Removal of Pb(II), Cd(II), Cu(II), and Zn(II) by hematite nanoparticles: effect of sorbent concentration, pH, temperature, and exhaustion

Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions (Pb(II), Cd(II), Cu(II), Zn(II)) to nanohematite was examined as a function of sorbent concentration, pH, temperature, and exhaustion. Adsorption experiments were conducted with 0.05, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water. The adsorption data showed the ability of nanohematite to remove Pb, Cd, Cu, and Zn species from solution with adsorption increasing as the nanoparticle concentration increased. At 0.5 g/L nanohematite, 100 % Pb species adsorbed, 94 % Cd species adsorbed, 89 % Cu species adsorbed and 100 % Zn species adsorbed. Adsorption kinetics for all metals tested was described by a pseudo second-order rate equation with lead having the fastest rate of adsorption. The effect of temperature on adsorption showed that Pb(II), Cu(II), and Cd(II) underwent an endothermic reaction, while Zn(II) underwent an exothermic reaction. The nanoparticles were able to simultaneously remove multiple metals species (Zn, Cd, Pb, and Cu) from both a pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that at pH 8, exhaustion did not occur for the nanoparticles but adsorption does decrease for Cd, Cu, and Zn species but not Pb species. The strong adsorption coupled with the ability to simultaneously remove multiple metal ions offers a potential remediation method for the removal of metals from water.     

Photocatalytic degradation of contaminants of concern with composite NF-TiO2 films under visible and solar light

This study reports the synthesis and characterization of composite nitrogen and fluorine co-doped titanium dioxide (NF-TiO₂) for the removal of contaminants of concern in wastewater under visible and solar light. Monodisperse anatase TiO₂ nanoparticles of different sizes and Evonik P25 were assembled to immobilized NF-TiO₂ by direct incorporation into the sol–gel or by the layer-by-layer technique. The composite films were characterized with X-ray diffraction, high-resolution transmission electron microscopy, environmental scanning electron microscopy, and porosimetry analysis. The photocatalytic degradation of atrazine, carbamazepine, and caffeine was evaluated in a synthetic water solution and in an effluent from a hybrid biological concentrator reactor (BCR). Minor aggregation and improved distribution of monodisperse titania particles was obtained with NF-TiO₂-monodisperse (10 and 50 nm) from the layer-by-layer technique than with NF-TiO₂?+?monodisperse TiO₂ (300 nm) directly incorporated into the sol. The photocatalysts synthesized with the layer-by-layer method achieved significantly higher degradation rates in contrast with NF-TiO₂-monodisperse titania (300 nm) and slightly faster values when compared with NF-TiO₂-P25. Using NF-TiO₂ layer-by-layer with monodisperse TiO₂ (50 nm) under solar light irradiation, the respective degradation rates in synthetic water and BCR effluent were 14.6 and 9.5?×?10^?3?min^?1 for caffeine, 12.5 and 9.0?×?10^?3?min^?1 for carbamazepine, and 10.9 and 5.8?×?10^?3?min^?1 for atrazine. These results suggest that the layer-by-layer technique is a promising method for the synthesis of composite TiO₂-based films compared to the direct addition of nanoparticles into the sol.     

Investigation of an Escherichia coli environmental benchmark for waterborne pathogens in agricultural watersheds in Canada

Canada's National Agri-Environmental Standards Initiative sought to develop an environmental benchmark for low-level waterborne pathogen occurrence in agricultural watersheds. A field study collected 902 water samples from 27 sites in four intensive agricultural watersheds across Canada from 2005 to 2007. Four of the sites were selected as reference sites away from livestock and human fecal pollution sources in each watershed. Water samples were analyzed for Campylobacter spp., Salmonella spp., Escherichia coli O157:H7, Cryptosporidium spp., Giardia spp., and the water quality indicator E. coli. The annual mean number of pathogen species was higher at agricultural sites (1.54 ± 0.07 species per water sample) than at reference sites (0.75 ± 0.14 species per water sample). The annual mean concentration of E. coli was also higher at agricultural sites (491 ± 96 colony-forming units [cfu] 100 mL(-1)) than at reference sites (53 ± 18 cfu 100 mL(-1)). The feasibility of adopting existing E. coli water quality guideline values as an environmental benchmark was assessed, but waterborne pathogens were detected at agricultural sites in 80% of water samples with low E. coli concentrations (<100 cfu 100 mL(-1)). Instead, an approach was developed based on using the natural background occurrence of pathogens at reference sites in agricultural watersheds to derive provisional environmental benchmarks for pathogens at agricultural sites. The environmental benchmarks that were derived were found to represent E. coli values lower than geometric mean values typically found in recreational water quality guidelines. Additional research is needed to investigate environmental benchmarks for waterborne pathogens within the context of the "One World, One Health" perspective for protecting human, domestic animal, and wildlife health.     

A Framework for Assessing Collaborative Capacity in Community-Based Public Forest Management

Community-based collaborative groups involved in public natural resource management are assuming greater roles in planning, project implementation, and monitoring. This entails the capacity of collaborative groups to develop and sustain new organizational structures, processes, and strategies, yet there is a lack of understanding what constitutes collaborative capacity. In this paper, we present a framework for assessing collaborative capacities associated with community-based public forest management in the US. The framework is inductively derived from case study research and observations of 30 federal forest-related collaborative efforts. Categories were cross-referenced with literature on collaboration across a variety of contexts. The framework focuses on six arenas of collaborative action: (1) organizing, (2) learning, (3) deciding, (4) acting, (5) evaluating, and (6) legitimizing. Within each arena are capacities expressed through three levels of social agency: individuals, the collaborative group itself, and participating or external organizations. The framework provides a language and set of organizing principles for understanding and assessing collaborative capacity in the context of community-based public forest management. The framework allows groups to assess what capacities they already have and what more is needed. It also provides a way for organizations supporting collaboratives to target investments in building and sustaining their collaborative capacities. The framework can be used by researchers as a set of independent variables against which to measure collaborative outcomes across a large population of collaborative efforts.     

