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| Distribution characteristics and pollution assessment of soil heavy metals in tea garden of Nanjing |
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| DOI：10.16768/j.issn.1004-874X.2017.10.008 |
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| Abstract: |
| Soil environmental quality is an important basis for tea plantation scientifically. To understand the
extent of soil acidification，heavy metal pollution characteristics and confirm the factors that influenced soil quality in
tea garden of Nanjing，the present study detected soil pH and heavy metal contents via GPS location technique. The
results suggested that soil acidification was accelerated in tea garden of Nanjing. From 2010 to 2012，soil pH ranging
from 4.1 to 5.0 was 29.7% higher than the pH from 2004 to 2006，accounting for 49.1% of total number of tea gardens.
The soil pH less than 4.0 increased by 3.8%. The single factor pollution index method combined with Nemerow
pollution index method was used to assess the pollution status of heavy metals on the basis of the Non-Environmental
Pollution Food Environmental Condition for Tea Production Area. The results suggested that the contents of heavy
metal（ Cu，Pb，Cd，Hg，As，Cr） were all below the limit of the Non-Environmental Pollution Food Environmental
Condition for Tea Production Area and soil quality were all assessed as clean. However，increased concentrations
of Cu，Pb and Cr were observed with prolonged planting. From 2010 to 2012，the average contents of Cu，Pb and Cr were higher than the background values of Jiangsu province，suggesting the accumulation of these metals in tea
orchard soils. Furthermore，a significantly negative correlation was observed between the contents of Pb，Hg and soil
pH by the correlation analysis. Therefore，controlling soil acidification is primarily able to reduce heavy metal bioavailability，
and therefore avoid the soil degradation owing to exceeding of Pb and Hg caused by soil acidification. |
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