Table of Content

Volume 37 Issue 6
25 June 2021
Research Progress of Microplastics Pollution and Its Effect on Plant Ecosystem in Farmland
LI Rui-jing, ZHAO Ya-fei, GENG Jia-hui, LI Jun-qing, LI Zhen-xia
2021, 37(6):  681-688.  doi:10.19741/j.issn.1673-4831.2020.0824
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This paper is to make a comprehensive and systematic review of research progresses and future directions of the study on microplastics in the farmland environment, to introduce morphology, sources and accumulation of microplastics (MPs), and effects of MPs on structure and function in the soil both in China and in other countries as well. This paper also elaborates ecological effects of MPs on organisms, plants and the effects of MPs and cadmium compound pollution on plants. In the end, the paper puts forward views and prospects of future researches on microplastics in the farmland environment. This paper is expected to be able to provide information and scientific guidance for comprehensive understanding of the presence and future of microplastics in the farmland environment.
A Spatialization Study of GDP Based on LJ1-01 Data in the Pearl River Delta
XU Jia-yuan, CHEN Mei-zhao, ZHENG Rong-bao, MA Xiao-ning
2021, 37(6):  689-697.  doi:10.19741/j.issn.1673-4831.2020.0579
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There is a strong correlation between light data and human social and economic activities. Therefore, building a GDP prediction model based on light data and GDP spatialization has important research value. Taking the Pearl River Delta region as an example, the night light data of Luojia No.1 were preprocessed, including mosaic registration, intra-year stability correction, mask denoising, and radiation correction, etc.,which aims to obtain the 2018 Pearl River Delta LJ1-01 night light data set; Based on the night light data, the spatial distribution characteristics were analyzed, and the total light radiation value of each administrative area in the Pearl River Delta region was extracted for hot spot analysis; In addition, based on the night light data and GDP statistics,four lighting indices (TNL, I, S, CNLI) for the districts and counties of the administrative area were extracted, and the linear, logarithmic, power index, and exponential models with GDP were constructed. The best lighting index and the best regression model were determined through the determination coefficients; Based on the optimal lighting indicators and the best regression model, error correction was performed to obtain a spatial density map of GDP for the Pearl River Delta in 2018. Research results show that the small-scale grid format data obtained based on the GDP spatialization of the LJ1-01 data can reflect the region's spatial differences and spatial accuracy in a more detailed way than NPP-VIIRS data.
Evaluation and Spatiotemporal Differentiation of Rural Development in the Yangtze River Delta, China
ZHANG Rong-tian, ZHANG Xiao-lin, LU Jian-fei
2021, 37(6):  698-705.  doi:10.19741/j.issn.1673-4831.2020.0744
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This study constructed a system for evaluation of regional rural development using the Yangtze River Delta region of China as an example. The improved entropy method was used to assess the level of rural development, and GIS spatial analysis, ESDA model, and a multiple regression model were used to analyze the differentiating characteristics and influencing factors of rural development in the Yangtze River Delta during 2000-2018. Results show that rural development exhibited an evolving trend of continuous improvement. Rural development decreased from east to west and an inverted U-type spatial pattern was presented from south to north, and the rural development of Yangtze River Delta showed positive autocorrelation. Local hot spots were concentrated primarily in the Suzhou-Wuxi-Changzhou-Shanghai and Hangzhou-Shaoxing-Ningbo regions, while cold spots were distributed mostly in northern Anhui, forming a stable low-value clustering and differentiation pattern. Economic social development, agricultural modernization, urbanization, and traffic accessibility were important factors affecting the spatiotemporal differentiation of rural development, while policy and institutional factors had a macro guiding effect on rural development differentiation in the Yangtze River Delta region.
Study on High-standard Farmland Construction Based on Ecological Security and Food Security
WANG Ke, LI Ling, LI Peng
2021, 37(6):  706-713.  doi:10.19741/j.issn.1673-4831.2020.0781
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The construction of high-standard farmland is the foundation for guaranteeing national food security and the prerequisite for realizing grain storage on the land. Taking Yuanyang County of Henan Province as the research area, and the basic farmland patches as the evaluation units, the ecological security and food security of the basic farmland were both evaluated. According to the evaluation results synthesized by the two-dimensional correlation matrix, the construction zoning of high-standard farmland in Yuanyang County is proposed. It indicates that the ecological safety levels in different places were different, with higher levels in the eastern and western towns than those in the central region. The food security of basic farmland varied significantly in different towns, with high in surrounding towns, and low in the middle towns. The second and third levels of food security were the main ones. The food security levels in the eastern towns were the best, those in the western were general, but those in the central regions were poor. The high-standard farmland in Yuanyang County could been mainly divided into priority construction area, subsequent construction area, ordinary construction area and reserve construction area. Their area was 7 302.04, 14 755.29, 24 473.36 and 21 889.54 hm2, respectively. The above results can provide guidance to the area division and the construction sequence of high-standard farmland in Yuanyang County in a certain extent, and can also provide a reference for the construction of high-standard farmland in other similar areas.
