Table of Content

Volume 35 Issue 2
25 February 2019
Ecological Corridor
ZHENG Hao, GAO Ji-xi, XIE Gao-di, ZOU Chang-xin, JIN Yu
2019, 35(2):  137-144.  doi:10.19741/j.issn.1673-4831.2017.0746
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Habitat fragmentation leads to decrease in biodiversity and to damage of ecological functions. Construction of ecological corridors can connect separated landscapes elements, which plays an important role in protecting and restoring of biodiversity and in maintaining and delivering of ecological functions. The concept, origin and development of ecological corridor are introduced and the ecological functions of the ecological corridor are analyzed with respect to biodiversity protection, environmental protection of ecological resources, development of ecological security and suitable responses to global climate change. Furthermore, methods of construction of ecological corridors are examined based on the minimum cost distance model and the circuit theory, and the influences of the biotic habitat and the length and quality of the corridor on the effectiveness of the ecological corridor are discussed. Research on ecological corridors had a late start in China, and has been limited to the topics of urban afforestation, landscape aesthetics and small-scale ecological protection. By analyzing the basis for, the approaches to and the existing cases of the construction of large-scale international ecological corridors in an international setting, references for the construction of ecological corridors in China are provided. It is concluded that in China the construction of ecological corridors should be focused on their ecological functions at the landscape and regional scale and could be based on the existing ecological planning.

A Global Standard for the Identification of Key Biodiversity Areas and Recommendations on China's Practice
CHEN Hui, WU Jian-yong
2019, 35(2):  145-150.  doi:10.19741/j.issn.1673-4831.2017.0847
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Identification of Key Biodiversity Areas (KBAs) is the primary step in the conservation of biodiversity. The International Union for Conservation of Nature (IUCN) formally released a Global Standard for the Identification of Key Biodiversity Areas in March 2016. This is the first time application of biodiversity elements in the consideration of highlighted sites that make significant contributions to the global persistence of biodiversity. Furthermore, the criteria of KBA incorporate elements of biodiversity across genetic, species, and ecosystem levels, helping countries and regions to identify areas and sites that contribute significantly to biodiversity across global terrestrial, inland waters, and marine environments. This paper provides an overview of the global standards identified by IUCN as KBA criteria, which is based on IUCN's 30 years of experience identifying important areas rich with biological species as well as ecologically and genetically diverse regions. The review focuses on several key principles of the standard and some suggestions for the identification of key biodiversity areas have been proposed in accordance with China's current research activities and practices.

A Review of Discussion on the Difference of Pollutant Discharge Permit Policy for the Pesticide Industry Between China and the US
SHI Ma-li, WANG Na, GUO Xin-yan, SHAN Zheng-jun, WANG Ying
2019, 35(2):  151-157.  doi:10.19741/j.issn.1673-4831.2018.0117
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The pollutant discharge permit system is a basic environmental management system for controlling pollutant discharge. Based on the development of pollutant discharge permit systems in China and the United States, and the pollution characteristics of the pesticides, a comparative analysis was performed on the respective permit system, including the pollutant types, the distributed object, the method on determining emission limits, and the self-monitoring procedures. It is found that the current pollutant discharge permit system for pesticide industry in China may be improved through the following recommendations:(1)the types of pollutants controled should be increased based on the discharge characteristics of the pesticide industry; (2)it is suggested to distinguish the regions as attainment and nonattainment areas based on the standard of environmental quality. This will enable specific pollution control strategy to be applied in each district to achieve targeted management outcomes; (3)the emission limits should not be determined only by pollution control levels and other technical regulations for specific production systems, but also by the impact on the environmental quality of the region as a whole; (4)incentive policies could be adopted to promote cost-effective mutually beneficial outcomes for the pesticide industry with outstanding performance in pollution control.

