Time filter

Source Type

Lu J.,CAS Wuhan Botanical Garden | Lu J.,University of Chinese Academy of Sciences | Zhou H.,Yunnan Institute of Environmental Science | Tian G.,CAS Wuhan Botanical Garden | Liu G.,CAS Wuhan Botanical Garden
Shengtai Xuebao/ Acta Ecologica Sinica

Nutrient limitation (mostly nitrogen or phosphorus) s thought be a driving force in ecosystem development. It was hypothesized that the N:P ratio of the vegetation directly reflects the nature of nutrient limitation. At vegetation level, N:P ratios < 14 and > 16 often correspond to N- and P-limited biomass production. The study on nitrogen (N) and phosphorus (P) contents of plants thus may greatly increase our limited knowledge of the nature of nutrient limitation and also provide guidance for ecological restoration. This paper investigated N and P contents of 44 wetland plants from the Lake Erhai basin. The results showed that the mean contents of N and P were 15. 7 mg/g and 3. 3 mg/g dry weight, and ranged from 6.4 to 34. 3 mg/g for N and 1.4 to 6. 5 mg/g for P, respectively, and they were markedly higher than those from other regions. The N:P ratio ranged from 2.2 to 9. 5, indicating that N was the limiting factor in the Lake Erhai basin. There was a significant difference in N and P contents between above- and belowground parts in plants. The mean N content (16. 7 mg/g) and P content (3.6 mg/g) of aboveground part were significantly higher than those (N content of 9. 8 mg/g and P content of 3. 1 mg/g) of belowground part. There was a significant difference in N and P contents among functional groups. Submerged species exhibited significantly higher N contents (17.7 mg/g) than the emergent species (12. 1 mg/g) and free-floating/floating-leaved species (13.4 mg/g), while mud-flat species had significantly higher P contents (3.6 mg/g) than submerged species (2. 6mg/g). Overall, the biomass, and N and P contents of above-ground tissue respectively accounted for 72%, 82% and 75% of those in the whole plant, which suggested that harvesting of above-ground tissue could effectively remove N and P from wetland ecosystem. Source

Zhang J.,Beijing Normal University | Zeng W.,Beijing Normal University | Wang J.,Chinese Research Academy of Environmental Sciences | Yang F.,Yunnan Institute of Environmental Science | Jiang H.,Chinese Research Academy of Environmental Sciences
Journal of Cleaner Production

As the largest energy consumer and CO2 emitting country, the Chinese government is committing to a low-carbon economy. It is meaningful and contributes to evaluate and analyze the low-carbon economy efficiency (LCEE) of China. A Super-slack-based measure (Super-SBM) model with undesirable outputs, as combined with the Malmquist productivity index, is proposed to measure the LCEE and the dynamic low-carbon economy efficiency (DLCEE) of 30 provinces in mainland China from 2005 to 2012. The Theil index is also used to measure the rationalization level of industrial structure (RLIS) for discussing the improvements to the LCEE in China. The results indicate that the proposed undesirable outputs Super-SBM model can effectively rank the SBM-effi{ligature}cient provinces. China's regional economic development does not follow a low-carbon pattern, with an average LCEE of 0.517. As a whole, the China's economic development is gradually following a low-carbon development pattern with an annual LCEE improvement of 4.5%. The RLIS of China is also gradually changing better, as well. Through a comparative analysis of the LCEE and RLIS, the 30 provinces are divided into three sub-areas, and relevant suggestions are presented for improving the LCEE of different sub-areas in the future. © 2015 Elsevier Ltd. Source

Cui L.-H.,South China Agricultural University | Zhu X.-Z.,South China Agricultural University | Ouyang Y.,St. Johns River Water Management District | Chen Y.,South China Agricultural University | Yang F.-L.,Yunnan Institute of Environmental Science
International Journal of Phytoremediation

