Arsenic (V) removal from groundwater by GE-HL nanofiltration membrane: effects of arsenic concentration, pH, and co-existing ions

A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200 μg·L^?1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl^?, Na⁺, SO ₄ ^2? , and Ca²⁺ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions.     

Urea as a nitrogen source for the phytoplankton in the Oslofjord

Ambient concentrations of urea in the inner Oslofjord, Norway, showed a pronounced yearly cycle in 1980, with values in the range 0.1 to 10.0 μg-at N l^-1; this cycle resemble that of ammonia although urea concentrations were usually lower. The uptake of urea by phytoplankton was investigated using ¹⁵N. Urea was usually a less important N source than NH ₄ ⁺ , and accounted for 0 to 53% (mean 19%) of summed NH ₄ ⁺ +NO ₃ ^- + urea uptake rates from April to October. Absolute as well as relative (specific) uptake rates of urea were higher in the summer (June–August) than at other times. Uptake of urea was inhibited by NH ₄ ⁺ concentrations higher than 1 to 2 μg-at N l^-1. The summed NH ₄ ⁺ +NO ₃ ^- + urea uptake rate was exponentially related to temperature.     

Trace element concentration in fine particulate matter (PM<Subscript>2.5</Subscript>) and their bioavailability in different microenvironments in Agra,India: a case study

Exposure to airborne particulate matter results in the deposition of millions of particle in the lung; consequently, there is need for monitoring them particularly in indoor environments. Case study was conducted in three different microenvironments, i.e., urban, rural and roadside to examine the elemental bioavailability in fine particulate matter and its potential health risk. The samples were collected on polytetrafluoroethylene filter paper with the help of fine particulate sampler during August–September, 2012. The average mass concentration of PM_2.5 was 71.23 µg m^?3 (rural), 45.33 µg m^?3 (urban) and 36.71 µg m^?3 (roadside). Elements in PM_2.5 were analyzed by inductively coupled plasma atomic emission spectroscopy. Percentage bioavailability was determined to know the amount of soluble fraction that is actually taken across the cell membrane through inhalation pathway. Cadmium and lead were found to have cancer risk in a risk evaluation using an Integrated Risk Information system.     

PM<Subscript>2.5</Subscript>-related health impacts of utilizing ammonia-hydrogen energy in Kanto Region,Japan

Ammonia has emerged as a promising hydrogen carrier with applications as an energy source in recent years. However, in addition to being toxic, gaseous ammonia is a precursor of secondary inorganic aerosols. The concentration of ambient fine particulate matter (PM_2.5) is intrinsically connected to public health. In this study, PM_2.5-related health impacts of utilizing ammonia-hydrogen energy in Kanto Region, Japan, were investigated. It was assumed that 20% of the electricity consumption in Kanto Region, the most populated area in Japan, was supplied by ammonia-hydrogen energy. The PM_2.5 resulted from incomplete ammonia decomposition was simulated by a chemical transport model: ADMER-PRO (modified version). Based on the incremental PM_2.5 concentration, health impacts on the elderly (individuals over 65 years old) were quantitatively evaluated. The ammonia emission in this scenario increased PM_2.5 by 11.7% (0.16 μg·m^–3·y^–1) in winter and 3.5% (0.08 μg ·m^–3·y^–1) in summer, resulting in 351 premature deaths per year. This study suggests that costeffective emissions control or treatment and appropriate land planning should be considered to reduce the associated health impacts of this type of energy generation. In addition, further in-depth research, including cost-benefit analysis and security standards, is needed.

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Characteristics of chemical components in PM<Subscript>2.5</Subscript> at a plateau city,South-west China

A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM_2.5 at three sites of Kunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions (WSI), organic and element carbon (OC and EC) in PM_2.5 were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 µg·m^-3, 17.83±9.57 µg·m^-3 and 5.11±4.29 µg·m^-3, respectively. They totally accounted for 53.0% of PM_2.5. Secondary organic and inorganic aerosols (SOA and SIA) were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM_2.5 concentration. The low proportion suggested the primary emission was the main source of PM_2.5 in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.

