Dissolved organic matter (DOM) from wastewater rejected by nanofiltration from a landfill leachate treatment plant was fractionated into humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) fractions. It was found that humic substances (HA and FA) composed 75% of the total dissolved organic carbon (DOC) concentration of the DOM, with an average molecular weight of about 1000 Da. Elemental analysis, infrared spectroscopy, UV-visible spectroscopy and acid-base titration observations showed that the HA and FA of the DOM exhibited lower fractions of condensed aromatic functional groups but larger fractions of acidic groups compared with other aquatic DOMs. The properties of HA and FA were similar, but HA exhibited more complete humification, while the HyI fraction had more acidic groups. An aminated polymeric adsorbent NDA-8 was used to adsorb the DOM in the wastewater along with primary coagulation. Results of bench-scale experiments indicated that the treatment process could effectively remove the DOM and heavy metals while desorption liquid was 10 times more condensed than raw wastewater. Results of desorption and reproducibility tests consolidated the strong application potential of this treatment process as an advanced landfill leachate treatment technology. 相似文献
A total of 47 passive air samples and 25 soil samples were collected to study the temporal trend, distribution, and air–soil exchange of polychlorinated naphthalenes (PCNs) in Shanghai, China. Atmospheric PCNs ranged from 3.44 to 44.1 pg/m3 (average of 21.9 pg/m3) in summer and 13.6 to 153 pg/m3 (average of 40.0 pg/m3) in winter. In the soil samples, PCN concentrations were 54.7–1382 pg/g dry weight (average of 319 pg/g). Tri-CNs and tetra-CNs were two dominant homolog groups in air samples, while di-CNs were also found at comparable proportions to tri-CNs and tetra-CNs in soil samples. Most air and soil samples from the industrial and urban areas showed higher PCN concentrations than those from suburban areas. However, some soil samples in urban centers presented higher PCN concentrations than industrial areas. Analysis of PCN sources indicated that both industrial thermal process and historical usage of commercial PCN mixtures contributed to the PCN burden in most areas. The fugacity fraction results indicated a strong tendency of volatilization for lighter PCNs (tri- to hexa-CNs) in both seasons, and air–soil deposition for octa-CNs. Moreover, air–soil exchange fluxes indicate that soil was an important source of atmospheric PCNs in some areas. The results of this study provide information for use in the evaluation of the potential impact and human health risk of PCNs around the study areas.
Forest management often has cumulative, long-lasting effects on wildlife habitat suitability and the effects may be impractical
to evaluate using landscape-scale field experiments. To understand such effects, we linked a spatially explicit landscape
disturbance and succession model (LANDIS) with habitat suitability index (HSI) models to assess the effects of management
alternatives on habitat suitability in a forested landscape of northeastern China. LANDIS was applied to simulate future forest
landscape changes under four management alternatives (no cutting, clearcutting, selective cutting I and II) over a 200-year
horizon. The simulation outputs were linked with HSI models for three wildlife species, the red squirrel (Sciurus vulgaris), the red deer (Cervus elaphus) and the hazel grouse (Bonasa bonasia). These species are chosen because they represent numerous species that have distinct habitat requirements in our study area.
We assessed their habitat suitability based on the mean HSI values, which is a measure of the average habitat quality. Our
simulation results showed that no one management scenario was the best for all species and various forest management scenarios
would lead to conflicting wildlife habitat outcomes. How to choose a scenario is dependent on the trade-off of economical,
ecological and social goals. Our modeling effort could provide decision makers with relative comparisons among management
scenarios from the perspective of biodiversity conservation. The general simulation results were expected based on our knowledge
of forest management and habitat relationships of the species, which confirmed that the coupled modeling approach correctly
simulated the assumed relationships between the wildlife, forest composition, age structure, and spatial configuration of
habitat. However, several emergent results revealed the unexpected outcomes that a management scenario may lead to. 相似文献