Vertical-flow constructed wetland (VFCW) is an effective alternative for removal of nutrients, heavy metals, and organic pollutants from wastewaters. This study investigated the uptake and removal of total phosphorus (TP) by Cyperus alternifolius from domestic wastewaters in the simulated VFCWs. The total of eight simulated VFCW treatments, including two different substrates, two different wet-to-dry ratios, and with and without C. alternifolius species (2 × 2 × 2 = 8), were utilized for an operation period of two years in this study. Results show that about 1.1 to 1.4 times more TP was removed from the influent with the presence of C. alternifolius as compared to without this plant species. A linear correlation existed between the aboveground biomass and its TP content. An increase in total biomass by 1000 g would result in an increase in TP accumulation in the aboveground biomass by 4.9g. Large amounts of TP were removed by the substrate adsorption as compared to those by the aboveground biomass. Results suggest that, although substrate adsorption played a major role in TP removal, C. alternifolius uptake was an alternative pathway for further removal of TP from wastewaters in the VFCWs. © Taylor &Francis Group, LLC. Source

Cui L.,South China Agricultural University | Ouyang Y.,St. Johns River Water Management District | Lou Q.,South China Agricultural University | Yang F.,Yunnan Institute of Environmental Science | And 3 more authors.
Ecological Engineering

Constructed wetlands are becoming increasingly popular worldwide for removing contaminants from domestic wastewater. This study investigated the removal efficiency of nitrogen (N) and phosphorus (P) from wastewater with the simulated vertical-flow constructed wetlands (VFCWs) under three different substrates (i.e., BFAS or blast furnace artificial slag, CBAS or coal burn artificial slag, and MSAS or midsized sand artificial slag), hydraulic loading rates (i.e., 7, 14, and 21 cm d-1), and wetland operational periods (0.5, 1, and 2 years) as well as with and without planting Canna indica L. The wastewater was collected from the campus of South China Agricultural University, Guangzhou, China. Results show that the percent removal of total P (TP) and ammonium N (NH4 +-N) by the substrates was BFAS > CBAS > MSAS due to the high contents of Ca and Al in substrate BFAS. In contrast, the percent removal of total N (TN) by the substrates was CBAS > MSAS > BFAS due to the complicated nitrification/denitrification processes. The percent removal of nutrients by all of the substrates was TP > NH4 +-N > TN. About 10% more TN was removed from the wastewater after planting Canna indica L. A lower hydraulic loading rate or longer hydraulic retention time (HRT) resulted in a higher removal of TP, NH4 +-N, and TN because of more contacts and interactions among nutrients, substrates, and roots under the longer HRT. Removal of NO3 -N from the simulated VFCWs is a complex process. A high concentration of NO3 -N in the effluent was observed under the high hydraulic loading rate because more NH4 +-N and oxygen were available for nitrification and a shorter HRT was unfavorable for denitrification. In general, a longer operational period had a highest removal rate for nutrients in the VFCWs. © 2010 Elsevier B.V. All rights reserved. Source

Ma X.,Yunnan Institute of Environmental Science | Ma X.,CAS Kunming Institute of Botany | Xu J.,CAS Kunming Institute of Botany | Xu J.,World Agroforestry Center | van Noordwijk M.,World Agroforestry Center Southeast Asia
Hydrological Processes

Global climate change will likely increase temperature and variation in precipitation in the Himalayas, modifying both supply of and demand for water. This study assesses combined impacts of land-cover and climate changes on hydrological processes and a rainfall-to-streamflow buffer indicator of watershed function using the Soil Water Assessment Tool (SWAT) in Kejie watershed in the eastern Himalayas. The Hadley Centre Coupled Model Version 3 (HadCM3) was used for two Intergovernmental Panel on Climate Change (IPCC) emission scenarios (A2 and B2), for 2010-2099. Four land-cover change scenarios increase forest, grassland, crops, or urban land use, respectively, reducing degraded land. The SWAT model predicted that downstream water resources will decrease in the short term but increase in the long term. Afforestation and expansion in cropland will probably increase actual evapotranspiration (ET) and reduce annual streamflow but will also, through increased infiltration, reduce the overland flow component of streamflow and increase groundwater release. An expansion in grassland will decrease actual ET, increase annual streamflow and groundwater release, while decreasing overland flow. Urbanization will result in increases in streamflow and overland flow and reductions in groundwater release and actual ET. Land-cover change dominated over effects on streamflow of climate change in the short and middle terms. The predicted changes in buffer indicator for land-use plus climate-change scenarios reach up to 50% of the current (and future) range of inter-annual variability. Copyright © 2010 John Wiley & Sons, Ltd. Source

Discover hidden collaborations