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From a large number of case studies on terrestrial deposits we know that Late Holocene climate fluctuations have an important impact on the terrestrial environments. However, it is hitherto not clear how the marine sediments can be used to shed light on the environment and climate change of the catchment. To provide such insight, we used the major element, trace element and rare earth element (REE) compositions in the southern Yellow Sea (SYS) sediments to reconstruct the changes in weathering and erosion of their source regions. The sediments originate predominantly from the upper crust of East China and are transported into the basin especially by the Yellow River (Huanghe) and to a lesser extent by the Yangtze River (Changjiang). The chemical index of alteration (CIA; 53.7-59.7) suggests low chemical weathering of the source rocks since the Middle Holocene. This is consistent with the relatively cool and arid climate in North China after the Holocene Megathermal. Comparison of element ratios, including Al/Ca, K/Ca, Al/Na, K/Na, Rb/Sr, Li/Ba and the CIA shows that we can use the latter as a robust proxy for climate change. The CIA-based mean annual precipitation and mean annual temperature show a series of climate fluctuations in the catchment. A relatively warm and humid Period I (5.3-2.9 cal. ka BP), a relatively cool and dry Period II (2.9-0.9 cal. ka BP) and an increasingly cool and dry Period III (0.9-0.3 cal. ka BP). These periods can be linked to climate intervals recognized elsewhere. [ABSTRACT FROM AUTHOR]

Abstract: The distributions, annual sedimentation and atmospheric deposition flux of heavy metals have been studied in sediments of the South Yellow Sea (SYS), in order to evaluate their levels and pollution status. The higher concentrations of heavy metals were generally found in the central part of the SYS, which may be associated with the organic matters due to their high affinity to the metals. According to the calculated enrichment factor (EF) of the studied metals, Cd in the sediments posed a high risk to local environments, while Mn, Hg, Pb and Zn were at moderate risk levels. Sedimentation fluxes study in the SYS showed that most heavy metals were deposited in the Chinese offshore. Annual dry deposition flux of these metals indicated that the particulate heavy metals deposition via atmosphere also play an important role in biogeochemical cycles in the SYS. [Copyright &y& Elsevier]

Surface partial pressure of CO 2 ( p CO 2 ) and pertinent parameters (i.e., pH, total alkalinity, dissolved oxygen, chlorophyll a) were investigated in the southern Yellow Sea (SYS) and the East China Sea (ECS) basing on two surveys conducted in June and August of 2013. The results suggested carbonate chemistry dynamics and related controlling factors were provided with significant temporal and spatial variations in different subregions of these two continental shelf seas. The western of SYS (SYSW) was CO 2 -undersaturated both in June and August, with the average F CO 2 −1.88 mmol m −2 d −1 and −3.72 mmol m −2 d −1 , respectively. The phytoplankton initiated CO 2 -absorption and the suspended sediment induced CO 2 -emission jointly controlled the air–sea CO 2 exchange there. The center of SYS (SYSC) also behaved as an obvious CO 2 sink (−1.57 mmol m −2 d −1 and −3.99 mmol m −2 d −1 in June and August, respectively), probably due to elevated TA/DIC ratio and the subsequent effects of spring bloom. As for the Yangtze River estuary (YRE), it changed from an obvious CO 2 sink (−1.28 mmol m −2 d −1 ) in June into a very weak CO 2 source (0.04 mmol m −2 d −1 ) in August. This change was probably associated with the rising of seawater temperature and monthly variation of Yangtze River discharge. The inner shelf of ECS (ECSS) experienced obvious air–sea CO 2 flux changes during from June (−8.88 mmol m −2 d −1 ) to August (−0.36 mmol m −2 d −1 ) as well. Biological DIC consumption in the upper layer and DIC regenerated from respiration in the subsurface jointly controlled this p CO 2 variation. As a whole, the SYS and ECS acted as an obvious CO 2 sink during summer and could absorb atmospheric CO 2 with the average air–sea flux ( F CO 2 ) −2.68 mmol m −2 d −1 . The summary of air–sea CO 2 flux in the ECS and SYS during recent two decades indicated the ECS served as quite a stable CO 2 sink, whereas the SYS experienced obvious change. Discharge of Yangtze River and anthropogenic nutrients loading could profoundly affect the variations of p CO 2 and F CO 2 in future. [ABSTRACT FROM AUTHOR]

The partial pressure of CO2 (pCO2) and air-sea CO2 exchange flux (FCO2) in the southern Yellow Sea (SYS, 120–125°E, 31.5–37°N) were investigated basing on the field surveys conducted in April of 2011, and June, July, October of 2012. With significant spatial variations, surface pCO2 ranged from 243 to 574μatm, 206 to 620μatm, 102 to 655μatm and 328 to 557μatm in April, June, July and October, respectively. Nearshore area of Shandong Peninsula and Jiangsu Shallow (depth<50m) were pCO2-supersaturated (pCO2=400–600μatm), as the result of intensive water mixing which brought the bottom CO2-rich water to the surface layer. Conversely, offshore area of SYS center (depth>50m) was pCO2-undersaturated (pCO2<390μatm) in April, June and October, but supersaturated in July. Phytoplankton production sustained by abundant nutrient and suitable hydrodynamic conditions was of great importance for this undersaturated pCO2. Moreover, extreme low pCO2 (pCO2<300μatm) was observed in the Changjiang plume (32.5–33.5°N, 123–125°E) in July, which was also related with the biological uptake of CO2. Average air-sea CO2 exchange flux of the SYS in April, June, July and October was −3.16±0.40mmolm−2 d−1,−4.56±0.34mmolm−2 d−1, −0.36±0.51mmolm−2 d−1, and 6.67±0.57mmolm−2 d−1, respectively. As a whole, the SYS behaved as a weak CO2 sink during April to October, with an average flux for about −0.35mmolm−2 d−1. As for the controlling factors for pCO2 variation, temperature played the dominant role in October, whereas the non-temperature factors, such as vertical mixing, Changjiang plume and biological activity, were considered as the primary controlling factors in June and July. Spatially, the control of temperature on pCO2 was predominant in the offshore SYS; the non-temperature factors were predominant in the shallow nearshore area, especially in coast of Shandong Peninsula and the Jiangsu Shallow. [ABSTRACT FROM AUTHOR]