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Table of Content

Volume 37 Issue 11
25 November 2021
The Source, Occurrence Characteristics and Migration Behavior of Microplastics in Soil
SANG Wen-jing, WANG Xiao-xia, WANG Xia-mei, XIAO Lu-rui, XU Shi-hong, LI Deng-xin
2021, 37(11):  1361-1367.  doi:10.19741/j.issn.1673-4831.2020.0723
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As emerging persistent organic pollutants, microplastics have the characteristics of small particle size, difficult degradation in the environment and easy to adsorb toxic pollutants, which led to increasing global concern. In recent years, the pollution of microplastics in soil has become increasingly serious. The source, occurrence characteristics, detection methods and transfer behavior of microplastics in soil environment were reviewed in this paper, and the transfer mechanism and influencing factors of microplastics-loaded pollutants in soil were analyzed and summarized. Finally, some prospects are put forward for the controlling of both pollution and transfer behavior of microplastics in soil. The conclusions of this paper could provide some ideas for the remediation of microplastics pollution in soil.
Spatiotemporal Dynamics and Scenarios Analysis on Trade-offs between Ecosystem Service in Three Gorges Reservoir Area: A Case Study of Zigui County
LA Lu-meng, GOU Meng-meng, LI Le, WANG Na, HU Jian-wen, LIU Chang-fu, XIAO Wen-fa
2021, 37(11):  1368-1377.  doi:10.19741/j.issn.1673-4831.2021.0224
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The Three Gorges Reservoir Area is an important and fragile ecosystem. Zigui County located in the heart of Three Gorges Reservoir Area, is facing a series of ecological threats including water and soil loss, as well as ecosystem degradation due to intensive anthropogenic interference and rapid urbanization. Thus, it is urgent to study the changes in ecosystem services and the dynamics of trade-offs, to find a strategy for optimization of regional ecosystem services. In this study, the spatial-temporal dynamic characteristics and trade-off relationships of the three ecosystem services, namely water yield (WY), carbon storage (CS), and soil conservation (SC) were firstly evaluated for Zigui County. The production possibility frontier (PPF) curve was used to determine the optimal development model for describing the trade-off characteristics among ecosystem services under the three scenarios. These were the business-as-usual scenario (BaU), ecological protection scenario (EP), and comprehensive development scenario (CD). The results show that:(1) all the three ecosystem services displayed spatial-temporal heterogeneity. From 2005 to 2015, CS increased by 2.20%, SC increased by 15.13%, while WY originally increased and then decreased. In a spatial sense, the highest values of WY were mainly distributed in the south of the county, the highest values of CS were distributed in the northeast and southeast, and the highest values of CS were distributed in the northwest and south. (2) CS-WY and SC-WY both showed significantly trade-off relationships, however, the relationship between CS and WY was stronger. Overall, the intensity of trade-offs was scale-dependent. (3) the relationships among the ecosystem services were closer to the PPF curve under CD, indicating that the allocation of land use is better under CD scenario. Therefore, future ecological management should simultaneously consider ecological security, food security, and economic and social development when formulating ecological protection and restoration measures for promoting the coordination of ecosystem services.