Bearing Capacity of Livestock and Poultry Manure in Huang-Huai-Hai Region Based on Nitrogen and Phosphorus Farmland Utilization
CHEN Guang-yin, CAO Hai-nan, DING Tong-gang, HUO Wei-jie, PAN Yi-xin
2021, 37(6):  714-723.  doi:10.19741/j.issn.1673-4831.2020.0516
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To evaluate the land bearing capacity of livestock and poultry (LP) manure in Huang-Huai-Hai region, the total amount of LP manure, nitrogen (N) and phosphorus (P) load of LP manure in farmland, and environmental risk index of LP breeding in Huang-Huai-Hai region were calculated using the handbook of "Pollutant Generation Coefficient and Discharge Coefficient in Livestock and Poultry Breeding Industry" and the data of national and local statistical yearbooks in 2018. The land bearing capacity and development potential of LP manure in this region were then estimated based on the N and P utilization in farmland. The results show that, (1) in 2017, the amount of livestock and poultry manure in Huang-Huai-Hai region was 314.341 8 million tons, including TN 1.729 0 million tons and TP 0.311 0 million tons; the livestock and poultry manure, N and P load in farmland were 12.00 t·hm-2, 66.05 kg·hm-2and 11.88 kg·hm-2, respectively. (2) Farmland load of livestock and poultry breeding pollutants in most areas of Huang-Huai-Hai region were at a low level, as livestock and poultry manure load in 81.82% of cities, N load in 70.91% of cities, and P load in 78.18% of cities were less than 15 t·hm-2, 75 kg·hm-2, and 15 kg·hm-2, respectively. (3) According to the environmental risk level of livestock and poultry breeding, Beijing belonged to the Cut-breeding area; Tianjin, Qinhuangdao and Yantai belonged to Strictly-controlled area; Weihai, Rizhao, Dezhou, Binzhou, Luoyang, Xuchang and Luohe belonged to Proper-control area; Xingtai, Anyang, Shangqiu, Zaozhuang, Bozhou, Huaibei, Xuzhou, Lianyungang, Yancheng and Huai'an belonged to Key-development area; and the others belonged to General-development area. (4) Land bearing capacity in the whole Huang-Huai-Hai region based on N and P utilization in farmland was 422.627 0 million pig equivalent, and the livestock and poultry breeding potential value was 264.698 2 million pigs equivalent; about 0.663 4 million pig equivalent should be cut in Beijing, while the development potential of livestock and poultry manure in Tianjing, Anhui, Jiangsu, Hebei, Henan and Shandong were 1.045 6, 35.691 4, 36.917 7, 41.899 0, 83.712 6 and 66.095 3 million pigs equivalent, respectively.
