Toxicity of imidazolium- and pyridinium-based ionic liquids and the co-metabolic degradation of N-ethylpyridinium tetrafluoroborate

We examined the effects of the ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆], N-ethylpyridinium tetrafluoroborate [EtPy][BF₄], and N-ethylpyridinium trifluoroacetate [EtPy][CF₃COO] on Pseudomonas fluorescens, a ubiquitous soil bacterium. In the presence of 0.5- and 1% of [BMIM][PF₆] or [EtPy][CF₃COO] the growth of bacteria was inhibited, whereas exposing them to 1% [EtPy][BF₄] increased the lag period wherein bacteria adapt to growth conditions before continuing to grow. However, at higher concentrations (5% and 10%), no growth was observed. The inhibitory effects were evident by a decrease in the optical density of the culture, a decline in the consumption of the carbon source, citric acid, and a change in the size of the bacterium. At concentrations below 1%, [EtPy][BF₄] was metabolized by P. fluorescens in the presence of citric acid. Oxidation of the side alkyl-chain of [EtPy][BF₄] caused the accumulation of N-hydroxylethylpyridinium and pyridinium as major degradation products.     

黄菖蒲和狭叶香蒲根系对氮磷的吸收动力学

采用改进的常规耗竭法，研究了黄菖蒲（Iris pseudacorus L.）和狭叶香蒲（Typha angustifolia L.）根系对NH₄⁺、NO₃^-和H₂PO₄^-的吸收特征及差异。结果表明，这2种植物根系对NH₄⁺、NO₃^-和H₂PO₄^-的吸收动力学特征均可采用Michaelis-Menten方程描述。2种植物根系对NH₄⁺、NO₃^-和H₂PO₄^-的亲和力（Km）和最大吸收速率（Vmax）有显著差异。吸收H₂PO₄^-时，黄菖蒲根系具有较高的Vmax值和较低的Km值，说明黄菖蒲具有嗜磷特性，并能够适应广范围浓度的H₂PO₄^-环境，适宜用于污染水体磷的去除；吸收NO₃^-时，狭叶香蒲根系具有较高的Vmax值和较低的Km值，表明狭叶香蒲可用于广范围浓度NO₃^-污染的水体修复；吸收NH₄⁺时，黄菖蒲根系具有较低的Vmax值和Km值，而狭叶香蒲根系具有较高的Vmax值和Km值，说明黄菖蒲适宜用于NH₄⁺污染较轻水体的修复，而在NH₄⁺污染较重水体中宜选用狭叶香蒲作为先锋植物。     

Monthly and annual bias in weekly (NADP/NTN) versus daily (AIRMoN) precipitation chemistry data in the Eastern USA

Previous comparisons of the data from the National Atmospheric Deposition Program, National Trends Network (NTN) against collocated event sampled data and daily sampled data suggest a substantial bias in the concentration of ammonium [NH₄⁺] and concentrations of several base cations, while the comparability of other ion concentrations ranges among the studies. Eight years of collocated data from five NTN and Atmospheric Integrated Research and Monitoring Network (AIRMoN) sites are compared here. Unlike previous analyses, the data from these two data sets were analyzed in the same laboratory using the same analytical methods; therefore, factors that influence concentration differences can be isolated to sampling frequency and sample preservation techniques. For comparison, the relative biases for these data have been calculated using both median value and volume-weighted mean concentrations, following two different approaches in the literature. The results suggest a relative bias of about 10% in [NH₄⁺] (NTN less than AIRMoN), which is smaller than previous estimates that included the influence of inter-laboratory comparisons. The annual relative bias of [H⁺] increases over the analysis period, which results in a larger total relative bias for [H⁺] than found in a previous analysis of AIRMoN and NTN data. When comparing NTN and AIRMoN data on monthly time scales, strong seasonal variations are evident in the relative bias for [H⁺], [NH₄⁺], and [SO₄²⁻]. Large biases in [SO₄²⁻] (NTN greater than AIRMoN) on monthly times scales have not been detected in previous analyses where data for all seasons were considered together.     

Time Trends and Seasonal Variation of the Rainwater Chemical Composition in Spain

Abstract

A multiple regression model was used to describe temporal variations of the concentrations of H⁺, SO₄ ^{2 -}, NO₃ ^- and NH₄ ⁺ in Spanish rainwater. The model included the effects of linear trend, annual cycle, and precipitation quantity simultaneously.