Using RUSLE Model to Analyze Temporal and Spatial Characteristics of Soil Erosion in Tongren Area From 1987 to 2015
HU Xian-pei, ZENG Cheng, QIAN Qing-huan, WANG Quan, LI Yang-bing
2019, 35(2):  158-166.  doi:10.19741/j.issn.1673-4831.2018.0439
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Based on digital elevation model (DEM), daily rainfall, land use date and remote sensing imagery as basic data, combined with GIS, RS techniques and landscape pattern analysis tool, the modified revised universal soil loss equation (RUSLE) was used to analyze temporal and spatial distribution characteristics of soil erosion in Tongren Area from 1987 to 2015. The results show that the soil erosion in the study area was relatively serious from 1987 to 1995. However, From 1995 to 2015, the soil erosion was significantly improved. During this period, the soil erosion intensity in most areas and karst trough areas shifted to a lower level. Among them, the violent and extremely strong grade erosions were mostly transferred to the moderate and mild grades. From the perspective of landscape pattern, the soil erosion status was increasingly dominated by the slightly erosion and mild erosion landscape types.

Study of Spatial and Temporal Distribution of Ozone and Its Influencing Factors in Ningxia Based on OMI
CHEN Xue-ping, XIAN Long, JU Tian-zhen, ZHANG Jiang-yu, WANG Pei-yu, LIU Hong-qing, PEI Jie
2019, 35(2):  167-173.  doi:10.19741/j.issn.1673-4831.2017.0831
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The spatial and temporal distribution tendency, as well as the influencing factors of atmospheric O3 in Ningxia region from 2006 to 2016 were analyzed using the OMI sensor satellite inversion data. For the time distribution, the interannual variation of ozone column concentration increased during the years before 2010, reaching to maximum value of 368.23 DU, and then decreased with the years, reaching a minimum value of 287.57 DU in 2016. The average annual growth rate of ozone column before 2010 was 2.95% and then the average annual reduction rate is 3.2%. The ozone column concentration had an obvious season change characteristics. The seasonal mean concentration was the highest in spring and was the lowest in autumn. The mean seasonal values in 11 years had the same order of spring (325.61 DU) > winter (290.92 DU) > summer (268.19 DU) > autumn (265.61 DU). For the spatial distribution, due to the effect of the prevailing wind of the northern atmosphere, the high ozone column concentration areas were mainly distributed in the northern and southwestern regions in the study area. With the interannual changes, the high ozone column concentration areas had the characteristic moving tendency of from north to south and from east to west. The ozone column concentration in the study areas was little affected by several human factors, and it was negatively correlated with atmospheric NO2 column concentration with the correlation coefficient of 0.683. It was greatly affected by the photochemical reaction of precursors, as well as and atmospheric transport of prevailing wind and north wind.

Research on the Spatial Distribution and Correlation of PM2.5 in Beijing-Tianjin-Hebei Urban Agglomeration
LI Xue-mei, XU Dong-ming
2019, 35(2):  174-179.  doi:10.19741/j.issn.1673-4831.2017.0818
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Based on daily averaged values of PM2.5 mass concentration in Beijing-Tianjin-Hebei Urban Agglomeration from 2014 to 2016, this study employed ArcGIS 10.2 to analyze the temporal-spatial characteristics of pollution distribution. The spatial correlation of indices such as the percentage of superior, heavily and severely polluted days during typical PM2.5 months was also performed. The results show that the profile of the monthly rate of non-polluted days was consistent with the trend of the overall air quality fluctuation during the observation period. The higher proportion of PM2.5-superior period was concentrated from May to September. The heavily and severely polluted days spanned between November and February. From the regional distribution, the proportional spatial pattern of PM2.5 heavy and severe pollution decreased from central cities as Shijiazhuang and Baoding to surrounding places. The typical months were selected to carry out spatial correlation of PM2.5. Corresponding results indicate that PM2.5 had a positive spatial correlation. The spatial distribution of PM2.5 mass concentration showed spatial clustering profile.

