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Lake Sedimentation Rate and Its Influencing Factors in Jiuzhaigou World Natural Heritage Site
SHEN Xiaoxue, TANG Lili, DU Jie, JIANG Xianchenghao, QIU Guoyu, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (6): 951-960.   DOI: 10.13209/j.0479-8023.2023.068
Abstract （125）   HTML    PDF（pc） （10822KB）（53）       Save
After the “8.8” earthquake (June 2020), Arrow Bamboo Lake and Rhino Lake, with different input degrees of earthquake damage sources, were selected to analyze the lake sedimentation rates by isotope dating method. Moreover, vertical distribution characteristics of grain size composition, total carbon (TC), total nitrogen (TN), total phosphorus (TP), and carbonate content were analyzed. By analyzing the vertical variation characteristics of sediment environmental indicators and their relationship with natural disasters and human activities, the long-term and short-term factors affecting lake sedimentation were explored. The results showed that the sedimentation rates of the Arrow Bamboo Lake and Rhino Lake from 1900 to 2020 were about 0.32 and 0.44 cm/a, respectively. The vertical distribution characteristics of the environmental indicators on the surface (0–10 cm) were as follows: the specific activity of 210Pbex significantly increased, the sediment particle size was relatively large, TC, TN and calcium carbonate were enriched, and the vertical variation was violent. Meanwhile, the disturbance depth of surface sediment in the Arrow Bamboo Lake, which was obviously affected by seismic damage sources, was greater. These revealed that a large number of loose material sources of land disasters caused by the “8.8” earthquake entered the lake, rapidly intensifying the lake sediment deposition in the short time. The deep vertical distribution features recorded the long-term slow impact of human activities such as deforestation, unreasonable discharge and environmental protection on lake sediment.
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Utilization Status and Development Countermeasures of Mangrove Medicinal Resources in the Marine-Terrestrial Interlaced Zone
WANG Lingli, ZHANG Xin, WANG Jiansong, SHEN Xiaoxue, TANG Lili, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (4): 704-718.   DOI: 10.13209/j.0479-8023.2023.041
Abstract （306）   HTML    PDF（pc） （971KB）（89）       Save
This study summarizes and reviews Chinese medicinal mangroves’ chemical constituent and medicinal effect researches in the past 50 years. Since 2000, the research on medicinal mangroves has increased exponentially, and the most attention is paid to Pongamia pinnata. 27 kinds of medicinal mangroves have been confirmed, and the main medicinal components include terpenoids, flavonoids, steroids, quinones, carbohydrates, phenylpropanoids and alkaloids. Most medicinal mangroves have anti-tumour, antioxidant and anti-inflammatory effects, and some mangrove plants have unique medicinal effects, including anti-depression and anti-Alzheimer's disease. Existing research mainly focuses on the medicinal effects of mangrove plants, but the pharmacological mechanism needs further study. In view of the problems in medical components and the pharmacological effect of mangroves, some suggestions are put forward for their further development and utilization.
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Environmental Quality Mineralogical Analysis of Trace Metals in Urban Mangrove Surface Sediments
GUAN Chunya, LI Ruili, WANG Qian, GUO Wenxiao, SHEN Xiaoxue
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 1091-1100.   DOI: 10.13209/j.0479-8023.2022.101
Abstract （697）   HTML    PDF（pc） （655KB）（126）       Save
Mineral composition and trace metal elements content of mangrove surface sediments were measured in Futian, Baguang, Shajing and Xixiang district in Shenzhen city. The mineralogical evaluation system was used to explore the relationship between mineral composition and trace metal enrichment. The results showed that the mineral composition of surface sediments of Shenzhen urban mangrove was mainly clay minerals and quartz and there were variation among sample sites. The trace metal pollution in Shajing mangrove was the most serious, followed by Xixiang mangrove and Futian mangrove, and Baguang mangrove was the least serious. The enrichment of trace metal was affected by human activities. The enrichment of trace metals was related to the mineral composition of sediments. Gypsum and clay minerals had stronger trace metal enrichment ability.