Alleviating Heat Island Effect of Urban Artificial Rivers in Shijiazhuang, Hebei Province
LIU Ya-nan, CHEN Yan-mei, ZOU Chang-xin, LI Han-cong, LI Xin
2021, 37(11):  1378-1385.  doi:10.19741/j.issn.1673-4831.2021.0377
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As the urban heat island (UHI) effect has been intensified, cooling effect of urban artificial rivers has gradually gained more attention. Based on the remote sensing image of Shijiazhuang City on August 31, 2016, the cooling effect of the artificial Minxin River in the third ring road of Shijiazhuang City was evaluated by using buffer analysis method. The results show that:(1) The range of urban thermal field variation index (UTFVI) within the third ring road of Shijiazhuang City was -0.23-0.37. The high values of UTFVI represent the urban construction land, while the low values of UTFVI represent the water bodies and green spaces. The average surface temperature of Minxin River was 35.82℃, and its average UTFVI was lower than 0.02, leading to a strip-shaped " cold zone" in the urban region with high-temperature area. (2) The average cooling distance across the Minxin River was 165 m. Within the buffer zone on both sides of the river, the average surface temperature raised rapidly with the increasing buffer distance and then basically remained unchanged. (3) The average UTFVI values in the whole region of Minxin River were lower than 0.05. The cooling effect of east line of Minxin River was the best, the cooling distance reached to 210 m, and the cooling amplitude was 1.59℃. The cooling effect of the second Minxin River is the worst, and the cooling distance was only 60 m, and the cooling amplitude was about 0.19℃. The cooling distances of the west, south, north and middle lines of Minxin River were 150, 120, 180 and 270 m, respectively, and the corrsponding cooling amplitudes were 0.65, 0.40, 1.60 and 1.39℃, respectively. (4) Within 60 m of the minimum cooling distance of the Minxin River, a cold island effect occured when the proportion of green space was higher than 50%, the proportion of urban construction land was lower than 48%, and the average UTFVI of the urban water body was lower than zero. At that time, the comprehensive cooling effect of green space and the Minxin River was the largest. The research will provide guidance for construction of urban artificial rivers and the rational layout of shoreside landscape structures.
Objective Synoptic Classification on Ground-level Ozone Pollution in Changsha
YANG Meng, HUA Rui-yang, LI Wei, YE Cheng-zhi, NI Chang-jian
2021, 37(11):  1386-1393.  doi:10.19741/j.issn.1673-4831.2021.0170
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Weather classification is the basis for research ground-level ozone (O3) pollution potential and the key technical support for atmospheric environmental management in summer. The principal component analysis in T-mode (PCT), an objective synoptic classication method, was applied to identify the synoptic types in Changsha based on the ERA-interim reanalysis data, the O3 hourly monitoring data, and conventional meteorological observations during 2016 to 2018. The sealevel pressure field in Changsha was objectively divided into six weather patterns:uniform pressure type (T1), bottom of high pressure type (T2), edge of high pressure type (T3), west side of high pressure type (T4), rear of high pressure type (T5) and two high pressure shear type (T6). A further analysis of O3 over-standard rates under different weather types indicate that T1, T4, and T6 are ozone-polluted weather types, with corresponding O3 over-standard rates of 20.39%, 8.59% and 8.40%, respectively. Under the control of ozone-polluted weather type, the meteorological conditions were manifested as high radiation, high temperature and low relative humidity, which were conducive to the photochemical production of local O3. At the same time, the O3 pollution in Changsha was not only originated from the photochemical generation of local O3, but also closely related to the transport effect of O3 and its precursors from the northwest cities.
The Evaluation of an Ecological Engineering System for the Utilization of Spartina alterniflora in Chongming Dongtan
XIN Yue, ZOU Cai-yu, WANG Lei, LIU Jin-e, LI Xiu-zhen
2021, 37(11):  1394-1403.  doi:10.19741/j.issn.1673-4831.2020.0751
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According to the principles of ecoengineering sciences,Spartina alterniflora in Chongming Dongtan can be utilized as a resource by an industrial chain, i. e. plant growth-harvest and transportation-bio-mineral liquid-lipid-lowering capsule-biochar-revetment materials. The emergy synthesis was used to comprehensively evaluate emergy and economic yields of such resource utilization system regarding S. alterniflora. The system has good economic yields, with a net yield of 9.64E+09 $ and an output-input ratio of 27.78, being significantly greater than other similar coastal economic systems and other ecological engineering regarding S. alterniflora. The lipid-lowering capsule subsystem had the greatest economic input-output ratio among all subsystems, with net economic yield of 9.28E+09 $, accounting for 96% of the entire system. The net emergy yield of such entire system was 3.98E+22 sej, indicating a high emergy input-output ratio. The high social and economic inputs increased the environmental load of the system, with an environmental load ratio of 154.634 and an emergy sustainable development index of 0.182. In conclusion, the resource utilization system for S. alterniflora has a strong economic competitiveness and a long-term development potential.
