Distributions of carbohydrates, including uronic acids, in estuarine waters of Galveston Bay

The concentrations of carbohydrates, including uronic acids, in dissolved ( less than or equal to 0.45 mum) and colloidal (1 kDa-0.45 mum) phases were measured in estuarine waters of Galveston Bay, TX, in order to study their role in heavy metal detoxification. The concentrations of dissolved monosac charides (MCHO) in Galveston Bay ranged from 13 to 62 muM-C, and those of d issolved polysaccharides (PCHO) ranged from 10 to 42 muM-C. On average, MCH O and PCHO contributed about 11% and 7% to dissolved organic carbon (DOC), respectively. The colloidal carbohydrates (CCHO) in Galveston Bay varied fr om 7 to 54 muM-C, and accounted for 9% to 24% of the colloidal organic carb on (COC), with an average value of 17%, suggesting that CCHO is abundant in the high molecular weight (HMW) fraction of DOG. The concentration of CCHO is generally significantly higher than that of PCHO. This result is attrib uted to entrainment of low molecular weight (LMW) carbohydrates into the re tentate fraction during ultrafiltration. The concentration of total dissolv ed uronic acids (DUA) in the same samples varied from 1.0 to 8.3 muM-C, wit h an average value of 6.1 muM-C, while the colloidal uronic acids (CUA) ran ged from 0.8 to 6.4 muM-C, with an average value of 4.8 muM-C. The concentr ations of DUA are higher than the previously reported values in coastal wat ers. Furthermore, CUA represent a dominant component of DUA in Galveston Ba y waters. More importantly, significant correlations of PCHO and DUA to dis solved Cu concentrations (less than or equal to0.45 mum) were found, sugges ting that acid polysaccharides were produced in response to trace metal str essors. (C) 2001 Published by Elsevier Science B.V.