@article{gao_zong_2021, title={Using water age to study the biogeochemistry of nutrients in a large-river estuary and the adjacent shelf area}, volume={214}, ISSN={["1879-1573"]}, DOI={10.1016/j.jmarsys.2020.103469}, abstractNote={Whether a large-river estuary and the adjacent area behave as a water sink or as a source for important terrestrial biogeochemical compounds is a challenging question. Such aquatic systems are very complex and can be overwhelmed by physical circulation and estuarine mixing. In this study, physical oceanography and marine biogeochemistry were combined to address this question. Seven cruises were conducted in the Changjiang River (Yangtze) Estuary and the adjacent East China Sea shelf in February–March and in July over a three year period (2014 to 2016). During each cruise, nutrient concentrations (NO3−, SiO32−, PO43−, NH4+, and NO2−) and salinity were measured at the surface, middle, and bottom layers of 75–106 sampling stations, and water age was derived from numerical modeling. Two-variable regression analysis among salinity, water age, and nutrients was applied to calculate the specific variation rates of nutrient concentration versus water age. A positive rate value indicated that the water was a source of nutrients, and a negative value indicated the site as a sink. In both seasons tested, calculations for the five nutrients analyzed showed that all biogeochemical processes occurring in Changjiang Diluted Water (salinity <31.5) could distinctly change terrestrial fluxes from the Changjiang River in both seasons. Thus, the proposed method has the potential to elucidate the nonconservative behaviors, net fluxes, and budgets of important biogeochemical compounds through large-river dominated estuarine, coastal, and shelf areas worldwide.}, journal={JOURNAL OF MARINE SYSTEMS}, author={Gao, Lei and Zong, Haibo}, year={2021}, month={Feb} } @article{robbins_daly_barbero_wanninkhof_he_zong_lisle_cai_smith_2018, title={Spatial and Temporal Variability of pCO(2), Carbon Fluxes, and Saturation State on the West Florida Shelf}, volume={123}, ISSN={["2169-9291"]}, url={https://doi.org/10.1029/2018JC014195}, DOI={10.1029/2018JC014195}, abstractNote={AbstractThe West Florida Shelf (WFS) is a source of uncertainty for the Gulf of Mexico carbon budget. Data from the synthesis of approximately 135,000 pCO2 values from 97 cruises from the WFS show that the shelf waters fluctuate between being a weak source to a weak sink of carbon. Overall, the shelf acts as a weak source of CO2 at 0.32 ± 1.5 mol m−2 yr−1. Subregions, however, reveal slightly different trends, where surface waters associated with 40–200‐m isobath in the northern and southern WFS are generally weak sinks all year, except for summer when they act as sources of CO2. Conversely, nearshore waters (<40 m) are a source of CO2, particularly the southern shallow waters, which are a source all year round. The pCO2 of seawater has been increasing at a rate of approximately 4.37 μatm/year as compared to atmospheric pCO2 which has increased at a rate of about 1.7 μatm per year from 1996 to 2016. The annual CO2 flux has increased from −0.78 to 0.92 mol m−2 yr−1 on the shelf from 1996–2016. The WFS is emitting 9.23 Tg C/year, with the southern nearshore region emitting the most at 9.01 Tg C/year and the northern region acting as a sink of −1.96 Tg C/year. Aragonite saturation state on the WFS shows seasonal and geographic trends with values ranging from 2 to 5. Lowest values are found in winter associated with subregion <40‐m isobath.}, number={9}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Robbins, L. L. and Daly, K. L. and Barbero, L. and Wanninkhof, R. and He, R. and Zong, H. and Lisle, J. T. and Cai, W. -J. and Smith, C. G.}, year={2018}, month={Sep}, pages={6174–6188} } @article{zeng_he_zong_2017, title={Variability of Changjiang Diluted Water revealed by a 45-year long-term ocean hindcast and Self-Organizing Maps analysis}, volume={146}, ISSN={["1873-6955"]}, DOI={10.1016/j.csr.2017.08.010}, abstractNote={Based on long-term realistic ocean circulation hindcast for in the Bohai, Yellow, and East China Seas, 45 years (1961–2005) of sea surface salinity data were analyzed using Self-Organizing Maps (SOM) to have a better understanding of the Changjiang Diluted Water (CDW) variation. Three spatial patterns were revealed by the SOM: normal, transition, and extension. The normal pattern mainly occurs from December to May while the CDW hugs China's east coast closely and flows southward. The extension pattern is dominant from June to October when the CDW extends northwestward toward Jeju Island in an omega shape. The transition pattern prevails for the rest of the year. Pattern-averaged temperature, circulation, and chlorophyll-a concentration show significant differences. CDW area and its eastern most extension were explored as a function of the Changjiang runoff and regional upwelling index. We found that Changjiang runoff and upwelling index can be reasonable predictors for the overall CDW area, while ambient circulation determines the distribution and structure of the CDW, and thus the CDW eastern most extension.}, journal={CONTINENTAL SHELF RESEARCH}, publisher={Elsevier BV}, author={Zeng, Xiangming and He, Ruoying and Zong, Haibo}, year={2017}, month={Aug}, pages={37–46} }