Department of Chemical and Geological Sciences, University of Cagliari, 09127, Cagliari, Italy,
Environ Sci Pollut Res Int. 2014;21(11):6775-82. doi: 10.1007/s11356-013-1886-4. Epub 2013 Jul 7.
An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota.
在撒丁岛的纳拉库里溪流中，与蓝藻 Leptolyngbya frigida 和硅藻一起形成的无定形 Zn 生物矿化作用（“白泥”），通过电子显微镜和 X 射线吸收光谱进行了研究。初步的衍射分析表明，在纳拉库里溪流床采样的沉淀物主要是无定形的，有一些可归因于石英和层状硅酸盐的峰，外加一些未归属的小峰。扫描电子显微镜分析表明，与季节性生物膜一起沉淀的白泥由富含 Zn、Si 和 O 的鞘组成，外加可能由有机物制成的细丝。透射电子显微镜分析表明，鞘由尺寸在 100 到 200nm 之间的较小单元组成。在 Zn K 边缘收集的 X 射线吸收近边结构和扩展 X 射线吸收精细结构数据表明，生物矿具有类似于水锌矿的局部结构，水锌矿是一种锌硅氧酸盐。与在同一纳拉库里溪流上游约 3 公里处记录的水锌矿生物矿化作用相比，这种生物矿的差异可能与涉及的生物群的物理化学参数变化和/或不同的代谢行为有关。
