Ma R.,Key Laboratory of Arable Land Conservation |
Ma R.,Huazhong Agricultural University |
Cai C.,Key Laboratory of Arable Land Conservation |
Cai C.,Huazhong Agricultural University |
And 9 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014
Rainfall splash erosion, usually the first step in soil loss and sediment transport, is a critical process in hillslope water erosion. It is recognized that antecedent moisture content influences the re-aggregation of soil particles and their subsequent enhanced ability to resist exogenic soil erosional forces. The purpose of this study was to determine the effect of antecedent moisture on aggregate stability and splash for Utisols in subtropical China. Four soil samples derived from Shale and Quaternary red soil and five antecedent moisture contents (3%, 5%, 10%, 15%, and 20%) were tested in this study. Effects of antecedent moisture on aggregate stability and splash erosion were discussed based on the analysis of aggregate water stability using wet-sieving method and rainfall simulation with an intensity of 60 mm/h for 45 minutes in laboratory. Mean weight diameter of aggregate water stability (MWDwa) was used as the aggregate stability index. The fragments splashed out were measured by wet sieving with sieves of 2.0 mm, 1.0 mm, 0.5 mm, 0.25 mm, respectively. And fragments less than 0.25 mm in size were then measured by a laser diffraction sizer in five classes (0.2-0.25 mm, 0.15-0.2 mm, 0.10-0.15 mm, 0.05-0.10 mm, and < 0.05 mm). The results showed that aggregate water stability significantly increased with increasing antecedent moisture content and slaking was the most efficient breakdown mechanism. With the increase of antecedent moisture content, MWDwa values of the soils derived from Shale significantly increased. However, the MWDwa values of soils derived from Quaternary red clay increased initially then decreased, with the most stable value at the moisture of 15%. With antecedent moisture content increasing, the total mass of splash for soils derived from Shale decreased, but decreased first then increased for soils derived from Quaternary red clay, with a minimum value at the moisture of 15%. The size-selectivity was determined by the size distribution and surface structure at different antecedent moisture contents. For more stable soils, size distribution of the splashed fragments is bimodal with a major peak at 1-0.5 mm and < 0.05 mm. For less stable soils, size distribution of splashed is unimodal with a large peak at 1-0.25 mm except the ones at the moisture of 20%. The results can provide a reference for agricultural water-soil engineering and water erosion mechanisms of Utisols, which has great significance for improving soil erosion models.
Wang P.-F.,Huazhong Agricultural University |
Wang P.-F.,Key Laboratory of Arable Land Conservation |
He J.-J.,Changjiang Engineering Management Consulting Co. |
Gao M.,Huazhong Agricultural University |
And 5 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014
Potential cancer risk to human beings caused by typical endocrine disrupting chemicals (EDCs), including Cd, DDT and polychlorinated biphenyls (PCBs), in Pearl River Basin was investigated based on the US EPA guidelines for carcinogen risk assessment. The risk sources, exposure media and pathways, as well as the risk contribution from each component, were analyzed through the multi-media/multi-pathway human exposure model. Results showed that the daily exposure doses of Cd, DDT and PCBs to the residents in Pearl River Basin were 2.36×10-4, 6.46×10-5, 4.62×10-5 mg/(kg·d), respectively, which were englobed mainly by oral intake. The total cancer risk was 2.04×10-4 that was higher than the highest acceptable cancer risk level (1×10-4). Vegetables and rice were the major exposure media. Cd and PCBs were the dominant contributors to cancer risk, accounting for 44% and 45%, respectively.
Wang L.-T.,Huazhong Agricultural University |
Wang L.-T.,Key Laboratory of Arable Land Conservation |
Duan B.-Z.,Huazhong Agricultural University |
Duan B.-Z.,Key Laboratory of Arable Land Conservation |
And 6 more authors.
