Hypoxia and cyanobacteria blooms - are they really natural features of the late Holocene history of the Baltic Sea?
Hypoxia and cyanobacteria blooms - are they really natural features of the late Holocene history of the Baltic Sea?
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DOI：
10.5194/bg-7-2567-2010
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发表时间：
2010-01-01
期刊：
影响因子：
4.9
通讯作者：
Conley, D. J.
中科院分区：
文献类型：
--
作者：
Zillen, L.;Conley, D. J.
在上个世纪（1900年代），工业化的农业和人类活动造成了波罗的海沃茨的富营养化。因此，波罗的海的缺氧区增加，特别是在过去50年中，造成了严重的生态系统干扰。气候强迫已被认为是造成近100年来低氧（< 2 mg/l O-2）趋势的原因。100年（自C。公元1900年）和中世纪时期。相比之下，在长时间尺度（千年和更长）上对生态系统的人为强迫程度的调查尚未得到彻底解决。本文通过对流域人口增长、技术发展和土地利用变化的分析，探讨了上个世纪以来人类活动对海洋环境干扰的证据。自然环境的变化，即波罗的海盆地和岩床的形态和深度的变化，可能是全新世早期（8000-4000卡年BP）大规模缺氧的主要驱动力。我们发现，在过去的两千年缺氧遵循欧洲的一般扩张和收缩趋势，人类干扰一直是缺氧的重要驱动力。缺氧发生在中世纪时期与人口的两倍（从c。4.6在波罗的海流域，大规模开垦已开垦和边缘耕地，土壤养分释放显著增加。气候强迫对波罗的海缺氧的作用尚未得到令人信服的证明，尽管它可能有助于通过增加盐水流入或通过水文输入的变化来维持缺氧。此外，蓝细菌水华并不是先前推断的波罗的海的自然特征，而是缺氧期间海底磷释放增加的结果。
During the last century (1900s) industrialized forms of agriculture and human activities have caused eutrophication of Baltic Sea waters. As a consequence, the hypoxic zone in the Baltic Sea has increased, especially during the last 50 years, and has caused severe ecosystem disturbance. Climate forcing has been proposed to be responsible for the reported trends in hypoxia (< 2 mg/l O-2) both during the last c. 100 years (since c. 1900 AD) and the Medieval Period. By contrast, investigations of the degree of anthropogenic forcing on the ecosystem on long time-scales (millennial and greater) have not been thoroughly addressed. This paper examines evidence for anthropogenic disturbance of the marine environment beyond the last century through the analysis of the human population growth, technological development and land-use changes in the drainage area. Natural environmental changes, i.e. changes in the morphology and depths of the Baltic basin and the sills, were probably the main driver for large-scale hypoxia during the early Holocene (8000-4000 cal yr BP). We show that hypoxia during the last two millennia has followed the general expansion and contraction trends in Europe and that human perturbation has been an important driver for hypoxia during that time. Hypoxia occurring during the Medieval Period coincides with a doubling of the population (from c. 4.6 to 9.5 million) in the Baltic Sea watershed, a massive reclamation of land in both established and marginal cultivated areas and significant increases in soil nutrient release. The role of climate forcing on hypoxia in the Baltic Sea has yet to be demonstrated convincingly, although it could have helped to sustain hypoxia through enhanced salt water inflows or through changes in hydrological inputs. In addition, cyanobacteria blooms are not natural features of the Baltic Sea as previously deduced, but are a consequence of enhanced phosphorus release from the seabed that occurs during hypoxia.