查看更多>>摘要：Drained peatlands are a large emission source and a shift to paludiculture (rewetting and cultivation of wettolerant plants) is emerging as a potential emission reduction measure. Paludiculture can potentially results in emission savings from direct emissions, product substitution and carbon storage, but the whole life cycle climate impacts are rarely studied. In this study, we evaluated two paludiculture product systems (cattail (Typha) construction board and common reed (Phragmites) horticultural vermicompost) with cradle-to-grave life cycle assessment (LCA) applied global sensitivity analysis to identify, which parts of the product system would need more research and product development to ensure net emission savings. Based on the results, both product systems result in much lower emissions than current agricultural land use and may be net greenhouse gas sinks (average - 6.0 tCO2eq ha-1 for cattail board; -3.0 tCO2eq ha-1 for reed growing media). The uncertainty in the product life cycle is concentrated to a few key processes: the direct CO2 and CH4 emissions from paludiculture, construction board additives, and CH4 emissions from vermicomposting reed. Further research to these would minimize the uncertainty and help in maximizing the climate mitigation potential of paludiculture derived products.
查看更多>>摘要：Soil pH is a fundamental parameter of soil chemical properties, and changes in soil pH (CIPs) alter hydrogeochemical processes in the Earth's critical zone. Afforestation has long been reported to change surface soil pH at the site scale or regional scale, while few studies have discussed the effects of afforestation and microtopography on soil pH at the catchment scale. We hypothesize that both afforestation and microtopography affect surface soil pH in a catchment. To test this hypothesis, two neighboring catchments in which one catchment was restored with natural vegetation and the other was afforested in 1954 were selected and surface soils were sampled. The soil pH, soil water content (SWC), total nitrogen (TN), soil organic and inorganic carbon (SOC and SIC) were analyzed for those soil samples. Moreover, trees coverage, LAI and grass cover were investigated in the two catchments. The results showed that over 60 years of afforestation in the catchment reduced the soil pH values at the depth of 0-80 cm in only the topography of the downhill gully, and the CIPs ranged from -0.02 to -0.15. In the topography of the upper hillslope, afforestation showed no significant impacts on soil pH. The reduction in soil pH in the gullies of the forestland catchment had a significant linear and negative relationship with TN and SOC. Moreover, microtopography showed significant impacts on soil pH. In the forestland catchment, the downhill gully showed lower soil pH values than those in the upper hillslope, while the opposite difference was detected in the grassland catchment. The high coverage of vegetation in the forestland gully and frequent gravity erosion in the grassland gully could explain the contrasting trends of soil pH differences between the two landforms in the catchment. The results of this study deepen our understanding of the effects of afforestation and catchment topography on soil pH and the related critical zone processes.
查看更多>>摘要：Afforestation combats desertification and improves the ecological environment but leads to huge consumption of water resources. Understanding how ecological restoration affects the regional water balance is important for scientific desertification management. Using remote sensing satellite images and meteorological data, we analyzed the impacts of ecological restoration on water resources in the Kubuqi Desert during 1986-2017. Human activities accounted for 60.14% of the desertification reversal: annual average NDVI increased by 94%, the severe desertification area decreased by 30%, and the non-desertification area increased threefold. Vegeta-tion restoration accounted for 70.96% of the evapotranspiration increase of 5.17 mm.yr(-1). However, precipitation could not support the increased water demand, which relied on replenishment from groundwater and Yellow River diversion. Therefore, to ensure water security in the Kubuqi, species that use less water should be used in future ecological restoration, and decision-makers should carefully consider the huge water consumption cost of ecological restoration.
查看更多>>摘要：The study is aimed at the distribution of heavy metals in Phragmites australis growing in constructed wetlands as well as in natural stands. Three full-scale constructed wetlands and five natural wetlands were selected. The shoots of P. australis were analysed for Cu, Cd, Cr, Ni, Pb and Zn. The results revealed that the highest biomass was recorded in base parts of the shoots - 38% in constructed and 42% in natural wetlands. On the other hand, the lowest biomass occurred in top part of the shoots - 30% in constructed wetlands and 24% in natural wetlands. The highest amount of heavy metals was accumulated in the base parts of stems followed by top part of leaves. The only exception was the highest accumulation of Cu and Zn in top leaves in constructed wetlands. The accumulation of heavy metals decreases from the base to the top in stems and in the same direction the accumulation in leaves increases. Sequestration of heavy metals followed the same pattern in both constructed and natural wetlands. The average heavy metal standing stock in stems amounted to 56% in both constructed and natural wetlands, In leaves, the respective standing stocks amounted to 43.9% and 44%.
