造纸废水灌溉下芦苇体内铜化学形态研究

Chemical Forms of Copper in Reeds under Papermaking Wastewater Irrigation

为探究造纸废水灌溉下芦苇体内铜化学形态的分布,采用模拟湿地试验,研究了不同造纸废水浓度灌溉下芦苇各部位(根、茎、叶、穗)中铜化学形态(乙醇、水、氯化钠、醋酸、盐酸提取态)分布特征以及芦苇生长期(发芽期、展叶期、快速生长期、抽穗期、成熟期)对铜化学形态影响规律。结果表明:芦苇对铜元素含量受废水浓度影响,受芦苇生长时期的影响。废水浓度为300mg·L^(-1)时,芦苇体内铜含量最高(12.65mg·kg^(-1)),主要分布在根部(10.67mg·kg^(-1)),茎中含量最低(6.02mg·kg^(-1));展叶期内铜含量最高(14.52mg·kg^(-1)),成熟期最低(5.57mg·kg^(-1));芦苇体内铜形态分布受生长期影响较大,且各部位间有较大差异。芦苇体内铜以乙醇(3.43mg·kg^(-1))和水(3.00mg·kg^(-1))提取态为主,其中根部乙醇(32.02%)和水(24.77%)提取态含量最高,而穗中铜HCl提取态含量最高(42.33%)。芦苇生长期中,展叶期HAC提取态所占比例最高(30.83%),乙醇(18.97%)和水(21.54%)提取态次之,其余生长期,铜均以乙醇和水提取态为主,二者合计分别占总量的67.31%,54.34%,52.49%,49.23%;芦苇体内铜主要来源于土壤中弱酸态铜。废水浓度升高提高了芦苇对土壤中铜的吸收率,废水浓度为300mg·L^(-1)时,芦苇对土壤中铜的吸收率最高(9.62%),在展叶期,芦苇对土壤中铜的吸收率最高(3.46%),高于土壤中弱酸态铜总量。造纸废水灌溉促进了芦苇对铜的吸收,在试验的废水浓度灌溉下,芦苇体内铜的各形态含量所占比例变化不大。

The experiments we re performed in one simulated wetland environment located at our laboratory. Multiple chemical forms of copper（extracted respectively by the order of ethanol, water, Na Cl, HAC and HCl） had been measured throughout the growth periods of reeds（including germination, leaf extension, rapid growth, heading and maturity） and in different tissues（including root, stem, leaf, panicle） to get the distribution characteristics and the evolution of copper speciation in reeds under the irrigation conditions with various wastewater concentrations. The results showed that the absorption of copper in reeds was influenced by both the wastewater concentration and growth periods. When the papermaking wastewater was 300 mg·L^-1, the concentration of copper in the body of reeds was the highest 12.65 mg·kg^-1, and roots absorbed the most abundant copper with10.67 mg·kg^-1, while stem absorbed the least copper with 6.02 mg·kg^-1. The highest concentration of copper occurred at leaf extension period with 14.52 mg·kg^-1, and the case with the lowest concentration occurred at maturity with 5.57 mg·kg^-1. The copper forms in reeds were greatly influenced by growth periods, and had a big difference between various parts of reeds. The extractable copper by ethanol and water was 3.43 mg·kg^-1and 3.00 mg·kg^-1respectively, which were the main contents of copper in reeds. Extractable copper by ethanol and water accounted for 32.02% and 24.77% respectively of the total copper in roots. At leaf extension period, the highest proportion of extractable copper by HAC was 30.83%, and extractable copper by ethanol and water took second place, which accounted for 18.97% and 21.54% respectively. However, in the other periods, themost abundant copper was extractable content by ethanol and water, and the sum accounted for 67.31%, 54.34%, 52.49% and49.23%, respectively. Copper absorbed in reeds was origined mostly from weak acid copper in soil. The increase of wastewater concentration improved absorption rate of copper in reed. When the papermaking wastewater was 300 mg·L^-1, the highest absorption rate of copper in reeds was 9.62%, and the highest absorption rate of copper in reeds was 3.46% at leaf extension period, which was higher than weak acid copper in soil. Papermaking wastewater irrigation could promote the absorption of copper in reeds, and the percentage of various copper chemical forms in the body of reeds changed slightly under the experimental conditions of wastewater concentration.