Search Result

Select

Distributions Characteristics of Nutrients and Corresponding Ecological Effects in Dongting Lake

LIN Jie, LI Bin, CHEN Qian

Acta Scientiarum Naturalium Universitatis Pekinensis 2024, 60 (2): 341-349. DOI: 10.13209/j.0479-8023.2024.008

Abstract （37）

HTML

PDF（pc）（1709KB）（19）

Save

Based on monitoring data of monthly average COD, TN, and TP concentrations at Chenglingji hydrological station in Dongting Lake from 1990 to 2015, the intra-annual variation, inter-annual variation patterns of nutrients in the water column of Dongting Lake were systematically studied by trend analysis, and further revealed their stoichiometric ratio characteristics and discussed the effects of nutrient concentrations and structure on algal growth. The findings showed that the intra-annual variation patterns of average COD, TN, and TP were similar, indicating that the nutrient content in dry season was higher than that in wet season. However, as for multi-year trend, the annual average COD, TN, and TP in Dongting Lake showed a significant increase since 1990, while C:N and C:P ratios decreased and N:P ratio increased over time. The average C:N:P ratio in the water column of Chenglingji station in Dongting Lake was 13:18:1, and redundancy analysis showed that nutrient concentrations and stoichiometry ratios in the water would affect algae growth, with C:N, C:P and COD playing a dominant role. During the study period, the overall nitrogen and phosphorus content of the water column in Chenglingji station was generally high and has already met the algae growth demand. In order to avoid adverse ecological consequences such as harmful algal bloom events, external nitrogen and phosphorus inputs should be controlled to maintain the stoichiometric ratio balance in the water column of Dongting Lake.

Related Articles | Metrics | Comments（0）

Select

Seasonal Variation and Drivers of Zooplankton Community in Reservoirs of Chaobai River Basin

ZHANG Qun, XU Xuming, CHEN Qian

Acta Scientiarum Naturalium Universitatis Pekinensis 2023, 59 (2): 290-300. DOI: 10.13209/j.0479-8023.2023.006

Abstract （334）

HTML

PDF（pc）（1452KB）（153）

Save

To reveal the seasonal variations of zooplankton community and their drivers in reservoirs of the Chaobai River basin, 12 reservoir monitoring stations were deployed in September (autumn) and December (winter) of 2020, and March (spring) and June (summer) of 2021, respectively. Totally 90 zooplankton species belonging to 67 genera were identified in the four seasons, with the highest richness in summer and the lowest in spring. The mean abundance (231.5 ind./L) and biomass (0.199 mg/L) of zooplankton peaked in summer, while they were merely 60.8 ind./L and 0.075 mg/L in spring, respectively. Significant seasonal differences were observed in the structure of zooplankton community. Rotifers contributed the largest proportion of richness and abundance in autumn and summer, but the zooplankton in winter and spring were mainly dominated by protozoa. Strobilidium sp. was the most abundant species occurred in the four seasons of the reservoirs. Correlation analysis showed that the Shannon-Wiener diversity index of zooplankton was positively related with nitrite nitrogen and total organic carbon, while the richness was strongly associated with nitrate nitrogen, total nitrogen and total phosphorus. Canonical correspondence analysis exhibited that dissolved oxygen, water temperature, nitrite nitrogen, total organic carbon and conductivity were crucial in driving the seasonal distribution of zooplankton community. This study further provided supplementary data for the assessment of ecosystem health in reservoirs of the Chaobai River basin.

Related Articles | Metrics | Comments（0）

Select

Microbial Nitrogen Transformation Key Processes and Its Influencing Factors in Water and Sediment of Xining Section of the Huangshui River

SHANG Yunyi, LI Zhilong, SUN Liyu, CHEN Qian

Acta Scientiarum Naturalium Universitatis Pekinensis 2023, 59 (1): 92-104. DOI: 10.13209/j.0479-8023.2022.122

