## 4 Estimates of Tidal Export of DIC, DOC, POC, CH\({}_{4}\), and Alkalinity  
High concentrations of DIC, DOC, CH\({}_{4}\), and total alkalinity in the interstitial water pool and subsurface transport results in significant export to adjacent tidal waters of the coastal ocean (Table 2). Only comparatively few locations, most in Australia, have been used to measure transport, but they are consistent in revealing high rates of export. Mean DIC, alkalinity, DOC, and CH\({}_{4}\) exports were 339.6, 211.5, 229.1, and 0.66 mmol m\({}^{-2}\) d\({}^{-1}\), respectively (Table 2).  
Unlike the data for DIC, alkalinity, and CH\({}_{4}\), there are earlier estimates of DOC export, as summarized by [PERSON] and [PERSON] [7]. Combining the data in Table 2 and in [7], DOC export averaged \(85.3\pm 35.8\) (\(\pm 1\) SE) mmol m\({}^{-2}\) d\({}^{-1}\) over 41 measurements. POC export, derived from data in [7; 10], averaged \(25.1\pm 9.2\) (\(\pm 1\) SE) mmol m\({}^{-2}\) d\({}^{-1}\) over 63 measurements.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters** & **Mean** & **Median** & **Number of Measurements** \\ \hline Total alkalinity & \(1317.6\pm 153.3\) & \(1211.0\) & \(41\) \\ \hline \(p\)CO\({}_{2}\) & \(3202.8\pm 306.6\) & \(1233.0\) & \(219\) \\ \hline CO\({}_{2}\) & \(1446.3\pm 162.3\) & \(1270.5\) & \(44\) \\ \hline DIC & \(1838.0\pm 71.4\) & \(2024.0\) & \(83\) \\ \hline CH\({}_{4}\) & \(244.7\pm 49.1\) & \(135.5\) & \(60\) \\ \hline CO\({}_{2}\) fluxes & \(78.9\pm 8.0\) & \(50.0\) & \(143\) \\ \hline CH\({}_{4}\) fluxes & \(530.4\pm 78.5\) & \(260.1\) & \(134\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Mean (\(\pm 1\)SE) and median concentrations of alkalinity (uM), \(p\)CO\({}_{2}\) (uatm), CO\({}_{2}\) (uM), dissolved inorganic carbon (DIC, uM), and CH\({}_{4}\) (nM) and CO\({}_{2}\) (mmol m\({}^{2}\) d\({}^{-1}\)) and CH\({}_{4}\) fluxes (umol m\({}^{-2}\) d\({}^{-1}\)) across the water-air interface in mangrove waters worldwide. Data from [66; 67; 68; 69; 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Location** & **DIC Export** & **Alkalinity Export** & **DOC Export** & **CH\({}_{4}\) Export** & **Reference** \\ \hline Southern Moreton Bay, & \(186\pm 37\) & \(69\pm 14\) & \(72\pm 15\) & \(0.014\pm 0.0023\) & \\ Queensland, Australia & \(205\pm 41\) & \(88\pm 18\) & \(65\pm 13\) & \(0.0056\pm 0.0011\) & [94] \\  & \(247\pm 49\) & \(132\pm 26\) & \(40\pm 8\) & \(0.017\pm 0.0034\) & \\ \hline Evans River estuary, & \(125\pm 82\) & \(51\pm 34\) & \(136\pm 89\) & \(0.6\pm 0.4\) & \\ New South Wales, & \(559\pm 292\) & \(321\pm 172\) & \(562\pm 293\) & \(2.3\pm 1.4\) & \\ Australia & \(165\pm 102\) & \(59\pm 37\) & \(202\pm 125\) & \(0.8\pm 0.6\) & \\ \hline Maowei Sea, Guangxi & \(700\pm 820\) & ND & \(310\pm 300\) & ND & [96] \\ Province, & \(250\pm 240\) & & \(250\pm 230\) & ND & [96] \\ south China & & \(440.4\pm 232.6\) & \(365.5\pm 177.2\) & \(846.1\pm 936.5\) & \\ Eastern Gulf of & \(146.2\pm 125.1\) & \(896.4\pm 459.3\) & \(176.2\pm 529.9\) & \\ Carpentaria, & \(610.9\pm 342.0\) & \(564.0\pm 383.5\) & \(2110.5\pm 1762.8\) & ND & [97] \\ Australia & \(774.3\pm 223.5\) & \(726.9\pm 261.0\) & \(294.2\pm 1276.2\) & \\  & \(730.0\pm 416.5\) & \(679.2\pm 367.3\) & \(153.4\pm 626.7\) & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mean (\(\pm 1\)SE) rates (mmol m\({}^{-2}\) d\({}^{-1}\)) of DIC, total alkalinity, dissolved organic carbon (DOC), and CH\({}_{4}\) export from mangrove forests to adjacent mangrove and coastal waters measured recently from various locations worldwide. These empirical estimates were derived from using a Eularian approach of time-series water sampling and tracing of radium isotopes. ND = no data.