Spatial-temporal Differentiation of Black Carbon Aerosol in Chengdu-Chongqing Urban Agglomeration and Its Relationship with Land Use and Cover Change
WANG Jun-xiu, MU Feng-yun, TIAN Tian, CHEN Lin, LI Qiu-yan
2021, 37(6):  724-732.  doi:10.19741/j.issn.1673-4831.2020.0641
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Based on MEERA-2 black carbon aerosol (BC) spatial distribution data and land use and land cover change (LUCC) data between 2000 and 2015, the distribution of BC mass concentration over time and space and characteristics of LUCC in Chengdu-Chongqing urban agglomeration is analyzed by using GIS spatial analysis methods and geographical weighted regression model. The response relationship between BC mass concentration and LUCC is discussed in this study. The results show that:(1) In general, BC concentration showed a concentric pattern of higher in the center and lower around the center, which hadn't changed obviously within the 15 years. The annual mean concentration of BC in 2000, 2005, 2010 and 2015 were 3.86, 4.97, 4.91 and 4.51 μg·m-3, respectively, which showed a trend of first increase and then decrease, with the inflection point appearing in 2005. The spatial scope of the high value was the largest in 2005, which went through an "expand-shrink" changing process. The seasonal mean concentration showed high values in winter, followed by autumn and spring, with the lowest content in summer. So the BC pollution was serious in autumn and winter. (2) The cultivated land, forests, and grassland were the main land-use types from 2000 to 2015. The total area proportion of these three lands accounted for more than 94.61%, and with no significant changes in land-use patterns. The decreasing cultivated land, grassland and increasing construction land were the main trends of LUCC, while water surface, forests and unused land had increased slightly. (3) Generally, BC concentration was the highest on construction land, followed by cultivated land, water surface, forest, and unused land, and was the lowest on grassland. BC concentration decreased when artificial land was transformed to natural land, and vice versa, it would increase. (4) The results of the geographical weighted regression model showed that areas with higher Local R2 value were the areas where LUCC had significant influence on BC concentration, which represented an obvious spatial differentiation.
Temporal and Spatial Variation Characteristics of Chlorophyll a and Analysis of Related Environmental Factors in the Estuary Area of Gehu Lake
LIU Yu, YANG Fei, ZHANG Yi-min, GAO Yue-xiang, ZHANG Zhi-wei, ZHU Yue-ming, KONG Ming, ZHAO Yuan, QIAN Wen-han
2021, 37(6):  733-739.  doi:10.19741/j.issn.1673-4831.2020.0804
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Chlorophyll a (Chl-a), physical and chemical factors of water samples in the 13 estuaries of Gehu Lake were monitored and analyzed monthly for 2 years from January 2018 to January 2020.The spatio-temporal characteristics and their correlation with major environmental factors were studied such as water temperature, pH and nutrients. The results show that:(1) ρ(Chl-a) changed significantly over time, with the highest in summer, followed by autumn and winter, and the lowest in spring; (2) In terms of spatial distribution, ρ(Chl-a) in the estuary area of the northwest was significantly higher than that in the south of Gehu Lake; (3) ρ(Chl-a) is extremely significantly positively correlated with water temperature, pH, and permanganate index (CODMn), negatively correlated with DO, and had no significant correlations with ρ(TN), ρ(NH4+-N), ρ(NO3--N), ρ(PO43--P) and ρ(DOC). The logarithm of ρ(Chl-a) had a significant positive correlation with the logarithm of TP, and a significant negative correlation with the logarithm of N/P ratio; (4) Phosphorus was the main determinant of ρ(Chl-a) in the estuary area of Gehu Lake. The results can provide reference for the water environment treatment of Gehu Lake.
Predictive Simulation of Ecological Spatial Evolution Based on Ann-CA-Markov Model: A Case Study of Wanzhou District, Chongqing
XING Rui-shen, ZHOU Qi-gang
2021, 37(6):  740-750.  doi:10.19741/j.issn.1673-4831.2020.0653
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Ecological space is an important area for providing ecological service functions and protecting national ecological security. Simulation and prediction for future ecological space can provide reference for the formulation of policies for ecological environment protection, the optimization and control of national space. Taking Wanzhou District as the research area, the data of land use, digital elevation model (DEM), roads, rivers, administrative centers, ecological red lines, and natural protected areas of the District in 2000, 2006, 2012 and 2018 were used to define the types of ecological space of the District. According to the data, the types of ecological space of Wanzhou District include forest land, grassland, water areas, and unused land. The characteristics of the variations of the ecological spaces were analyzed to build the ANN-CA-Markov model for the simulated prediction of the ecological space of Wanzhou District in 2024, and the quality of the habitats of the ecological space of was also evaluated. The results show that the ANN-CA-Markov model has relatively high simulation accuracy by using the cellular automata model (CA) as the main body, which is the effective solution to the deficiency of the CA model. As the simulation is able to deal with impact factors and ecological space changes, a complex nonlinear relation forecasting the distribution of ecological space with the model has higher simulation accuracy (precision reaching 0.9 836) towards transferring quantities and probability forecasts of the ecological spaces. The Wanzhou District has shown a trend of continuous increase in fragmentation degree, differentiation degree, and area uniformity degree, while the stability of the ecological space is gradually declining. The habitat quality of the ecological space is presenting a declining trend year by year. Therefore, while ensuring the increase of the quantity and scale of ecological space, both ecological environment protection and ecological space optimization and control should be taken into account to ensure the stability of the ecological space and habitat quality.
