Revisiting carbon flux through the ocean's twilight zone
Buesseler, K.O., Lamborg, C.H., Boyd, P.W., Lam, P.J., Trull, T.W., Bidigare, R.R., Bishop, J.K.B., Casciotti, K.L., Dehairs, F., Elskens, M., Honda, M., Karl, D.M., Siegel, D.A., Silver, M.W., Steinberg, D.K., Valdes, J., Van Mooy, B., Wilson, S.
POC flux versus depth at ALOHA (22° 45′ N, 158° W) and K2 (47° N 160° E). (A) POC flux at ALOHA (triangles) and K2 (circles) with open and solid symbols for deployments 1 and 2, respectively (deployment start dates in Table 1). (B) Same data normalized to 150 m POC flux and compared with Martin et al. (4) (dashed line). For each depth, up to three independent NBSTs were deployed from the same launch site, and the POC fluxes are shown (A) for each NBST, with a slight vertical offset, as the mean and standard deviation of replicate POC measurements (n from 2 to 4). Fits to normalized data (B) used a power function of the form F/F150 = (z/150)–b, where z is the depth of the trap, F150 is the POC flux at the 150-m reference depth, and b describes the rate of flux attenuation.
Science. 316:567-570. (2007)
The oceanic biological pump drives sequestration of carbon dioxide in the deep sea via sinking particles. Rapid biological consumption and remineralization of carbon in the “twilight zone” (depths between the euphotic zone and 1000 meters) reduce the efficiency of sequestration. By using neutrally buoyant sediment traps to sample this chronically understudied realm, we measured a transfer efficiency of sinking particulate organic carbon between 150 and 500 meters of 20 and 50% at two contrasting sites. This large variability in transfer efficiency is poorly represented in biogeochemical models. If applied globally, this is equivalent to a difference in carbon sequestration of more than 3 petagrams of carbon per year.
Last updated: December 14, 2011