大型海藻对重金属镉_铜的富集动力学研究_王增焕

Kinetic study on the bioconcentration of cadmium and copper by large-sized seaweed Gracilaria lemaneiformis. WANG Zeng-huan, LIN Qin*, LI Liu-dong, WANG Xu-nuo (Key Laboratory of Fishery Ecology Environment, Guangdong Province, Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China). China Environmental Science, 2013,33(1)：154~160 Abstract：The large-sized seaweeds are important renewable resources, which can be developed to delicious food and industrial materials. They were used to deal with sewage due to its accumulation of heavy metal. The living seaweeds are sensitive to light and temperature, and its growth was inhibited because of the toxicity of heavy metal. Gracilaria lemaneiformis is large-sized seaweed, which was suit for large-scale cultivation offshore. The uptake and clearance of copper and cadmium by Gracilaria lemaneiformis were investigated using artificial cultivated living Gracilaria lemaneiformis coupled with the low copper and cadmium concentrations in this paper. In order to test the practicability of two-compartment model adapted for accumulation of heavy metal by large-sized seaweeds, the experiment results were analyzed with nonlinear curve fitting. The results showed that the accumulation of heavy metal by Gracilaria lemaneiformis was accordance with two-compartment model, the uptake rate constant (Ku) and clearance rate constant (Kc) were also obtained. The Gracilaria lemaneiformis can accumulate copper and cadmium from waters, the contents of copper and cadmium accumulated in Gracilaria lemaneiformis were increased along with the concentrations of copper and cadmium in waters, and increased with the exposed time. Meanwhile, Gracilaria lemaneiformis can eliminate cadmium and copper strongly, because Gracilaria lemaneiformis accumulate mainly cadmium and copper from water by bio-absorption, which is a two-way process. Gracilaria lemaneiformis can also accumulate cadmium and copper by active transport, and those elements were combined to make into organic metals. The uptake rate constant of copper and cadmium accumulated by Gracilaria lemaneiformis was from 15.4 to 51.1, from 13.9 to 55.7, respectively. The clearance rate constant was from 0.023 to 0.070, from 0.030 to 0.050, respectively. The uptake rate constants decreased with
