三亚湾近10年pH的时空变化特征及对珊瑚礁石影响分析

Spatial and temporal distribution of pH in Sanya Bay in recent 10 years and its effects on coral reef

文章对三亚湾近10年的海水酸碱度(pH)数据分析发现,三亚湾的pH变化范围表层为8.01～8.23,底层为8.01～8.24,平均为8.14。2001年后三亚湾水体pH呈现明显的下降趋势,从年平均的8.30以上下降到8.07,下降了0.2,大于全球平均海水酸化速度。从pH垂直分布来看,出现4种类型:1)上层pH小,下层pH大;2)上层和下层pH大,中层pH小;3)上层和下层pH小,中层pH大;4)上层、中层和下层pH出现明显的递减趋势。从pH的平面分布来看,不同季节pH的分布有一定的变化,但在河口区域,pH相对较小的趋势出现概率较大。珊瑚礁石溶钙试验表明,pH由7增加至8时,溶钙量约由12 mg.L-1呈指数下降至约1 mg.L-1,下降约91.67%。目前三亚湾pH仍然处于珊瑚礁正常生长的范围之内(8.0～8.3),pH在一定程度的降低还未对珊瑚生长产生较大的负面影响。

According to the 10-year monitoring data of pH in Sanya Bay, the ranges of pH in the surface and bottom water are 8.01 8.23 and 8.01 -8.24, respectively, with 8. 14 on average. The pH has showed a decreasing trend since 2001, decreasing from 8.30 to 8. 07 on annual average during 2001 - 2010, which is greater than the global ocean acid velocity. Four types of vertical distributions of pH are found in Sanya Bay： 1） Upper layer is smaller while bottom layer is greater; 2） Upper layer and bottom layer are greater while middle layer is smaller ; 3 ） Upper layer and bottom layer are smaller while middle layer is greater; 4） Upper layer, middle lay- er and bottom layer reveal an obvious decreasing trend. From the aspect of horizontal distribution, the pH varies greatly in different seasons and lower pH is mainly found in the estuary. By analyzing the effects of pH on coral reef, we find that when the pH increased from 7 to 8, the content of dissolved calcium decreased from 12 mg·L^-1 to 1 mg.L^-1. Therefore, the pH in Sanya Bay is currently still within the range of normal growth of coral reef （ 8.0 - 8.3）, and no negative effects are found.