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广州夏季办公室内细颗粒中多环芳烃污染特征研究

大部分的都市办公人群每天在办公室至少度过8 h。而室外环境的渗透、办公室内吸烟、办公设备使用和中央通风系统均可能导致细颗粒物及多环芳烃(PAHs)在室内积聚而造成微环境污染。2015年5—6月,在广州市3种不同功能区(商住区、高新产业区、工业区)共选取了14间不同类型的办公室,对其室内外PM_(2.5)和多环芳烃进行同步监测。结果表明,(1)14间中有12间办公室内的PM_(2.5)浓度水平高于世界卫生组织(WHO)的推荐值25μg·m-3;(2)与国内外类似研究相比,办公室内外∑16PAHs及Ba P-eq的监测浓度水平均较低,并呈现一致规律:文印>室外>吸烟>多人>单人>无窗(无人),其中Ba P-eq低于欧盟规定的安全限值1 ng·m-3;(3)文印工作和吸烟行为与室内PM_(2.5)和PAHs浓度升高有密切关系,分别对5环和4环PAHs贡献明显;(4)其他无明显内源的办公室的细颗粒中PAHs污染在监测期间主要来源于室外贡献。     

Enhanced biohydrogen generation from organic wastewater containing NH 4 + by phototrophic bacteria Rhodobacter sphaeroides AR-3

NH ₄ ⁺ is typically an inhibitor to hydrogen production from organic wastewater by photo-bacteria. In this experiment, biohydrogen generation with wild-type anoxygenic phototrophic bacterium Rhodobacter sphaeroideswas found to be sensitive to NH ₄ ⁺ due to the significant inhibition of NH ₄ ⁺ to its nitrogenase. In order to avoid the inhibition of NH ₄ ⁺ to biohydrogen generation by R. sphaeroides, a glutamine auxotrophic mutant R. sphaeroides AR-3 was obtained by mutagenizing with ethyl methane sulfonate. The AR-3 mutant could generate biohydrogen efficiently in the hydrogen production medium with a higher NH ₄ ⁺ concentration, because the inhibition of NH ₄ ⁺ to nitrogenase of AR-3 was released. Under suitable conditions, AR-3 effectively produced biohydrogen from tofu wastewater, which normally contains 50–60 mg/L NH ₄ ⁺ , with an average generation rate of 14.2 mL/L·h. This generation rate was increased by more than 100% compared with that from wild-type R. sphaeroides.     

Exposure assessment,chemical characterization and source identification of PM2.5 for school children and industrial downwind residents in Guangzhou,China

To assess the exposure doses of PM_2.5 and to investigate its chemical components for the subpopulation (i.e., school children and industrial downwind residents), simultaneous sampling of indoor and outdoor PM_2.5 was conducted at an elementary school close to traffic arteries and a residence located in the downwind area of a steel plant in metropolitan Guangzhou in 2010. Chemical components, i.e., organic carbon, elemental carbon and 6 water soluble ions were analyzed in PM_2.5. A survey was also conducted to investigate the time-activity patterns of the school children and the industrial downwind residents. Indoor and outdoor PM_2.5 were 63.2 ± 20.1 and (76.7 ± 35.8) μg/m³ at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m³ in the community, respectively. Indoor PM_2.5 was found to be highly related to outdoor sources, and stationary sources were the significant contributors to PM_2.5 at both sites. The daily average doses of PM_2.5 for the school children at the school (D _children) and the industrial downwind residents in the community (D _residents) were (7.6 ± 1.9) and (36.1 ± 36.8) μg/kg-day, respectively. The daily average doses of particulate organic mass and SO₄ ^2? were the two most abundant chemical components in PM_2.5. PM_2.5 exposure for the school children was contributed by indoor and outdoor environments by 48.8 and 51.2 %, respectively; for the industrial downwind residents, the contributions were 66.0 and 34.0 %, respectively. Age and body weight were significantly and negatively correlated with D _children, while age, body weight and education level were significantly and negatively correlated with D _residents; gender was not a significant factor at both cases.     

