The geochemistry preserved in massive scleractinian corals has long been used as proxies for river runoff, but its reliability in naturally extreme environment (i.e., strong hydrodynamics and intensive thermal stress) has not been tested yet. Using Porites coral collected from the macrotidal nearshore Kimberley region of northwestern Australia, we assess the impacts of river runoff and associated changes in this extreme environment using elemental (Ba/Ca) and isotopic (δ¹⁸O and δ¹³C) compositions at both near monthly and annual resolutions. On the monthly timescales, significant terrestrial signatures were noted in skeletal Ba/Ca, ∆δ¹⁸O, and to a lesser extent in δ¹³C time series, highlighting their linkage to runoff input of Fitzroy River. However, all the geochemical time series as well as the observational coastal sea surface salinity exhibited a consistent ~1‐ to 2‐month lag with river discharge, possibly a manifestation of the sluggish water and sediments exchange in King Sound which are likely induced by strong tidal forcing. On the annual timescales, Ba/Ca follows the variation in river discharge, while freshwater supplied by both runoff and rainfall all contributed to δ¹⁸O variations. In contrast, annual δ¹³C is mainly dominated by the ¹³C Suess effect, showing a gradually downward trend. Importantly, we find that δ¹⁸O and Ba/Ca records exhibit consistent and significant long‐term trends, with δ¹⁸O being decreasing and Ba/Ca being increasing, coupled with the increased Australian monsoon, indicating that strengthened monsoon precipitation has likely brought more freshwater and sediment loads to the nearshore Kimberley region.

中文翻译：

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澳大利亚西北部金伯利地区大潮主导的近岸礁环境中珊瑚Ba / Ca，δ18O和δ13C记录中的陆地特征

长久以来，保存在大型巩膜珊瑚中的地球化学一直被用作河流径流的代理人，但其在自然极端环境（即强水动力和强烈热应力）中的可靠性尚未得到测试。使用滨从澳大利亚西北部的macrotidal近岸金伯利区域收集珊瑚，我们评估河川径流的在这种极端的环境中使用的元素（的Ba / Ca）的影响和相关的变化和同位素（δ ¹⁸ O和δ ¹³ C）的组合物在两个邻近每月和每年的决议。在每月的时间尺度，显著地面签名骨骼肌的Ba / CA，Δδ，注意到¹⁸ O，以及在较小程度上在δ ¹³C时间序列，突显了它们与菲茨罗伊河径流输入的联系。然而，所有的地球化学时间序列以及观测到的沿海海表盐度都与河水流量表现出一致的〜1-2个月的滞后，可能是国王之声水和泥沙交换缓慢的表现，这很可能是由强烈的潮汐强迫。在年度的时间尺度，钡/钙如下在河流流量的变化，而由两者径流供给和降雨量都促成了δ淡水^18种ö变化。与此相反，每年δ ¹³ C主要由主导¹³ Ç休斯效果，呈现出逐渐下降的趋势。重要的是，我们发现δ ¹⁸O和钡/钙记录表现出一致的，显著的长期趋势，δ ¹⁸ O为减少和Ba /钙是越来越多，再加上增加了澳季风，表明加强季风降水可能已经带来了更多的淡水和泥沙量的金伯利地区近岸。