Huanjing Kexue/Environmental Science | Year: 2015
Six kinds of impermeable underlying surface, cement tile roof, asbestos roof, cement flat roof, residential concrete pavement, asphalt pavement of restaurants, asphalt pavement of oil depot, and a combined sewer overflow canal in the Jiansheng town of Dadukou district in Chongqing city were chosen as sample plots to study the characteristics of nutritional pollutants and heavy metals in town runoff. The research showed that the average mass concentrations of TSS, COD, TN, TP in road runoff were (1 681.2±677.2), (1 154.7±415.5), (12.07±2.72), (3.32±1.15) mg·L-1, respectively. These pollutants were higher than those in roof runoff which were (13.3±6.5), (100.4±24.8), (3.58±0.70), (0.10±0.02) mg·L-1, respectively. TDN accounted for 62.60%±34.38% of TN, and TDP accounted for 42.22%±33.94% of TP in the runoff of impermeable underlying surface. Compared with the central urban runoff, town runoff in our study had higher mass concentrations of these pollutants. The mass concentrations of TSS, COD, TDN, TN, TDP and TP in the combined sewer overflow were (281.57±308.38), (231.21±42.95), (8.16±2.78), (10.60±3.94), (0.38±0.23) and (1.51±0.75) mg·L-1, respectively. The average levels of heavy metals in this kind of runoff did not exceed the class VI level of the surface water environmental quality standard. Most pollutants in the combined sewer overflow had first flush. However, this phenomenon was very rare for TSS. There was a significant positive correlation between TSS and COD, TP in the combined sewer overflow. And this correlation was significant between NH4+-N and TP, TDP, TN, TDP. However, a negative correlation existed between NO3--N and all other indicators. ©, 2015, Huanjing Kexue/Environmental Science. All right reserved.
Bu R.,Huazhong Agricultural University |
Bu R.,Key Laboratory of Arable Land Conservation |
Lu J.,Huazhong Agricultural University |
Lu J.,Key Laboratory of Arable Land Conservation |
And 8 more authors.
PLoS ONE | Year: 2015
Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils. © Copyright 2015 Bu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Li Y.,Huazhong Agricultural University |
Li Y.,Key Laboratory of Arable Land Conservation |
Li L.,Huazhong Agricultural University |
Li L.,Key Laboratory of Arable Land Conservation |
And 10 more authors.
2014 The 3rd International Conference on Agro-Geoinformatics, Agro-Geoinformatics 2014 | Year: 2014
Chlorophyll content plays an important role in the growth of crop. Chlorophyll content of crop not only shows the situation of crop growth but also has important significance in disease diagnosis. By using hyperspectral imaging technology, chlorophyll content can be diagnosed non-destructively. Before the correlation analysis, the experiment gets the SPAD values and vegetation indexes. The result shows that VOG1 quadratic model has the best performance (R2=0.83 and RMSE=2.68). After using the best model for each pixel of the image, we can get a grayscale image, on which each pixel value is the SPAD value of this point. Then grayscale image is changed into pseudo-color image. As can be seen from the image, both from the veins to the mesophyll and from the bottom to the top, chlorophyll content is increased gradually. The study can provide the rape researchers with more information and a new thinking of rape studies. © 2014 IEEE.
Si K.,Huazhong Agricultural University |
Si K.,Key Laboratory of Arable Land Conservation |
Zhang J.,Huazhong Agricultural University |
Zhang J.,Key Laboratory of Arable Land Conservation |
And 7 more authors.
2014 The 3rd International Conference on Agro-Geoinformatics, Agro-Geoinformatics 2014 | Year: 2014
In order to construct the high-precision and high-fidelity 3D plants model quickly and economically, this study present a new approach to combing the color structured light with silhouette-based method to repair the model's depth information. First, project the coded color structured light which is coded using spatial code method on the surface of the plants. And photograph the plants using two non-contract cameras from different angles. Second, we need to extract the center of the stripes and decode the structured light base on color space conversion. Then, gain the feature points using the method of color stripes matching base on epipolar constraint. Finally, calibration the camera and computation of feature points' coordinates. Reconstruct the 3D model of plants base on the feature points. Experimental results show that the method could repair the 3D model's depth information effectively. © 2014 IEEE.