Risk Assessments and Partition Characteristics of Heavy Metals in Water and Sediments of Freshwater Polyculture Ponds in Partial Area of Chengdu City
HUO Qing-lin, XIAO Hui, WANG Jun-jie, DONG Yuan-yuan, ZHANG Yu-hao, WANG Dan, CHENG Zhang, ZHANG Shi-rong, XU Xiao-xun
2019, 35(2):  180-188.  doi:10.19741/j.issn.1673-4831.2018.0078
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In order to survey the partition characteristics and potential ecological risks of heavy metals in environment of freshwater polyculture ponds in partial areas of Chengdu City, the concentration of six heavy metals (Cu, Zn, Cd, Pb, Cr, Ni) in water and sediments of 10 sampling sites were detected. BCR sequential extraction method was used to analyze the speciation of six heavy metals, and the potential risks of heavy metals were evaluated. The results show that, the annual average concentration of heavy metals in water were up to the Fishery Water Quality Standards, except the concentration of Zn in S8 and S10 sites. The heavy metal concentrations in spring and summer seasons were higher than those in autumn and winter seasons. The annual average concentration of heavy metals in sediments were up to the ERL (effects range-low)standards, except the concentration of Cu in S3、S4 and S8 sites. The Cd in sediments had the highest potential risk. There was no obvious seasonal variation in heavy metal concentrations in sediments. The ratio of weak acid extractable fraction of Cd (22.91%-64.51%) was the highest among all the heavy metals. The reducible fraction of Pb and Cu occupied a large proportion. Zn mainly dominated in residual fraction, with a larger proportion of weak acid extractable fraction and reducible fraction. Cr and Ni were dominated in residual and oxidizable fraction. The order of partition coefficient of heavy metals in water-sediments was Ni > Pb > Cr > Cu > Cd > Zn. Therefore, the pollution control of Cd in freshwater polyculture ponds of Chengdu City should be strengthened.

Characteristics and Influencing Factors in Sap Flow of Four Broadleaved Tree Species for Typical Weather Conditions of Beijing
LI Shao-ning, LU Shao-wei, ZHAO Yun-ge, ZHAO Na, CHEN Bo
2019, 35(2):  189-196.  doi:10.19741/j.issn.1673-4831.2017.0869
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To illustrate the differences in characteristics of sap flow of broadleaved species and their main influences in typical weather condition, sap flow rates of four broadleaved tree species were continuously monitored through the thermal dissipation probes (TDP) in plain areas of Beijing, combining simultaneous observations of environmental factors via automatic weather station, to explore the transpiration patterns of tree species and influencing environmental factors. The results show that diurnal variations in sap flow rates of 4 broadleaved species presented single-peak curves in sunny days, bimodel curves in cloudy days and multi-peaks curves in rainy days. The sap flow began at 6:00 a.m. in sunny and cloudy days which were earlier than that in rainy days (06:30 a.m.). The diurnal patterns of solar radiation were consistent with that in sap flow. There exist interactions among environmental factors. Particularly, there is a lag-effect in variations between solar radiation and temperature. Considering the influencing extent of environmental factors on sap flow, solar radiation, temperature, wind speed and water vapor pressure deficit (VPD) were significantly positively related with the sap flow rates of four tree species (P<0.01), whereas there were remarkable negative correlationships between relative air humidity and sap flow rates (P<0.01). Diurnal variations of environmental factors were not in synchrony with that of sap flow rates of tree species. Based on the principal component analysis, as the main influentors, air temperature and solar radiation were responsible for 74.37% on variations of sap flow of tree species, while water vapor pressure deficit contributing 14.33%. Total monthly water consumptions of four tree species in July were ranked as Populus tomentosa (289.23 kg) > Robinia pseudoacacia (235.04 kg) > Sophora japonica (151.53 kg) > Koelreuteria paniculata (133.80 kg). The daily water consumption of above species had the same sequence with that of monthly water consumption mentioned above. The water consumptions of tree species in sunny days were observed higher than that in rainy days. The results of the study can provide a certain scientific basis for the comprehensive evaluation on ecological hydrological processes and determination on influencing factors of garden tree species in Beijing.

