Abstract
Purpose
Longjing (Dragon Well) tea from the West Lake region of Hangzhou, China, is one of the highest quality green teas prized for drinking and is often called the national drink of China. However, the ever-increasing accumulation of lead (Pb) in Westlake Longjing tea has been continually reported in the recent decades, while the exact Pb sources still remain unclear. Our purpose is to investigate the key factors that account for the concentration increase of Pb accumulated in Longjing tea based on a broad regional scale.
Materials and methods
Eighty-one young tea leaves and corresponding soil and air samples where the tea plants grow in and around, respectively, were collected from three typical Longjing tea gardens for illustrating the sources of Pb that accumulated in Longjing tea. The sampling lines were arranged with the proximity to the traffic area. Pb concentrations in the tea leaves and soil and air samples were determined, respectively. Wash procedures were also conducted to trace the removable possibility and rates of Pb in young tea leaves. Simple statistical analysis and spatial geostatistics were further applied for the investigation of the potential relationship of Pb levels among young tea leaves and the relevant soil and air samples.
Result and discussion
The regional differences and seasonal variation of Pb concentration were found for young tea leaves, with the order of Longwu > Meijiawu > Longjing and spring > summer (p < 0.05), respectively. The significant positive correlation was found only for the Pb concentration between young tea leaves and air samples (r = 0.34, p < 0.01). The results from wash experiment showed that a substantial portion of Pb in young tea leaves could be removed by wash, and the removable rates of Pb showed an obvious decrease with the increasing distance from the traffic area in Longwu and Meijiawu. A similar geographic distribution tendency of Pb between young tea leaves and air was also revealed by further geographic spatial analysis taking Longwu as a case. The significant correlations and similar distribution tendency of Pb concentration between young tea leaves and air suggested that atmospheric deposition could be an important, even predominant, source for Pb accumulated in Longjin tea. This non-edaphic contribution was further validated in wash experiment and testified to be distance dependent on the proximity to the main traffic area. This might be attributed to the large rough pubescent surface of tea leaves which are conducive to foliar deposition and/or absorption of Pb. The lack of correlations between young tea leaves Pb and soil Pb indicated that the contribution of soil Pb would be limited (especially near the traffic area where the influence of atmospheric Pb was dominant) and might be attributed to the low bioavailability of Pb in soils and finite uptake and transport of Pb from roots to shoots. Meanwhile, the higher Pb concentration in spring teas (compared with summer teas) might be due to the long growth period that allowed for a long time interception of Pb by young tea leaves through atmospheric deposition.
Conclusions
The Pb that rooted in air was suggested as the main source accounting for the accumulation of Pb in Longjing Tea of the tested tea gardens. This non-edaphic contribution of atmospheric deposition was distance dependent on the proximity to the main traffic area. For alleviating the accumulation and elevation of Pb amount in Longjing Tea, efforts should be made especially during the period of spring tea growth. The additional wash procedure was also recommended before the tea leaf processing in factories.
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References
Adriano DC (2001) Trace elements in terrestrial environments: biogeochemistry, bioavailability, and risks of metals. Springer, New York
Capannesi G, Cecchi A, Sedda AF (1993) Feasibility of oak leaves as monitor for airborne pollution. J Radioanal Nucl Chem Art 167:309–320
Chen T, Liu XM, Xu JM et al (2008) Identification of trace element sources and associated risk assessment in vegetable soils of the urban-rural transitional area of Hangzhou, China. Environ Pollut 151:67–78
Chen T, Liu XM, Xu JM et al (2009) Heavy metal sources identification and sampling uncertainty analysis in a field-scale vegetable soil of Hangzhou, China. Environ Pollut 157:1003–1010
Corwin DL, Lesch SM, Shouse PJ et al (2003) Identifying soil properties that influence cotton yield using soil sampling directed by apparent soil electrical conductivity. Agron J 95:352–364
Cressie C (1990) The origins of kriging. Math Geol 22:239–252
Dalenberg JW, Wandriel W (1990) Contribution of atmospheric deposition to heavy metal concentrations in field crops. Neth J Agric Sci 38:369–379
Gilbert C, Wayne H (2008) Kriging analysis of soil properties. J Soils Sediments 8:193–202
Goovaerts P (1999) Geostatistics in soil science: state-of-the-art and perspectives. Geoderma 89:1–45
Han WY (2006) Study on the causes of Pb contamination in Westlake Longjing tea and their control techniques (in Chinese). Dissertation, Zhejiang University
Han WY, Zhao FJ, Shi YZ et al (2006) Scale and causes of lead contamination in Chinese tea. Environ Pollut 139:125–132
Han WY, Shi YZ, Ma LF et al (2007) Effect of liming and seasonal variation on lead concentration of tea plant (Camellia sinensis (L.) O. Kuntze). Chemosphere 66:84–90
Harrison RM, Laxen DPM (1984) Lead in soil. In: Lead pollution: causes and control. Chapman and Hall, London
