Using an improved satellite-derived salinity algorithm in the East China Sea (ECS), we presented and examined a general view on summertime Changjiang River plume variation during 1998-2010. Three types of plume shapes were identified: (1) the commonly known northeastward transportation, (2) a case in which most of the plume water crossed the Cheju Strait into the Tsushima-Korea Straits with only a small fraction staying on the shelf of the ECS, and (3) a rare case in which the plume front moved southeastward. Satellite time-series data suggested that, during the peak river discharge time in July with favorable southwest monsoon, the plume area was highly correlated with the river discharge of the same month. Interestingly, the plume area in August was also dominated by the discharge in July. In August, as the direct effect of freshwater discharge weakening, the plume area also became positively correlated with wind speed in the 45 and 60 direction, suggesting that the plume extension was more influenced by the southwesterly wind during periods of smaller discharge. Furthermore, a few special cases with unique plume extensions were found under extreme weather conditions. Finally, we found no significant long-term trend of plume area change over 1998-2010 in summertime and concluded that the interannual variation was probably regulated by natural variation rather than anthropogenic effects, such as construction of the Three Gorges Dam. This study will have implications for biogeochemical and modeling studies in large river plume areas.

[1] Distributions and fluxes of methane were determined during two surveys in March-May 2001 in the Yellow Sea and the East China Sea. Methane concentrations in the surface and bottom waters range from 2.52 to 5.48 and 2.81 to 8.17 nM, respectively. The distributions of methane are influenced obviously by the Yangtze River effluent and Kuroshio water. CH 4 input via the Yangtze River is estimated to be 3.17 mol/s, of which a considerable part may be lost by air-sea exchange during estuarine mixing. Net CH 4 flux exported from the shelf to the Kuroshio is about 1.84 mol/s. Methane enrichments in bottom waters occur widely, which reveals sediment sources of CH 4 . However, the CH 4 input from the sediments of the studied region in spring is lower than other shelf regions due to low organic carbon in the sediments and high O 2 contents in the water column. The sea-to-air methane fluxes are estimated to be 1.36 ± 1.45 and 2.30 ± 2.36 mmol m À2 d À1 using Liss and Merlivat [1986] and Wanninkhof [1992] relationships, respectively, and the estimated spring emission rate of methane ranges from 9.32 Â 10 À3 to 15.7 Â 10 À3 Tg CH 4 yr À1 . However, these estimations suffer from the neglect of seasonal variability and should be taken as a low limit. Therefore more measurement campaigns should be carried out to enhance our understanding of this particular oceanic region.

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Little is known about the effects of air-drying and freezing on the transformation of phosphorus (P) fractions in soils. It is important that the way in which soils respond to such perturbations is better understood as there are implications for both P availability and loss to surface waters from soils. In this study, the effects of air-drying and freezing were investigated using two soils, one being a forest soil (FS) high in organic matter and the other being a sterile soil (SS) low in organic matter. Soil P was fractionated using a modified Hedley fractionation method to examine the changes of phosphorus fractions induced by air-drying and freezing. Generally, there were no significant differences of total phosphorus among the three treatments (CV% < 10%). Compared with field moist soils, freezing the soil evoked few changes on phosphorus fractions except that the resin-P increased in FS soil. On the contrary, air-drying significantly changed the distribution of phosphors fractions for both soils: increased the labile-P (especially resin-P) and organic-P (NaHCO 3 -Po, NaOH-Po and Con.HCl-Po) at the expense of NaOH-Pi and occlude-P (Dil.HCl-P and Con.HCl-Pi). Resin-P significantly increased by 31% for SS soil and by 121% for FS soil upon air-drying. The effect of air-drying seemed to be more pronounced in the FS soil with high organic matter content. These results indicated that drying seem to drive the P transformation form occlude-P to labile-P and organic-P and accelerated the weathering of stable P pool. This potentially could be significant for soil P supply to plants and P losses from soils to surface waters under changing patterns of rainfall and temperature as predicted by some climate change scenarios.