Characteristics and Nitrogen-Phosphorus Stoichiometry of Rock Herb Communities in Huajiang Gorge
YAO Kai, AO Jia-lin, XU Hui
2019, 35(2):  197-204.  doi:10.19741/j.issn.1673-4831.2018.0151
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Huajiang Gorge is a typical middle subtropical dry hot valley in Karst area. Taking the rock herb communities in Huajiang Gorge as research objects, the community characteristic, nitrogen-phosphorus stoichiometry and relationships between them were studied. The results show that a total of 16 species of rock herbs and 4 different rock herb communities (Arthraxon hispidus+Phaenonperma globosum, Arthraxon hispidus, Arthraxon hispidus+Imperata cylindrica and Imperata cylindrica+Festuca parvigluma) were found in study area. There was positive correlation between altitude and species similarity coefficient, and negative correlation between altitude and species diversity, substitution rate, soil nitrogen and phosphorus content, hydro-thermal feature. There was a trend of single peak curve in biomasses variation of 4 communities, and plot 2 had the largest biomass. The N and P contents of soils and plant leaves were extremely low in all plots, and the ratios of N/P indicate most of plants growth was limited by N. Strong positive correlation was found between the important value of the plants and the N/P ratios of plant leaves, moderate degree negative correlation was found between the important value of the plants and the P contents of plant leaves, and no significant relation was found between the important value of the plants and N content.

Host Selection and Distribution Patterns of Liana Plants in a Deciduous Broadleaf Forest in Jigong Mountain
JU Yu-xi, SHANG Qing, WANG Zhong-wei, LIU Yan-chun
2019, 35(2):  205-209.  doi:10.19741/j.issn.1673-4831.2018.0196
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Liana plant is a prominent component in forest ecosystems in subtropical and tropical regions, which plays a crucial role in maintaining species diversity and improving ecosystem function. However, whether liana plant selectively attached host species and if any distribution patterns exist while liana infests trees remain unclear. To examine the host selection and distribution patterns of liana plant, a field investigation with random sample method was conducted in a deciduous broadleaf forest in Jigong Mountain, Central China. It was found that broadleaf tree species (Liquidambar formosana and Quercus acutissima) had more liana infested than that of coniferous tree species (Pinus massoniana). Moss present or not on trunk surface showed no effect on the infestation of liana plants. Distribution of liana plant on tree surface showed substantial variations between upslope and downslope directions, with greater liana density on downslope direction at 5 cm height but lower density on the downslope direction at 130 cm height. The study indicates that to some extent liana plants show host selection while infesting trees and the distribution of liana plant on tree surface changes with microclimate. The finding also provides scientific evidence for the mechanism of coexistence and maintaining for different function species in forest ecosystems.

Effects of Different Tillage Methods on Weed Community Diversity in Winter Wheat Fields
ZHANG Zhen, CAO Ya-meng, WU Jian-yong, MA You-hua, HE Jin-ling, ZHOU Di
2019, 35(2):  210-216.  doi:10.19741/j.issn.1673-4831.2018.0106
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In order to analyze the impact of farmland management on the diversity of farmland weed community, a long-term observation experiment of different tillage and fertilization treatments was carried out in the farmland of Chaohu Lake in Anhui Province since 2011. Through the investigation of sample plots, the effects of different treatments on the weed species, density, dominance and other related indicators in the winter wheat field were determined. The results show that:(1)Crop straw returning could effectively reduce weed population density, and straw crushing and returning to field was better than that of straw directly returning to field, corresponding to the weed density decreased by 40%, diverse index and diversity index were increased by 30% and 130%. (2)The dominant species in each treatment were Echinochloa hispidula and Avena fatua, and their mean values of dominance were 1.460 6 and 2.024 5, respectively, and their overlap with other plants exceeded 0.721. (3)Optimization of fertilization made the diversity index of weed community increased by 35% and controlled fertilization made the diversity index increased by 75%.The experimental results show that the change of tillage and fertilization can have a significant impact on the weed community.

