<p> 1</p><p>Table S1. Weighted mean turnover times of bulk dissolved organic matter (DOM) in surface and deep waters of the North Atlantic and North Pacific Oceans.</p><p>Surface Oceana Deep Oceanb Turnover Turnover Relative Relative Organic and 14C age, A rate 14C age, A rate i contribution of i contribution of size fractions (years B.P.) c constant, (years B.P.) c constant, fraction, Fi -1 d fraction, Fi -1 d ki (year ) ki (year ) Atlantic LE Fractione 8,140 0.0002 1.84E-08 14,250 0.0002 1.40E-08 PL Fractionf 10 0.0200 2.00E-03 1,950 0.0229 1.17E-05 CL Fractiong 5 0.0713 1.43E-02 2,970 0.0338 1.14E-05 MUC Fractionh 230 0.0587 2.55E-04 2,270 0.0430 1.89E-05 LMW Fractioni 2,640 0.8502 3.22E-04 3,890 0.9003 2.31E-04 Sum = 1.68E-02 Sum = 2.74E-04 TOTj = 59 years TOTj = 3,656 years Pacific LE Fractione 6,430 0.0005 7.00E-08 17,100 0.0003 1.75E-08 PL Fractionf 170 0.0285 1.68E-04 3,240 0.0169 5.22E-06 CL Fractiong 5 0.0539 1.08E-02 4,180 0.0411 9.83E-06 MUC Fractionh 1,780 0.0674 3.78E-05 5,550 0.0417 7.51E-06 LMW Fractioni 2,640 0.8503 3.22E-04 6,220 0.9003 1.45E-04 Sum = 1.13E-02 Sum = 1.67E-04 TOTj = 89 years TOTj = 5,977 years aSurface ocean calculations for 3m (Atlantic) and 20m (Pacific) depths. bDeep ocean calculations for 1500m (Atlantic) and 1800m (Pacific) depths. c Relative contributions, Fi, of LE, PL, CL and MUC fractions to DOM are equal to (%LE/100), (%PL/100), (%CL/100) and (%MUC/100), respectively, multiplied by the relative amount of high- molecular-weight DOM, FHMW, in DOM. Percentage contributions of each organic fraction to </p><p>DOMHMW are shown in Table 1. DOMHMW was assumed to comprise of 15% of DOM in surface waters and 10% in deep waters. The relative contribution, Fi, of low-molecular-weight (LMW) </p><p>DOM to DOM was calculated as FLMW = 1.0 - FHMW.</p><p>F d i -1 k i  , in year . See Methods section for complete explanation of the calculation. Ai eLE – lipid-extract fraction fPL – protein-like fraction gCL – carbohydrate-like fraction hMUC – molecularly-uncharacterised fraction iLMW – low-molecular-weight fraction, <1,000 Daltons</p><p>Loh, Bauer and Druffel (2003-12-13160B) 2</p><p>1 j weighted mean turnover time of bulk DOM, TOTDOM  , in years.  k i</p><p>Loh, Bauer and Druffel (2003-12-13160B)</p>