藻类对重金属富集能力强、具有选择性,吸 附容量高,同时具有成本低廉、来源丰富的优点, 被用于污水处理及水质净化 [1 5]. 由于活体海藻 对重金属的耐受性不同,生长受到重金属的抑制. 目前海藻对重金属富集的研究多是针对非活性 海藻进行的,将海藻制成生物吸附剂,对其吸附容 量及影响条件、 吸附动力学等进行研究[6 10],对活 体海藻累积重金属的研究报道很少[11]. 龙须菜 (Gracilaria lemaneiformis) 是红藻门 江蓠藻属中一种重要的大型经济海藻,原产于我 国北方沿海,目前已在东南沿海开始养殖.本文通 过在较低质量浓度条件下,活体龙须菜对重金属 铜(Cu)、 镉(Cd)的吸收与排出实验,采用两箱模型, 对实验数据进行了非线性拟合,探讨两箱模型用 于大型海藻对重金属富集动力学研究的可行性. 在动力学拟合的基础上,讨论了龙须菜对 Cu、 Cd 的富集特征.以期为海藻产品的开发与质量安全, 以及大型海藻菜对重金属污染水体的净化及修 复应用提供基础资料. 1 1.1 材料与方法
实验与暂养条件基本一致,在水族箱内进行. 水族箱(约 30L)置于大棚内,采用自然光照.参照 水生动物的富集实验,本文吸收实验和排出实验 均持续 28d,在实验的第 3, 7, 14, 21, 28d,随机抽 取 3 份适量龙须菜样品,用于 Cu、Cd 质量分数 的测定.富集实验结束后,将龙须菜移至空白人工 海水中进行排出实验. 1.3 样品测定 将采集的龙须菜样品于 60℃烘至恒重、研 磨过筛.准确称取 0.50.7g 样品,用 HNO3-HClO4 混合酸消解完全,定容后用石墨炉原子吸收光谱 法测定 Cu、 Cd 的含量(质量分数,下同).所用仪器 为日立 Z-2000 型塞曼效应原子吸收分光光度计. 龙须菜中 Cd、Cu 的含量以干重表示. 1.4 数据拟合 采用两箱模型,对实验结果进行拟合.根据两 箱模型的原理[13 14],龙须菜对 Cu、Cd 的吸收和 排出过程描述如下: k Ct C0 Cw u (1 e k t ) (0 t t * ) (1) kc k Ct C0 Cw u (e k (t t *) e k t ) (t t * ) (2) kc
收稿日期：2012-04-30 基金项目：中央级公益性科研院所基本科研业务费专项资金项目(2009TS07) * 责任作者, 研究员, linqinscs@21cn.com
1期
王增焕等：大型海藻对重金属镉、铜的富集动力学研究
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exposure concentrations, while the clearance rate constants were no obviously related exposure concentrations. The bioaccumulation factor of copper and cadmium accumulated by Gracilaria lemaneiformis was from 663 to 1008, from 463 to 1113, respectively; and the biological half-life was 23.1 d, 20.1 d, respectively. Key words：large-sized seaweed；bioaccumulation kinetic；cadmium；copper；Gracilaria lemaneiformis
中国环境科学
2013,33(1)：154~160
China
Environmental
Science
大型海藻对重金属镉、铜的富集动力学研究
王增焕,林 钦*,李刘冬,王许诺 (中国水产科学研究院南海水产研究所,广东省渔业生态环境重点实验室,农业
部水产品加工重点实验室,广东 广州 510300)
摘要：以人工培育的龙须菜 (Gracilaria lemaneiformis)活体为实验材料 ,在低浓度 Cu2+、 Cd2+污染水体中 ,进行龙须菜对 Cu、Cd 富集的 模拟实验 ,探索龙须菜对 Cu、 Cd 的污染水体的修复 ,以及龙须菜食品的安全性 .应用两箱动力学模型 ,对实验结果进行了曲线拟合 ,对拟 合优度进行检验 .结果表明 ,在本实验条件下 ,龙须菜对重金属 Cu、Cd 的生物累积符合两箱动力学模型 ,并获得龙须菜富集 Cu、Cd 的吸 收速率常数(Ku)和排出速率常数(Kc).当 Cu2+的浓度50g/L、Cd2+的浓度20g/L 时 ,经过 28 d 的暴露 ,随 Cu2+、Cd2+的暴露浓度以及暴 露时间增大 ,龙须菜中 Cu、 Cd 的含量升高 .龙须菜对 Cu、 Cd 的Fra Baidu bibliotek收速率常数分别为 15.451.1 和 13.955.7,基本随实验水体中元素的 暴露浓度升高而降低;排出速率常数分别为 0.0230.070 和 0.0300.050,与暴露浓度无明显相关性 .理论平衡状态下龙须菜中 Cu、Cd 含 量 (质量分数)随水体中暴露浓度升高而增加 .龙须菜对 Cu、 Cd 的生物富集因子分别为 6631008 和 4631113,Cu、 Cd 的生物半衰期分 别为 23.1 d 和 20.1d. 关键词：大型海藻；富集动力学；镉；铜；龙须菜 中图分类号：X171 文献标识码：A 文章编号：1000-6923(2013)01-0154-07
实验材料 实验材料为广东省南澳县人工培育的龙须 菜,除去杂藻,用人工海水清洗去除污泥,暂养 20d 后选取大小均匀的健康藻体用于实验.暂养条件 为海水盐度 30‰、温度 20℃,每天更换人工海水 (人工海水用纯净水配制,所用试剂氯化钠、硫酸 镁等为分析纯以上),连续充气. 1.2 实验方法 Cd2+、Cu2+各设 4 个实验浓度组.Cd2+、Cu2+ 的浓度(质量浓度,下同)分别为 1, 5, 10, 20µg/L 和 5, 10, 20, 50µg/L,以空白人工海水作为对照 Cu2+质量浓度参考 《海水水质标准》 (GB 组.Cd2+、 [12] 30971997) 设置,在此浓度范围内龙须菜能正 常生长[3].