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241.
Zhao Xuxin Ji Jie Sun Hongyuan Ma Rui Wu Qixing 《International Journal of Green Energy》2016,13(3):229-240
The heat-pipe solar water heating (HP-SWH) system and the heat-pipe photovoltaic/thermal (HP-PV/T) system are two practical solar systems, both of which use heat pipes to transfer heat. By selecting appropriate working fluid of the heat-pipes, these systems can be used in the cold region without being frozen. However, performances of these two solar systems are different because the HP-PV/T system can simultaneously provide electricity and heat, whereas the HP-SWH system provides heat only. In order to understand these two systems, this work presents a mathematical model for each system to study their one-day and annual performances. One-day simulation results showed that the HP-SWH system obtained more thermal energy and total energy than the HP-PV/T system while the HP-PV/T system achieved higher exergy efficiency than the HP-SWH system. Annual simulation results indicated that the HP-SWH system can heat the water to the available temperature (45°C) solely by solar energy for more than 121 days per year in typical climate regions of China, Hong Kong, Lhasa, and Beijing, while the HP-PV/T system can only work for not more than 102 days. The HP-PV/T system, however, can provide an additional electricity output of 73.019 kWh/m2, 129.472 kWh/m2, and 90.309 kWh/m2 per unit collector area in the three regions, respectively. 相似文献
242.
Biochar increased water holding capacity but accelerated organic carbon leaching from a sloping farmland soil in China 总被引:2,自引:0,他引:2
243.
Zhigao Sun Xiaojie Mou 《Environmental science and pollution research international》2016,23(6):5189-5202
From April 2008 to November 2009, a field decomposition experiment was conducted to investigate the effects of sediment burial on macro (C, N) and microelement (Pb, Cr, Cu, Zn, Ni, and Mn) variations in decomposing litter of Phragmites australis in the coastal marsh of the Yellow River estuary. Three one-off sediment burial treatments [no sediment burial (0 mm year?1, S0), current sediment burial (100 mm year?1, S10), and strong sediment burial (200 mm year?1, S20)] were laid in different decomposition sites. Results showed that sediment burials showed significant influence on the decomposition rate of P. australis, in the order of S10 (0.001990 day?1)?≈?S20 (0.001710 day?1)?>?S0 (0.000768 day?1) (p?<?0.05). The macro and microelement in decomposing litters of the three burial depths exhibited different temporal variations except for Cu, Zn, and Ni. No significant differences in C, N, Pb, Cr, Zn, and Mn concentrations were observed among the three burial treatments except for Cu and Ni (p?>?0.05). With increasing burial depth, N, Cr, Cu, Ni, and Mn concentrations generally increased, while C, Pb, and Zn concentrations varied insignificantly. Sediment burial was favorable for C and N release from P. australis, and, with increasing burial depth, the C release from litter significantly increased, and the N in litter shifted from accumulation to release. With a few exceptions, Pb, Cr, Zn, and Mn stocks in P. australis in the three treatments evidenced the export of metals from litter to environment, and, with increasing burial depth, the export amounts increased greatly. Stocks of Cu and Ni in P. australis in the S10 and S20 treatments were generally positive, evidencing incorporation of the two metals in most sampling times. Except for Ni, the variations of C, N, Pb, Cr, Cu, Zn, and Mn stocks in P. australis in the S10 and S20 treatments were approximated, indicating that the strong burial episodes (S20) occurred in P. australis marsh in the future would have little influence on the stocks of these elements. With increasing burial depths, the P. australis was particularly efficient in binding Cu and Ni and releasing C, N, Pb, Cr, Zn, and Mn, implying that the potential eco-toxic risk of Pb, Cr, Zn, and Mn exposure might be very serious. This study emphasized the effects of different burials on nutrient and metal cycling and mass balance in the P. australis marsh of the Yellow River estuary. 相似文献
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245.
