Fingerprinting sources of bacterial input into small residential watersheds: fate of fluorescent whitening agents     

Thomas?B.?BovingEmail author  Debra?L.?Meritt  Jon?C.?Boothroyd 《Environmental Geology》2004,46(2):228-232

The presence of fecal coliform bacteria in many watersheds is often linked to septic system effluent. Fluorescent whitening agents (FWA) are part of most laundry detergent formulations and previously have been used for fingerprinting anthropogenic sewage waters. This study was carried out to investigate the fate of FWA in spring water downstream from a well-monitored septic system in a small forest watershed. Samples for FWA were collected at the spring and along the flow path downstream and analyzed fluorometrically. Selected sampling events were scheduled at night and daytime and after rainstorms to investigate possible changes in the spring water composition. In addition, reference fluorescence spectra were prepared for humic and tannic acid and for the laundry detergent used exclusively in the household discharging into the test septic system. The results indicate that FWA can be detected in spring water, but interference with increasing humic acid concentration downstream limits the fingerprinting value of the method to the vicinity of the spring. Also, sampling for FWA after rainstorms only yielded results if at least 4 days had passed. Otherwise, dissolved organic substances transported into the spring water interfered with the FWA spectrum. No significant differences between night and daytime sampling were found. Overall, the method, as used at this study site, is of limited value for fingerprinting FWA in natural waters.  相似文献   

Geopolymer formation and its unique properties   总被引：3，自引：0，他引：3  

Daeik Kim  Hsuan-Ting Lai  George V. Chilingar  Teh Fu Yen 《Environmental Geology》2006,51(1):103-111

The characteristic property of naturally-occurring geopolymers is a high content of humic materials that are recognized by the nitrogen function. Through a simulated geopolymerization, biopolymers with non-nitrogen function, such as xanthan gum, were found to have the characteristics of humic acid by means of UV–Vis spectrometry. This fact ascertains that any kind of biopolymer may naturally transform to a geopolymer. A geopolymer is a type of crosslinked long-chain compound, built in three-dimensional structures whose property is immune to microbial degradation. A crosslinked biopolymer was shown to have the same characterization as a geopolymer that has a long life due to its crosslinking capacity and anti-microbial properties. In this study, the formation of petroleum-based geopolymers (e.g., kerogen) was introduced. This study may elucidate the structure of geomacromolecules and the mechanism of their formation, closely related with crosslink reaction between inorganic and organic molecules. This will further change the conventional definition of geopolymer that involves only the inorganic geopolymer.  相似文献