The model fit very well for SO₄ ^{2 -} and NO₃ ^-, with statistical evidence of annual cycle and effect of precipitation quantity for these two ions and for NH₄ ⁺, but not for H⁺. There is no trend for any ion, with the single exception of a decreasing trend for H⁺ in one of the stations used.     

Levels of persistent organic pollutant and their predictors among young adults

Exposure to persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethane (p,p′-DDE), and hexachlorobenzene (HCB) continues to be of concern due to their ubiquitous distribution and high persistence. Current toxicant body burden is still a primary concern within the Akwesasne Mohawk Nation since other studies conducted within the community have shown relationships between these POPs and endocrine disruption.In this article we describe the levels of these toxicants in young adults of the Akwesasne Mohawk Nation between the ages of 17 and 21 years of age (mean age 18.1 years), and investigate potential influences of their current body burden. Seventeen congeners in fourteen chromatographic peaks were detected in 50% or more of the individuals sampled (geometric mean [GM] of the sum of these congeners = 0.43 ppb). Congeners 118, 138[+163 + 164] and 153 had the highest rate of detection (?98%) within the Akwesasne young adults. Of the other organochlorines, HCB (GM = 0.04 ppb) and p,p′-DDE (GM = 0.38 ppb) were found in 100% and 99% of the sample respectively.Significantly higher levels of PCBs were found among individuals who were breastfed as infants, were first born, or had consumed local fish within the past year. When compared to levels of p,p′-DDE, HCB, and 13 specific congeners reported by the CDC for youth between the ages of 12 and 19 years, the geometric means of several congeners (CBs 99, 105, 110, and 118) among the Akwesasne were higher than the reported CDC 90th percentile. In contrast, levels of CB 28 in Akwesasne young adults were ∼50% or less than those of the CDC cohort. p,p′-DDE and HCB levels were generally higher in the CDC cohort (GM of 0.516 and 0.065 ppb, respectively for Mohawks vs. 2.51 and 0.123, respectively, for CDC). Concentrations of non-persistent PCBs among this sample of Akwesasne young adults were higher than those reported by the CDC suggesting continued exposure, but lower than those associated with severe contamination.Additional research into the concentration trends of individual PCB congeners within Akwesasne youth and young adults is warranted to further improve our insight into the determinants and influences of organochlorine concentrations within members of the Akwesasne community.     

富含活性氯与Al_(13)水处理药剂对铜氰络合物去除效能

含重金属铜离子与氰离子(CN)的络合物广泛存在于电镀、冶金等工业废水中,是一种较难处理的污染物。富含活性氯和Al13聚合体的水处理药剂(PACC)兼具氧化和絮凝效能,在处理含重金属氰络合物([Cu(CN)3]2-)废水方面具有良好的应用前景。研究PACC与[Cu(CN)3]2-的反应计量学、动力学,考察了pH、反应时间和投药量等影响因素,确定PACC的最佳工作参数。结果表明,PACC可同时实现对CN的氧化和对Cu2+的絮凝,有效去除水中[Cu(CN)3]2-。使用PACC对[Cu(CN)3]2-的无害化处置过程分为2个阶段:CN-首先被氧化成氰酸根(OCN-);然后OCN-被进一步氧化并生成碳酸氢根和氮气,同时所释放的游离态铜离子被絮凝去除。这2个阶段反应的最佳pH分别为11和8,去除1 mol[Cu(CN)3]2-的最佳投药量为9.35 mol Cl2的PACC;在此条件下反应43 min后,其出水中CN-和Cu2+的浓度均达到排放标准(GB21900-2008)要求。     