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Mangrove Restoration Technology and Application in Difficult Site in Shenzhen Bay
SONG Xue, WANG Hui, SHI Jianya, WANG Xuguang, SHEN Xiaoxue, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 929-936.   DOI: 10.13209/j.0479-8023.2022.077
Abstract （455）   HTML    PDF（pc） （13167KB）（183）       Save
This research used three technical means of hollow bricks, customized bamboo basket I and customized bamboo basket II to carry out the mangrove restoration test under difficult site condition in Shenzhen Bay in 2016. The effect of plantation was evaluated in terms of colonization technology, economic cost, mangrove population characteristics and sediment environmental quality after 4 years. The results showed that 1) three technical methods in the mangrove plantation area could create an Aegiceras corniculatum restoration. The preservation rate of A. corniculatum gained over 87%. 2) The cost of the hollow brick technology was lower than those of the groups of customized bamboo basket I and customized bamboo basket II. 3) The total organic (TOC) and total phosphorus (TP) of the sediments in the mangrove planting area were significantly higher than those in the intertidal zone, which indicated that mangroves could promote the retention of organic matter and phosphorus and reduce the risk of their escape to the offshore marine environment. The conclusion is that the technical means of hollow bricks, customized bamboo basket I and customized bamboo basket II can successfully restore mangroves under the difficult site condition of Shenzhen Bay. Considering the restoration effect and economic cost, it is recommended to use hollow brick technology to restore mangrove under difficult site conditions.
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Meta-analysis of Mangrove Salt-Waterlogging Tolerance and Application Strategies
JIANG Biqian, LI Ruili, SHEN Xiaoxue, ZHANG Zhi, ZHANG Yueqi
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 687-699.   DOI: 10.13209/j.0479-8023.2022.062
Abstract （639）   HTML    PDF（pc） （1269KB）（196）       Save
The success of mangrove afforestation depends on the selection and plantation of mangrove species, in which salinity and waterlogging are important factors. In this study, based on literature retrieval and meta-analysis, we evaluated the salt and waterlogging tolerance of five mangrove species commonly used in domestic afforestation projects. The results showed that Avicennia marina was the most tolerant to salinity and waterlogging, which could grow in extreme salinity (40‰) and long-term waterlogging (16 h/d) site. Meanwhile, Kandelia obovata and Aegiceras corniculatum had the ability to withstand salinity and waterlogging, which could adapt to moderate salinity (30‰) and short-term inundation (12 h/d) environment. While Bruguiera gymnorrhiza and Sonneratia apetala were salt-sensitive, which grew better at low level of salinity (20‰) place, and the former could be planted in short-term immersion (12 h/d) area. When salinity or duration of immersion was out of the limit, compound stress would decrease the tolerance capabilities of mangroves. In the practical application of afforestation, A. marina, K. obovata and A. corniculatum were highly adaptable to aquatic environments with a high level of salinity and prolonged waterlogging, which were suitable afforestation species for mangrove wetland in southern China. This study also put forward the corresponding application strategies which contributes to the ecological restoration of mangroves in China.
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Correlation Study of Tourist Respiration with Travertine Landscape Degradation in Jiuzhaigou
QIU Guoyu, XIANG Jiao, YAN Chunhua, QIN Longjun, MAO Peng, XIONG Bowen, LI Ruili, TANG Ya, DU Jie, QIAO Xue, SHEN Xiaoxue, SHI Cong, JIANG Xianchenghao, CHEN Zhi, SHI Zhe, HUANG Ying, DING Junjie
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (2): 291-296.   DOI: 10.13209/j.0479-8023.2021.125
Abstract （559）   HTML    PDF（pc） （22584KB）（139）       Save
With the continuous increase of global CO2 emission, the CO2 emission of tourists leads to an increase rate of atmospheric CO2 around popular scenic spots which is much higher than global average. Based on the eddy covariance system, long-term monitoring of CO2 concentration was conducted in Rhino Lake, Shuzheng Village, Jiuzhaigou World Heritage. Combined with the annual runoff and the rate of travertine loss (CaCO3) based on CO2 concentration, the annual amount of travertine loss in Jiuzhaigou World Heritage Site was estimated to explore the mechanism of travertine degradation. The research finds that the breath of tourists can increase the local atmospheric CO2 concentration by 250–300 μL/L, which can increase travertine loss rate by 18%–21%. Increase in CO2 caused by the breath of tourists is the main reason leading to the degradation and disappearance of the world heritage travertine. CO2 emission of tourists is indeed destroying the world heritage.
