南京林业大学学报(自然科学版) ›› 2019, Vol. 43 ›› Issue (02): 100-106.doi: 10.3969/j.issn.1000-2006.201803029

• 研究论文 • 上一篇    下一篇

河岸杨树人工林缓冲带对径流水中磷素截留效果的研究

周子尧,吴永波*,余昱莹,杨 静   

  1. (南京林业大学,南方现代林业协同创新中心,南京林业大学生物与环境学院,江苏 南京 210037)
  • 出版日期:2019-03-30 发布日期:2019-03-30
  • 基金资助:
    收稿日期:2018-03-16 修回日期:2018-09-19
    基金项目:国家重点研发计划(2016YFC0502704); 国家林业局“948”项目(2013-4-63); 江苏高校优势学科建设工程资助项目(PAPD)。
    第一作者:周子尧(1256515843@qq.com),ORCID(0000-0002-0778-0084)。
    *通信作者:吴永波(yongbowu0920@163.com),副教授,ORCID(0000-0001-8517-3880)。

Effects of riparian poplar plantation buffer strips on phosphorus removal in runoff water

ZHOU Ziyao, WU Yongbo*, YU Yuying, YANG Jing   

  1. (Co-Innovation Center of the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China)
  • Online:2019-03-30 Published:2019-03-30

摘要: 【目的】河岸植被缓冲带可以有效截留和吸收地表径流水中的磷素,从而减少进入湖泊水体中的磷。笔者在平缓坡地上构建适宜的植被缓冲带并研究其生态效果,为减缓农业面源污染、生态修复富营养化湖泊提供参考。 【方法】选定太湖流域4块大小为20 m×50 m不同密度的杨树林河岸缓冲带为研究对象,在缓冲带不同宽度处地面下不同深度(20、40和60 cm)处平行埋设PVC管,每个宽度分别设置3组淋溶管作为重复,每组3个,作为地表径流水的收集装置。分别于4、5、6、7、9月强降雨后采集水样,低温保存并测定其中磷素质量浓度。分析不同季节各宽度和密度的杨树林缓冲带截留径流水中磷素的差异,以确定适宜的河岸人工林缓冲带。【结果】① 7月径流水中可溶性磷(DP)、总磷(TP)去除率达到最大值(36.91%、26.50%),PO3-4去除率在6月达到63.30%,4、9月3种不同形态磷的去除率相比6、7月有所下降,不同月份PO3-4、DP、TP质量浓度呈显著性差异(P<0.05,F=2.382,2.052,2.758,df=180),去除率与时间呈极显著相关(P<0.01; F=3.464,3.265,3.279; df=180)。② 径流水中污染物去除率与缓冲带密度并不呈简单的正比例关系。稀植杨树林河岸缓冲带杨树数量稀少,截留污染物能力不足; 密植杨树林河岸缓冲带由于栽植密度较大,不利于杨树自由生长,吸收含磷污染物效果不佳。栽植密度并非越大越好,而是存在一个适宜栽植密度阈值。③ 随着河岸缓冲带宽度的增加,径流水中PO3-4、DP、TP质量浓度呈现下降趋势,截留率呈现上升趋势。河岸缓冲带对PO3-4的去除率最高,其次是TP,DP效果最差。不同宽度的缓冲带对20 cm深度径流水中PO3-4、DP的去除率较高,对40 cm深度的径流水中TP去除率总体高于20 cm深度的,60 cm深度径流水中PO3-4、DP、TP的去除率最低。在不同深度径流水中的3种磷素质量浓度在杨树缓冲带前15 m宽度变化差异显著(P<0.05; F=3.232,2.808,2.175; df=180); 之后随着宽度增加径流水中PO3-4、DP、TP的质量浓度变化不显著。15 m宽度的缓冲带对径流水中磷素平均去除率接近50 m宽度缓冲带的,说明15 m宽度的缓冲带基本能满足截污需求。【结论】杨树人工林河岸缓冲带在夏季对径流水中磷素的截留效果较好; 中等密度人工林缓冲带对径流水中磷素有较高去除率,但不同密度杨树林对于径流水中磷素截留差异并不显著; 15 m宽度的河岸缓冲带可以有效去除径流水中的各形态磷。含磷污染物只是造成湖泊湿地富营养化因素之一,合理的河岸缓冲带还应考虑对于其他污染物的截留作用。由于磷能促进植物苗期根系生长,因此在植物生长初期对磷的去除率较大。随着植物的生长和植物群落演替,磷素截留效率的动态变化尚有待长期的观测研究,以利于更为准确地评价其截留磷的能力。