Niche Characteristics of Plant Populations in Understory Herbaceous Layer of Cunninghamia lanceolata Pure Forest and Mixed Forest
FENG Yu-chao, ZHENG Xiao-yang, WANG Zheng-ning, LIU Bo, LAN Si-ren
2019, 35(2):  217-224.  doi:10.19741/j.issn.1673-4831.2018.0231
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Niche is an important factor to evaluate intraspecific and interspecific relationships, and it is of vital significance to silviculture and plantation management. Shannon-Wiener, Levins' niche width, Levins' niche overlap and niche proportional similarity were used to compare the niche characteristics of understory herbaceous layers in Cunninghamia lanceolata pure forest and mixed forest. The results indicate that (1) When the occurrence frequency of a plant was higher in the community, its niche was broader. Alpinia chinensis and Woodwardia japonica, with the widest niches, showed the highest frequency under both forest types. That is, the two species were dominant in the community. Compared with the species having narrow niche width, these two species can acquire resources more efficiently because of their strong environmental adaptability and competitiveness. (2) There were no apparent positive relationships between niche width and niche overlap. However, niche width increased with the increase in the combined niche overlap by these species over that of the other plants. (3) When compared with the pure forest, the number of plant species in the understory herbaceous layer of the mixed forest was higher, and the niche width in the mixed forest was higher than that in the pure forest. This finding indicates that the plants in the understory herbaceous layer in the mixed forest make more complete use of the resources. Moreover, plant populations in the mixed forest have better developmental advantages than the plants in the pure forest community. (4) The niche overlapping indexes of both the mixed and pure forests were not high. The interspecific competition intensity was not strong, and there was a differentiation between the populations. The study suggests that both forest resources are abundant, but the average value of niche overlapping indexes and niche proportional similarity under mixed forest are higher than those in the pure forest. In general, compared with the pure forest, species diversity and the ability of plant species to use resources in the understory herbaceous layer in the mixed forest are higher as well as management mode.

Effect of Temperature Increase on Dynamic Changes of Soil Respiration in Alpine Wetlands
ZHAO Shuang-kai, CHEN Ke-long, WU Cheng-yong, MAO Ya-hui
2019, 35(2):  225-233.  doi:10.19741/j.issn.1673-4831.2018.0102
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Experiment was conducted to determine the soil respiration rate, the soil temperature in 5, 10, and 15 cm layers and soil water content of Kobresia humilis in the sample plot by LI-8100 automated soil CO2 flux system (open path) from June 2016 to September 2017, so as to study the dynamic changes of soil respiration in alpine wetlands in the simulated temperature increase state, and to investigate the effects of temperature increase on soil respiration. It can be seen from the results that simulated temperature increase is beneficial to the increase of soil respiration rate, which is significantly different from the rates both in the natural state (CK) and in the temperature increase state (W) (P<0.01); that the soil respiration rate is significantly correlated with the soil temperature and soil water content of each layer (P<0.01). The temperature sensitivity values Q10 in the natural state are larger than those in the temperature increase state, and the Q10 value increases as the soil depth increases. However, soil respiration was jointly influenced by the soil temperature and soil water content and it decreased after 2 years. The temperature increase is helpful to the increase of above-ground and below-ground biomass, and has a significant effect on shallow underground biomass. When compared with no temperature increase, temperature increase is conducive to increase the soil organic matter content, and the difference decreases as the soil depth increases. The experiment results have shown that temperature increase for 2 consecutive years can promote soil respiration in alpine wetlands, and a warming environment is conducive to promoting soil carbon release.