Hangzhou Soil Survey Office (1991) Hangzhou soils (in Chinese). Zhejiang Science and Technology Press, Zhejiang
Ho YB, Tai KM (1988) Elevated levels of lead and other metals in roadside soil and grass and their use to monitor aerial metal deposition in Hong Kong. Environ Pollut 49:37–51
Jiang HY (2005) Comparison on accumulation and distribution of tea-plant varieties & Pb contamination on processing and packing of tea (in Chinese). Dissertation, Zhejiang University
Jin CW, He YF, Zhang K et al (2005a) Lead contamination in tea leaves and non-edaphic factors affecting it. Chemosphere 61:726–732
Jin CW, Zheng SJ, He YF et al (2005b) Lead contamination in tea garden soils and factors affecting its bioavailability. Chemosphere 59:1151–1159
Kang ML (2004) Accumulation and distribution of lead and its effects on the development and physiological characteristic of tea plant (Camellia Sinensis) (in Chinese). Dissertation, Zhejiang University
Li YG, Lu YF (2008) Lead isotopes as a tracer of tea Pb contamination in the west lake tea plantation (in Chinese). Geophys Geochem Explor 32:180–185
Lin DH, Zhu L, He W et al (2006) Tea plant uptake and translocation of polycyclic aromatic hydrocarbons from water and around air. J Agric Food Chem 54:3658–3662
Liu XM, Xu JM, Zhang MK et al (2004a) Application of geostatistics and GIS technique to characterize spatial variabilities of bioavailable micronutrients in paddy soils. Environ Geol 46:189–194
Liu XM, Xu JM, Zhang MK et al (2004b) Effects of land management change on spatial variability of organic matter and nutrients in paddy field A case study of Pinghu, China. Environ Manage 34:691–700
Liu XM, Wu JJ, Xu JM (2006) Characterizing the risk assessment of heavy metals and sampling uncertainty analysis in paddy field by geostatistics and GIS. Environ Pollut 141:257–264
Liu XM, Zhao KL, Xu JM et al (2008) Spatial variability of soil organic matter and nutrients in paddy fields at various scales in southeast China. Environ Geol 53:1139–1147
Lu YF, Yang HM, Zhou GH et al (2005) Lead isotopes in soil as a tracer of environmental lead pollution in Hangzhou (in Chinese). Quat Sci 25:355–362
Lu YF, Chen HS, Chen ZD et al (2006) Lead isotopes composition of sediments from West Lake and the Grand Canal in Hangzhou and its significance for lead source tracing (in Chinese). Geochimica 35:333–345
Monaci F, Moni F, Lanciotti E et al (2000) Biomonitoring of airborne metals in urban environments: new tracers of vehicle emission, in place of lead. Environ Pollut 107(3):321–327
Munch D (1993) Concentration profiles of arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc, vanadium and polynuclead aromatic hydrocarbons in forest soil beside and urban road. Sci Total Environ 138:47–55
Onyari JM, Wanddiga SO, Njentebe JO (1991) Lead contamination in street soils of Nairobi City, Mombassa Island, Kenya. Bull Environ Contam Toxicol 46:782–789
Serrano-Belles C, Leharne S (1997) Assessing the potential for lead release from road dusts and soils. Environ Geochem Health 19:89–100
Shi YZ (2003) Studies about the source of lead coming from and the absorption and accumulation of lead in tea (in Chinese). Dissertation, Zhejiang University
Shi YZ, Ma LF, Han WY et al (2003) Studies of the absorption and accumulation of lead in tea plant (in Chinese). Scientia Agricultura Sinica 36:1272–1278
Shi JC, Wang HZ, Xu JM et al (2007) Spatial distribution of heavy metals in soils: a case study of Changxing, China. Environ Geol 52:1–10
Shi JC, Xu JM, Huang PM (2008) Spatial variability and evaluation of status of micronutrients in selected soils around Taihu Lake, China. J Soils Sediments 8:415–423
Ward NI, Brooks RR, Reeves RD (1974) Effect of lead from motor vehicle exhausts on trees along a major thoroughfare in Palmerston North, New Zealand. Environ Pollut 6:149–158
Ward NI, Brooks RR, Roberts E et al (1977) Heavy metal pollution from automotive emissions and its effect on roadside soils and pasture species in New Zealand. Environ Sci Technol 11:917–920
Webster R, Oliver MA (2001) Geostatistics for environmental scientists. Wiley, New York
Wilcke W (2000) Small-scale variability of metal concentrations in soil leachates. Soil Sci Soc Am J 64:138–143
Xin J, Xu J, Pan P (1990) Laboratory manual for environmental science. Higher Education Press, Beijing, in Chinese
Yang YJ (2005) The sciences of China tea cultivation. Shanghai Science and Technology Publisher, Shanghai, in Chinese
Zhang SB, Bao WQ (2000) Research on tea garden pollution by lead from car tail gas (in Chinese). Jiangsu Environ Sci Technol 13:1–2
Zhao FJ, Adams ML, Dumont C et al (2004) Factors affecting the concentrations of lead in British wheat and barley grain. Environ Pollut 131:461–468
Zheng YM, Chen TB, He JZ (2008) Multivariate geostatistical analysis of heavy metal in topsoils from Beijing, China. J Soils Sediments 8:51–58
Acknowledgments
This research was jointly sponsored by National Nature Science Foundation of China (40701069) and the National Key Technologies R&D Program of China (2008BADA7B06). We thank WenYan Han for providing practical assistance.
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Shi, J., Wang, G., He, Y. et al. Lead accumulation in Westlake Longjing tea: non-edaphic genesis as revealed by regional scale estimate. J Soils Sediments 10, 933–942 (2010). https://doi.org/10.1007/s11368-010-0189-3
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DOI: https://doi.org/10.1007/s11368-010-0189-3