Seasonal variations of acidic air pollutants in Seoul,South Korea

The annular denuder system (ADS) was used to characterize seasonal variations of acidic air pollutants in Seoul, South Korea. Fifty- four 24 h samples were collected over four seasons from October 1996 to September 1997. The annual mean concentrations of HNO₃, HNO₂, SO₂ and NH₃ in the gas phase were 1.09, 4.51, 17.3 and 4.34 μg m^-3, respectively. The annual mean concentrations of PM_2.5(d_p≤2.5 μm in aerodynamic diameter, 50% cutoff), SO^2-₄, NO^-₃ and NH⁺₄ in the particulate phase were 56.9, 8.70, 5.97 and 4.19 μg m^-3, respectively. All chemical species monitored from this study showed statistical seasonal variations. Nitric acid (HNO₃) and ammonia (NH₃) exhibited substantially higher concentrations during the summer, while nitrous acid (HNO₂) and sulfur dioxide(SO₂) were higher during the winter. Concentrations of PM_2.5, SO^2-₄, NO^-₃ and NH⁺₄ in the particulate phase were higher during the winter months. SO^2-₄, NO^-₃ and NH⁺₄ accounted for 26–38% of PM_2.5. High correlations were found among PM_2.5, SO^2-₄, NO^-₃ and NH⁺₄. The mean H⁺ concentration measured only in the fall was 5.19 nmole m^-3.     

Analysis of Hong Kong daily bulk and wet deposition data from 1994 to 1995

Results from a 1-year daily rainwater sampling program, employing both wet and bulk deposition samplers with replicate samples, from 1994 to 1995 in Hong Kong are presented and analysed. Analyte concentrations were found to vary over a wide range of several orders of magnitude, with [H⁺] for example, from 0.16 to 208.9 μeq dm^-3. Diurnal pH values less than 3.83 were measured on five occasions. A significant correlation between pH and lognormal windspeed has been found. This is taken to indicate the minor importance of long-range transport in determining rainwater acidity, since local pollutant emissions accumulate and react under conditions of atmospheric stability in the sub-tropical climate. The H⁺ wet deposition flux onto a polythene surface was 90 meq m^-2 yr^-1 during 1994–1995 at City University. Dry deposition exerts a neutralizing influence upon the acidity from this wet deposition. Although paired t-tests indicated significant differences between the bulk versus wet deposition datasets for cations, but not anions, the dataset means consequently showed such large standard deviations that t-tests indicated no significant differences. In rainwater, the charges from SO^2-₄ and NO^-₃ anions seldom balance the proton charges, implying that they are also derived from solubilization of primary and secondary airborne Ca²⁺, Mg²⁺ and NH⁺₄ particulate matter in rainwater. Use of the [SO^2-₄]/[NO^-₃] ratios in rainwater in fingerprinting pollutant origins has drawbacks, but is generally indicative of a predominantly regional contribution of these secondary pollutants to rainwater. Bulk deposition pH in Hong Kong would be in the region of 4.1 if basic Ca²⁺ compounds alone did not neutralize acidity. The regional rainout pH, inferred after exhaustive below-cloud scavenging, is about 5. The temporal trends in Hong Kong rainwater acidity are blurred.     

Photochemical Conversion of NO to NO2 by Hydrocarbons in an Outdoor Chamber

Significant differences occur between results of chamber work conducted outdoors versus work conducted indoors under constant light intensity. Under outdoor conditions at constant [NO_X]_O, lower [HC]o resulted in lower [NO₂]_max and NO₂ dosage during the daylight hours. The percent reduction in [NO₂]_max was a function of the [HC]₀ reduction and the [NO_X]_O level. Under all experimental conditions the 10 hour N0₂ average to maximum N0₂ concentration ratio appeared to be constant at 0.73 during the daylight hours. A regression equation relating [NO_x]_max to [NO_X]_O, [HC]_O, and measures of solar radiation accounted for 92% of the variance in the data. Although there is unavoidable confoundment between [HC]₀ and solar radiation, the HC term in this regression equation can introduce ±20 % change in [N0₂]_max - This variation can be partially offset or enhanced by variations in solar radiation.     

Rate constant for the reaction of ozone with diethyl sulfide

The rate constant for the reaction of diethyl sulfide (DES; C₂H₅SC₂H₅) with ozone was determined for the first time, which was (2.77±0.27)×10⁻¹⁹ cm³ molecule⁻¹ s⁻¹ under a room temperature of (289±1) K. Experiments were conducted under supposedly pseudo-first-order decay conditions, keeping [DES]₀>50[O₃]₀, but having different combinations of [DES]₀ and [O₃]₀. Cyclohexane was added into the reactor to eliminate the effect of OH radicals. The wall decay of ozone and the role of cyclohexane were also discussed in the present work.     