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Characteristics and Influencing Factors of Mineral Composition of Urban Mangrove Sediments
WANG Qian, SHEN Xiaoxue, CAO Ye, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (2): 282-290.   DOI: 10.13209/j.0479-8023.2021.119
Abstract （562）   HTML    PDF（pc） （732KB）（104）       Save
Taking the sediments of Shenzhen urban mangrove wetland as the research object, the mineral composition and physical and chemical properties of the sediments are analyzed, and the characteristics of mineral composition and influencing factors are explored. The main results show that the whole rock mineral composition in surface sediment is given priority to clay minerals (16.5%?73.5%) and quartz (22.0%?81.2%), and there are differences in the contents of potash feldspar, pyrite, and rock salt in different samples at different depths. The main types of clay minerals in surface sediments are imonite (44%?76%), kaolinite (0%?40%), chlorite (0%?24%), and illite (2%?21%), and are dominated by imonite. The distribution characteristics of clay minerals at different depths are basically the same as those in surface sediments. There are significant differences in the composition of clay minerals in the sediments of the Pearl River Estuary and Daya Bay without vegetation. Correlation analysis shows that the composition of whole rock minerals is mainly affected by salinity, TS and TOC, while the composition of clay minerals is mainly affected by pH, salinity, TOC, and sediment particle size.
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A Meta-Analysis of the Overall Accuracy of Extent and Species of the Coastal Mangroves
SHEN Xiaoxue, ZHANG Zhi, ZHAI Chaoyang, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (1): 135-146.   DOI: 10.13209/j.0479-8023.2021.096
Abstract （567）   HTML    PDF（pc） （2477KB）（127）       Save
A meta-analysis of the research on the extent and species identification of mangroves has been conducted using remote sensing since 2000. The study clarified the overall accuracy status of mangrove extent and species identification, as well as the influence of remote sensing data source, classification algorithm, feature type and species number on the overall accuracy. The results showed that the overall accuracy range of mangrove extent identification was 55.7% – 99.7% and about 66% of the researches were based on Landsat series satellite data, and had the highest overall accuracy (75% – 99.7%). Optical remote sensing and radar data fusion could effectively improve the overall accuracy of extent identification (>90%). The simpler the type of ground features (≤3 types) or the more complex (≥6 types), the overall accuracy of extent identification is higher and more stable. The overall accuracy of mangrove species identification ranged from 64% to 98.6%; the closer the spatial resolution is to the size of the plant canopy, the higher the overall accuracy of species identification. Among the high spatial resolution remote sensing data sources, the overall accuracy of the species identification of data sources with shortwave infrared bands was higher than that of non-shortwave infrared bands. Multi-source remote sensing data fusion and plants themselves feature information that helps to improve the overall accuracy of category identification. Support vector machines (SVM), maximum likelihood classification (MLC), and random forest (RF) algorithms in supervised machine learning algorithms were the most widely used and had better overall accuracy. As the number of species increases, the overall accuracy of species identification varies with remote sensing data sources and classification algorithms. In summary, the identification accuracy of mangrove extent and species may be improved to a certain extent, and remote sensing data sources, classification algorithms, feature types, and the number of species will all affect the identification accuracy.
