纳米二氧化钛在老化环境条件下对铜诱导毒性的影响

纳米二氧化钛颗粒(nTiO₂)可以通过吸附表层水中共生重金属来改变它们对淡水无脊椎动物的毒性。然而,影响这种交互过程的几种环境因子的相对重要性仍不清楚。因此,本研究通过连续72 h的培养试验,评估了老化对Cu与nTiO₂对大型蚤Daphnia magna联合急性毒性的影响。在老化过程中,对老化时间以及离子强度、pH值和不同质量有机物质等因子都进行了考察。研究结果表明,尽管影响效应的大小不同,nTiO₂的存在往往减少了老化后Cu对大型蚤的诱发毒性,在没有nTiO₂的情况下,Cu对大型蚤急性毒性的EC₅₀值提高了3倍之多。此外,各种形态Cu的形成受到介质中的离子组成、pH值以及有机添加剂存在的影响,这一过程受到极大的调控,并随着老化时间对大型蚤生态毒性的响应有一定影响。尽管如此,该研究的结论对nTiO₂在淡水生态系统中不同环境条件下,改变重金属诱发毒性的潜在作用提供了有力的支持。然而,这种模式需要进一步验证,比如结合不同性质的重金属离子与不同的环境因素,如紫外线照射。
精选自Ricki R. Rosenfeldt, Frank Seitz, Ann-Cathrin Haigis, Johanna H?ger, Jochen P. Zubrod, Ralf Schulz, Mirco Bundschuh. Nanosized titanium dioxide influences copper induced toxicity during aging as a function of environmental conditions. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1766–1774, July 2016. DOI: 10.1002/etc.3325
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3325/full
     

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged membrane bioreactor. The developed model was calibrated under the reference condition. Simulation results were in good agreement with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters: hydraulic retention time (HRT), dissolved oxygen concentration, and sludge retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant. The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality, reduce the content of SMP, and minimize operating costs; the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process, less membrane fouling potential, and acceptable organic removal efficiency.     

Macrozoobenthos diversity in an oxygen minimum zone off northern Namibia

A benthological survey in the Benguela upwelling area off northern Namibia (located at 17.3°S and water depth ranging between 26 and 117 m) showed the concentration of dissolved oxygen and the accumulation of organic-rich sediments to control macrozoobenthic community patterns. In contrast to highly biodiverse nearshore areas with well-structured shell deposits of the brachiopod Discinisca tenuis (Sowerby 1847), the benthic community in the oxygen minimum zone (OMZ) decreased strongly in species numbers. Nevertheless, a well-established community ranging from 13 to 31 species persisted. Species densities (300–3,350 ind m⁻²) and biomass (4–109 g afdw/m²) were surprisingly high for areas with near bottom oxygen concentrations from 0.06 to 0.88 ml l⁻¹. In contrast to OMZ’s of other upwelling areas, where the benthic macrofauna is generally dominated by small-bodied polychaetes, off Namibia larger key organisms like the bivalve Nuculana bicuspidata (Gould 1845) and the snail Nassarius vinctus (Marrett 1877) accounted for a large proportion of the macrozoobenthos >1 mm. This is supposed to have a distinct effect on the functional properties of the sediments.

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Nativ-basierte Grundöle für die Produktion von Kühlschmierstoffen

Aims and Scope

Compared to mineral oil products, cooling lubricants based on fatty acid esters have technological advantages. Moreover, they are more environmentally compatible and make a contribution to a sustainable economy. Nevertheless, they are rarely applied in practice, because of their comparably high price, that is based on raw-material and synthesis costs. Alternatives concerning raw-materials and synthesis pathways are considered and properties of resulting ester products are compared.

Methods

The investigations aimed at three fatty acid-2-ethyl-hexylesters that were synthesized in an enzymatic-catalytic routine based on peanut oil, suet, and waste edible fat and at esters that were conventionally produced from animal and plant fats and 2-ethyl-1-hexanol. Physical properties, fatty acid patterns, contents of free fatty acids, as well as oxidative and hydrolytic stabilities were determined. Thermolysis experiments were performed.

Results

The physical properties of the seven esters, density, viscosity, pourpoint, and flash point, were comparable and gave reason for the assumption, that the products could be used as basis oils in lubricant formulations. Hydrolysis stabilities of the esters were high and thermal stress did not point at high potential of hazardous compounds formation. Especially the enzymatic-catalytically produced esters showed deficits concerning oxidation stabilities and free fatty acid contents.

Outlook

For practice it will be necessary to define minimum qualities for raw-materials and resulting ester oils to be used as lubricant basis oils. Moreover, processes have to be developed, that yield high quality ester products from waste edible and animal fats without loosing the advantage of low-cost raw-materials by high production and refinement costs. Surely, one contribution is the further development of the energy-saving enzymtic alcoholysis for ester production.     

Comparing indoor wastewater-fed aquaculture with two conventional wastewater treatment plants using adopted sustainable process indices

Highly aggregating 'Sustainable Process Indices' (SPI) were calculated for an indoor wastewater-fed aquaculture and two conventional wastewater treatment plants to make a direct comparison between the three facilities possible. The goal was to find out which technology would be better suited for use in a sustainable economy. The SPI provides a type of 'ecological footprint' for the three facilities on the basis that, in a sustainable economy, solar energy would be our main energy source and that surface area would become the limiting factor for economic development, because the transformation of solar energy into other forms of energy, products or services requires area. SPI calculations consider the area necessary for the sustainable dissipation of byproducts and wastes of a process into the environment. The SPI thus uses area as its basic unit for comparisons between different technologies, products or services.

Energy consumption, as well as treatment performance (both the quality and quantity of treated effluent), and multi-functionality of facilities were key variables in determining how much area a wastwater treatment plant would need to be embedded sustainably into the environment. The calculated SPIs reveal that the wastewater-fed aquaculture requires the least area to be embedded sustainably into the environment, therefore, it would be better suited for use in a sustainable economy compared to the two conventional wastewater treatment plants.     

A comparison of predicted and measured levels of runoff-related pesticide concentrations in small lowland streams on a landscape level

Short-term pollution events via runoff are typical of streams in agricultural areas. Existing runoff models that simulate pesticide loss from agricultural fields require extensive input of information. There is thus a need for a simple model that can predict runoff-related pesticide concentrations in many streams on a landscape level when only limited data are available. To validate such a model, the runoff-related pesticide load of 18 small lowland streams was predicted with an extended version of the model "simplified formula for indirect loadings caused by runoff" (available from the Organisation for Economic Cooperation and Development, OECD). The authors suggest that the model presented here is suitable for use in routine exposure assessment of pesticides on a landscape level, as all input data (soil, slope, precipitation, pesticide application) are readily available from public authorities or could be generated by simple regional flood hydrograph curves. The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 microg/l for the fungicide azoxystrobin and 0.3 microg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 microg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; por=0.5 microg/l).     

Giardia and Cryptosporidium in pristine protected catchments in central eastern Australia

We report the first confirmed records of the pathogenic protozoa Giardia lamblia and Cryptosporidium parvum from small remote streams in pristine protected areas in Australia, beyond the reach of urban or agricultural contamination.