4 Conclusion
We systematically examined the accumulation, risk, source, and the
relationship between available concentration and planting year of 8 HMs
in typical PC soils from 16 cities of 8 provinces, China. In the current
PC soils, HMs showed different degrees of accumulation characteristics,
especially Cu, Zn, Pb, Cd, As exceeding rate reached 15.2, 4.5, 3.0,
27.3, and 2.3%, respectively. The SFPI of Cd suggested slight Cd
contamination in the whole area, while Cu reached the slightly
contaminated level only in Yunnan Province. Both the NCPI and IICQ
indicated that PC soil was slightly contaminated in the whole area,
while Yunnan and Henan provinces were severely affected. Cu and Zn
accumulation was mainly related to frequent anthropogenic agricultural
activities and showed a strong correlation with SOM. Also, available Cu
and Zn showed a significant linear correlation with the planting years
in PC. However, Pb and Cd were only significantly related to soil
texture that could be the main source of soil-forming parent material,
while their available state did not correlate with the planting years.
We suggest that reasonable selection of agricultural materials and
scientific planting systems in PC can be effective strategies to avoid
the risk of excessive soil HMs accumulation, delay soil quality
degradation, and reduce agricultural non-point source pollution to
ensure healthy and efficient PC for sustained development.