Andrea Emili Alessandro Acquavita Stefano Covelli Lucia Spada Antonella Di Leo Santina Giandomenico Nicola Cardellicchio 《Environmental science and pollution research international》2016,23(13):12582-12595
In situ benthic flux experiments were conducted at two stations in the Mar Piccolo of Taranto (Italy), one of the most industrialised and contaminated coastal areas of the Mediterranean. Sediments of the two stations are notably different in their trace metal content, with a station closer to a Navy harbour showing higher mean concentrations of almost all investigated metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn). Conversely, both stations are characterised by significant Hg contamination, compared to the local baseline. Results of a sequential extraction scheme on surface sediments suggest a relatively scarce mobility of the examined metals (Zn > Ni > Cr > As > Cu > Pb). A Hg-specific extraction procedure showed that most of the element (93.1 %) occurs in a fraction comprising Hg bound to Fe/Mn oxi-hydroxides. Reduction of these oxides may affect Hg remobilisation and redistribution. Porewater profiles of dissolved trace metals were quite similar in the two sites, although significant differences could be observed for Al, Cu, Fe and Hg. The highest diffusive fluxes were observed for As, Fe and Mn. Mobility rates of several trace elements (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn) were directly measured at the sediment–water interface. Results from benthic in situ incubation experiments showed increasing dissolved metal concentrations with time, resulting in higher fluxes for Cu, Fe, Hg, V and Zn in the most contaminated site. Conversely, fluxes of Mn, Ni and Pb were comparable between the two stations. The estimated flux of Hg (97 μg m?2 day?1) was the highest observed among similar experiments conducted in other highly contaminated Mediterranean coastal environments. Benthic fluxes could be partially explained by considering rates of organic matter remineralisation, dissolution of Fe/Mn oxy-hydroxides and metal speciation in sediments. Seasonal and spatial variation of biogeochemical parameters can influence metal remobilisation in the Mar Piccolo area. In particular, metals could be promptly remobilised as a consequence of oxygen depletion, posing a serious concern for the widespread fishing and mussel farming activities in the area. 相似文献
246.
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248.
Lee Jaewoong Park Taejin Kim Min-seob Kim Jongmin Lee Seunghyun Lee Su Kyuong Lee Young Sun Lee Won-seok Yu Soonju Rhew Doughee 《Environmental science and pollution research international》2016,23(18):18175-18182
Environmental Science and Pollution Research - We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we... 相似文献
249.
Sun Yang Wang Yuesi Zhang Changchun 《Atmospheric environment (Oxford, England : 1994)》2009,43(2):468-472
This paper reports altitude-resolved concentrations of sulfur dioxide (SO2) and particulate matter up to 10 microns in diameter (PM10) in the planetary boundary layer of major urban centers during extreme pollution episodes. The concentration of SO2 was observed continuously from November 24, 2004, to December 4, 2004, in Beijing during the heating period. Fluorescence SO2 analyzers were used to measure the atmospheric SO2 concentrations. Four SO2 analyzers were placed at 4 different levels (8 m, 47 m, 120 m, and 280 m) of the 325-m high meteorological observation tower of the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences. A maximal SO2 concentration of 172.3 ppb was measured during this pollution episode, and SO2 concentration increased with altitude and reached its maximal value at ~50 m. The study also analyzed the meteorological situation before, during, and after the pollution episode. 相似文献
250.
J. Juri Ayub D.E. Di Gregorio H. Velasco H. Huck M. Rizzotto F. Lohaiza 《Journal of environmental radioactivity》2009
The 7Be wet deposition has been intensively investigated in a semiarid region at San Luis Province, Argentina. From November 2006 to May 2008, the 7Be content in rainwater was determined in 58 individual rain events, randomly comprising more than 50% of all individual precipitations at the sampling period. 7Be activity concentration in rainwater ranged from 0.7 ± 0.3 Bq l−1 to 3.2 ± 0.7 Bq l−1, with a mean value of 1.7 Bq l−1 (sd = 0.53 Bq l−1). No relationship was found between 7Be content in rainwater and (a) rainfall amount, (b) precipitation intensity and (c) elapsed time between events. 7Be ground deposition was found to be well correlated with rainfall amount (R = 0.92). For the precipitation events considered, the 7Be depositional fluxes ranged from 1.1 to 120 Bq m−2, with a mean value of 32.7 Bq m−2 (sd = 29.9 Bq m−2). The annual depositional flux was estimated at 1140 ± 120 Bq m−2 y−1. Assuming the same monthly deposition pattern and that the 7Be content in soil decreases only through radioactive decay, the seasonal variation of 7Be areal activity density in soil was estimated. Results of this investigation may contribute to a valuable characterization of 7Be input in the explored semiarid ecosystem and its potential use as tracer of environmental processes. 相似文献