The Spatial Effect of Agricultural Finance on Agricultural Greenhouse Gas Emission Intensity: An Empirical Analysis Based on the Spatial Durbin Model
HAN Jin-yu, QU Jian-sheng, XU Li, LI Heng-ji, LIU Li-na
2021, 37(11):  1404-1412.  doi:10.19741/j.issn.1673-4831.2020.0783
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To support and regulate agricultural development, Chinese government is providing financial subsidies to farmers. This has greatly improved the agricultural production, and it has also an implication on greenhouse gas (GHG) emission intensities. The aim of this research is to assess the relationship between agriculture finance and GHG emission intensities. Based on the panel data of 31 provinces from 1997-2017, the research was carried out through the Spatial Durbin Model. The results show that the proportion of provincial agricultural finance increased significantly, leading to a decline in agricultural GHG emission intensities. The agriculture-supporting finance had a reducing effect on the intensity of agricultural GHG and had obvious spatial spillover characteristics; that is to say, the effect of a neighboring province's agriculture-supporting finance on the province's agricultural GHG reduction is stronger than that of the province's agriculture-supporting finances itself. In addition to agricultural finance, factors such as economic structure, urbanization level, urban-rural gap, agricultural development level, agricultural mechanization level, and cultivated land occupancy have affected the agricultural GHG intensities to varying levels, and there are spatial spillover effects to varying degrees. Because the agricultural finance has decreased the GHG intensities, it is necessary to choose this instrument to develop and promote lowcarbon agriculture. In addition, optimizing the agriculture structure and coordinating the spatial distribution should also be the direction of future agricultural finance.
Spatio-temporal Variations of Fractional Vegetation Coverage and Influencing Factors in Qianxi'nan Prefecture from 2000 to 2015
GU Yang-yang, ZOU Chang-xin, QIAO Xu-ning, HUANG Xian-feng, YE Xin, XU Mengjia, YANG Zhong-qing, DU Shi-peng
2021, 37(11):  1413-1422.  doi:10.19741/j.issn.1673-4831.2020.0806
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It is essential to appraise the spatio-temporal variations of vegetation coverage in Karst rocky desertification areas for ecological protection and restoration. Taking Qianxi'nan Prefecture in Guizhou Province as an example, based on MOD13Q1 image data, the fractional vegetation coverage (FVC) was calculated by using pixel dichotomy method. With the trend analysis, Hurst index, residual analysis and hotspot analysis, the spatial-temporal variations and future trend of FVC in Qianxi'nan Prefecture from 2000 to 2015, as well as the impacts of climate change and human activities on FVC were analyzed. The results show that:(1) The FVC of Qianxi'nan Prefecture was increasing from 2000 to 2015, which was higher in the southeast and lower in the north. The growth rate of FVC in non-Karst areas was higher than that in Karst areas. (2) The FVC of Qianxi'nan Prefecture was improving. The improvement area accounted for 40.38%, mainly distributed in the eastern part of Zhenfeng County, the western part of Wangmo County and the south-central part of Pu'an County. The proportion of vegetation improvement area in non-Karst area (41.53%) was greater than that in Karst area (39.37%). The degradation areas were mainly distributed in the built-up areas of cities, counties and their surrounding areas, and the basically unchanged areas are widely distributed. (3) The predicted area of future continuous improvement (13.30%) was greater than that of future continuous degradation (9.77%), and the uncertain future change area accounted for 68.02%. Therefore, it is necessary to strengthen ecological management and restoration in uncertain change area and vegetation degradation area. (4) Among temperature and precipitation factors, the former played a substantial role in Qianxi'nan Prefecture. The Grain for Green Project and the urban development intensity are the main human factors leading to variations of FVC in Qianxi'nan Prefecture.
