Effluents from food, fermentation, and sugar industries contain a large quantity of glucose which has to be removed to limit the chemical oxygen demand (COD) of the water discharged. This work proposes novel thin-film nanocomposite (TFN) membranes incorporated with MgFe2O4 and ZnFe2O4 nanoparticles to address this concern. The nanoparticles synthesized by the sol–gel method was extensively characterized and then incorporated into the active polyamide layer of the thin-film composite polysulfone membranes. The change in membrane morphology, wettability, chemical structure, and mechanical strength with the incorporation of nanoparticles was studied in detail. Membranes with 0.005 wt.% MgFe2O4 nanoparticle exhibited highest glucose rejection (96.52?±?2.35%) at 10 bar, 25 °C, and sufficiently high pure water flux (50.54?±?1.92 L/m2h). This membrane also displayed 69.1?±?5.12% salt rejection when challenged with 2000 ppm synthetic NaCl solution.
The objective of this study was to identify the main sources of variation in pesticide losses at field and catchment scales using the dual permeability model MACRO. Stochastic simulations of the leaching of the herbicide MCPA (4-chloro-2-methylphenoxyacetic acid) were compared with seven years of measured concentrations in a stream draining a small agricultural catchment and one year of measured concentrations at the outlet of a field located within the catchment. MACRO was parameterized from measured probability distributions accounting for spatial variability of soil properties and local pedotransfer functions derived from information gathered in field- and catchment-scale soil surveys. At the field scale, a single deterministic simulation using the means of the input distributions was also performed. The deterministic run failed to reproduce the summer outflows when most leaching occurred, and greatly underestimated pesticide leaching. In contrast, the stochastic simulations successfully predicted the hydrologic response of the field and catchment and there was a good resemblance between the simulations and measured MCPA concentrations at the field outlet. At the catchment scale, the stochastic approach underestimated the concentrations of MCPA in the stream, probably mostly due to point sources, but perhaps also because the distributions used for the input variables did not accurately reflect conditions in the catchment. Sensitivity analyses showed that the most important factors affecting MACRO modeled diffuse MCPA losses from this catchment were soil properties controlling macropore flow, precipitation following application, and organic carbon content. 相似文献
Summary Environmental education is currently fashionable. However, some educators are viewing it with suspicion as a trendy subject which will disrupt their carefully planned syllabii which are geared largely towards the passing of examinations. In the South Pacific there have been a number of attempts to increase people's awareness of their surroundings and to build up a respect for what is loosely termed our physical environment. These programmes have included, increasing the amount of environmental examples in a range of primary and secondary school subjects, formal courses in environmental planning at the tertiary level, and conservation messages through the media.Dr Jenny Bryant is a Lecturer in Geography at the University of the South Pacific, and recently Secretary, now Acting Chairperson, of the South Pacific Action Committee for Human Ecology and the Environment (SPACHEE). 相似文献
Odorous gases associated with livestock operations are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75-microm solid-phase microextraction fibers, polyvinyl fluoride (PVF; Tedlar), fluorinated ethylene propylene copolymer (FEP; Teflon), foil, and polyethylene terephthalate (PET; Melinex) air sampling bags, sorbent 2,b-diphenylene-oxide polymer resin (Tenax TA) tubes, and standard 6-L Stabilizer sampling canisters after sample storage for 0.5, 24, and 120 (for sorbent tubes only) hrs at room temperature. The standard gas mixture consisted of 7 volatile fatty acids (VFAs) from acetic to hexanoic, and 4 semivolatile organic compounds including p-cresol, indole, 4-ethylphenol, and 2'-aminoacetophenone with concentrations ranging from 5.1 ppb for indole to 1270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5- and 24-hr sample storage time, respectively. This was followed by the Tenax TA sorbent tubes (94.8% and 88.3%) for 24 and 120 hr, respectively; PET bags (71.7% and 47.2%), FEP bags (75.4% and 39.4%), commercial Tedlar bags (67.6% and 22.7%), in-house-made Tedlar bags (47.3% and 37.4%), foil bags (16.4% and 4.3%), and canisters (4.2% and 0.5%), for 0.5 and 24 hr, respectively. VFAs had higher recoveries than semivolatile organic compounds for all of the bags and canisters. New FEP bags and new foil bags had the lowest and the highest amounts of chemical impurities, respectively. New commercial Tedlar bags had measurable concentrations of N,N-dimethyl acetamide and phenol. Foil bags had measurable concentrations of acetic, propionic, butyric, valeric, and hexanoic acids. 相似文献
Outreach nurseries are favored conservation and social forestry tools globally, but, as with many integrated conservation
and development programs (ICDPs), they do not always produce anticipated results. A synopsis of the experience of South African
practitioners is provided in this study of 65 outreach nurseries. South African outreach nurseries frequently include financial
objectives, creating additional challenges in simultaneously attaining conservation and socioeconomic goals. Progress was
hindered by biophysical problems (e.g., lack of water, poor soils, etc.) as well as the harsh socioeconomic conditions facing
most communities in which nurseries had been established. Attaining financial viability was challenging. Business management
skills were often restricted, and few viability studies included adequate market research. Costs to community participants
were usually high, and benefits were limited. Conservation objectives were frequently lost in the struggle to attain financial
viability. The management of social processes also proved challenging. Although small scale and relatively straightforward
compared with many ICDPs, nurseries usually require substantial institutional support, including a range of technical, business,
and development services. Project time frames need to be reconsidered, as practitioners estimate that it takes 5–10 years
for nurseries to start meeting objectives, and donors and implementing agencies often operate on 2–3-year project cycles.
Detailed viability studies are essential, incorporating a social probe and an assessment of potential impacts of projects
on community participants. Progress needs to be continuously evaluated to enable institutions and community participants to
adapt to changing conditions as well as ensure that the spectrum of objectives are being achieved. 相似文献
Climate change will require novel conservation strategies. One such tactic is a coarse‐filter approach that focuses on conserving nature's stage (CNS) rather than the actors (individual species). However, there is a temporal mismatch between the long‐term goals of conservation and the short‐term nature of most ecological studies, which leaves many assumptions untested. Paleoecology provides a valuable perspective on coarse‐filter strategies by marshaling the natural experiments of the past to contextualize extinction risk due to the emerging impacts of climate change and anthropogenic threats. We reviewed examples from the paleoecological record that highlight the strengths, opportunities, and caveats of a CNS approach. We focused on the near‐time geological past of the Quaternary, during which species were subjected to widespread changes in climate and concomitant changes in the physical environment in general. Species experienced a range of individualistic responses to these changes, including community turnover and novel associations, extinction and speciation, range shifts, changes in local richness and evenness, and both equilibrium and disequilibrium responses. Due to the dynamic nature of species responses to Quaternary climate change, a coarse‐filter strategy may be appropriate for many taxa because it can accommodate dynamic processes. However, conservationists should also consider that the persistence of landforms varies across space and time, which could have potential long‐term consequences for geodiversity and thus biodiversity. 相似文献