查看更多>>摘要：The efficacy of two low-cost locally available aggregate filter materials (gravel and terracotta rubble) were tested in a semi-controlled pilot setup deployed to treat dry weather flows in an open stormwater drain in Bangalore, India. The treatment setups were operated at a similar hydraulic loading rate (HLR) of 265 mm/day using dry weather flows (DWF) in open stormwater drains from surrounding land uses for a period of 14 months. Sig-nificant variability in the quality dry weather flows was observed during the testing period. The average COD, BOD5, TN and TP levels of 1528 mg/l, 439 mg/l, 28.6 mg/l and 9.8 mg/l respectively were observed corre-sponding to high strength wastewater. Differences in porosity resulted in different hydraulic retention times (HRT), with 1.21 days and 1.52 days for the gravel and terracotta setup. While no significant difference was observed in the quality of effluent from both setups, the KBOD5 estimated for gravel setup (0.89) was significantly higher than the terracotta setup (0.70). Similar BOD5 mass removed per day (MMR) efficiency of 78% was observed for both setups. Data suggests the usefulness of gravel material in treating inflows rich in organic matter. Terracotta setup provided higher MRR reduction of 48%, 24% and 43% for DCOD, TP and TN, whereas higher MRR reduction of 70% and 65% for TSS and COD was observed in gravel setup. Neither materials were effective at removing Fecal Coliform (FC), particularly in the later stages of the study. Ammonium-N levels showed periodic increases in both setups, which could be attributed to low HRT leading to incomplete nitrification-denitrification processes. While outflows did not meet discharge standards, specified by India's Central Pollution Control Board (CPCB), the results suggest that a significant reduction in common contaminants can be achieved informing future interventions and modelling studies promoting sustainable urban water management in the megacity context. Study shows that an average BOD5 and COD mass loading rate (MLR) of 28 g/m(2)/day and 138 g/m(2)/day respectively should be targeted as a baseline condition in inflows to meet na-tional discharge standards set by the CPCB (30 mg/l and 250 mg/l respectively).
查看更多>>摘要：Modern mine rehabilitation aims at thorough restoration of an ecosystem with emphasis on not only land area covered by vegetation but also the structure and function of that vegetation. However, assessment of current restoration success reveals a lack of attention to the spatial structure and its relationships with vegetation coverage and biomass. A forest's spatial structure is an important attribute of structural diversity. Complex spatial structures mean diverse species composition and spatial dissimilarity, which can provide a base for selfsustaining and regeneration. This study uses WorldView-2 images and field data to train the mind evolutionary algorithm-back propagation neural network (MEA-BP) model for the purpose of mapping three parameters (coverage, biomass, and spatial structure) across mine dumps. The results show that the spectral and textural features could effectively assess the coverage, biomass, and spatial structure, with an R-2 of 0.91, 0.86, and 0.62, respectively. The coverage is positively correlated with biomass, while the spatial structure is negatively correlated with coverage and biomass. Pure Hippophae rhamnoides L. had high coverage but very low spatial structure, while the mixed community dominated by Populus L. and Pinus tabulaeformis Carr had high coverage, high biomass, and medium structure at around 10 years. The results suggested that the artificial reforestation improves vegetation coverage and biomass but did not synchronously increase spatial structure. The initially planted species composition, substrates, and succession process have a significant influence on the forest parameter relationships. The future reforestation and optimization of community assemblages should take the relationships and their influence factors and effects on ecosystem services into account. The remote sensing based data and model has potential and advantages in dynamically guiding the rehabilitation and monitoring of the restored ecosystem.
NSTL
Elsevier