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Spatial Distribution Characteristics and Risk Assessment of Heavy Metals in Shenzhen Coastal Areas
ZHANG Haijun, SHI Benning, JIAO Xueyao, WU Hailun, ZHOU Lin, SHEN Xiaoxue, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (4): 679-690.   DOI: 10.13209/j.0479-8023.2021.032
Abstract （685）   HTML    PDF（pc） （1327KB）（151）       Save
This study analyzed the spatial distribution characteristics of heavy metal pollution in seawater and surface sediments in Shenzhen coastal areas by literature retrieval methods. The WQI (water quantity index), Species Sensitivity Distribution method, and potential ecological risk index method were applied to conduct the ecological risk assessments of heavy metal pollution in seawater and surface sediments. The results showed that: 1) The contents of Hg, Cu, Pb, and Cd in the seawater of the west was higher than that of the east, which may be related to the development of the west, more pollution and the poor water exchange of water in the Shenzhen Bay. 2) Based on the first category of Sea Water Quality Standard, WQI>1 indicated that there was no clean water in Shenzhen coastal areas; the ecological risk of heavy metals in offshore water was mostly at high or medium risk levels, in the order of Cu>Hg>Cd>Pb. 3) The contents of heavy metals Cd, Cu, Zn, Pb and Cr in the surface sediments of Shenzhen coastal areas decreased from the northwestern Pearl River Estuary to the southeastern seas; the pollution of Hg and As was concentrated in the Shenzhen Bay and the eastern seas; heavy metal pollution in surface sediments was closely related to the frequent human activities and consistent with the distribution in seawater. 4) The comprehensive potential ecological risk of heavy metals in surface sediments in Shenzhen coastal areas was extremely high, with Cd having the highest ecological risk, followed by Cu and Hg. 
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Study on the Occurrence Law of Red Tide and Its Influencing Factors in the Offshore Waters of China from 2001 to 2017
ZHANG Shanfa, WANG Qian, GUAN Chunya, SHEN Xiaoxue, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (6): 1129-1140.   DOI: 10.13209/j.0479-8023.2020.110
Abstract （1457）   HTML    PDF（pc） （1160KB）（329）       Save
By collecting and sorting the relevant data from 2001 to 2017, a preliminary study on the rules and influencing factors of red tide outbreaks in offshore areas of China was conducted. The results indicate that the occurrence pattern of red tide in the offshore areas of China increased firstly and then decreased. The area and frequency of red tide in China seas increased significantly from 2001 to 2005, while decreased significantly from 2006 to 2017. From 2008 to 2017, a total of 608 red tides occurred in China, and 65 species were the first dominant species that triggered red tides. Prorocentrum donghaiense was the organism that caused the most red tides, 106 times totally. The influencing factors of red tide in each sea area were different: the changes in red tide area in the Bohai Sea were mainly affected by nutrients and total nitrogen; the changes in area and frequency of red tide in East China Sea were significantly affected by nutrients, total nitrogen, total phosphorus, and nitrite nitrogen; the changes in the area of red tide in South China Sea were significantly positively correlated with pollutants entering the sea and CODcr (P<0.05). In order to further reduce red tide outbreaks, several suggestions were proposed for prevention and control of red tide in offshore areas of China: establish online monitoring stations; take control measures based on local conditions; strengthen source pollution management; improve emergency response systems; carry out marine ecological restoration.
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Study on the Dust Retention Effect of Common Garden Plants in Shenzhen
YIN Zhuojun, SHEN Xiaoxue, LI Ruili, GAO Huihui, YU Lingyun, ZHOU Lin, WU Hailun, CAO Ye
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (6): 1081-1090.   DOI: 10.13209/j.0479-8023.2020.096
Abstract （785）   HTML    PDF（pc） （36922KB）（158）       Save
Taking six most common garden plants in Shenzhen were used as research objects, the amount of dust retention per unit leaf area and the particle size composition of dust were studied. The microscopic morphology and the structure of leaf surface as well as the composition and distribution characteristics of the retained particles were investigated. The influence of meteorological factors on the dust retention characteristics of plants was clarified. The results showed that: 1) The dust retention amount per unit leaf area of different plant types was Ficus microcarpa (0.74±0.21 g/m2) > Schefflera arboricola (0.42±0.26 g/m2) > Ficus hispida (0.24±0.26 g/m2) > Ixora chinensis (0.20±0.07 g/m2) > Ophiopogon bodinieri (0.18±0.10 g/m2) > Plumeria rubra (0.15±0.10 g/m2). 2) The six types of garden plants were mainly composed of particles with particle size α>10 μm. The weight of particles with size α>10 μm accounts for 59.21%~88.92% (except for F. microcarpa) of the total weight. S. arboricola had the strongest dust-retaining ability for particles with size α>10 μm (0.34±0.20 g/m2). F. microcarpa had the strongest dust-retaining ability for particles with size 3 μm<α<10 μm (0.51±0.15 g/m2) and 0.15 μm<α<3 μm (0.14±0.07 g/m2). 3) Stoma, fold, groove, flocculent protuberance and villi on the surface were conducive to the retention of dust. The main elements of the retained particles were O, Si and Al. 4) The large particles (α>10 μm) detained by the leaves of the six garden plants were susceptible to wind speed and temperature. The results of this study can be used to guide the arrangement of garden plants in Shenzhen and provide a scientific evidence for the plant dust retention effect to improve air quality.
