Chu J.,Nanjing Forestry University |
Xue J.,Nanjing Forestry University |
Jin M.,Suzhou Academy of Agricultural science Institute of Agricultural science in Taihu Lake District |
Wu Y.,Nanjing Forestry University |
And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015
Agricultural non-point pollution caused by the overuse of fertilizer in farmland has become one of the main factors for water quality deterioration and eutrophication in Taihu Lake. In order to select suitable agroforestry intercropping system to control soil nitrogen loss in Taihu Lake basin, a study was conducted at a distance of 1 km away from the lakeshore to find out how poplar-wheat intercropping system with 2 kinds of densities (AS1: poplar spacing 2 m×5 m; and AS2: poplar spacing 2 m×15 m) affected the amount of surface runoff, leaching and soil nitrogen loss. The interception of rainfall by the poplar canopy was mainly concentrated from April to October and ranged from 8.6% to 44.5%. The control effects of canopy layer on sprinkle and moderate rain (<1.0 mm/h) were obvious, which were reduced by 47.7% on average. Rainfall interception by canopy was mainly related to the LAI (leaf area index). The volume of rainfall difference between AS1 and MS (monoculture system) was only 0.8% during the defoliated period while the control effect of AS1 was raised to 6.4% during the growing period. Compared to AS2R (means removing litter) and MSL0 (monoculture of wheat without litter coverage), the runoff amount of AS1R decreased by 9.1% and 11.2%, respectively. There was a significant difference between AS1R and AS2R/MSL0 (P<0.05), while the difference between AS2R and MSL0 was not significant (P>0.05). Compared to MS, the volume of surface runoff, leaching and soil nitrogen loss were all effectively controlled by the 2 poplar-wheat intercropping systems. The control effects were more significant under the higher intercropping density. There was no significant difference between the average runoff volume of AS1S (means saving litter) and AS2S/MSL0 during the whole growing period (P>0.05), while their average concentration and leaching amount of total nitrogen (TN) and NO3--N were both significantly lower than MSL0 (P<0.05). The average leaching water amount of AS1S in the depth of 60 cm was significantly different from that of AS2S and MSL0 (P<0.05), while the difference between AS2S and MSL0 was not significant (P>0.05). The difference of average concentration and leaching amount of TN and NO3--N in 20 cm was not significant among AS1S, AS2S and MSL0 (P>0.05) while that in 60 cm was significant (P<0.05). The average runoff amounts of 2 intercropping systems without litter coverage were both higher than those with litter coverage during the poplar defoliated period. It was obvious that the runoff amount, average concentration and leaching amount of TN and NO3--N with litter coverage were lower than those without litter coverage in AS1 (P<0.05), while there was no significant difference between AS2 with litter coverage and without (P>0.05). The litter volume was the major factor to decide whether there was significant difference between the surface runoff and leaching loss. The average surface runoff, concentration and leaching amount of TN and NO3--N with the litter coverage of 0.4 t/hm2 were significantly lower than those of 0.2, 0.1 and 0 t/hm2. The average leaching water volumes of AS1R in 20 and 40 cm soil depth were higher than those of MSL0 while the result in 60 cm was opposite. The decreasing range of leaching volume of AS1R in 60 cm depth was 1.3 times higher than that of MSL0, and the leaching volume of AS1R were different significantly in 20 and 60 cm (P<0.05), while there was no significant difference among 20, 40 and 60 cm for leaching volume of MSL0 (P>0.05). There was significant difference between average concentration of TN in 20 and 60 cm for AS1R, which were respectively 1.8 and 1.5 times lower than those for MSL0. The leaching loss of TN and NO3--N in 60 cm for AS1R was significantly lower than those in 20 cm. Thus it can be concluded that the effects of surface runoff, leaching and nitrogen loss reduction are more significant under the poplar-wheat intercropping system with the spacing of 2 m×5 m. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.
Cheng X.,Nanjing University of Information Science and Technology |
Zhao T.,Nanjing University of Information Science and Technology |
Gong S.,Chinese Academy of Meteorological Sciences |
Xu X.,Chinese Academy of Meteorological Sciences |
And 5 more authors.
