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古树广玉兰和臭椿年轮Pb元素积累的动态比较

张前进*,刘华,苏守香,王嘉楠,吴泽民   

  1. (安徽农业大学林学与园林学院, 合肥 230036)
  • 出版日期:2019-12-10 发布日期:2019-12-10

Dynamic comparison of Pb accumulation in the ancient tree-rings ofMagnolia grandiflora and Ailanthus altissima.

ZHANG Qian-jin*, LIU Hua, SU Shou-xiang, WANG Jia-nan, WU Ze-min   

  1. (School of Forestry and Landscape Architecture, Anhui Agricultural University, Hefei 230036, China).
  • Online:2019-12-10 Published:2019-12-10

摘要:

Pb污染是城市环境污染的一个重要方面,不仅影响城市环境质量,还直接或间接影响人体的健康,因此被高度关注。本研究以合肥城市两种常见园林树木——广玉兰和臭椿为对象,测定其树木年轮内Pb元素的积累情况,来反映城市Pb污染历史动态,并分析这种动态产生的原因。结果表明:广玉兰110年的年轮中平均Pb浓度为(1.114±0.055) mg·kg-1,臭椿60年的年轮中平均Pb浓度为(0.667±0.037) mg·kg-1;两种树木年轮中的Pb浓度动态变化呈现出显著的波动性和很大的相似性,大部分的年轮Pb浓度都处于较低水平,在同一时间段内两个树种均出现高于平均线的峰值;两种树木年轮中Pb浓度与树龄、年轮宽度的相关性不明显,与年轮段相对应的年平均降水量则呈现较好的相关性,相关系数分别为0.89和0.84;两个树种Pb浓度变化格局较好反映了城市环境受Pb污染的历史情况,在年轮中Pb浓度高于平均值的年份中,一般表现为战争、城市经济增长、城市规模发展。研究时段内Pb在年轮中积累的总趋势则呈下降态势,而且臭椿下降趋势明显大于广玉兰。
 

关键词: 气候变化, 天然橡胶, 气候适宜性

Abstract: Pb pollution, an important type of urban environmental pollution, affects environmental quality and human health and thus has received many concerns. In this study, Pb accumulation in tree rings of Magnolia grandiflora and Ailanthus altissima, two common garden tree species in Hefei City, was measured to understand the temporal dynamics of urban Pb pollution and the underlying reason. The results showed that the average Pb concentration was 1.114±0.055 mg·kg-1  in the tree rings of Magnolia grandiflorafor 110 years and 0.667±0.037 mg·kg-1 in Ailanthus altissimafor 60 years. The variations of Pb concentrations in the tree rings of both species showed substantial fluctuation and great similarity. For most of the tree rings, Pb concentrations were at a lower level. The peak of both tree species appeared in the same period. Pb concentration had no significant correlation with tree age and ring width, but was well correlated with annual average precipitation corresponding to tree ring segments, with correlation coefficients of 0.89 and 0.84, respectively. The variation pattern of Pb concentration in both species reflected the historical Pb pollution. The years with Pb concentration in the tree rings higher than the average concurred with war, urban economic growth, and/or urban expansion. During the period of study, the overall trend Pb accumulation in tree rings showed a downward trend, and such trend was significantly greater for Ailanthus altissima than for Magnolia grandiflora.

Key words: climate change, rubber, climatic suitability