Diversity of Birds in Yongde County, Yunnan Province during Breeding Season
ZHANG Jian-song, LU Wen-zhu, TANG Jin-tao, DUAN Yu-bao
2021, 37(11):  1423-1429.  doi:10.19741/j.issn.1673-4831.2021.0101
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In order to investigate the diversity of birds in Yongde County, Lincang, Yunnan Province and reveal their community dynamics, the fixed line transect method was used to observe birds twice a year during the breeding season (from March to June) between 2018 and 2020. A total of 15 orders, 52 families and 197 species of birds were recorded and 6 135 individuals were observed. The local bird assembly was dominated by Passerine birds, accounting for 73.60% of the total number of species surveyed. In terms of the residence type, there were 158 species of resident birds (80.20%), 19 species of summer migratory birds (9.64%), 18 species of winter migratory birds (9.14%) and 2 species of travelling birds (1.01%). Resident and summer migratory birds added up to 177 species (89.85%), which constitute the breeding birds in Yongde County. Among breeding birds, there were 113 Oriental species, 64 widely distributed species and no Palearctic species. Among different habitats, species richness (121 species), Shannon-Wiener index (H=4.147) and evenness index (J=0.864) were the highest in broad-leaved forest, while in shrub habitat, birds species richness (64 species), Shannon-Wiener diversity index (H=3.270) and evenness index (J=0.786) were the lowest. The results of oneway ANOVA indicate significant differences in encounter rate among habitats (F=2.751, df=4, P=0.037), with the highest encounter rate discovered in both farmland and shrub habitat. The Sorensen similarity of bird communities show that the species composition was most similar between broad-leaved forest and mixed forest, while it was significantly different between broad-leaved forest and shrub habitat. The Shannon-Wiener diversity index and evenness index of bird community show little difference among the three years, and the species composition of bird community was relatively stable with limited fluctuation. This study facilitates a better understanding of the species composition, community structure and diversity status of birds in breeding season of Yongde County, providing a basis for the protection and management of local bird resources.
Analysis of Bird Community Structure and Birdstrike Prevention Measures in a Coastal Airport in Summer
LIU Zhen-jiang, FAN Li-hong, YAN Zheng
2021, 37(11):  1430-1436.  doi:10.19741/j.issn.1673-4831.2020.0890
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Airports usually have larger area of grassland with abundant vegetation which may provide suitable and ideal habitats for some birds. Summer is the best season for birds to breed and fledglings to leave out their nests. This will inevitably increase the probability of bird strike around airport and may cause loss of human lives and properties. It is essential to figure out the bird community structure and dynamics prior to taking active measures to prevent bird strike from happening. However, little is known about the bird community structure in Eastern Coastal Airports of China. To fill in this gap, we conducted a survey on avian composition in 6 habitats including grassland, beach, forest and scrubland, wetland, farmland and village in the range of 5 km of peripheral areas of a coastal airport in eastern China from June to August 2019. Both the faunal characteristics, community composition and nocturnal activity of birds were recorded. The risks of bird strike due to increased activity of birds around the airport were systematically analyzed and summarized. Totally 52 species of birds, belonging to 9 orders, 24 families were found in 8 line-transects. Among those species of birds, 10 were residents, 29 were summer residents, 13 were passing migrants that occupied 19.23%, 55.77% and 25.00% in the whole bird community around this airport, respectively. Natatores and waders accounted for 55.77% of the total bird species. The ranking of high-risk of bird strike is Hirundo rustica>Passer montanus>Larus ridibundus>Columba domestica>Larus canus. Wetland had the largest diversity index (2.703 5) and evenness index (0.839 9) which hosted 25 bird species accounting for 48.07% of the total bird species around the airport. There were also 4 nocturnal species of birds which might threaten flight safety. They are Caprimulgus indicus, Otus scops, Athene noctua and Asio otus. It is proposed to reduce and prevent bird strike from occurring by implementing classified ecological environment management, strengthening precise prevention, and control of birds with high-risk, such as, nocturnal bird species, around the airport area.