Atmospheric Environment | Year: 2016
Air quality change is generally driven by two factors: pollutant emissions and meteorology, which are difficult to distinguish via observations. To identify the contribution of meteorological factor to air quality change, an aerosol simulation from 1995 to 2004 with the global air quality model GEM-AQ/EC was designed without year-to-year changes in the anthropogenic aerosol (including sulfate and organic and black carbon) emissions over the 10-year span. To assess the impact of interannual variations of East Asian monsoon (EAM) on air quality change in China, this modeling study focused on the region of central-eastern China (CEC), a typical East Asian monsoon (EAM) region with high anthropogenic aerosol emissions. The simulation analysis showed that the interannual variability in surface aerosols over CEC was driven by fluctuation in meteorological factors associated with EAM changes. Large amplitudes of interannual variability in surface aerosol concentrations reaching 20-30% relative to the 10-year averages were found over southern CEC in summer and over northern CEC in winter. The weakened near-surface winds of EAMs in both summer and winter were significantly correlated with aerosol increases over most areas of CEC. The summer and winter monsoon changes enhance the surface aerosol concentrations with increasing trend rates exceeding 30% and 40% over the southern and northern CEC region, respectively, during the 10 years. The composite analyses of aerosol concentrations in weak and strong monsoon years revealed that positive anomalies in surface aerosol concentrations during weak summer monsoon years were centered over the vast CEC region from the North China Plain to the Sichuan Basin, and the anomaly pattern with "northern higher" and "southern lower" surface aerosol levels was distributed over CEC in weak winter monsoon years. Aerosol washout by summer monsoon rainfall exerted an impact on CEC aerosol distribution in summer; aerosol dry depositions in connection with atmospheric boundary layer conditions resulted in wintertime aerosol variations over CEC. Climate change with regard to EAMs could modulate the interannual variations in aerosols and air quality over CEC by changing near-surface winds, precipitation and atmospheric boundary layer. © 2016 Elsevier Ltd.
Tan C.,Nanjing University of Information Science and Technology |
Zhao T.,Nanjing University of Information Science and Technology |
Xu X.,Nanjing University of Information Science and Technology |
Liu J.,Nanjing University |
And 3 more authors.
Atmospheric Environment | Year: 2015
Recently, haze events frequently occurred in East China. To assess the impacts of aerosols on air quality over the region, we investigate the interannual variations of the total aerosols and the submicron aerosols, in terms of the aerosol mass concentration (AMC) and Fine Mode Fraction (FMF), respectively, using the Moderate Resolution Imaging Spectrometer (MODIS) aerosol products, which can be used for regional air quality assessment, from 2003 to 2013. On average, the AMC distributes as "northern high and southern low", whereas the FMF shows a "northern low and southern high" pattern. High FMF occurs in the warm seasons, but low FMF appears in the cool seasons. During the 10 years, the AMC shows increasing trend in northern and decreasing trend in southeastern parts of the region, whereas an increasing trend in the FMF is observed over the entire East China, likely related to elevated submicron aerosols from anthropogenic sources. The East Asian summer monsoon impacts the submicron aerosols more than the total aerosols. The enhanced submicron aerosols are responsible for rapid deterioration of air quality in East China in recent years. © 2015 Elsevier Ltd.
Yan C.,China Pharmaceutical University |
Zhang B.,Jiangsu Province Environmental Monitoring Center |
Liu W.,China Pharmaceutical University |
Feng F.,China Pharmaceutical University |
And 2 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2011
A sensitive and very fast analytical method has been developed for the simultaneous quantification of sixteen sulfonylurea herbicides in surface water. An ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry method with solid phase extraction for sample cleanup has been developed for screening sixteen sulfonylurea herbicides (oxasulfuron, thifensulfuron-methyl, cinosulfuron, metsulfuron methyl, sulfometuron methyl, triasulfuron, rimsulfuron, ethametsulfuron methyl, sulfosulfuron, tribenuron methyl, bensulfuron methyl, iodosulfuron methyl, pyrazosulfuron ethyl, prosulfuron, chlorimuron ethyl, ethoxysulfuron) in water samples simultaneously within 12 min. Water samples were acidified, and the target herbicides were extracted by passing through ProElut C18 extraction cartridges. After drying by nitrogen flow, the cartridges were eluted with elution solvents, and the eluate was then evaporated to dryness, redissolved and analyzed. The mobile phase composed of 0.02% formic acid and acetonitrile using gradient elution. A triple quadrupole mass spectrometer equipped with an electrospray ionization source operated in the positive ion with selective reaction monitoring mode. Each of the analytes in all the samples was monitored using protonated molecule and its two characteristic fragment ions for confirmation. The limits of detection for all analytes were below 1.0. ng/mL, except for sulfosulfuron and prosulfuron, and limits of quantitation were between 1 and 8 ng/mL for this method. Three water types were used for the validation of the method. © 2011 Elsevier B.V.