Spatio-temporal Characteristics and Driving-factors Analysis of Ecological Quality Change in Qinling Mountains of Shaanxi Province: Case Study in Liuba County, Northwest China
HU Ke-hong, ZHANG Zhen
2021, 37(6):  751-760.  doi:10.19741/j.issn.1673-4831.2020.0884
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Liuba County, the hinterland of the southern foot of the Qinling Mountains, was selected for this case study. Based on Landsat 5 TM and Landsat 8 OLI images, the remote-sensing ecological index (RSEI) was constructed to analyze the spatio-temporal variations of the quality of ecological environment in Liuba County from 1990 to 2020. The geographical detector model was used to attribute the spatial variation of the quality of ecological environment. The results show that, temporally, from 1990 to 2003, the quality of ecological environment in Liuba County showed a large area of slight deterioration, and the area where RSEI grade decreased by one level accounted for 96.47% of the total degraded area. From 2003 to 2020, the quality of ecological environment in Liuba County showed a large area of minor improvement, and the area where RSEI grade increased by one level accounted for 89.73% of the total improved area. Spatially, the overall distribution of RSEI grade in Liuba County was medium or better. Areas with poor and inferior RSEI grades were mainly distributed in the bare land at western Liuhou Town and the residential areas in the hills, accounting for less proportion of the study area. The dominant driving factors of the quality of ecological environment in Liuba County were elevation, annual average temperature, and agricultural production. Annual precipitation and roads were the secondary factors. Natural factors and human factors had combined effects on the ecological environment of Liuba County. Human factors such as agricultural production, roads and population pressure were still the critical points to concern for future ecological construction in Liuba County.
Analysis on Climate Response of Pseudotsuga sinensis Tree-rings in Ta-pa Mountains, the Northern Boundary of Natural Belt Distribution
XU Hong-fan, ZHANG He-li, SHANG Hua-ming, WANG Yong-hui, CHEN You-ping
2021, 37(6):  761-768.  doi:10.19741/j.issn.1673-4831.2020.0928
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Douglas fir(Pseudotsuga sinensis), as a kind of the national class Ⅱ endangered tree species, has been attracting comparatively less attention on its dendroclimatology so far instead. A standard tree-ring width chronology was established based on the tree-ring sample cores collected from Zhenping county, Ankang City, Shaanxi Province. Pearson correlation was introduced to analyze the correlation of tree-ring width index to the precipitation, the temperature as well as the PDSI. Results show that the width of Douglas fir was mainly affected by precipitation and air temperature, which was significantly positively correlated with the total precipitation in the growing season (r=0.386, P<0.05), negatively correlated with the average maximum temperature in November of the previous year (r=-0.364, P<0.05), and positively correlated with PDSI in October of last year (r=0.485, P<0.01). In addition, under the background of global warming, the monthly average maximum temperature may inhibit the radial growth of Douglas fir. Studying the response of tree-ring width to temperature and precipitation, and understanding the influence of climatic factors on the tree species of Douglas fir in the research area can provide theoretical basis for relevant departments in the climate change study of this region.
Evaluation of Biodiversity Conservation Priority Area and Nature Reserve System Optimization in County Level Area: A Case Study of Wuyishan City
MOU Xue-jie, RAO Sheng, ZHANG Xiao, WANG Xia-hui, ZHU Zhen-xiao
2021, 37(6):  769-777.  doi:10.19741/j.issn.1673-4831.2020.0737
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Taking the national key ecological function area-Wuyishan City as the case area, 54 rare and endangered species are selected as indicator species. Based on the assessment of species habitats, the MARXAN model, a systematic conservation planning tool, is used to assess priority areas for biodiversity conservation. The results show that:the total area of the priority areas for biodiversity conservation in Wuyishan is 734.7 km2, accounting for 26.1% of the research area, which are concentrated in the northeast, northwest and southeast regions; in the priority conservation areas, the protection ratios of the eight first-level protected species habitats exceed 50% of the total area of their respective habitats. The GAP analysis indicates that there is a spatial mismatch between the priority biodiversity conservation areas and the existing nature reserves. It is recommended to expand and build new nature reserves within the first-level priority area for biodiversity conservation, including the eastward expansion of Wuyishan National Park, the southward expansion of Wuyishan Huanglongyan Provincial Nature Reserve, the newly built forests-wetlands and aquatic wildlife nature reserves in Wutunxi, Dongxi Reservoir and surrounding areas in Wutun Township, the newly built forest nature parks in Shangmei Township and Wufu Township.