Decomposition of perfluorooctanoic acid by microwaveactivated persulfate: Effects of temperature, pH, and chloride ions

Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S₂O ₈ ^2? ) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH = 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01?C0.15 mol·L^?1), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol·L^?1 at 90°C and 0.06 mol·L^?1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature.     

The pollution characteristics of PM<Subscript>2.5</Subscript> and correlation analysis with meteorological parameters in Xinxiang during the Shanghai Cooperation Organization Prime Ministers’ Meeting

The pollution characteristics of PM_2.5 and correlation analysis with meteorological parameters in Xinxiang during the Shanghai Cooperation Organization Prime Ministers’ Meeting were investigated. During the whole meeting, nine PM_2.5 samples were collected at a suburban site of Xinxiang, and the average concentration of PM_2.5 was 122.28 μg m^?3. NO₃ ^?, NH₄ ⁺, SO₄ ^2? accounted for 56.8% of the total water-soluble ions. In addition, with an exception of Cl^?, all of water-soluble ions decreased during the meeting. Total concentrations of crustal elements ranged from 6.53 to 185.86 μg m^?3, with an average concentration of 52.51 μg m^?3, which accounted for 82.5% of total elements. The concentrations of organic carbon and elemental carbon were 7.71 and 1.52 μg m^?3, respectively, lower than those before and after the meeting. It is indicated that during the meeting, limiting motor vehicles is to reduce exhaust emissions, delay heating is to reduce the fossil fuel combustion, and other measures are to reduce the concentration of PM_2.5. The directly dispersing by mixing layerheight increase and the indirectly reducing the formation of secondary aerosol by low relative humidity, andthese are the only two key removing mechanisms of PM_2.5 in Xinxiang during the meeting.     

Source apportionment of ambient PM10 in urban areas of Wuxi, China

A total of 168 PM₁₀ samples were collected during the year of 2005 at eight sites in the city of Wuxi in China. Fifteen chemical elements, three water-soluble ions, total carbon and organic carbon were analyzed. Six source categories were identified and their contributions to ambient PM₁₀ in Wuxi were estimated using a nested chemical mass balance method that reduces the effects of colinearity on the chemical mass balance model. In addition, the concentrations of secondary aerosols, such as secondary organic carbon, sulfate and nitrate, were quantified. The spatially averaged PM₁₀ was high in the spring and winter (123 ??g·m^?3 and low in the summer-fall (90 ??g·m^?3). According to the result of source apportionment, resuspended dust was the largest contributor to ambient PM₁₀, accounting for more than 50% of the PM₁₀ mass. Coal combustion (14.6%) and vehicle exhaust (9.4%) were also significant source categories of ambient PM₁₀. Construction and cement dust, sulfates, secondary organic carbon, and nitrates made contributions ranging between 4.1% and 4.9%. Other source categories such as steel manufacturing dust and soil dust made low contributions to ambient PM₁₀.     

Kinetics of the oxidation of endocrine disruptor nonylphenol by ferrate(VI)

The kinetics of the oxidation of endocrine disruptor nonylphenol (NP) by potassium ferrate(VI) (K₂FeO₄) in water as a function of pH 8.0–10.9 at 25°C is presented. The observed second-order rate constants, k _obs, decrease with an increase in pH 269–32 M^?1 s^?1. The speciation of Fe(VI) (HFeO ₄ ^? and FeO ₄ ^2? ) and NP (NP–OH and NP–O^?) species was used to explain the pH dependence of the k _obs values. At a dose of 10 mg L^?1 (50 μM) K₂FeO₄, the half-life for the removal of NP by Fe(VI), under water treatment conditions, is less than 1 min.     