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Evaluation and Promotion Countermeasures of Bird Carrying Capacity of Mangrove Wetland in Guangdong-Hong Kong-Macau Greater Bay Area: A Case Study of Futian Mangrove, Shenzhen Bay
WU Hailun, ZHOU Lin, XU Hualin, SHEN Xiaoxue, CHAI Minwei, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (6): 1056-1064.   DOI: 10.13209/j.0479-8023.2020.066
Abstract （1052）   HTML    PDF（pc） （599KB）（203）       Save
Focus on bird carrying capacity assessment in wetland ecological health assessment, the conversion method of ash free dry weight (AFDW) data of benthos was established, and the classification standard was optimized based on bird length. Taking Futian mangrove wetland as an example, the total food mass of benthos, the maximum calories for shorebirds and the field metabolic rate of shorebirds population were calculated. Furthermore, the carrying capacity of shorebirds was evaluated. The results are as follows. 1) The total food mass of benthos in Futian mangrove wetland had evident seasonal characteristics: winter (4.67×104 kg) < spring (6.08×104 kg)4 kg)5 kg). In autumn, the food mass density (in AFDW) of different
habitats was as follows: mangrove area (89.22 g/m2) > beach area (3.58 g/m2) > gei wei fish pond area (0.22 g/m2). 2) The maximum calories for shorebirds in different seasons were winter (1.03×108 kJ) < spring (1.36×108 kJ) < summer (1.76×108 kJ) < autumn (2.70×108 kJ). 3) The field metabolic rate of the shorebirds population in Futian mangrove wetland was 467.27 kJ/d. 4) Autumn, winter and spring were the migration periods for migratory birds, and the carrying capacity of Futian mangrove wetland to shorebirds was 6431, 2438 and 3235 birds respectively. The actual observation data was higher than the research results, indicating that the current carrying capacity of shorebirds in the Futian mangrove wetland was insufficient to meet the food needs of birds in migration season, and the number of shorebirds might be reduced. It is suggested that the ecological protection of mangrove wetland in Futian should be strengthened in the following three aspects: the restoration and reconstruction of mangrove
vegetation, the ecological restoration and functional improvement of gei wei fish pond, and the dynamic monitoring of birds and benthos. In this way, the total food mass of benthos and the bird carrying capacity can be lifted.
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Problems and Treatment Countermeasures of Water Environment in Guangdong-Hong Kong-Macao Greater Bay Area
LIU Chang, LIN Shenhui, JIAO Xueyao, SHEN Xiaoxue, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (6): 1085-1096.   DOI: 10.13209/j.0479-8023.2019.087
Abstract （1547）   HTML    PDF（pc） （656KB）（262）       Save
This study identifies the current situation of water pollution in the rivers, reservoirs and coastal waters in the Guangdong-Hong Kong-Macao Greater Bay Area, and analyzes the issues about urban water-logging as well as the changes in water volume in rivers and estuaries. The water pollution in the Bay Area is mainly caused by the intensive population and industrial activities in large cities. The imperfect sewage treatment system and management strategies have exacerbated the pollution. Water quantity problems mainly derived from the excessive encroachment of ecological water. By summarizing the development experience of the international advanced Bay Area, including improving legislation, raising standards, limiting emissions, and protecting the ecological water environment, this study proposes the following countermeasures for further management of water environment in the Guangdong-Hong Kong-Macao Greater Bay Area: 1) improving water use efficiency and strengthening sewage treatment; 2) promoting the construction of sponge cities; 3) controlling cofferdams and improving ecological protection; 4) accelerating the transformation of social economy.
