythromycin A in aquaculture sediments

“…In aquatic systems, the solubility of chemicals and the presence of sorptive materials, such as clays and colloidal organic matter, affect the biodegradation [22]. Since the protonated species of erythromycin A (pK a ¼ 8:36) can be strongly adsorbed to clay particles [9,11], the soil-sorbed molecules are less likely accessible to microorganisms.…”

Pyrene and chrysene fate in surface soil and sand microcosms

“…The [5,6,11,[12][13][14] C]chrysene (specific activity ϭ 47.57 mCi/mmol), [4,5,9,[10][11][12][13][14] C]pyrene (specific activity ϭ 32 mCi/ mmol), and [UL- 14 C]salicylic acid (specific activity ϭ 10 mCi/ mmol) were purchased from Sigma Chemical (St. Louis, MO, USA). 1-Hydroxypyrene, 1-hydroxy-2-naphthoic acid, and NaN 3 were also purchased from Sigma Chemical.…”

“…By observing systems where aerobic biotransformations are inhibited and comparing them to uninhibited systems, both the bioavailability of compounds for degradation and the impact of biotransformations on hydrophobic organic contaminant availability can be assessed. Sorption to and partitioning into soil organic matter (SOM) have been considered to be the primary interactions limiting the bioavailability of hydrophobic organic contaminants [1,6,[10][11][12][13][14][15].…”

Studies on Bioremediation of Polycyclic Aromatic Hydrocarbon-Contaminated Sediments: Bioavailability, Biodegradability, and Toxicity Issues

“…Because PAHs are hydrophobic and sorb strongly to the * To whom correspondence may be addressed (tabak.henry@epa.gov). natural organic matter in sediments [6], the bulk of the contaminant mass resides in a phase separate from degrading microbiota. This makes mass transfer an efficiency-controlling process [7], thus emphasizing the need to study the availability of PAHs to the degrading microorganisms.…”