Changes in Community Assembly of Microbiomes in Black Soil under Distinct Scenarios of Long-term Field Fertilization
GAO Wei, WANG Lian-feng, JIA Zhong-jun
2021, 37(11):  1437-1448.  doi:10.19741/j.issn.1673-4831.2020.0807
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Intensive agricultural management is influential to soil microbiome and its functions. Based on a 36-year fertilization experiment at the Ministry of Agriculture Key Field Observation Station of Harbin Black Soil Ecological Environment, effects of four fertilization managements (CK:no fertilizer; NPK:mineral fertilizer; OM:organic fertilizer; MNPK:mineral NPK plus organic fertilizer) on soil fertility and microbial respiration were quantitively studied, and microbial community assembly mechanisms were analyzed using the high-throughput sequencing and community assembly models. Results show that long-term fertilization improved soil fertility, such as soil organic carbon, total nitrogen, available phosphorus and microbial activity. Soil microbial respiration was increased in the order of CK-1), soil microbial respiration in MNPK (calculated in carbon, 228.7 μg·g-1) was increased by 22.4%. Linear discriminant analysis effect size (LEfSe) indicates that NPK and MNPK treatments had similar keystones including Dyella marensis, Bacillus megaterium and Herbaspirillum sp., while OM was predominated by Bacillus acidiceler and Bacillus megaterium. As compared with CK, long-term fertilization stimulated the growth of ammonia oxidizing bacteria (AOB) with the Nitrosospira-like AOB increased by 3.61 times in NPK treatment. The dominant phylotypes of ammonia oxidizing archaea (AOA) and nitrite oxidizing bacteria (NOB) were Nitrososphaera and Nitrospira, respectively. The co-occurrence network analysis revealed that soil microbial community in MNPK had the most closely links, with the proportion of positive links reached 99.6% versus 78.4% in NPK and 97.4% in OM. The analysis of β NTI indicates that long-term fertilization strengthened the deterministic processes of microbial community assembly, with the strongest determinism occurred in MNPK. Structural equation models (SEMs) further suggest strongly positive correlations between soil fertility improvement and microbial respiration (explaining > 90% of variation) among fertilization managements. This study demonstrates that long-term fertilization significantly stimulated the growth of functional microbiomes, altered community structure and improved soil fertility. Compared with NPK and OM, MNPK treatment was more efficient in enhancing soil fertility and stability of microbial community. As a whole, these results provide scientific basis for optimizing the efficient fertilization managements in black soils.
Quantitative Analysis of the Sources of N2O Emissions on Maize-cultivated Fluvo-aquic Soil
LIU Yao-bin, XU Cong, WANG Ji-dong, WANG Lei, HAN Xiao, JI Cheng, ZHANG Yong-chun
2021, 37(11):  1449-1457.  doi:10.19741/j.issn.1673-4831.2020.0838
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Quantifying the sources of N2O emissions is essential for clarifying the N2O production mechanism and estimating the emission factor of nitrogen (N) fertilizer. Most published studies focused on the N2O which emitted directly from N fertilizer, while there were only limited reports determined the patterns of native soil-derived N2O emissions following N fertilization. In this study, a pot experiment was carried out to elucidate the impacts of the 15N fertilization and plant cropping (maize) on fertilizerand native soil-derived N2O emissions in a fluvo-aquic soil. Four treatments, i. e., no N fertilization and no plant maize (N0P0), plant maize without N fertilization (N0P1), N fertilization without plant maize (N1P0), and N fertilization plus plant maize (N1P1), were established in the experiment. Results show that the total N2O emissions were stimulated by N fertilization. The soiland fertilizer-derived N2O emissions accounted for 22.5% and 77.5% of the total emissions, respectively. Compared with non-N-fertilized control, N fertilization significantly enhanced soil-derived N2O emissions by 162%-460% (P<0.05), and this increased soil-derived N2O emissions (4.16-6.98 mg N2O-N·m-2) contributed about 13.7%-18.1% to the total emissions. N fertilization also enhanced CO2 fluxes, and a significant linear relationship between CO2 emissions and the change of soil-derived N2O emissions was observed (P<0.05), which suggests that the stimulated soil-derived N2O emissions were highly related to the promoted soil organic matter turnover. The results of the two-way ANOVA indicate that the interactions between N fertilization and plant maize had a significant effect on the rates and sources of N2O emissions (P<0.01). Compared with N1P0, N2O emissions under N1P1 were significantly reduced by 55.0% (P<0.05); but the proportion of the stimulated native soil-derived N2O emissions was higher under N1P1. The total inorganic N (NO3--N and NH4+-N) content under N1P0 was significantly (P<0.05) higher than that under N1P1 treatment, but contrary trends were found for NH4+-N content, indicating that plant cropping significantly affected the fates and dynamics of soil N. In conclusion, in the soil-crop system, the exogenous N application stimulated not only the fertilizer-derived N2O emissions but also the emissions from native soil and the participation of the plant has significant impacts on the source of N2O emission. Our study highlights that, in intensively farmed fluvo-aquic soils, future N2O mitigation strategies should pay more attention to the emission from native soil.
