环境酸化引起钙失衡的生理生态学效应

Eco-physiological effect of calcium imbalance caused by environmental acidification:A review

环境酸化是全球气候变化引起的主要问题之一,陆地和湖泊等生态系统受酸雨的长期影响,呈现出pH下降的趋势,而海洋生态系统也由于大气CO2浓度的急剧上升而出现酸化。环境的酸化对生态系统中Ca的平衡造成巨大影响。在海洋生态系统中表现为,随着pH下降海水中CO32-浓度降低,富Ca海洋生物无法维持其体内CaCO3形成的硬质结构,造成珊瑚钙化生长变缓、翼足目软体动物外壳腐蚀穿孔等,影响其种群繁衍。另外,在陆地生态系统中,由于酸雨的长期淋溶,大量的生物可利用Ca从生态系统中流失,动植物无法获得充足的Ca来满足其生理需要。蜗牛、水虱等土壤及湖泊中高Ca动物的生长、繁殖受抑制,鸟类也由于缺Ca造成种群数量下降。陆地植物体内依赖于Ca的信号转导系统也遭受严重干扰,进而影响光合、抗逆和繁殖等诸多生理过程,表现出不同程度的生产力、物种多样性下降和森林的衰退。环境酸化导致不同生态系统中Ca循环失衡,大多表现出不利于富Ca生物体的存活,这可能是一个较为普遍的生态学模式。

Environmental acidification is one of the major problems caused by global climate change. Due to the long-term effects of acid rain, the pH of terrestrial and lake ecosystems presents a declining trend, and in the meanwhile, acidification of marine ecosystem also occurs because of the dramatic increase of atmospheric C02 concentration. Calcium homeostasis in organ＇ isms or/and ecosystems can be disturbed by environmental acidification. In marine ecosystem, calcium-rich species will have difficulties in maintaining their external calcium carbonate skeletons, resulting in the declining of coral calcification and the corroding of pteropod shell. With the decrease of ocean pH and carbonate ion concentration, the reproduction of marine organisms may be declined. In terrestrial ecosystem, organisms cannot absorb enough essential calcium because large quantity of bio-available calcium has been depleted from the ecosystem by the long-term acid rain. Therefore, anthropogenic acidification has caused the decline in calcium-rich species populations such as snail and Daphnia in soil and fresh waters, and birds also have low reproductive success as a result of calcium deficiency under long-term acid rain stress. In plants, acid rain disturbs calcium signal transduction cascades, and further, negatively affects physiological processes such as photosynthesis, stress-resistance, and reproduction, with the ecological conse- quences such as primary productivity and biodiversity decrease and forest decline. It may be a universal ecological pattern that calcium-rich species will be much more difficult in survival under the scenario of calcium homeostasis in ecosystems being disturbed by environmental acidification.