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Li W.-C.,China National Bamboo Research Center | Wang S.-D.,China National Bamboo Research Center | Zhong Z.-K.,China National Bamboo Research Center | Sheng H.-Y.,Institute of Environmental Protection Science | Zhou Y.,China National Bamboo Research Center
Forest Research | Year: 2011

The authors studied the shoot growth rhythm of wine bamboo, Oxytenanthera braunii, which is of great economic importance in Tanzania and has been introduced to China recently. And also, individual-based model was used to delineate and capture the essence of the shoot growth system well enough addressing specific characteristics of parameters about the system. The results showed that the power function could be used to set up the relationship between leaf number and node number, which was the same as branch number after truncating. Compensation effect of mother individuals after transplanting was important for wine bamboo adapting to the semi-arid area in southwest China. The quadratic function could be used to express the relationship between the number of residual nodes with branch and the percentage of branch number contributing to the total number of the individual without truncating which was also shown by the percentage of leaf number. The probability distribution function such as Weibull and Gamma were used to simulate the distribution of branch and leaf number on each culm node after truncating and transplanting with stump. Results indicated that distribution curve was successfully simulated, and Weibull and Gamma functions gave the best answer compared with normal distribution. Repression models based on DBH (diameter at breast height) showed that the fitted curve of power functions was more significant than others except the groups of one-year-old culm and two-years-old branch. The height growth and dynamic germination process of shoots fitted to the sigmoid curve, which could be well described by Logistic equation. And both the processes of different levels were divided into three sub-periods like beginning, flourish and end periods according to the first and second order derivatives of Logistic equation. The shoot's germination period lasted about 150 days, which was about from May to October and coincident with the local rain season essentially. The beginning sub-period finished at the 48-51 days, and flourishing sub-period arrived at the 69-72 days, then the germination speed was down and the end sub-period showed at the 90-93 days similarly, following the rules of slow-quick-slow, shoot individuals displayed Logistic growth and showed a significant plastic growth rhythm responding to the local rain season. Height growth of shoot lasted longer at beginning sub-period and spent more time before entering fast growth stage. Meanwhile, the slow growth stage lasted only 12 days. And the shoots in the end sub-period displayed the contrary behavior, which was threatened by the decreasing rainfall and low humidity. There were only two stages for shoots in the flourishing sub-period which was no initial stage and shoots entered the fast growth stage directly. The whole growth period was the shortest. So humidity was the main ecological factor influencing the growth of bamboo shoots. Understanding the advantage of plasticity response and its limits is of critical importance for numerous issues in ecology and evolution for O. braunii. Source

Zhang Y.,CAS Nanjing Institute of Geography and Limnology | Yin Y.,CAS Nanjing Institute of Geography and Limnology | Yin Y.,University of Chinese Academy of Sciences | Liu X.,CAS Nanjing Institute of Geography and Limnology | And 7 more authors.
Organic Geochemistry | Year: 2011

From 2005 to 2009, the spatial distribution and the seasonal dynamics of chromophoric dissolved organic matter (CDOM) were explored in Lake Taihu in eastern China. The spatial-seasonal dynamics of CDOM absorption and three CDOM composition variables, including spectral slope (S), spectral slope ratio (SR) and the M value, defined as the ratio of absorption at 250nm/365nm, were analyzed and discussed. Furthermore, river input processes and degradation of phytoplankton were studied to assess their impact on CDOM composition and the factors involved in the spatial-seasonal variability of CDOM. The CDOM absorption coefficient at a wavelength of 350nm, a(350), ranged from 1.37-9.55m-1 with a mean of 3.33±1.32m-1. Spatially, higher a(350) values, but lower spectral slope, spectral slope ratio and M values, were recorded in the northern algae dominated bays while lower values were recorded in southeastern macrophyte dominated bays. The a(350) was significantly higher in inshore waters than in offshore waters. Values of S, SR and M decreased during the flood and algal bloom season in spring and summer whereas a(350) increased. In the three river profiles, the gradual decrease of a(350) along the trajectory from the river mouth into the lake during the flood season showed the contribution of allochthonous CDOM. A laboratory phytoplankton degradation experiment was conducted to determine the contribution of CDOM production from phytoplankton. The significant increase of a(350) with time in the CDOM production experiment underlines the importance of autochthonous CDOM production during the algal bloom season. In summary, the significant increase of a(350) in spring and summer (algal bloom season) may be due to both the allochthonous CDOM input from the surrounding rivers and the autochthonous production of CDOM from degrading phytoplankton. © 2011 Elsevier Ltd. Source