Effects of Salinity on Soil Ammonia Volatilization and Denitrification Rates
SHI Zhen-qi, SHE Dong-li, CHEN Xin-yi, XIA Yong-qiu
2021, 37(11):  1458-1464.  doi:10.19741/j.issn.1673-4831.2020.0883
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The coastal area is an important land reserve. However, the saline-alkaline soil in coastal area is characterized by poor soil structure, low nitrogen use efficiency, and obviously seasonal and annual variation in sodium salinity changes which has resulted in an unique soil nitrogen cycle process. The sodium salinity is an important factor influencing the nitrogen cycle, so it is of great theoretical value to clarify its influence on ammonia volatilization and denitrification rate. In this study, cultivation experiments were established with five sodium salinity gradient, namely <1, 1, 2, 4, and 10 g·kg-1, to study the effects of salinity on ammonia volatilization and denitrification in coastal soil. Ammonia volatilization and denitrification rates and related water and soil environmental parameters were measured. The results show that high salinity gradient not only reduced the NH4+ adsorption capacity of soil and promoted the release of NH4+ into the water, but also affected pH and nitrogen concentration. The soil environment became alkaline. Alkaline environment promoted the conversion of NH4+ to NH3, and the ammonia volatilization rate increased significantly. Soil denitrification rate decreased obviously with increasing salinity. The study also found a significant negative correlation between salinity (Na+ concentration) and abundance of denitrifying bacteria (nirK and nosZ genotypes). High salinity inhibited microbial activity and reduced denitrification rate.
Eutrophic Status and Functional Genes Responsible for Nitrogen Cycling in the Sediment of the Sheyang Lake
ZHENG Hao, FAN Xiang-ke, ZHONG Fei, GAO Hai-you, ZHANG Xiao-qian, LI Bo-wen, ZHANG Zhao-hui, ZHANG Yong-jiang
2021, 37(11):  1465-1472.  doi:10.19741/j.issn.1673-4831.2020.0739
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To evaluate the environmental quality of the Sheyang Lake National Aquatic Germplasm Reserve, the seasonal changes in water quality at the sampling stations from May 2018 to February 2019 were monitored. Eleven sampling stations were distributed in the periphery (S1-S6) and core area (S7-S11) of the reserve. Several representative stations were selected to monitor the carbon, nitrogen and sulfur contents and the abundance of nitrogen cycling functional genes in the sediment. Comprehensive trophic level index (TLI) method was used to assess water eutrophication status. The interpolation method was used to simulate the spatial-temporal variation of nitrogen and phosphorus concentrations. The relationship between nitrogen cycling functional genes and essential environmental parameters was examined. The results indicate that the Sheyang Lake was slightly eutrophia; the concentration of total nitrogen reached the maximum in winter[(1.64 ±0.29) mg·L-1], whereas the concentration of total phosphorus was the maximum in summer[(0.21±0.13) mg·L-1]. They were the critical factors determining the grade of environmental quality. The abundance of denitrifying functional genes (e. g., narG and nirS) was relatively higher during the investigation. The abundance of nirS gene in summer was significantly higher than that in spring and in autumn (P<0.05). These findings suggest that the sewage discharge and agricultural pollution might be responsible for the eutrophication problem in the Sheyang Lake. Thus, it is essential to initiate the control of rural environmental pollution sources as well as to encourage the development of eco-agriculture, so as the water quality can be improved and aquatic germplasm resources can be conserved.
Research of Adsorption Characteristics of Sulf Antibiotics on Corn Stover Biochar
SONG Dou-dou, LI Li, LIU Wei-ting
2021, 37(11):  1473-1480.  doi:10.19741/j.issn.1673-4831.2021.0021
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In this study, biochar was prepared from corn straw (BC) and modified by nitric acid (HBC). The adsorption properties of biochar on sulfachloropyridazine(SCP), sulfamethoxazole(SMZ) and sulfamethazine(SMA) before and after modification were investigated. The results show that the adsorption kinetics of both kinds of biochar on the three antibiotics were all well fitted by the quasi-second-order kinetic equations. The adsorption rate of acid-modified biochar was higher than that of unmodified biochar. The whole adsorption processes of the two kinds of biochar were spontaneous, endothermic and disordered which can be better described by Langmuir model. The adsorption capacity of HBC was greater than that of BC. In the mixed system, the adsorption capacity of SCP and SMZ on BC and HBC was better than that of SMA. Overall, the adsorption effect of SCP, SMZ and SMA on acid-modified biochar was better than that on unmodified biochar.
