Impact of Soil Heavy Metal Pollution on Food Safety in China

<div><p>Food safety is a major concern for the Chinese public. This study collected 465 published papers on heavy metal pollution rates (the ratio of the samples exceeding the Grade II limits for Chinese soils, the Soil Environmental Quality Standard-1995) in farmland soil throughout China. The results showed that Cd had the highest pollution rate of 7.75%, followed by Hg, Cu, Ni and Zn, Pb and Cr had the lowest pollution rates at lower than 1%. The total pollution rate in Chinese farmland soil was 10.18%, mainly from Cd, Hg, Cu, and Ni. The human activities of mining and smelting, industry, irrigation by sewage, urban development, and fertilizer application released certain amounts of heavy metals into soil, which resulted in the farmland soil being polluted. Considering the spatial variations of grain production, about 13.86% of grain production was affected due to the heavy metal pollution in farmland soil. These results many provide valuable information for agricultural soil management and protection in China.</p></div

Number of the soil samples in the collected data records

<p>Number of the soil samples in the collected data records</p

Percentages of affected grain production in each province accounting for the total grain production in China.

<p>Percentages of affected grain production in each province accounting for the total grain production in China.</p

The averages of heavy metal pollution rates in the non-ferrous mining and smelting areas (%).

<p>The averages of heavy metal pollution rates in the non-ferrous mining and smelting areas (%).</p

Statistical information of the heavy metal pollution rate.

<p>* This data was cited from the Bulletin of National Soil Pollution Survey, 2014</p><p>** This data was cited from the published paper by Niu et al. (2013).</p><p>Statistical information of the heavy metal pollution rate.</p

Pearson correlation coefficients between pollution rates of heavy metals in arable soil.

<p>* Levels of significance: p < 0.01.</p><p>Pearson correlation coefficients between pollution rates of heavy metals in arable soil.</p

Percentages of the data records with the pollution rates in different ranges.

<p>Percentages of the data records with the pollution rates in different ranges.</p

A Review of Spatial Variation of Inorganic Nitrogen (N) Wet Deposition in China

<div><p>Atmospheric nitrogen (N) deposition (N_dep), an important component of the global N cycle, has increased sharply in recent decades in China. Although there were already some studies on N_dep on a national scale, there were some gaps on the magnitude and the spatial patterns of N_dep. In this study, a national-scale N_dep pattern was constructed based on 139 published papers from 2003 to 2014 and the effects of precipitation (P), energy consumption (E) and N fertilizer use (F_N) on spatial patterns of N_dep were analyzed. The wet deposition flux of NH₄⁺-N, NO₃^--N and total N_dep was 6.83, 5.35 and 12.18 kg ha^-1 a^-1, respectively. N_dep exhibited a decreasing gradient from southeast to northwest of China. Through accuracy assessment of the spatial N_dep distribution and comparisons with other studies, the spatial N_dep distribution by Lu and Tian and this study both gained high accuracy. A strong exponential function was found between P and N_dep, F_N and N_dep and E and N_dep, and P and F_N had higher contribution than E on the spatial variation of N_dep. Fossil fuel combustion was the main contributor for NO₃^--N (86.0%) and biomass burning contributed 5.4% on the deposition of NO₃^--N. The ion of NH₄⁺ was mainly from agricultural activities (85.9%) and fossil fuel combustion (6.0%). Overall, N_dep in China might be considerably affected by the high emissions of NO_x and NH₃ from fossil fuel combustion and agricultural activities.</p></div

Percentage contributions of aged sea salt, crust, agriculture, fossil fuel combustion, and biomass burning to annual wet deposition flux of NH₄⁺-N, NO₃^--N in China between 2003 and 2014.

<p>Percentage contributions of aged sea salt, crust, agriculture, fossil fuel combustion, and biomass burning to annual wet deposition flux of NH₄⁺-N, NO₃^--N in China between 2003 and 2014.</p

The flowchart of this study.

<p>The flowchart of this study.</p