Habitat Suitability Evaluation and Corridor Design of Muntiacus crinifrons in Qianjiangyuan National Park
LI Qiong-wen, LI Shuang, CAO Ming-chang, XU Hai-gen
2021, 37(6):  778-785.  doi:10.19741/j.issn.1673-4831.2020.0822
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Muntiacus crinifrons, the national first-class protected animal, whose habitat has been destroyed, is now in danger due to human disturbance. Therefore, it is very important to identify the key areas of suitable habitat for Muntiacus crinifrons and construct habitat corridors among the broken habitats. This paper took Qianjiangyuan National Park as the research area, based on the data from distribution point and environmental variables of Muntiacus crinifrons. The habitat suitability of Muntiacus crinifrons was evaluated by MaxEnt model. The corridor was designed with Linkage Mapper corridor design model and minimum cumulative resistance model (MCR). Results show that the accuracy of MaxEnt model is excellent in predicting the potential habitat, with an AUC value of 0.959 and 0.943 for model training and testing. The suitable habitat area is 44.78 km2, which only accounts for 17.8% of the total area of national park. The main environmental factors that affect the habitat distribution are the distance from broad-leaved forest (29.4%), as well as that from water source (15.2%) and the altitude (19.2%). Three potential habitat corridors are designed in the selected key areas, which are mainly located in Liyangtian village, Tianfan village, Kukeng village and Xiachuan village. The minimum width of the corridor is 766 m and the total length is 12.70 km, which provides scientific basis for the protection of Muntiacus crinifrons.
Phylogenetic Diversity of Cyanophage g20 Gene in Different Eutrophic Plateau Lakes in Yunnan Province
CAI Yi-ming, LIU Yu-shan, WANG Zhi-long, LI Chun-xiao, LIU Li
2021, 37(6):  786-793.  doi:10.19741/j.issn.1673-4831.2020.0978
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In order to investigate the genetic diversity and distribution of g20 gene of cyanophages among different eutrophic plateau lakes in Yunnan Province, water samples were collected from Dianchi Lake, Xingyun Lake and Fuxian Lake. The phylogenetic tree was constructed to analyze the phylogenetic diversity of cyanophage g20 genes in the autumn and winter of 2018. A total of 43 g20 genes of cyanophage were cloned and sequenced. Phylogenetic analysis show that the distribution of cyanophage g20 genes in water samples of these lakes was closely related to those in other lakes and oceans, but far from those in paddy water. Between autumn and winter, the genetic diversity of g20 genes among the lakes was not significantly different. The genetic diversity of the cyanophage g20 genes of the three plateau lakes in Yunnan province is relatively rich, and novel groups of g20 genes are existing.
Study on the Characteristics and Coefficient Measurement of Rural Domestic Sewage Generation in Liaoning Province
LIU Lan-xin, HE Jun, WANG Liu-suo, ZHAO Peng-lei, SHI Mei-ling
2021, 37(6):  794-800.  doi:10.19741/j.issn.1673-4831.2020.0813
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To understand the pollution characteristics and evaluate the status of rural domestic wastewater pollution correctly in Liaoning Province. 5 typical cities in different regions with different income levels were investigated. The characteristic indices of rural domestic wastewater, including the daily discharge per capita, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), NH3-N, total nitrogen (TN), total phosphorus (TP), and animal and vegetable oil, were monitored. Through in-situ monitoring and houosehold survey, the factors that influencing rural domestic wastewater discharge characteristics were analyzed by the software SPSS. The results indicate that "region" played a dominant role in the daily discharge per capita of and NH3-N in rural domestic wastewater, and that the concentrations of COD, BOD5, NH3-N, TN, TP were influenced by region and income level. The average per capita pollution generation coefficients of rural domestic wastewater were 26.49 L·p-1·d-1 for wastewater, 23.85 g·p-1·d-1 for COD, 11.78 g·p-1·d-1 for BOD5, 0.12 g·p-1·d-1 for NH3-N, 0.64 g·p-1·d-1 for TN, 0.11 g·p-1·d-1 for TP, and 0.43 g·p-1·d-1 for animal and vegetable oil, respectively.
