全球开阔海洋由于人类活动排放CO2增加引起的酸化速率平均在-0.0016pH.yr-1。而在沿岸海域水体中pH的变化幅度远大于此，其中受生物代谢过程的酸化信号最显著，可达0.3pH。近岸系统对酸化过程也呈现出更敏感和脆弱的一面。根据近年的调查结果显示，东海近岸次表层水体出现了季节性海水酸化信号加强的现象(pH在几周内降低了0.3)，但关于其形成的生物地球化学机制的研究仍然相对薄弱。本申请拟通过分析已有文献和现场调查数据，建立端元混合模型，厘清主要水团来源端元值的变化对东海近岸底层水体酸化缓冲能力的影响；在明确酸化背景信号的基础上，依托高分辨率的生化剖面参数进行半定量分析，重点探讨生物过程（主要是有机质降解释放的CO2在次表层水中的累积效应）在东海近岸底层水酸化加剧过程中的贡献，并尝试建立东海近岸酸化敏感度模型。项目的开展将有助于深入认识东海近岸酸化的调控机制，并为预测沿岸酸化提供科学依据。

The average acidification rate caused by CO2 emissions in open ocean is -0.0016 pH.yr-1. The change of pH in the coastal waters is much severe than that in the open ocean. Overall, biological metabolic influence is as significant, up to 0.3 pH. The offshore system also presents a more sensitive and fragile to ocean acidification. According to the results of the field survey in recent years, the phenomenon of intensified seasonal coastal acidification (decrease pH of 0.1 in few weeks) appears in the subsurface waters of the East China Sea. The preliminary analyses indicate that, on the basis of the acidified source water from Kuroshio Subsurface Water, biological process may further aggravate this acidification signal. However, the ecological formation mechanism is rarely studied. Based on these, this project establishes the end-element mixed model after assuring background acidification signal of subsurface water, and focuses on the contribution of biological process imposed on this acidification phenomenon. In particular, the cumulative effect of organic matter degradation (that release CO2 on subsurface water) will be emphasized. This project will help to understand the regulation mechanism of acidification in the East China Sea and provide a scientific basis for predicting the acidification along the coast.