Abstract: 【Objective】The riparian vegetated buffer strip can effectively absorb and remove phosphorus from surface runoff, thus significantly reducing the input of phosphorus into lakes. Several riparian vegetated buffer strips were built on a slight slope and their ecological effects were studied to reduce agricultural non-point source pollution and ecologically restore the eutrophic Taihu Lake.【Method】In this study, we examined four poplar buffer strips(20 m × 50 m)of different densities next to Taihu Lake. PVC tubes were laid underground parallel to each other at different depths(20, 40, and 60 cm)in each width in the buffer strips. Three groups of leaching tubes, which were used as collecting devices for surface runoff water, were set in each width as duplicates with three tubes in each group. Water samples were collected after heavy rainfall events during April, June, July and September and samples were preserved at a low temperature for phosphorus content analysis. Concentrations of phosphorus which was removed by poplar buffer strips with different widths and densities in different seasons were analyzed in the runoff water to determine which buffer strips are most suitable.【Result】①Removal rates of dissolved phosphorus(DP)and total phosphorus(TP)in runoff water reached a maximum of 36.91% and 26.50%, respectively, and a maximum removal rate of 63.30% for PO3-4 occurred in June. Removal rates of PO3-4,DP and TP decreased in April and September compared with that in June and July. Significant differences were observed in PO3-4, DP and TP concentrations among months(P<0.05; F=2.382,2.052,2.758; df=180), and phosphorus removal rates were significantly correlated with time(P<0.01; F=3.464,3.265,3.279; df=180). ②There was no significant relationship between the removal rate of pollutants in runoff water and buffer strip density. Buffer strips with low plant densities did not effectively remove pollutants, and buffer strips with high plant densities were not conducive to healthy poplar growth. Thus, there was a threshold of optimum plant density. ③As the widths of buffer strips increased, concentrations of PO3-4, DP and TP in runoff water decreased and removal effectiveness increased. The removal rate of PO43- was higher than that of TP, while the removal rate of DP was the lowest. Removal rates of PO3-4 and DP in 20 cm deep water were high in each width. The removal rate of TP in 40 cm deep water was higher than that in 20 cm deep water, and the removal rates of PO3-4, DP and TP in 60 cm deep water were the lowest. Concentrations of PO3-4, DP and TP in different runoff water depths in the anterior 15 m width varied significantly(P<0.05; F=3.232,2.808,2.175; df=180). As width increased, the concentrations of PO3-4, DP and TP in runoff water did not change significantly. The effects of the 15 m wide buffer strip was close to that of 50 m wide buffer strip for phosphorus removal so that would effectively remove large amounts of phosphorus from runoff water.【Conclusion】The riparian buffer strip of poplar plantation showed higher phosphorus removal efficiency in runoff water in summer. The removal rate of phosphorus in runoff water was high in medium density popular, while there were no significant differences in phosphorus removal rates between buffer strips with different densities. Results showed that the 15 m wide strip effectively removed large amounts of phosphorus from runoff water. Phosphorus-containing pollutants are only one of the factors contributing to the eutrophication of lake wetlands; thus, the efficiency of removing other pollutants should also be considered. The removal rate of phosphorus is high in the early growing stage, as phosphorus can promote the growth of seedling roots. Long-term studies are needed to examine changes in phosphorus removal efficiencies with the continuous growth and succession of plant communities.

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