Leaching and primary biodegradation of sulfonated naphthalenes and their formaldehyde condensates from concrete superplasticizers in groundwater affected by tunnel construction.
Sulfonated naphthalenes and their formaldehyde condensates (SNFC) are used as concrete superplasticizers fortunnel construction through aquifers.This paperdiscusses their primary biodegradation in groundwater affected by construction activities. The analyses of groundwater samples collected 5 m away from a construction site clearly indicated that components of the applied SNFC product leached into the groundwater. A maximum total concentration of these compounds of 233 microg/L was found, and it was shown that only the monomeric sulfonated naphthalenes andthe condensates uptothetetramerleached in substantial amounts. The decrease in concentration of several monomeric components could not be explained by mere dispersion but rather indicates a biological transformation in the aquifer. This was confirmed at a second field site and by laboratory degradation experiments with piezometer material as inoculum. Lag phases for the individually degradable sulfonated naphthalenes ranged from 0 to 96 d. Naphthalene-1,5-disulfonate and the oligomeric components were neither degraded in the aquifer nor in the laboratory experiments within an observation time of up to 195 d. This clearly indicates their persistence in subsurface waters.
EAWAG, Swiss Federal Institutefor Environmental Science and Technology, and ETH, Swiss Federal Institute of Technology, Dübendorf.
Sabine
S
Ruckstuhl
Marc J F
MJ
Suter
Hans-Peter E
HP
Kohler
Walter
W
Giger
D004202:Disinfectants / Q000737:chemistry / Q000378:metabolism*; D004784:Environmental Monitoring; D005160:Facility Design and Construction; D005557:Formaldehyde / Q000737:chemistry / Q000378:metabolism*; D008420:Manufactured Materials; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism*; D010968:Plasticizers / Q000737:chemistry / Q000378:metabolism*; D014873:Water Pollutants / Q000032:analysis*
D004202:Disinfectants; D009281:Naphthalenes; D010968:Plasticizers; D014873:Water Pollutants; D005557:Formaldehyde