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Wu R.,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control | Wu R.,Nanjing University of Information Science and Technology | Ge Q.,Nanjing University of Information Science and Technology | Zhan X.,The Center for Satellite Applications and Research | And 2 more authors.
Journal of Natural Disasters | Year: 2014

To construct effective drought monitoring and evaluation index, the moderate resolution imaging spectrometer (MODIS) data and the NCEP/NCAR reanalysis data were utilized, and on the basis of remote sensing process model (BEPS), the surface evapotranspiration was simulated in this paper. At the same time, using the data of flux observation network AmeriFlux, the reliability and adaptability of this model was validated. On this basis, relative moisture index (BMI) was constructed to analyze the temporal and spatial distribution characteristics of regional dry and wet conditions in 2007-2009, and was compared with other drought index. The findings suggest that, BEPS model has a good effectiveness for terrestrial ecosystem evapotranspiration in the United States of America. The correlation coefficient of 12 sites reaches 0. 8568 (p < 0.01). Spatial distribution characteristics of BMI value is obvious, and is consistent with latitudinal change and longitude of the precipitation and evapotranspiration. The temporal distribution characteristic of BMI values shows that, its seasonal variation is significant too. It is closely linked with the terrain, climatic characteristic and vegetation distribution. Affected by precipitation, good indication effectiveness of BMI on drought monitoring is in the month scale or seasonal scale. The correlation coefficients of BMI and USDM show that, the constructed index based on the BEPS model simulating ET is feasible in drought monitoring. Source


Xu D.,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control | Xu D.,Nanjing University of Information Science and Technology | Gu J.,Nanjing University of Information Science and Technology | Li Y.,Nanjing University of Information Science and Technology | And 5 more authors.
Environmental Science and Pollution Research | Year: 2016

The response of purifying capability, enzyme activity, nitrification potentials, and total number of bacteria in the rhizosphere in December to wetland plants, substrates, and earthworms was investigated in integrated vertical flow constructed wetlands (IVFCW). The removal efficiency of total nitrogen (TN), NH4–N, chemical oxygen demand (COD), and total phosphorus (TP) was increased when earthworms were added into IVFCW. A significantly average removal efficiency of N in IVFCW that employed river sand as substrate and in IVFCW that employed a mixture of river sand and Qing sand as substrate was not found. However, the average removal efficiency of P was higher in IVFCW with a mixture of river sand and Qing sand as substrate than in IVFCW with river sand as substrate. Invertase activity in December was higher in IVFCW that used a mixture of river sand and Qing sand as substrate than in IVFCW which used only river sand as substrate. However, urease activity, nitrification potential, and total number of bacteria in December was higher in IVFCW that employed river sand as substrate than in IVFCW with a mixture of river sand and Qing sand as substrate. The addition of earthworms into the integrated vertical flow constructed wetland increased the above-ground biomass, enzyme activity (catalase, urease, and invertase), nitrification potentials, and total number of bacteria in December. The above-ground biomass of wetland plants was significantly positively correlated with urease and nitrification potentials (p < 0.01). The addition of earthworms into IVFCW increased enzyme activity and nitrification potentials in December, which resulted in improving purifying capability. © 2015, Springer-Verlag Berlin Heidelberg. Source


Zheng Y.,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control | Zheng Y.,Nanjing University of Information Science and Technology | Xu W.,Nanjing University of Information Science and Technology | Wu R.,Nanjing University of Information Science and Technology | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