Stable Remediation of Arsenic-contaminated Soil by Sludge-based Biochar
QIN Song-yan, XIA Di, ZHAO Li-xin
2021, 37(11):  1481-1486.  doi:10.19741/j.issn.1673-4831.2020.0879
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Sewage sludge-based-biochar and bioleaching sewage sludge-based-biochar were used as restorative to remediate arsenic polluted soil. Brassica chinensis was planted in pot to explore the influence of biochar on soil and plants absorbing arsenic. Arsenic content in pots were 20, 40, 60, and 100 mg·kg-1. The results show that:After adding biochar, the soil pH was decreased, and the content of sulfur, phosphorus, iron, and aluminum were greatly increased. However, the aluminum content of bioleaching sludge-biochar is 4.64 mg·g-1 lower than that of sludge-biochar. The effective arsenic content in the soil was reduced by 16.9%-33.6%; while the fixed arsenic content was increased by 8.3%-31.0%. Compared with sludge-biochar adding pots, the bioleaching sludge-biochar adding pots had a higher residual arsenic percentage in 3.9-11.4 percentage point. The application of biochars can significantly reduce the arsenic content in Brassica chinensis, and the arsenic enrichment coefficient is about 0.1, but there is no significant difference between the two biochars treatments.
Effects of High Nitrogen Load Liquid Digestate Irrigation on Nitrogen Accumulation, Leaching and Microbial Diversity in Purple Soil
WANG Kang-ting, WU Fu-lin, ZHOU Zhong-bo, CHEN Yu-cheng
2021, 37(11):  1487-1496.  doi:10.19741/j.issn.1673-4831.2020.0923
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Liquid digestate returning to the field is an important method for the disposal of animal manure and wastewater, but it will also increase the risk of soil and water nitrogen pollution. In this work, liquid digestate was used to irrigate the soil column for 78 days to investigate the changes in soil nitrogen accumulation and in leaching solutions at the bottom of the soil column as well as the changes of soil microbial diversity and community structure. Several testing conditions were set as equal amount liquid digestate irrigation by one-time (T1), equal amount liquid digestate irrigation divided into 6 times (T2), planting ryegrass under equal amount liquid digestate irrigation by one-time (T3), with field compound fertilizer (CK1) and water (CK2). The nitrogen accumulation in the soil surface layer (0-20 cm) and middle layer (>20-40 cm) could be shown in all the three treatments in the early stage of liquid digestate irrigation, and till the late stage (78 d), the nitrogen accumulation in the lower layer (>40-60 cm) was shown in the irrigation treatment of liquid digestate. In terms of nitrogen leaching, there was a surge at 42 and 60 d for T1 and T2, while the cumulative irrigation amount was 6 and 24 days later than that of the field compound fertilizer treatment, respectively. However, the surge of nitrogen leaching was not observed in T3. The nitrate nitrogen content of leaching solution under T1, T2 and T3 treatments reached the peak value after 60 d of irrigation. The ratio of nitrate nitrogen to the total nitrogen in the leaching solution was much higher than the ratio of ammonium nitrogen to the total nitrogen. Soil microorganism Chao 1 index was ordered as:T3 > T1 > CK1 > CK2 > T2; and Shannon index:CK2 > T3 > T1 > T2 > CK1. The results of the heatmap show that T2 was the farthest from other treatments. Fisher's exact test results show that the relative abundance of Sphingomonas in T2 treatment was significantly lower than those in the rest treatments, while the relative abundance of norank_o__Saccharimonadales was significantly higher. Overall, planting crops can delay nitrogen migration to groundwater and reduce the risk of nitrogen leaching. Compared with compound fertilizer, liquid digestate irrigation can improve the species richness and diversity of the soil microbial community, especially for the T3 treatment. The irrigation of liquid digestate in the equal amount and divided times has the most obvious influence on the structure of microbial communities.