Characteristic Analysis of Dissolved Organic Matter in Different Surface Waters
YANG Yin, FENG Gui-zhen, JIANG Li-wen
2021, 37(6):  801-807.  doi:10.19741/j.issn.1673-4831.2020.0512
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In order to understand the characteristics of dissolved organic matter (DOM) in different surface waters, the Ganjiang River and Poyang Lake were studied from four aspects:hydrophilicity/hydrophobicity, SUVA, molecular weight distribution and three-dimensional fluorescence characteristics. The results of hydrophilicity and hydrophobicity analyses show that as a whole the hydrophobic fractions and the hydrophilic fractions in the two surface waters each accounted for roughly half, and the high hydrophobic fraction (HPO) and neutral hydrophilic fraction (N-HPI) accounted for a relatively high amount, while the transphilic fraction (TPI) and charged hydrophilic fraction (C-HPI) had less content, in which the proportions of HPO, N-HPI, TPI and C-HPI (calculated as DOC) in the Ganjiang River were 37.28%, 38.99%, 14.54% and 9.19%, respectively. The SUVA values of the fractions in the two surface waters were different. The SUVA values (4.47, 3.44, 4.14) of the HPO, TPI, and C-HPI in the Ganjiang River were much higher than that of the N-HPI (1.22). However, the SUVA value (1.49, 1.51) of the HPO and TPI in the Poyang Lake were slightly higher than that of the C-HPI (1.00) and N-HPI (0.70). Moreover, the molecular weight distribution show that the molecular weight of DOM in the two surface waters presented a relatively similar rule, i.e. the DOM with a medium molecular weight (1-10 kDa) was the main component, and it also contained a small amount of DOM with a small molecular weight (<1 000 Da), while for the high molecular weight (>10 kDa) no response peak appeared in the region. Three-dimensional fluorescence spectroscopy show that the surface waters were mainly humic acid-like hydrophobic DOM such as fulvic acid and humic acid, but the protein-like fluorescence peaks in the surface water of Poyang Lake were more obvious than those in the Ganjiang River. This research idea provids a reference for understanding the characteristics of dissolved organic matter in raw water from different sources, and the research results also offer a theoretical basis for taking reasonable control measures (such as ozone oxidation, activated carbon adsorption or membrane filtration technology, etc.).
Effects of Silicon-Calcium-Magnesium Fertilizer and Modified Humic Acid on Soil Cadmium Chemical Fractions and Accumulation in Wheat
YANG Jin-kang, ZHU Li-nan, YANG Qiu-yun, ZHANG Yu-peng, HUA Dang-ling
2021, 37(6):  808-816.  doi:10.19741/j.issn.1673-4831.2020.1022
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In order to select cadmium pollution remediation materials suitable for slightly alkaline soil, two kinds of amendments including silicon-calcium-magnesium fertilizer and modified humic acid and their complex combination were adopted to conduct pot experiments with farmland Cd contaminated soil. The deactivation efficiency was evaluated via diethylenetriaminepentaacetic acid (DTPA) extraction method and Tessier analysis of soil Cd activity as well as determination of the content in various organs of wheat. The scanning electron microscopy and energy dispersive spectrometer (SEM-EDS) was utilized to explore the surface microscopic morphology and elemental composition of the amendment. Results demonstrate that silicon-calcium-magnesium fertilizer could significantly increase soil pH value, change the chemical form of Cd in soil and reduce the content DTPA extraction Cd. Compared with the control, the Cd content in wheat root was decreased by 73.95% and 97.15% at jointing stage and mature stage, respectively, after the application of silicon-calcium-magnesium fertilizer (3%); and the Cd content in wheat grains was decreased by 86.44% after the application of silicon-calcium-magnesium fertilizer (1.2%). In terms of reducing Cd content in soil DTPA extracted form and Cd content in wheat grains, the effect of modified humic acid was lower than that of the silicon-calcium-magnesium fertilizer. The contents of Cd in wheat treated with 1.2% and 3.0% modified humic acid were decreased by 35.98%-38.01% compared with the control. The content of Cd in wheat grains was decreased by 81.77% after the application of silicon-calcium-magnesium fertilizer and modified humic acid. In conclusion, the combination of silica-calcium-magnesium fertilizer and modified humic acid has the best effect, which can effectively inactivate the activity of Cd in soil and significantly reduce the content of Cd in wheat grains.