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Value Evaluation of Birds Resources in Futian Mangrove Wetland of Shenzhen Bay
GONG Yuan, SHEN Xiaoxue, DING Huan, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (6): 1078-1084.   DOI: 10.13209/j.0479-8023.2019.085
Abstract （1023）   HTML    PDF（pc） （543KB）（117）       Save
This study comprehensively evaluated the value of bird resources in wetlands based on the birds survey data of Futian mangrove wetland of Shenzhen Bay. The evaluation indicators include the economic value of birds, the benthic value of birds foraging, the value of bird manure, the value of pest control, the value of scientific research, the value of ecotourism and the value of natural education. The results show that the total economic value of bird resources in Futian mangrove wetland of Shenzhen Bay is 326.5385 million RMB. The economic value of birds and the value of benthic foraging by birds act as the main components of the value of bird resources, accounting for 60.50% and 39.32%, respectively. The values of pest control, bird manure and scientific research are less than 0.1%. The results indicate that the economic value of bird resources in Futian mangrove wetland of Shenzhen Bay is high, but its social service value needs to be further developed.
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Ecological Problems and Protection Countermeasures of Mangrove Wetland in Guangdong-Hong Kong-Macao Greater Bay Area
YU Lingyun, LIN Shenhui, JIAO Xueyao, SHEN Xiaoxue, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (4): 782-790.   DOI: 10.13209/j.0479-8023.2019.051
Abstract （1955）   HTML    PDF（pc） （521KB）（430）       Save
This paper summarized the experience of the technical, policy and regulatory of the San Francisco Bay Area, New York Bay Area, Tokyo Bay Area and other typical bay areas, induced the ecological environment problems and wetland ecosystem health assessment of the typical mangrove communities in the Guangdong-Hong Kong-Macao Greater Bay Area, and summarized the situation of various pollutants in mangrove wetlands in the Greater Bay Area. Combining the actual situation and future development of the Greater Bay Area, some suggestions for the protection of mangrove wetlands in Greater Bay Area are proposed: 1) mangrove recovery and reconstruction; 2) handling the contradiction between urban construction and ecological protection; 3) strengthening management, publicity and popular science education; 4) further scientific research and protection scientifically; 5) establishing more mangrove wetland nature reserves and strengthening the joint cooperation of the Guangdong-Hong Kong-Macao Greater Bay Area.
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Experimental Study on Ecological Restoration of Degraded Mangroves
SHEN Xiaoxue, JIANG Lide, TAO Jiawei, YU Lingyun, NIU Zhiyuan, CHEN Zhiteng, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (4): 699-708.   DOI: 10.13209/j.0479-8023.2019.046
Abstract （748）   HTML    PDF（pc） （7490KB）（115）       Save
Taking Kandelia obovata forest as the research object, through periodical replenishment experiment, the improvement of physicochemical properties of the sediments and the plant physiological indicators were used to ascertain the repair effect of water supplemnet on K. obovata. The main results were as follows. 1) The water content, pH, salinity, total nitrogen and organic matter content of sediments in the hydration group were higher than those in the control group, indicating that water supplement improved the nutrient conditions and salinity of the sediment. 2) Water supplementation significantly increased net photosynthetic rate, water use efficiency, and chlorophyll a content (P<0.05), while decreased intercellular CO2 concentration, indicating that water replenishment effectively improved the photosynthesis status and promoted the absorption and transformation of light energy for K. obovata. 3) The maximum fluorescence efficiency (Fv/Fm) of the photosystem II (PS II) in the control group was significantly lower than 0.8 (common threshold), indicating that the degraded K. obovata forest was in the photoinhibitory state, while Fv/Fm was significantly increased after water supplementation (P<0.01), approaching 0.8, indicating a significant improvement in plant health status. 4) Water supplementation improved the photochemical efficiency of the PS II reaction center of K. obovate and significantly improved the imbalance of the excitation energy distribution between the two-optical systems. Moreover, water supplementation also effectively reduced the heat dissipation of the antenna pigments and made the distribution of light energy tend to be efficient, thus increasing the foliar photochemical utilization efficiency. In summary, periodic replenishment is an effective method for the rehabilitation of land-based degraded mangroves.
