PII S0016-7037(00)00450-6 Terrestrially derived dissolved organic matter in the Chesapeake Bay and the Middle Atlantic Bight

Abstract—Concentrations of lignin-phenols were analyzed in high molecular weight dissolved organic matter (0.2 mm. HMW DOM. 1 kDa) isolated from surface waters of the Chesapeake Bay (C. Bay), and surface and bottom waters of the Middle Atlantic Bight (MAB). The abundance of lignin-phenols in HMW DOM was higher in the C. Bay (0.128 6 0.06 mg L21) compared to MAB surface waters (0.016 6 0.004 mg L21) and MAB bottom waters (0.005 6 0.003 mg L21). On an organic carbon-normalized basis, lignin-phenol abundances in the HMW DOM (i.e., L6), were significantly higher ( p, 0.05) in bottom waters compared to sediments at some stations in the MAB. Ratios of syringyl to vanillyl phenols (S/V) in HMW DOM, indicative of angiosperm-derived lignin, ranged from 0.165 to 0.422 in C. Bay, 0.100 to 0.314 in MAB surface waters, and 0.076 to 0.357 in MAB bottom waters. Ratios of vanillic acid to vanillin (Ad/Al)V in HMW DOM, indicative of lignin decay, ranged from 0.611 to 1.37 in C. Bay, 0.534 to 2.62 in MAB surface waters, and 0.435 to 1.96 in MAB bottom water. Ratios of S/V and (Ad/Al)V showed no significant differences between each environment, providing no evidence of any compositionally distinct input of terrestrial organic matter into each environment. When considering depth profiles of suspended particulate matter in the MAB, with C:N ratios, and bulk radiocarbon ages and stable carbon isotopic values in HMW DOM isolated from these areas, two scenarios present themselves regarding the sources and transport of terrestrially derived HMW DOM i