TY - JOUR
T1 - Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil
AU - Madsen, Peter Lindequist
AU - Thyme, Jesper Bandsholm
AU - Henriksen, Kaj
AU - MØldrup, Per
AU - Roslev, Peter
PY - 1999/8/1
Y1 - 1999/8/1
N2 - Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2- ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [14C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial mineralization activity was described well by first-order kinetics (r2 > 0.97), whereas mineralization in long-term incubations (>40 days) was described better by fractional power kinetics (r2 > 0.95). The mineralization activity was much lower in the late phase presumably due to a decline in the bioavailability of DEHP caused by diffusion-limited desorption. The initial DEHP mineralization rate in sludge-amended soil varied between 3.7 and 20.3 ng of DEHP (g dw)-1 d-1 depending on incubation conditions. Aerobic DEHP mineralization was 4-5 times faster than anaerobic mineralization. DEHP mineralization in sludge-amended soil was much more temperature sensitive than was DEHP mineralization in soil without sludge. Indigenous microorganisms in the sewage sludge appeared to dominate DEHP degradation in sludge-amended soil. It was estimated that >41% of the DEHP in sludge-amended soil will have escaped mineralization after 1 year. In the absence of oxygen, >68% of the DEHP will not be mineralized within 1 year. Collectively, the data suggest that a significant fraction of the DEHP in sludge-amended soils may escape mineralization under in situ conditions.
AB - Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2- ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [14C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial mineralization activity was described well by first-order kinetics (r2 > 0.97), whereas mineralization in long-term incubations (>40 days) was described better by fractional power kinetics (r2 > 0.95). The mineralization activity was much lower in the late phase presumably due to a decline in the bioavailability of DEHP caused by diffusion-limited desorption. The initial DEHP mineralization rate in sludge-amended soil varied between 3.7 and 20.3 ng of DEHP (g dw)-1 d-1 depending on incubation conditions. Aerobic DEHP mineralization was 4-5 times faster than anaerobic mineralization. DEHP mineralization in sludge-amended soil was much more temperature sensitive than was DEHP mineralization in soil without sludge. Indigenous microorganisms in the sewage sludge appeared to dominate DEHP degradation in sludge-amended soil. It was estimated that >41% of the DEHP in sludge-amended soil will have escaped mineralization after 1 year. In the absence of oxygen, >68% of the DEHP will not be mineralized within 1 year. Collectively, the data suggest that a significant fraction of the DEHP in sludge-amended soils may escape mineralization under in situ conditions.
UR - http://www.scopus.com/inward/record.url?scp=0033178437&partnerID=8YFLogxK
U2 - 10.1021/es981015o
DO - 10.1021/es981015o
M3 - Journal article
AN - SCOPUS:0033178437
SN - 0013-936X
VL - 33
SP - 2601
EP - 2606
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 15
ER -