| Comments |
P.484 4th paragraph: "A part of the gross production [FP(gross) or P] is recycled in the surface layer via the dissolution (D) of the biogenic silica. The material that escapes dissolution is exported toward the ocean interior in sinking particles. Multiplying the gross
production by D:P, the ratio of annual biogenic silica dissolution to production, yields the export production. The first estimate of D:P was calculated at 0.58 based on 45 vertically integrated sets of data for production and dissolution simultaneously determined using isotopic tracer methods (Nelson et al. 1995). Table 1 gives an expanded set of data. Noteworthy are the many D:P values
>1 in the top half of Table 1, reflecting scenarios where the integrated dissolution rate measured
in the photic zone exceeds the measured integrated production rate, which is possible only over short timescales or small areas. Studies measuring D:P have generally occurred during the spring
or summer, making it unwise to average the data in Table 1 to produce a typical global annual D:P value. Also complicating the D:P estimate is that different methods have been used to quantify silica dissolution rates. However, time series (italicized locations in the bottom half of Table 1) offer an alternative way to estimate the annual average D:P for a region." See notes beneath table |