Water pollution and bioremediation by microalgae: absorption and adsorption of heavy metals by microalgae.
Water pollution and bioremediation by microalgae: absorption and adsorption of heavy metals by microalgae.
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水污染与微藻生物修复：微藻对重金属的吸收和吸附。
DOI：
10.1002/9780470995280.ch26
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
D. Kaplan
中科院分区：
文献类型：
--
作者：
D. Kaplan
从化学角度来看，元素周期表中的大多数元素是金属和类金属。只有H、B、C、N、P、O、S、卤素和惰性气体不包括在这一类中。金属离子又分为A类、B类和过渡金属阳离子(Morgan&Stumm，1991)。从生物学的角度来看，金属和金属离子可以根据其对环境的影响或毒性进行分类。密度大于5gcm±3的金属元素称为重元素。因为这些元素对生物体有毒性作用，所以它们被称为有毒重金属。一些重金属，如铜、镍和锌，在非常低的浓度下对生命是必不可少的，因为它们在活细胞中发生的新陈代谢过程中发挥着重要作用(Gadd1993)。然而，这些金属离子水平的升高对大多数原核生物和真核生物都是有毒的。其他重金属如镉、铅和汞不是必需的，已知即使在非常低的浓度下也会对生物体造成严重损害。金属以不同的形式存在：以离子的形式溶解在水中，以蒸汽的形式存在，或以盐或矿物的形式存在于岩石、沙子和土壤中。它们也可以结合在有机或无机分子中，或附着在空气中的颗粒上(Raspor，1991；Wedepohl，1991)。金属毒性往往取决于其化学形态(金属形态)。人们普遍认为，对大多数金属来说，自由离子是对水生生物毒性最大的物种(Sunda&Guillard，1976；Anderson&Morel，1978)。一些有机形态，如甲基汞，被活的有机体非常有效地吸收。它比其他汞物种毒性更大(George，1991)。工业过程和集约化农业实践往往导致各种重金属释放到陆地和水生环境中。
From a chemical point of view, the majority of the elements in the periodic table are metals and metalloids. Only H, B, C, N, P, O, S, halogens, and noble gases are not included in this category. Metal ions are further grouped into type-A, type-B and transition metal cations (Morgan & Stumm, 1991). From the biological point of view, metals and metal ions can be sorted according to their environmental impact or toxicity. Metallic elements of densities greater than 5gcmÀ3 are called heavy. Since these elements exert toxic effects on living organisms they are termed toxic heavy metals. Some of the heavy metals, such as copper, nickel, and zinc are, at very low concentrations, essential for life because they play important roles in metabolic processes taking place in living cells (Gadd, 1993). However, elevated levels of these metal ions are toxic to most prokaryotic and eukaryotic organisms. Other heavy metals such as cadmium, lead, and mercury are nonessential and are known to cause severe damage in organisms even at very low concentrations. Metals occur in different forms: as ions dissolved in water, as vapors, or as salts or minerals in rocks, sand, and soils. They can also be bound in organic or inorganic molecules, or attached to particles in the air (Raspor, 1991; Wedepohl, 1991). Metal toxicity is often dependent on its chemical form (metal speciation). It is generally accepted that for most metals the free ion is the species most toxic to aquatic life (Sunda & Guillard, 1976; Anderson & Morel, 1978). Some organic forms such as methyl-mercury are taken up very efficiently by living organisms. It is more toxic than other mercury species (George, 1991). Industrial processes and intensive agricultural practices, often result in the release of various heavy metals into terrestrial and aquatic