Effects of Deer Dung and Microbial Fertilizer on the Bioavailability of Pb and Zn in Vegetable Soil
WANG Yu-wei, LI Li, WANG Xin-shuang
2019, 35(2):  234-241.  doi:10.19741/j.issn.1673-4831.2018.0040
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The influence of different dosage of deer dung and microbial fertilizer on the content of DTPA-Pb and DTPA-Zn in vegetable soil and the content of Pb and Zn in Brassica campestris was studied through the pot experiment. Results show that the addition of deer dung and microbial fertilizer could significantly decrease the contents of DTPA-Pb and DTPA-Zn in vegetable soil. The content of DTPA-Pb was decreased significantly by 25.81% (P<0.05) with 5% deer dung addition and the content of DTPA-Pb was decreased significantly by 26.48% (P<0.05) with 10% microbial fertilizer addition. Application of deer dung and microbial fertilizer colud promote the transformation of acid-extractable Pb, reducible Pb and oxidation state of Pb to residual Pb. Compared with the blank experiment, the content of Pb and Zn in the Brassica campestris among the six treatment groups decreased significantly, 5% deer dung treatment group was the most effective on the decrease of the content of Pb in the plant by 48.50%. 10% microbial fertilizer treatment group was most effective on the decrease of the content of Zn in the plant by 32.51%. The content of Pb and Zn in Brassica campestris were most significantly and positively correlated with the content of DTPA-Pb and Zn in soil (P<0.01).

Effect of Simulated Acid Rain on Releases of Cadmium in a Contaminated Soil Immobilized by Sepiolite-DDTC Compound
FU Yun-cong, ZHAO Gui-shi, ZHANG Yi, LIU Chen, LI Peng-xiang, LI Hong-liang, LIU Dai-huan
2019, 35(2):  242-247.  doi:10.19741/j.issn.1673-4831.2018.0145
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In order to investigate the immobilization efficiency of heavy metals in soil by functionalized sepiolite materials, the leaching effect of different materials, sepiolite (SEP), sepiolite-diethyldithiocarbamate (SEP-DDTC), sepiolite-3-mercaptopropyltriethoxysilane (SEP-MPTES) on soil polluted by Cd were measured by soil column simulated acid rain leaching. The results show that the pH values of soil increased by 0.80~0. 99 after the leaching of simulated acid rain with pH 4.0, and the pH values of leaching also increased obviously. When the acid rain pH value was 4.0, compared with the CK treatment, the SEP treatment and SEP-MPTES treatment had significant increases in accumulation leaching amount of Cd by 66.45% and 11.49%, respectively. However, the SEP-DDTC treatment had a significant decrease in accumulation leaching amount of Cd by 45.98%. Compared with three layers of soil available cadmium content after simulated acid rain, SEP-DDTC treatment and SEP-MPTES treatment were lower than CK, SEP-DDTC treatment was 0.054 mg·kg-1 lower than SEP-MPTES treatment in average. It indicates that SEP-DDTC is a potential material for soil heavy metal Cd remediation.

Degradation of Benzonitrile by the Nitrogen-Fixing Bacterium Ensifer meliloti 1021 and the Cloning and Over-Expression of the Genes Encoding the Corresponding Metabolic Enzymes
GUO Jing-jing, GUO Lei-lei, ZHAO Yun-xiu, GE Feng, DAI Yi-jun
2019, 35(2):  248-254.  doi:10.19741/j.issn.1673-4831.2018.0035
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The degradation pathway of the environmental pollutant benzonitrile by the nitrogen-fixing bacterium Ensifer meliloti 1021 was investigated. And the genes encoding the relevant metabolic enzymes were cloned and over-expressed. High performance liquid chromatography (HPLC) analysis revealed that En. meliloti 1021 resting cells degraded benzonitrile to benzamide and benzoic acid. A whole-genome analysis indicated that En. meliloti 1021 lacks nitrilase gene, but contains one nitrile hydratase (NHase) gene and 12 amidase genes. Therefore, the benzonitrile degradation pathway appears to be mediated by the NHase-amidase system. The NHase gene was amplified by PCR and over-expressed in Escherichia coli Rosetta (DE3)cells.The resulting cells degraded 97 mmol·L-1 benzonitrile in 5 min (90% degradation rate). At 10 min, benzonitrile was undetectable, while 66.9 mmol·L-1 benzamide was present. A phylogenetic tree including the En.meliloti 1021 amidase genes and three benzamide amidohydrolase genes indicated that four amidase genes clustered with the three benzamide amidohydrolase genes. Gene cloning and over-expression experiments proved that an amidase (Genbank accession number CAC47672.1)exhibits the benzamidase activity responsible for converting benzamide to benzoic acid. Benzamidase comprises 434 amino acids, with a molecular weight of 47 kDa and an isoelectric point of 5.37. The results of this study have a certain theoretical value and may be useful for eliminating benzonitrile from the environment.