Beyond selectivity: Are behavioral avoidance and hormesis likely causes of pyrethroid-induced outbreaks of the southern red mite Oligonychus ilicis?

Secondary pest outbreak is a counterintuitive ecological backlash of pesticide use in agriculture that takes place with the increase in abundance of a non-targeted pest species after pesticide application against a targeted pest species. Although the phenomenon was well recognized, its alternative causes are seldom considered. Outbreaks of the southern red mite Oligonychus ilicis are frequently reported in Brazilian coffee farms after the application of pyrethroid insecticides against the coffee leaf miner Leucoptera coffeella. Selectivity favoring the red mite against its main predatory mites is generally assumed as the outbreak cause, but this theory has never been tested. Here, we assessed the toxicity (and thus the selectivity) of deltamethrin against both mite species: the southern red mite and its phytoseid predator Amblyseius herbicolus. Additionally, behavioral avoidance and deltamethrin-induced hormesis were also tested as potential causes of red mite outbreak using free-choice behavioral walking bioassays with the predatory mite and life-table experiments with both mite species, respectively. Lethal toxicity bioassays indicated that the predatory mite was slightly more susceptible than its prey (1.5×), but in more robust demographic bioassays, the predator was three times more tolerant to deltamethrin than its prey, indicating that predator susceptibility to deltamethrin is not a cause of the reported outbreaks. The predator did not exhibit behavioral avoidance to deltamethrin; however insecticide-induced hormesis in the red mite led to its high population increase under low doses, which was not observed for the predatory mite. Therefore, deltamethrin-induced hormesis is a likely cause of the reported red mite outbreaks.     

Insights into the dissolution and the three-dimensional structure of insensitive munitions formulations

Two compounds, 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO) are the main ingredients in a suite of explosive formulations that are being, or soon will be, fielded at military training ranges. We aim to understand the dissolution characteristics of DNAN and NTO and three insensitive muntions (IM) formulations that contain them. This information is needed to accurately predict the environmental fate of IM constituents, some of which may be toxic to people and the environment. We used Raman spectroscopy to identify the different constituents in the IM formulations and micro computed tomography to image their three-dimensional structure. These are the first three-dimensional images of detonated explosive particles.     

Green manure plants for remediation of soils polluted by metals and metalloids: Ecotoxicity and human bioavailability assessment

Borage, white mustard and phacelia, green manure plants currently used in agriculture to improve soil properties were cultivated for 10 wk on various polluted soils with metal(loid) concentrations representative of urban brownfields or polluted kitchen gardens. Metal(loid) bioavailability and ecotoxicity were measured in relation to soil characteristics before and after treatment. All the plants efficiently grow on the various polluted soils. But borage and mustard only are able to modify the soil characteristics and metal(loid) impact: soil respiration increased while ecotoxicity, bioaccessible lead and total metal(loid) quantities in soils can be decreased respectively by phytostabilization and phytoextraction mechanisms. These two plants could therefore be used for urban polluted soil refunctionalization. However, plant efficiency to improve soil quality strongly depends on soil characteristics.     

有机污染胁迫对人工湿地中浮萍抗氧化系统的影响

湿地植物在处理高负荷有机废水时会受到不同程度的氧化胁迫。本研究基于对浮萍的有机污染胁迫模拟系统,通过对浮萍脂质过氧化和抗氧化防御系统的监测与分析,研究了浮萍对有机污染胁迫的耐受能力及胁迫去除后浮萍的恢复规律。结果表明,浮萍对有机污染胁迫具有较高的耐受性,在胁迫去除后,具有一定的恢复能力。在COD小于400mg/L时,浮萍并未受到氧化胁迫;当COD达到800 mg/L时,浮萍体内ROS含量上升,细胞膜脂过氧化加剧,但抗氧化酶活性升高,抗氧化物质含量增加,浮萍可保持生长,胁迫去除后,抗氧化防御系统可恢复到对照水平;当COD过高（≥1 000mg/L）,ROS急剧上升,抗氧化防御系统遭受破坏,造成不可逆伤害,胁迫去除后不能恢复正常生长。     

Comprehensive Area Surveys in New York State

The proposed By-law changes have been suggested over the last two years. They are basically housekeeping changes which correct the language, eliminate duplications, and clarify the dates for the receipt and acceptance of the ballots for nominees for the Board. The major revision proposed is in Article XV of the Technical Council which was necessitated by the new structure of the Technical Council approved by the Board of Directors in June 1970.     

Problems in Judging Plume Opacity—A Simple Device for Measuring Opacity of Wet Plumes

The discoloration of exterior paint, has been shown to occur when H₂S in the air reacts with heavy metal salts used as pigments or fungicides in the paint. Simple field tests can give an indication whether H₂S was involved. An electron diffraction technique is described to identify the discolored compound in paint samples. Field experience in Jacksonville using this method is described.