Abstract （321）

HTML

PDF（pc）（4042KB）（166）

Save

A total of 58 water and sediment samples were collected in the typical sampling section of the Xining section of the Huangshui River during the wet season (July 2018) and the dry season (April 2019), respectively, and 6 wastewater samples were directly taken from the effluents of wastewater treatment plants (WWTPs) in the dry season. A total of 12 nitrogen functional genes were quantitatively analyzed by real-time fluorescence quanti-tative PCR technology (qPCR). The results showed that the average of total nitrogen (TN) concentration in Huangshui River was 3.06±1.23 (1.308–6.51) mg/L. The nitrogen functional genes with high relative abundance in water and sediments were narG, nirS and nosZ. There were significant seasonal differences in the abundance and composition of nitrogen functional genes in sediments rather than those in water. The key nitrogen transformation process was denitrification, and its average contribution to nitrogen removal in water and sediment were 88% and 98%, respectively. The nitrogen transformation process in water was mainly impacted by pH, TN and NO₃^--N, the ammonia oxidation process was negatively correlated with the NO₃^--N concentration, and the denitrification process was negatively correlated with the pH. The nitrogen transformation process in sediment was mainly related to the water nitrogen concentration, sediment pH, TN, total phosphorus and organic carbon concentration, etc., the ammonia oxidation process was negatively related to the water nitrogen concentration, and the denitrification process was related to the sediment properties. Further analysis showed that the wastewater treatment plant effluents significantly reduced the abundance of genes such as AOA-amoA, CMX-amoA, nirS, nxrB, napA, narG, hzsA in the received water, which might lead to the limitation of the denitrification, anammox, nitrification and comammox processes, but at the same time elevated the abundance of nrfA genes and increased the contribution rate of dissimilatory nitrate reduction to ammonium (DNRA) to nitrogen removal in water. The relative abundances, such as AOA-amoA, nxrB and CMX-amoA, were significantly reduced in the sediments in the affected river segments, and nitrification and comammox processes in sediments were suppressed. This study can provide a scientific basis for nitrogen pollution control in the Xining section of Huangshui River.

Related Articles | Metrics | Comments（0）

Select

Study on Nitrogen Release from Reservoir Sediments and Nitrogen Removal by Aerobic Microorganism

XIE Minzheng, CHEN Qian, DANG Chenyuan, PAN Boyue, AN Rui, WU Zhe, ZHOU Ming

Acta Scientiarum Naturalium Universitatis Pekinensis 2019, 55 (3): 561-570. DOI: 10.13209/j.0479-8023.2019.018

Abstract （764）

HTML

PDF（pc）（1025KB）（95）

Save

This study focuses on the Danjiangkou reservoir, and investigates the release regulation of total nitrogen, nitrate, nitrite and ammonia from sediments as a function of temperature, perturbation and aeration conditions. Moreover, a simulation reactor was set up to explore the elimination of endogenous nitrogen pollution through high-efficient aerobic denitrification microorganism augmentation. Effects of high-efficient aerobic denitrification microorganisms on the microbial community structure in the sediments was also evaluated by means of high-throughput sequencing technology. The results indicated that increasing temperature could promote the release of nitrate and nitrite from sediments, while inhibiting the release of ammonium. Disturbances of water was beneficial to nitrogen release from sediments, and the nitrogen amount accumulated in the overlying water was proportional to the agitation speed. Concentrations of dissolved oxygen had great effects on the nitrogen release from sediments. It was found that the aeration treatment significantly reduced the release of total nitrogen and nitrite from sediments, and the subsequent accumulation in water. After addition of the a high-efficient aerobic denitrification bacteria Pseudomonas stutzeri (PCN-1) into the simulation reactor, concentrations of all the forms of nitrogen in the reactor increased at first and then decreased. On the 65th day of the experiment, removal rates of total nitrogen and nitrate released from sediments were as high as 75.87% and 79.96% respectively, suggesting effective control of the endogenous nitrogen. The relative abundance of Proteobacteria, Bacteroidetes and Spirochaetes in sediments was significantly increased after PCN-1 addition, so the microbial community structure in the sediments was changed by microbial augmentation treatment with PCN-1 as well.

Related Articles | Metrics | Comments（0）

Select

Identification of an Aerobic Denitrifier and Its Denitrification Characteristics

LI Xue, LIU Sitong, CHEN Qian

Acta Scientiarum Naturalium Universitatis Pekinensis 2018, 54 (6): 1276-1282. DOI: 10.13209/j.0479-8023.2018.071

Abstract （762）

HTML

PDF（pc）（1606KB）（298）

Save

Strain HG-7 was identified as Pseudomonas sp. through 16s rRNA gene sequence analysis. The aerobic denitrification ability of strain HG-7 was further proved by the existence of the napA and nirK genes. Further studies showed that the optimal carbon resources for strain HG-7 were sodium acetate and sodium succinate, the optimal C/N ratio was 6−10, and the suitable temperature was 26−30℃. At this condition, with an initial nitrate nitrogen of 100 mg/L, 98% of nitrate could be removed in 48 hours and the amount of nitrite accumulation was very small. Moreover, with nitrite as the sole nitrogen source, 100% of nitrite could be removed at lower nitrite concentration. But the nitrite nitrogen removal rate was about 40% when the nitrite concentration increased to 91.4 mg/L, indicating that high nitrite concentration was harmful for aerobic denitrification by strain HG-7. The strain HG-7 has great potential to be used for biological nitrogen removal, which was particularly significant for actual wastewater treatment processes.