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Assessment of Heavy Metals Contamination in Three Kinds of Habitat of Futian Mangrove Forest in Shenzhen Bay
CHENG Shanshan, SHEN Xiaoxue, CHAI Minwei, LI Ruili
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 415-425.   DOI: 10.13209/j.0479-8023.2017.161
Abstract （1086）   HTML （1）    PDF（pc） （1352KB）（251）       Save

Taking Futian Mangrove National Nature Reserve as the study area, sediments cores (0–50 cm) were sampled among three kinds of habitat, including fish pond, Avicennia marina forest and mudflat. The spatial distribution features of physicochemical properties and heavy metals in sediment cores were analyzed. The potential ecological risk index of heavy metals was calculated and analyzed. Analysis of physicochemical properties revealed that pH value followed the order: mudflat>Avicennia marina forest>fish pond; electrical conductivity, salinity, and total organic carbon (TOC) followed the order: Avicennia marina forest>mudflat>fish pond. The metal concentrations in sediments decreased in the following order: Zn (103.45–214.14 μg/g), Cu (70.92–133.50 μg/g), Pb (54.90–84.65 μg/g), Cd (6.57–7.25 μg/g). The concentrations of Zn, Cu and Pb followed the order: Avicennia marina forest>mudflat>fish pond and the concentrations of Cd followed the order: Avicennia marina forest≈mudflat>fish pond. The lowest level was located at fish pond (P<0.05). The concentrations of Zn and Cu were extremely different (P<0.05) among different vertical depths. Only the concentration of Cu was significantly affected by the interaction effect of sites and depths (P<0.05). Bivariate correlations results indicated that TOC had a significantly positive correlation with Pb in the fish pond (P<0.05), and the correlation of different kinds of heavy metals were complicated in Avicennia marina forest and mudflat. Different kinds of heavy metals had a significantly positive correlation in the fish pond (P<0.05), indicating that the source of 4 species of heavy metals might be same. In addition, the average contents of Cd, Cu, Zn, and Pb in all sediments of the Futian Mangrove Nature Reserve exceeded the first class of criteria GB 18668-2002．The single potential ecological risk of heavy metals followed the order: Cd>Cu>Pb>Zn and Avicennia marina forest>mudflat>fish pond. The integrated potential ecological risks at sampling sites reached high risk level completely, mainly due to Cd contamination, followed by Cu.

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Characteristics of Water Quality Changes in the Futian Mangrove National Natural Reserve
NIU Zhiyuan, SHEN Xiaoxue, CHAI Minwei, XU Hualin, LI Ruili, QIU Guoyu
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 137-145.   DOI: 10.13209/j.0479-8023.2017.138
Abstract （981）   HTML （11）    PDF（pc） （2959KB）（482）       Save

The research monitored the water quality regularly and analyzed its spatial and temporal changes from 2014 to 2015 in the Futian Mangrove National Nature Reserve. Based on the water quality monitoring results from 2009 to 2014, the annual variation trend of water quality was also studied. The results showed that the DO was generally lower, and the average concentrations of TN, TP, COD and BOD, were 4, 2.6, 1.3 and 1.3 times higher than the class V standards of surface water respectively, the water was in heavy eutrophication status. The pollution level in dry season was significantly higher than in rainy season. From 2009 to 2014, the average concentrations of TN and TP showed a trend of decreasing firstly and then increasing, the BOD values kept rising and the COD values kept falling. Instead of heavy metals pollution, it was the organic pollution, mainly coming from the exogenous input, which have been the key problem of the water pollution, and it needs to take measures to control the pollution immediately.

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