Environmental Records Of Human Activities In Black Corals Of The South China Sea

Coral reefs are important parts of the ocean ecosystems. Corals can record environmental changes in the ocean, especially near the coast. Because of their long life spans, strong adaptability and wide geographic distribution, black corals (Antipatharia) have substantial potential as proxy records of oceanographic and biogeochemical changes. In this work, using the high spatial resolution spectroscopy and mass spectrometry techniques, the combination mechanisms and distribution of trace elements in the organic skeleton of black corals collected the South China Sea were analysed. According to the time-series variability of iron and lead in the skeleton of black corals, we investigated the connections between their records in black corals and the ambient environmental changes.Main conclusions of this thesis are as follows:These species (Cirrhipathes spp. and Antipathes spp.) were long lived and slow-growing organisms. They have been growing continuously for185-266years, with growth rates ranging from17.8to26.6μm/yr. The results of radionuclide210Pb in dating of black corals revealed a good conformity with that of the counting growing rings.The skeleton of black corals was composed mainly of proteins and chitin. The micro-Raman spectra exhibited vibration characteristics of a series of amino acids including glycine, histidine, methionine and phenylalanine. The trace metal elements in seawater via forming non-covalent bonds with oxygen atoms of protein macromolecular to enrich in the skeleton of black corals The sequence of the enrichment coefficients were Fe>Zn>Mn>Pb.The distribution of trace elements in the skeleton of black corals was affected by a series of factors. For instance, the concentrations of I and Ca were associated with gluing regions between cells in the skeleton. And the distribution of heavy metal elements Fe, Mn and Pb was mainly impacted by anthropogenic discharge. However, the distribution of Zn in the skeleton may reflect both skeletal morphology and anthropogenic discharge.Black corals showed strong iron-enriched capacity and were sensitive to the changes of iron concentration in seawater. The distribution of iron in the skeleton of black coral in sample LHT provided a faithful record of the development history of Tiandu iron mine. Response of back corals to the ambient environmental changes was sensitive and it is expected that iron in the skeleton can be served as a new proxy for past oceanic conditions.The distribution of Pb in the skeleton of black corals reflected the development history of Hainan island. The obviously high value recorded the pollution of the industrial production, motor vehicles exhaust and infrastructure constructions. It revealed reliable records of the environmental changes.