Journal of Geographical Sciences >
Spatio-temporal variation prediction on Cd content in the rice grains from Northern Zhejiang Plain during 2014-2019 based on high-precision soil geochemical data
Yin Hanqin (1978-), Senior Engineer, E-mail: 411097867@qq.com |
Received date: 2022-01-16
Accepted date: 2022-09-14
Online published: 2023-02-21
Supported by
Geological Prospecting Funds Program of Zhejiang Province, China(2018003)
Geological Prospecting Funds Program of Zhejiang Province, China(2020006)
Science and Technology Program of Department of Natural Resources of Zhejiang Province, China(2020-45)
Key R& D Program of Zhejiang Province, China(2021C04020)
Copyright
In recent years, Cadmium (Cd) pollution has been found in many soil geochemical surveys in Northern Zhejiang Plain, a crucial rice production area in East China, located in the lower Yangtze River. To more scientifically predict the effect of soil Cd on rice safety, data including 348 local rhizosphere soil-rice samples obtained in 2014 were used in this study. Meanwhile, we extracted 90% of random samples as variables based on soil Cd content (Cdsoil), soil organic matter (SOM), pH, and other indicators. In addition, a multivariate linear model for rice Cd content (Cdrice) prediction based on the indicators including the soil Cd content (Cdsoil), the soil organic matter (SOM), and the pH value. The remaining 10% of random samples were used for the significance test. Based on the 2014 soil Cd content (Cdsoil14) and the 2019 soil Cd content (Cdsoil19), this study predicted Cd content in 2019 rice grains (Cdp-rice19). The spatio-temporal variation of Cdrice was contrasted in the five years from 2014 to 2019, and the risk areas of rice safety production were analyzed using the Geographical Information System (GIS). The results indicated that compared with the actual Cd content in 2014 rice grains (Cdrice14), the proportion of Cdp-rice19, which exceeded the standard food level in China (GB2762-2017), increased dramatically. Moreover, the high-value areas of Cdrice distributed greatly coincidentally in these two years. By contrast, both Cdrice and Cdsoil show very different spatial scales. The dominant reason is the distribution of the local canal systems, indicating that economic activities and agricultural irrigation may aggravate the risk of soil Cd pollution, thus threatening safe rice production.
YIN Hanqin , LU Xinzhe , SUN Rui , HUANG Chunlei , KANG Zhanjun , XU Mingxing , WEI Yingchun , CAI ZiHua . Spatio-temporal variation prediction on Cd content in the rice grains from Northern Zhejiang Plain during 2014-2019 based on high-precision soil geochemical data[J]. Journal of Geographical Sciences, 2023 , 33(2) : 413 -426 . DOI: 10.1007/s11442-023-2089-7
Figure 1 Collaborative sampling positions of rice and root soil in Northern Zhejiang Plain of Zhejiang Province, China (Note: Based on the consideration of sample typicality, the rice-root samples in 2014 are almost set in the concentrated continuous rice planting areas which soil parent materials types are limnetic sludge, limnetic silt, marine sludge and marine silt.) |
Figure 2 Location of the soil sampling sites in 2019 in Northern Zhejiang Plain of Zhejiang Province, China |
Figure 3 The workflow diagram for data processing |
Table 1 Statistics of content characteristics of Cd, pH and SOM in soil in 2019 |
Parameter | n | Ave. | Std. | CV. | 10% | 25% | 50% | 75% | 90% | Over-limit ratio | Background value |
---|---|---|---|---|---|---|---|---|---|---|---|
Cdp-soil19 (mg kg-1) | 33809 | 0.192 | 0.889 | 462.0% | 0.110 | 0.130 | 0.170 | 0.210 | 0.264 | 2.04% | 0.152 |
pH | 33809 | / | 0.842 | / | 5.200 | 5.650 | 6.150 | 6.710 | 7.410 | / | |
SOM (%) | 33809 | 2.500 | 0.975 | 39.0% | 1.380 | 1.776 | 2.362 | 3.120 | 3.707 | / | 2.310 |
Note: C.V. means coefficient of variation |
Table 2 Partial correlation coefficients between the ln(Cdrice) and the soil parameters in 2014 (n=348) |
ln(Cdsoil14) | pH | ln(SOM) | ln(Clay) | ln(Sesoil14) | ln(Znsoil14) | |
---|---|---|---|---|---|---|
ln(Cdrice14) | 0.146 | -0.591 | -0.138 | -0.018 | -0.067 | 0.067 |
p | <0.01 | <0.01 | <0.01 | 0.763 | 0.384 | 0.215 |
Figure 4 Scatter plot of measured value and predicted value of ln(Cdrice) (a); Q-Q chart of normal distribution of d (b) |
Figure 5 Box diagram of ln transformed Cdrice14 and Cdp-rice19 |
Table 3 Cdrice in the Northern Zhejiang Plain and the Lower Changjiang Plain in 2014 and 2019 |
Parameter | N | Ave. | Std. | 10% | 25% | 50% | 75% | 90% | Exceeding standard rate | |
---|---|---|---|---|---|---|---|---|---|---|
NZP | Cdrice14 (mg kg-1) | 348 | 0.0213 | 0.0458 | 0.0056 | 0.0080 | 0.0135 | 0.0225 | 0.0377 | 1.45% |
Cdp-rice19 (mg kg-1) | 33809 | 0.0442 | 0.0477 | 0.0107 | 0.0198 | 0.0340 | 0.0549 | 0.0860 | 5.08% | |
LCPa | Cdrice14 (mg kg-1) | 150 | 0.02811 | 0.01519 | 0.01483 | 0.01857 | 0.02411 | 0.03224 | 0.04639 | / |
Cdrice04 (mg kg-1) | 12320 | 0.02299 | 0.01592 | 0.01214 | 0.01466 | 0.01906 | 0.02457 | 0.03699 | / |
a: Cite from Xia et al. (2019) |
Figure 6 The GIS cartography for spatio-temporal variation of Cdrice14 (a) and Cdp-rice19 (b) in Northern Zhejiang Plain |
Figure 7 Evaluation of Cd pollution in soil of Northern Zhejiang Plain in 2019 |
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