Bacterial Community Structure and Its Influence Factors of the Groundwater in an Industry Park
XU Xia, LIU Fei, XUE Yin-gang, TU Bo-wen, ZHOU Lu-lu, JIANG Xiao-dong, SHI Xin-lan, XUE Ke
2019, 35(2):  255-263.  doi:10.19741/j.issn.1673-4831.2018.0048
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The structure and diversity of bacterial community in groundwater are important indicators to reflect the environmental sensitivity of the ecosystem. In order to investigate the bacterial community structure and diversity of the groundwater in an industrial park, the groundwater samples from an industrial park in Changzhou were collected in December 2016, and the 16S rRNA gene of bacteria was sequenced by high-throughput sequencing. The results show that bacterial community structure of the groundwater present a typical characteristics of freshwater populations and could be divided into 55 phyla, 95 classes and 564 genera. Proteobacteria (86.40%), Bacteroidetes (5.06%) and Firmicutes (3.04%) are the dominant phyla in the studied groundwater. The abundant classes within the phyla Proteobacteria are Gammaproteobacteria (47.51%), Betaproteobacteria (29.58%) and Alphaproteobacteria (6.75%), respectively. At the genus level, Pseudomonas (16.38%), Perlucidibaca (9.17%) and Acinetobacter (8.12%) are predominant. The influence of the physical and chemical indicators on bacterial community show that the water quality affects the composition and diversity of bacterial community, and the better the water quality is, the higher the richness and evenness of bacterial community are. Redundancy analysis results show that chloride, calcium, conductivity, iron, fluoride and sulfate are the environmental factors that can significantly explain the groundwater bacterial community.

Effect of Air-Water Ratio on Reclaimed Water Treatment in a Biological Aerated Filter
ZHOU Guang-ji, ZHANG Lan-he, YE Zhen-qi, XU Yan, WEI Lai, FANG Guo-cheng
2019, 35(2):  264-271.  doi:10.19741/j.issn.1673-4831.2018.0014
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Water reuse is a feasible strategy to solve the problems of cost control and water-saving emission reduction in thermal power enterprises. The effect of air-water ratio on the pollutants removal was investigated using biological aerated filter (BAF) technology in the Xianren Island thermoelectric unit of Huaneng in Yingkou. The effect of backwashing air-water ratio on the recovery capacity of pollutant removal and operation time was also investigated. Results show that the removal efficiencies of COD, NH4+-N and NO3--N were 61.1%, 81.2% and 48.6%, respectively, when the ratio of air-water was 4:1 in the BAF, and the overall removal achieved a good overall removal performance with the ratio of air-water of 4:1. Moreover, the BAF had a good SS removal when the ratio of backwashing air-water was 4:1. The BAF was able to recover the COD removal ability, where the removal efficiency of COD was 60.3% within 4 h. The NH4+-N and NO3--N removal ability was also recovered in 5 h with a removal efficiency of 82.2% and 50.0%, respectively. The operation time could last 25 h. BAF has showed an excellent capacity prolonging the operation time and reducing the frequency of backwashing when the ratio of backwashing air-water was 4:1.

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2019, 35(2):  0-0. 
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