Broussonetia papyrifera, an important fast-growing economic tree species in China, has the advantages of strong adaptability, high-biomass, and high bioconcentration of heavy metals. Sewage sludge contains a great deal of nutrients and heavy metals. Planting B. papyrifera with sewage sludge can achieve the goals of sewage sludge remediation as well as resources production of B. papyrifera. A pot experiment was conducted to investigate growth, uptake and accumulation of nutrient and heavy metal in different organs (root, stem, leaf) of B. papyrifera, with treatments of control (lateritic red soil), 50% sewage sludge (mixed substrates of 50% sewage sludge and 50% lateritic red soil based on weight) and 100% sewage sludge. The comprehensive evaluation of capacity of uptake and accumulation was also carried out by principal component analysis and membership function. The results showed that B. papyrifera could grow normally in both 50% and 100% sewage sludge substrates, with higher plant height and biomass than that in the control, especially in 100% sewage sludge substrate. The quality index in 100% sewage sludge substrate (1.02) was 4.3 times and 2.4 times as that of the control and 50% sewage sludge substrate, respectively. The content of N in different organs and P in stem increased significantly in both 50% and 100% sewage sludge substrates. The content of K in stem and leaf was significantly decreased in 100% sewage sludge substrate, which were significant lower than that of control. The uptake of heavy metals such as Cu, Zn, Pb, Cd, Ni for B. papyrifera were mainly through roots. There was positive correlation between the content of heavy metals in root and sewage sludge ratio. The content of Pb and Cd in leaves were lower than the limit value of Hygienic Standard For Feeds (GB 13078-2017). The capacity for absorption and accumulation of Cd was better than that of other heavy metals. Compared with the control, rootretention rates of Zn, Pb and Cd significantly increased in both 50% and 100% sewage sludge substrates (57.8%-85.8%), while Cu and Ni significantly increased in 100% sewage sludge substrate (67.5% and 74.8%). Nutrient and heavy metal accumulations in total plant in both 50% and 100% sewage sludge substrates were significantly higher than that in the control, with 100% sewage sludge substrate being significantly higher than that in 50% sewage sludge substrate. Compared with 50% sewage sludge substrate, the increment rates of nutrient and heavy metal accumulations in different organs as well as total plants in 100% sewage sludge substrates were greatly increased. The rank of comprehensive evaluation scores of adaptability, element uptake and accumulation was in an order: 100% sewage sludge substrate (0.848) > 50% sewage sludge substrate (0.344) > control (0.080). With good adaptability to sewage sludge, B. papyrifera could grow normally in sewage sludge andeffectively absorb and fix nutrients and heavy metals. It is feasible to plant B. papyrifera into the sewage sludge for remediation of sewage sludge and resource production.
构树是我国重要速生经济树种,具有适应性强、生物量大和重金属富集能力强等优点,而污泥中含有大量养分和重金属,在污泥中种植构树有望同时实现污泥生态修复和构树资源生产。本研究通过盆栽试验,分析在对照(赤红壤)、50%污泥(污泥、赤红壤混合基质,重量比各50%)和100%污泥基质中构树生长及不同部位(根、茎、叶)养分和重金属吸收累积特征,并通过主成分分析和隶属度函数对吸收累积能力进行综合评价。结果表明: 构树在50%和100%污泥中均可正常生长且株高、生物量显著高于对照,在100%污泥中长势最好,质量指数(1.02)分别是对照和50%污泥处理的4.3和2.4倍。50%和100%污泥处理构树各部位N含量和茎P含量显著高于对照,100%污泥处理构树茎、叶K含量显著低于对照。构树对Cu、Zn、Pb、Cd、Ni的吸收部位以根为主,根系重金属含量与污泥比例呈正相关,叶Pb、Cd含量符合《饲料卫生标准》(GB 13078—2017)。构树对Cd的吸收累积效果好于其他重金属元素。与对照相比,50%和100%污泥处理构树根部Zn、Pb、Cd滞留率显著提高(57.8%~85.8%),100%污泥处理构树根部Cu、Ni滞留率显著提高(67.5%和74.8%)。污泥处理全株养分和重金属累积量均显著大于对照,其中100%污泥处理显著大于50%污泥处理。与50%污泥处理相比,100%污泥处理构树各部位及全株养分和重金属累积量大幅提高。不同处理下构树污泥适应性和元素吸收累积的综合评价得分为100%污泥(0.848)>50%污泥(0.344)>对照(0.080)。构树对污泥具有良好的适应性,在纯污泥中能够正常生长并具有较强的吸收累积养分和重金属能力,可在修复污泥的同时进行构树资源生产。.
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