Deep-Sea Research I 49 (2002) 2119–2132 Transport and diagenesis of dissolved and particulate terrigenous organic matter in the North Pacific Ocean Peter J. Hernes a,b , Ronald Benner a, * a Department of Biological Sciences and Marine Science Program, University of South Carolina, Columbia, SC 29208, USA b Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA Received 20 August 2001; received in revised form 8 March 2002; accepted 24 September 2002 Abstract Lignin measurements were made on suspended particulate organic matter (POM), total dissolved organic matter (DOM), high-molecular-weight (HMW) DOM, and low-molecular-weight (LMW) DOM in the North Pacific at Station Aloha. Carbon-normalized yields of lignin and d 13 C measurements indicate that while terrigenous organic matter accounts only for B1% of DOM in seawater, submicron POM has a substantial terrigenous component. The apparent size distribution and terrigenous nature of the particles is consistent with an aerosol source, but these particles could also be delivered to the ocean via rivers. Ratios of syringyl to vanillyl phenols as well as the fraction of dissolved lignin in HMW DOM provide molecular evidence of photochemical oxidation. Several differences in lignin composition and concentrations were evident between water masses. In particular, concentrations in North Pacific Intermediate Water were a factor of two greater than at all other depths. This is likely a reflection of higher riverine input via the Sea of Okhotsk. These trends suggest that lignin could serve as a general circulation tracer in addition to tracing riverine input and diagenetic processing of terrigenous organic matter in the ocean. r 2002 Elsevier Science Ltd. All rights reserved. Keywords: Terrigenous organic matter; Lignin; Dissolved organic matter; Particulate organic matter; Aerosol; Diagenesis; Photochemistry; North Pacific Ocean; Station Aloha 1. Introduction The fate of terrigenous organic matter (OM) in the ocean is poorly understood (Hedges et al., 1997). Riverine OM represents highly degraded vascular plant materials (Ertel et al., 1986; Ittekkot, 1988; Hedges et al., 1994), and riverine discharge of dissolved OM (DOM) is sufficient to support the turnover of dissolved organic carbon throughout the ocean (Williams and Druffel, 1987). Similarly, the discharge of riverine particu- late organic carbon is sufficient to account for all organic carbon preservation in marine sediments (Berner, 1989). However, there is little evidence that terrigenous DOM or particulate OM (POM) persist as major components of oceanic OM reservoirs. Bulk chemical and isotopic character- izations are either not sensitive to the terrigenous content of OM in seawater, or point toward a predominantly marine source. Only at the *Corresponding author. Tel.: +1-803-777-9561; fax: +1- 803-777-4002. E-mail address: benner@biol.sc.edu (R. Benner). 0967-0637/03/$-see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII:S0967-0637(02)00128-0