Tang C.,Central South University of forestry and Technology | Zhou X.,Central South University of forestry and Technology | Li C.,Institute of Environmental Protection Science
Advanced Materials Research | Year: 2012

A constant direct current density of 0.5 mA/cm 2 was applied in a laboratory experiment for studing the feasibility of electrokinetic treatment on the removal of Cd from red soils. The result shows that the removal efficiency of Cd was remarkably pH-dependent. The initial Cd concentration was1 490 mg/kg and over 79% of Cd was removed from the red soils after 96 hours' treatment. The energy expenditure was about 77.6 kW.h/m 3 and the cost was 42.6 RMB Yuan/m 3, which suggest that electrokinetic soil processing is a promising technology for remedying cd-contaminated red soils. © (2012) Trans Tech Publications, Switzerland. Source

Tang C.,Central South University of forestry and Technology | Li K.,Central South University of forestry and Technology | Li C.,Institute of Environmental Protection Science
Advanced Materials Research | Year: 2012

The effect of pH on Cd adsorption was studied using red soil as an adsorbent in this study.The curve of Cd adsorbed vs pH showed that the adsorption amount increased slowly at low pH, then quickly with the increase of pH, and reached the maximum amount at high pH. The adsorption data at different pH values and initial Cd(II) concentrations were fitted well by Langmuir isotherm. At last, a pH-dependent model of adsorption isotherms of Cd was established by substituting the fitting results obtained from experimental data for the parameters in Langmuir equation. © (2012) Trans Tech Publications, Switzerland. Source

Zhou Y.,CAS Nanjing Institute of Geography and Limnology | Zhou Y.,Sino Danish Center for Education and Research | Zhou Y.,University of Chinese Academy of Sciences | Zhang Y.,CAS Nanjing Institute of Geography and Limnology | And 8 more authors.
Water Research | Year: 2016

Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce undesirable disinfection byproducts during drinking water treatment. We studied the drinking water Lake Qiandao, China, and found that the concentrations of suspended particulate matter (SPM) in the lake increased significantly with inflow rate (p < 0.001). Similarly, close relationships between inflow rate and the CDOM absorption coefficient at 350 nm a(350) and with terrestrial humic-like fluorescence C3 and a negative relationship between inflow rate and the first principal component (PC1) scores, which, in turn, were negatively related to the concentrations and relative molecular size of CDOM (p < 0.001), i.e. the concentration and molecular size of CDOM entering the lake increased proportionately with inflow rate. Furthermore, stable isotopes (δD and δ18O) were depleted in the upstream river mouth relative to downstream remaining lake regions, substantiating that riverine CDOM entering the lake was probably driven by inflow rate. This was further underpinned by remarkably higher mean chlorophyll-a and in situ measured terrestrial CDOM fluorescence (365/480 nm) and apparent oxygen utilization (AOU), and notably lower mean PC1 and CDOM spectral slope (S275-295) recorded in the upstream river mouth than in the downstream main lake area. Strong negative correlations between inflow rate and a(250):a(365), S275-295, and the spectral slope ratio (SR) implied that CDOM input to the lake in rainy period was dominated by larger organic molecules with a more humic-like character. Rainy period, especially rainstorm events, therefore poses a risk to drinking water safety and requires higher removal efficiency of CDOM during drinking water treatment processes. © 2016 Elsevier Ltd. Source

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