Regular spatial and seasonal distribution patterns of sedimentary chloropigments occurred at 19 subtidal stations located in Long Island Sound (LIS) from MAY 1988 to APR 1989. Inventories of chloropigments were higher (2–10x) in western than central LIS, mirroring patterns of phytoplankton production in surface waters. Shallow water sediments (<25 m) received more chloropigments than deep stations (>25 m). Lateral resuspension and redistribution of particles, as shown by 234Th inventories, are partly responsible for these patterns. Seasonal variations of Chl-a inventories in LIS sediments follow the production pattern in the water column: higher values occur in spring and lower values in summer and fall. A time lag (about 1–2 months) exists between maximum Chl-a (during early spring) and maximum phaeopigment sedimentary inventories (during late spring). Vertical profiles of chloropigments often exhibited exponential decreases with depth, implying that degradation processes significantly affect chloropigment distributions. Based on temperature-dependent first-order decomposition rate constants, reactive Chl-a inventories were converted into planktonic carbon fluxes across the water-sediment interface. These agreed reasonably well (within a factor of 2) with total benthic O2 uptake at the same sites. Particle reworking rates were estimated by using chl-a profiles combined with diagenetic models of decomposition. The seasonal patterns and magnitudes of DB (sediment mixing coefficients) derived from chl-a distributions are similar (±2–3x) to those estimated from 234Th distributions.