A 3 year study of the aerosol in northwest Saxony (Germany)

Over three years (1993–1995) daily PM-10 aerosol samples were collected at two locations in Saxony, at the rural measurement station Melpitz and at the north-eastern border of Leipzig. By using ion chromatography the water soluble ions Na⁺, NH⁺₄, K⁺, Mg²⁺, Ca²⁺, Cl^-, NO^-₃and SO^2-₄ were analysed daily. Soot was detected by reflectance measurement and gravimetric analysis. Major trends during this period were observed for soot, nitrate, sulphate and calcium. Some components had typical seasonal distributions, e.g. soot, nitrate and sulphate. The rural station Melpitz was influenced more strongly by the power plants at both sides of the Polish border than the urban area of Leipzig-Halle. During inversion periods, maxima of all aerosol components were measured. However, the highest concentrations during inversion periods decreased during the last years at both locations.     

土壤渗滤介质系统去除雨水径流污染物

利用昆明当地的土壤在室内填装一个土柱渗滤系统，使用配水浓度模拟昆明市区雨水径流污染物浓度，进行去除雨水径流污染物的实验研究，考察系统对COD、TN、NH4＋、NO3^-、NO2^-和TP的去除效果。实验结果表明，该土壤渗滤系统对COD平均去除率为82．04％，对TN的平均去除率为22．64％，对NH；平均去除率为94．26％，但是对NO3^-、NO2^-去除效果较差，对TP平均去除率为96．95％；另外，系统长期运行导致下渗速度降低，出水效果反而变好。     

Toxic effect and mechanism of four ionic liquids on seedling taproots of Arabidopsis thaliana

Arabidopsis thaliana was selected as model organisms to investigate the toxic effect and mechanism of four kinds of imidazolium and pyridinium ionic liquids (ILs) on plant seedling taproots. After exposure to ILs, the growth of seedling taproots was significantly inhibited in a dose-dependent manner. The toxicity of ILs on seedling taproots was [Bmim][BF₄] > [Bmpy][BF₄] > [Bmim][Br] > [Bmpy][Br]. The reduction of seedling root cell vitality, aggravation of seedling root cell death, and repression of gravitropic growth responses were observed. The amounts of H₂O₂ and ROS in seedlings were enhanced with increasing concentrations of ILs. Moreover, the expression levels of cdc2a and pcna1 genes were decreased after exposure to ILs. Our results suggest that ILs can induce the overproduction of ROS in A. thaliana seedling taproots and thus cause oxidative damage to seedling taproots. Meanwhile, ILs alter the expression patterns of two cell cycle-related genes and hence cause the seedling taproot growth inhibition. This work provides an integrated understanding of the toxic effect and mechanism of ILs on A. thaliana seedlings at the molecular and physiological level and also provides theoretical basis and reference for the environmental safety evaluation of ILs, prior to their widespread use and release.

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Evaluating Environmental Parameters for Minimum Ammonium Losses during Composting of Trimming Residues

Abstract

A neural fuzzy system was used to investigate the influence of environmental variables (time, aeration, moisture, and particle size) on composting parameters (pH, organic matter [OM], nitrogen [N], ammonium nitrogen [NH₄ ⁺-N] and nitrate nitrogen [NO₃ ^--N]). This was to determine the best composting conditions to ensure the maximum quality on the composts obtained with the minimum ammonium losses. A central composite experimental design was used to obtain the neural fuzzy model for each dependent variable. These models, consisting of the four independent process variables, were found to accurately describe the composting process (the differences between the experimental values and those estimated by using the equations never exceeded 5–10% of the former). Results of the modeling showed that creating a product with acceptable chemical properties (pH, NH₄ ⁺-N and NO₃ ^--N) entails operating at medium moisture content (55%) and medium to high particle size (3–5 cm). Moderate to low aeration (0.2 L air/min · kg) would be the best compromise to compost this residue because of the scant statistical influence of this independent variable.     

Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009

Introduction

Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?P?Results and discussions Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO ₄ ^2? and NO ₃ ^? were the main anions, and NH ₄ ⁺ and Ca²⁺ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO ₄ ^2? ] to [NO ₃ ^? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH ₄ ⁺ ] to [Ca²⁺] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl^?] to [Na⁺] was about 0.67, somewhat lower than that of natural precipitation.