Related Articles | Metrics | Comments（0）

Select

The Host Specificity of a Nature Enemy Argyrogramma albostriata against Solidago canadensis

CHEN Qian, WANG Qiang, HE Jiaqing

Acta Scientiarum Naturalium Universitatis Pekinensis 2016, 52 (5): 776-784. DOI: 10.13209/j.0479-8023.2016.059

Abstract （2237）

HTML

PDF（pc）（670KB）（1093）

Save

The second generation larva of Argyrogramma albostriata of 4th instar, which were fed in the lab with Solidago canadensis under the condition of room temperature and natural light, were used as material for the experiment of host specify. 104 plant species from 52 families were used in testing host specify and the herbivory of leaves of different plants and survival time were observed. The results show that leaves of Conyza canadensis, Aster subulatus, Kalimeris indica, Erigeron annuus and S. canadensis were eaten by A. albostriata after 24 hours, while other plants were not eaten until the larva were starve to death. Then the life history of A. albostriata fed on C. canadensis, A. subulatus, K. indica, E. annuus and S. canadensis were observed and the main indexes of life history were recorded. The main results are as follows. 1) Survival rates of A. albostriata fed on C. canadensis, A. subulatus, K. indica, and S. canadensis are higher than larva fed on E. annuus significantly. 2) Fed on different plants have different influence on the length of different instars of A. albostriata. 3) Pupation rate, emergence rate, longevity and pupation weight of A. albostriata fed on C. canadensis, A. subulatus, K. indica, and S. canadensis are higher than that fed on E. annuus. The results indicate that A. albostriata is oligophagous, only eat C. canadensis, A. subulatus, K. isindica, E. annuus and S. canadensis. A. albostriata can complete its life history on C. canadensis, A. subulatus, K. indica, and S. Canadensis. However, the growth of lava of A. albostriata is constrained when fed on E. annuus.

Related Articles | Metrics | Comments（0）

Select

Cross-Language Sentiment Analysis Based on Parser

CHEN Qiang,HE Yanxiang,LIU Xule,SUN Songtao,PENG Min,LI Fei

Acta Scientiarum Naturalium Universitatis Pekinensis

Abstract （786）

PDF（pc）（475KB）（727）

Save

Using the syntactic analysis model, the statement is divided into several combinations of words. According to the subject-predicate component of compound words and emotional color difference of emotional words, different weights are given respectively. The authors statistically analyze the distribution of the emotional statement, use the characteristic parameter training the classifier, and employ the trained classifier for the test corpus emotional classification. Experiment results show that the emotion classification discriminant accuracy rate and recall rate of this method is more ideal, compared with the existing discrimination methods. This method can also be used in the statement of comparative discrimination and negative polarity judgment.

Related Articles | Metrics | Comments（0）

Select

Efficient Phosphorus Removal from Wastewater by a Newly Isolated Bacterium under High Salinity Condition

DENG Ruonan,CHEN Qian,NI Jinren

Acta Scientiarum Naturalium Universitatis Pekinensis

Abstract （757）

PDF（pc）（771KB）（383）

Save

A bacterium capable of phosphorus removal was isolated. Through morphology observation and 16S rRNA gene sequence analysis, the isolate was identified as Salinivibrio sp. (named HG-1). Salinity tolerance and phosphorus removal efficiency under different salinity conditions of the strain were further investigated. The results showed that HG-1 grew well with the salt content varying from 1% to 13% and achieved the highest phosphorus removal efficiency under salt content of 3%. Furthermore, the single-factor and orthogonal experiment results indicated that the optimal phosphorus removal performance was obtained under the conditions with an initial pH of 6.5?7.0, C/N ratio of 9, temperature of 30°C and inoculation ratio of 10%. Under such a condition, the phosphorus removal efficiency could reach 100% in 24 hours. The strain HG-1 can independently complete phosphorus removal process, and thus could provide a novel and promising alternative for biological phosphorus removal under high salinity conditions.

Related Articles | Metrics | Comments（0）