Shenzhen Engineering Laboratory for Big Data Analysis and Application of Ocean Environment, Shenzhen Institute of Advanced Technology Chinese Academy of Sciences, 518055, PR China; Center for Geospatial Information, Shenzhen Institute of Advanced Technology Chinese Academy of Sciences, 518055, PR China.
Shenzhen Engineering Laboratory for Big Data Analysis and Application of Ocean Environment, Shenzhen Institute of Advanced Technology Chinese Academy of Sciences, 518055, PR China; Center for Geospatial Information, Shenzhen Institute of Advanced Technology Chinese Academy of Sciences, 518055, PR China.
Environ Pollut. 2022 Jan 15;293:118487. doi: 10.1016/j.envpol.2021.118487. Epub 2021 Nov 10.
Coastal acidification is often much more intense than ocean acidification due to eutrophication. To better understand the relationship between long-term coastal acidification (CA) and coastal eutrophication (CE), in-situ monthly data over the past three decades (1986-2017) were analyzed from Hong Kong Coast (HKC). The coastwide annual mean pH change (ΔpH) was estimated at -0.0085 ± 0.0069 unit·yr in last decades, which was over four times stronger than current estimation on open ocean acidification rate (∼-0.0019 unit·yr). According to the CA spatial pattern, greater pH decline (ΔpH = -0.017 ± 0.009 unit·yr) occurred in northwest, central south and central east HKC areas, much higher than the less acidified (ΔpH = -0.004 ± 0.002 unit·yr) southwest and northeast HKC areas. The spatiotemporal CA variations were associated with water discharges, atmospheric CO increase and respiration/production that was indicated by DIN:DIP structure changes. The annual mean DIN:DIP ratio increased progressively from initial ∼16 in 1986 to ∼37 in 2017, revealing excess nitrogen load from rapid urbanization in this region. Such discharge-induced acidification was estimated as the major contributor for the total CA in HKC over the last three decades. In addition, our simulation results indicated that a potential CA rate at ∼0.0035 unit·yr could be reached if reducing mean DIN:DIP from discharged water to ∼23 from HKC. This study revealed a previously not recognized relationship between coastal acidification and changing coastal nutrient stoichiometry, and proposed possible management approaches.
由于富营养化，沿海酸化通常比海洋酸化剧烈得多。为了更好地了解长期沿海酸化（CA）与沿海富营养化（CE）之间的关系，分析了过去三十年（1986-2017 年）香港海岸（HKC）的现场每月数据。过去几十年，整个海岸的年平均 pH 值变化（ΔpH）估计为-0.0085±0.0069 单位·yr，是当前对开阔海洋酸化率（约-0.0019 单位·yr）估计值的四倍多。根据 CA 的空间格局，HKC 的西北、中南部和中东部地区的 pH 值下降幅度更大（ΔpH=-0.017±0.009 单位·yr），远高于酸化程度较低的西南和东北地区（ΔpH=-0.004±0.002 单位·yr）。CA 的时空变化与水排放量、大气 CO 增加和呼吸/生产有关，这表明 DIN:DIP 结构发生了变化。年平均 DIN:DIP 比值从 1986 年的初始∼16 逐渐增加到 2017 年的∼37，表明该地区快速城市化导致氮负荷过剩。这种由排放引起的酸化被估计为过去三十年 HKC 总 CA 的主要贡献者。此外，我们的模拟结果表明，如果将 HKC 排放水中的平均 DIN:DIP 从∼23 降低到∼23，那么潜在的 CA 速率可能达到约 0.0035 单位·yr。本研究揭示了沿海酸化与沿海营养化学计量变化之间以前未被认识到的关系，并提出了可能的管理方法。