Conclusions

Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.     

The algal toxicity of silver engineered nanoparticles and detoxification by exopolymeric substances

In this study, we report that silver ions (Ag⁺) from the oxidative dissolution of silver engineered nanoparticles (Ag-ENs) determined the EN toxicity to the marine diatom Thalassiosira weissflogii. Most of the Ag-ENs formed non-toxic aggregates (>0.22 μm) in seawater. When the free Ag⁺ concentration ([Ag⁺]_F) was greatly reduced by diafiltration or thiol complexation, no toxicity was observed, even though the Ag-ENs were better dispersed in the presence of thiols with up to 1.08 × 10⁻⁵ M Ag-ENs found in the <0.22 μm fraction, which are orders of magnitude higher than predicted for the natural aquatic environment. The secretion of polysaccharide-rich algal exopolymeric substances (EPS) significantly increased at increasing [Ag⁺]_F. Both dissolved and particulate polysaccharide concentrations were higher for nutrient-limited cells, coinciding with their higher Ag⁺ tolerance, suggesting that EPS may be involved in Ag⁺ detoxification.     

Chemical characteristics of precipitation at metropolitan Newark in the US East Coast

To investigate the chemical characteristics of precipitation in the polluted coastal atmosphere, a total of 46 event-based precipitation samples were collected using a wet-only automatic precipitation collector from September 2006 to October 2007 at metropolitan Newark, New Jersey in the US East Coast. Samples were analyzed by ion chromatography for the concentrations of major inorganic ions (Cl⁻, NO₃⁻, SO₄²⁻, F⁻, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺) and organic acid species (CH₃COO⁻, HCOO⁻, CH₂(COO)₂²⁻, C₂O₄²⁻). Selected trace metals (Sb, Pb, Al, V, Fe, Cr, Co, Ni, Cu, Zn, Cd) in samples were determined by ICPMS. Mass concentration results show that SO₄²⁻ was the most dominant anion accounting for 51% of the total anions, controlling the acidity of the precipitation. NH₄⁺ accounted for 48.6% of the total cations, dominating the precipitation neutralization. CH₃COO⁻ and HCOO⁻ were the two dominant water-soluble organic acid species, accounting for 42% and 40% of the total organic acids analyzed, respectively. Al, Zn and Fe were the three major trace metals in precipitation, accounting for 34%, 27%, and 25% of the total mass of metals analyzed. The pH values in precipitation ranged from 4.4 to 4.9, indicating an acidic nature. Enrichment Factor (EF) Analysis showed that Na⁺, Cl⁻, Mg²⁺ and K⁺ in the precipitation were primarily of marine origin, while most of the Fe, Co and Al were from crust sources. Pb, V, Cr, Ni were moderately enriched with EFs ranging 43–410, while Zn, Sb, Cu, Cd and F⁻ were highly enriched with EFs > 700, indicating significant anthropogenic influences. Factor analysis suggests 6 major sources contributing to the observed composition of precipitation at this location: (1) nitrogen-enriched soil, (2) secondary pollution processes, (3) marine sources, (4) incinerations, (5) oil combustions, and (6) malonate–vanadium enriched sources. To further explore the source–precipitation event relationships and seasonality, cluster analysis was performed for all precipitation events. Results show that about half of the precipitation events were characterized by mixed sources. Significant influences of nitrogen-enriched soil and marine sources were associated with precipitation events in spring and autumn, while secondary pollution processes, incineration and oil combustion contributed greatly in summer.     

用微电极测定曝气量对SBR系统中硝化作用的影响

为了研究曝气量对硝化作用的影响,实验采用3个相同的SBR装置,分别在曝气量为4、10和16 L/h的条件下处理人工污水,并采用自制的溶解氧、NO3-、NH4+和pH微电极测定了活性污泥絮体内部微元环境中相应基质的浓度。结果表明,曝气量为4 L/h时,活性污泥絮体内存在厌氧微区,NO3--N浓度减小了,发生了反硝化作用;而曝气量为10 L/h和16 L/h时,活性污泥絮体内发生的都是硝化反应,且NH4+-N浓度的减小量、NO3--N浓度的增大量都随着曝气量的增大而增大,pH随着曝气量的增大而减小。