During the last several decades, significant reductions in the concentrations of stratospheric ozone(O3) have been reported. This reduced ozone concentration causes an increment in ultraviolet-B radiation approaching to the surface earth. The elevated UV-B radiation and increased tropospheric O3 concentrations maybe occur together and cause reductions in physiological and biochemical characteristics of crops and economic plants. The effects of UV-B and O3 on plant growth and productivity have been reported separately for a large number of species by filed experiment, but only few experiments have focused on their interaction, it is not clear whether UV-B and O3 induced damages are brought about with similar mechanisms. This uncertainty has largely been due to the lack of an experimental approachs to investigate the responses of a single species exposed to UV-B and O3 under well-defined experimental conditions. Studies were conducted under the open-top-chambers conditions so as to assess photosynthesis changes of soybean (Glycine max, Bayuehuang) with supplemental UV-B radiation (10% -10. 9% higher than control group, T1) and enhanced ozone [(100 ±9) nmol/ mol, T2], separately and in combination (combination treatment, T3), by investigating photosynthetic pigment, flavonoid content and gas exchange parameters with application of LCpro + Portable Photosynthesis System. Results indicate that net photosynthetic rate(Pn),maximum photosynthetic rate(Pmax), somatic conductance(Gs), half-saturation light intensity (Ik)and stomatal limitation (Ls)of T1 treatment decreased significantly compared with CK (control group, natural air and UV-B radiant intensity condition). With same references, inter-cellular CO2 concentration (Ci) and flavonoid content increased, the apparent quantum yield(AQY) and the dark respiration rate (Rd)raised first and then decreased, and the cartenoid content decreased first and then raised while the content of chlorophyll had faint decrease if compared with CK. The change pattern of Pn, Pmax, Ik, Gs, Ci and Ls of T2 treatment was similar to those of T1 treatment while the content of chlorophyll and cartenoid decreased significantly compared with CK; flavonoid content of T2 showed slightly decrease at early stages, but sharp increase at latter stages. The change pattern of Pn, Pmax, Ik, Gs, Ls, Ci and Rd of T3 treatment was also similar to those of T1 treatment while the content of cartenoid and chlorophyll decreased obviously compared with CK with lower chlorophyll content than that of T1 and T2. Obviously, enhanced ozone caused significant decrease in chlorophyll content, but supplemental UV-B radiation had no impressive effect on it. Compared with UV-B and O3 alone, UV-B and O3 in combination enhanced the negative effects on soybean chlorophyll content, and ozone stress dominated the combination stress effect of O3 and UV-B. The decrease of photosynthesis was mainly due to non-stomatal factors. UV-B and O3 in combination enhanced the negative effects on soybean compared with UV-B and O3 alone. Source


Han Y.,Nanjing University of Information Science and Technology | Zheng Y.-F.,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control | Wu R.-J.,Nanjing University of Information Science and Technology | Yin J.-F.,Nanjing University of Information Science and Technology | Sun X.,Nanjing University of Information Science and Technology
Huanjing Kexue/Environmental Science | Year: 2014

Employing floating static chamber-chromatography method, the N2O diurnal fluxes at the water-air interface of four rivers(Tuanjie River, Jinchuan River, Inner and Outer Qinhuai River)and Jinniu Lake were monitored in Nanjing during summer. The results show that four rivers act as the sources of N2O emission, but Jinniu Lake is characterized by the absorption of N2O. The highest N2O flux from Inner Qinhuai presented at 20:00 because of the changing of hydrodynamic conditions. Both Jinchuan and Tuanjie rivers' minimum N2O fluxes were detected when the content of dissolved oxygen was extremely low. The tendency of N2O from Outer Qinhuai showed a double-peak because of its daytime nitrification and nocturnal denitrification. The flux of N2O from Jinniu Lake had been noted as being generally higher at night than that during light hours due to the effect of wind. For natural rivers, the proper sampling period is from 08:00 to 12:00, but for the river subjected to interference, the sampling period is different. Source


Han Y.,Nanjing University of Information Science and Technology | Zheng Y.-F.,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control | Wu R.-J.,Nanjing University of Information Science and Technology | Yin J.-F.,Nanjing University of Information Science and Technology | And 2 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2013

Employing floating static chamber-chromatography method, the greenhouse gases (GHGs) fluxes, which include CO2, CH4 and N2O, at the water-air interface of four rivers (Tuanjie River, Jinchuan River, Inner and Outer Qinhuai River)and Dingjie Reservoir were continuously monitored in Nanjing during spring in 2012. And based on these observed data, the variation and influencing factors of GHGs fluxes were analyzed. The results showed that the CO2 and CH4 emission fluxes of Tuanjie River were top, which were 1023.34 mg/(m2 · h) and 89.45 mg/(m2 · h), respectively, and Jinchuan River followed; CO2 fluxes from Inner and Outer Qinhuai River were at the same magnitude; CH4 fluxes emitted from Inner Qinhuai were one magnitude less than Outer Qinhuai; and CO2 and CH4 fluxes from Dingjie Reservoir were the lowest among the waters. As for N2O fluxes, Jinchuan River was the highest [151.31 μg/(m2 · h], followed by Tuanjie River (111.74 μg/m2 · h), and Inner/Outer Qinhuai River and Dingjie Reservoir perform modest with 101 magnitude. In addition, all of the waters were GHGs emission sources except Jinchuan River being N2O sink. We also concluded that the mainly influencing factors on GHGs fluxes of Inner Qinhuai/Dingjie Reservoir, Outer Qinhuai, Jinchuan and Tuanjie River were human's activities, water level, microbial activity and joint actions of wind speed and temperature, separately. The five waters studied in this paper were emission sources of the three major GHGs in spring. Source

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