This study examined the effects of solar light driven plastic degradation on carbon chemistry in the coastal waters of eastern Arabian Sea along the west coast of India. The research was conducted through experimental incubations exposed to natural sunlight at multiple locations between December 2023–February 2024. Photodegradation induced a significant pH decrease (up to 0.38 ± 0.02) between controls and plastic incubations ranging from 8.17 ± 0.01 to 7.54 ± 0.02 with the highest variation in the Mumbai coast ranging from 8.13 ± 0.01 to 7.75 ± 0.03. pH variations are primarily caused by the leaching of organic acids and CO2 release during solar irradiated incubation. Plastic leaching due to natural light irradiation and subsequent changes in the water chemistry is of prime significance with dissolved organic carbon (DOC) leaching of 0.002–0.03% of plastic weight into the coastal waters. Our estimations suggest 15–75 metric tonnes (MT) of DOC release per year by plastic pollution in the eastern Arabian Sea coastal waters. Further, the fluorescent dissolved organic matter (FDOM) fragmentation, a part of DOC, may act as an organic source of synthetic contaminants and would promote heterotrophic microbial action in the coastal waters. Photodegradation of plastic and the interaction of natural DOC and plastic-derived DOC resulted in longer wavelengths FDOM, which may affect the penetration of photosynthetically active radiation in the water column, thereby impacting primary production. Finally, future research work focussing on the role of plastic pollution in coastal ocean acidification and vice-versa is essential and will be increasingly intense in the upcoming decades.

中文翻译：

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自然光驱动的塑料浸出对阿拉伯海东部热带沿海水域碳化学的影响：一项实验研究


本研究考察了太阳光驱动的塑料降解对印度西海岸阿拉伯海东部沿海水域碳化学的影响。该研究是通过 2023 年 12 月至 2024 年 2 月期间在多个地点暴露在自然阳光下的实验孵化进行的。光降解导致对照和塑性培养之间的 pH 值显著降低（高达 0.38 ± 0.02），范围为 8.17 ± 0.01 至 7.54 ± 0.02，孟买海岸变化最大，范围为 8.13 ± 0.01 至 7.75 ± 0.03。pH 值变化主要是由太阳照射孵育过程中有机酸的浸出和 CO2 释放引起的。由于自然光照射和水化学性质的后续变化而导致的塑料浸出至关重要，溶解有机碳 （DOC） 的 0.002-0.03% 浸出到沿海水域中。我们的估计表明，阿拉伯海东部沿海水域每年因塑料污染而释放 15-75 公吨 （MT） 的 DOC。此外，荧光溶解有机物 （FDOM） 碎裂是 DOC 的一部分，可能作为合成污染物的有机来源，并会促进沿海水域的异养微生物活动。塑料的光降解以及天然 DOC 和塑料衍生的 DOC 的相互作用导致波长更长的 FDOM，这可能会影响光合有效辐射在水柱中的穿透，从而影响初级生产。最后，未来的研究工作侧重于塑料污染在沿海海洋酸化中的作用，反之亦然，这是必不可少的，并且在未来几十年内将越来越密集。