季风上升流对印尼爪哇岛南部海域pH影响的初步研究

Influence of monsoon upwelling on pH off the southern coast of Java Island,Indonesia:apreliminary study

基于2013年9月底至10月初在印尼爪哇岛南部海域调查得到的碳酸盐参数和相关水文数据,首次报道了该海域pH的分布,并重点探讨了南爪哇上升流(季风上升流)对其影响。结果显示上升流影响区表层pH低于周围非上升流影响区。通过两端元混合模型,定量讨论了上升流的物理输运和生物活动对pH的影响。研究表明,上升流的物理输运至少造成了海表层盐度增加0.4个单位,溶解无机碳(DIC)增加110μmol/kg,pH降低约0.2个单位;同时,在上升流区,强烈的生物活动(叶绿素a浓度大于0.4mg/m3)使得DIC的降低量达70μmol/kg,pH的增加量达0.15个单位。总体来看,该研究区域的物理输运作用大于生物作用,综合效应表现为DIC的增加和pH的降低。另外,同上升流的物理输运作用和生物作用相比,上升流引起的表层冷却和增盐对pH的影响较小(热力学作用)。

pH and its influence by upwelling process off the southern coast of Java Island, Indonesia were examined for the first time using carbonate and related hydrographic data collected from late September to early October 2013. We found that sea surface pH was lower in the upwelling area than in the nearby nonupwelling area. A two end-member mixing model was used to separate the two opposite effects of the upwelling process on pH： physical transport of CO2 rich waters from subsurface layers vs. biological production. Results showed that physical transport at least led to a dissolved inorganic carbon （DIC） increase of 110μmol/kg,and a pH decrease of about 0.2 units,while strong biological production （chlorophyll a level above 0.4 mg/ma） induced a DIC decrease by up to 70 μmol/kg,and a p H increase by up to 0. 15 units. Overall, the physical transport of CO2 rich waters was dominant, leading to a net decrease in pH. Also,we found that surface cooling and salinity increases induced by the upwelling played a relatively minor role in affecting pH （thermodynamically）, compared with effects of physical transport and subsequent biological production associated with the upwelling.