Gouvêa S P, Vieira A A H, Lombardi A T
Programa de Pós-Graduação em Ecologia e Recursos Naturais, Universidade Federal de São Carlos, Rodovia Washington Luiz Km 235, São Carlos, SP, CEP 13565-905, Brazil.
Chemosphere. 2005 Sep;60(9):1332-9. doi: 10.1016/j.chemosphere.2005.01.061.
High molecular weight materials (HMWM, >12000-14000 Da) excreted by the two cyanophyte species (Microcystis aeruginosa and Anabaena spiroides) and a diatom (Aulacoseira granulata) which are dominant phytoplankton species in a eutrophic reservoir, Barra Bonita, Brazil were investigated as copper (Cu) and cadmium (Cd) complexation agents and their monosaccharide and elemental analysis of C, H, N and S determined. Also, HMWM obtained from the reservoir water as well as from a mixture of the three algae materials were studied. The HMWM of the cyanophytes and the mixture of the three algae materials complexed Cu and Cd, whereas the HMWM of the diatom and that from the reservoir water complexed only Cu. Two classes of ligands of intermediate to weak binding strength were obtained after Scatchard plot analysis of the titration data. The cyanophytes and the mixture HMWM presented higher conditional stability constants for Cu class-1 ligands (logK1' = 9.2-9.5) than the HMWM derived from the diatom and the reservoir water (logK1' = 8.6-8.8). Higher proportions of acidic monosaccharides corresponded to higher K1' of Cu and Cd complexation, yet no relation was observed among complexation parameters and elemental analysis. This study points out Cu ligands of intermediate to weak binding strength in the excreted HMWM of dominant microalgae and in the HMWM of the reservoir water, while Cd was solely complexed by ligands isolated from the cyanophyte HMWM.
对巴西富营养化水库巴拉博尼塔中占优势的浮游植物物种——两种蓝藻（铜绿微囊藻和螺旋鱼腥藻）和一种硅藻（颗粒直链藻）分泌的高分子量物质（HMWM，分子量>12000 - 14000道尔顿）进行了研究，将其作为铜（Cu）和镉（Cd）的络合剂，并测定了它们的单糖以及碳（C）、氢（H）、氮（N）和硫（S）的元素分析。此外，还研究了从水库水中以及从三种藻类物质混合物中获得的HMWM。蓝藻的HMWM以及三种藻类物质的混合物能络合Cu和Cd，而硅藻的HMWM以及从水库水中获得的HMWM仅能络合Cu。对滴定数据进行Scatchard图分析后，得到了两类结合强度为中等至较弱的配体。蓝藻和混合物HMWM对Cu的1类配体呈现出比硅藻和水库水衍生的HMWM更高的条件稳定常数（logK1' = 9.2 - 9.5）（logK1' = 8.6 - 8.8）。较高比例的酸性单糖对应着较高的Cu和Cd络合K1'，但在络合参数和元素分析之间未观察到相关性。本研究指出，在优势微藻分泌的HMWM以及水库水的HMWM中存在结合强度为中等至较弱的Cu配体，而Cd仅被从蓝藻HMWM中分离出的配体络合。