Ecotypic differentiation of Laminaria longicruris in relation to seawater nitrate concentration

The ultraplankton (cell diameters >3 μm), which compromises about 70% of the biomass of phytoplankton in subtropical surface waters near Oahu, Hawaii, was isolated for growth rate studies. The specific growth rate (μ) was estimated from the rate of increase of the chlorophyll biomass during incubations in the absence of grazers. This growth rate of the ultraplankton ranged from 0.037 to 0.071 h^?1 (=1.3 to 2.5 doublings d^?1) during a period when P:B ratios of 5 to 14.5 μg C μg^?1 chl a h^?1 prevailed. The co-occurrence of atypically high P:B ratios and nonlimiting ambient nutrient concentrations suggests that the calculated values are higher than those characteristic of such subtropical ecosystems in general. Rates of ammonium uptake and photosynthesis by the >3 μm fraction were also compared to those of larger fractions. Organisms in the >3 μm fraction assimilated NH ₄ ⁺ at a rate which was about 75% greater than that of the 3 to 20 μm size fraction. Comparison of μ and P:B data collected over a 2 mo period (November–December, 1980) shows that the correlation between these two rate indices is nonlinear. The predominance of small-celled phytoplankton in oligotrophic waters is explained, in part, by its higher μ, its higher nutrient assimilation rates, and the absence of its loss through sedimentation.     

Ammonium regeneration and carbon utilization by marine bacteria grown on mixed substrates

We examined the impact of exposing natural populations of marine bacteria (from seawater collected near Woods Hole, Massachusetts, USA) to multiple nitrogen and carbon sources in a series of batch growth experiments conducted from 1989 through 1990. The substrate C:N ratio (C:N_s) was varied from 1.5:1 to 10:1 either with equal amounts of NH ₄ ⁺ and different amino acids or an amino acid mixture, all supplemented with glucose to maintain the C:N_s ratio equal to that of the respective amino acid, or with combinations of glucose and NH ₄ ⁺ alone. A common feature of the experiments involving amino acids was the concurrent uptake of NH ₄ ⁺ and amino acids that persisted as long as a readily assimilable carbon source (glucose in our case) was taken up. There was no net regeneration of NH ₄ ⁺ , even though catabolism of amino acids occurred. Regeneration of NH ₄ ⁺ was evident only after glucose was completely utilized, which usually occurred at the end of exponential growth. The contribution of¹⁵NH ₄ ⁺ to total nitrogen uptake by the end of exponential growth varied from ~60 to 80% when individual amino acids were present and down to ~24% when the amino acid mixture was added. These estimates are conservative because we did not account for possible isotope dilution effects resulting from amino acid catabolism. When NH ₄ ⁺ and glucose were the sole nitrogen and carbon sources, there was a stoichiometric balance between glucose and NH ₄ ⁺ uptake over a wide range of C:N_s ratios, leading to a constant bacterial biomass C:N ratio (C:N_B) of ~4.5:1. As a result NH ₄ ⁺ usage varied from 50% when the C:N_s ratio was 3.6:1, to 100% when the C:N_s ratio was 10:1. Gross growth efficiency varied from ~60% when NH ₄ ⁺ plus glucose were added alone or with the amino acid mixture, to 47% when the individual amino acids were used in place of the mixture. It is thus evident that actively growing bacteria will act as sinks for nitrogen when a carbon source that can be assimilated easily is available to balance NH ₄ ⁺ uptake, even when amino acids are available and are being co-metabolized.     

Effect of nitrogen source on short-term light and dark CO2 uptake by a marine diatom

Based on a series of short-term incubations involving the marine diatom Chaetoceros simplex (Bbsm), precultured in NH ₄ ⁺ -, NO ₃ ^- -and urea-limited continuous cultures at several dilution rates, we found that both the short-term specific rate of ¹⁴CO₂ uptake and the amount of CO₂ fixed after 8- and 16-min incubations were unaffected by enrichment with NH ₄ ⁺ , urea, or NO ₃ ^- when NH ₄ ⁺ or urea were the preconditioning forms of N, but were slightly suppressed when the cells were first grown on NO ₃ ^- . Similar enrichments in the dark, however, led to significant CO₂ uptake under all conditions of NH ₄ ⁺ enrichment and to similarly enhanced CO₂ uptake, but only at high growth rates, when urea was the source of enrichment nitrogen. Our light results are contrary to some contemporary findings, but there does seem to be agreement that photosynthetic rates of rapidly growing phytoplankton will not be affected by exposure to pulses of nitrogen. Enhanced dark uptake, in contrast, appears to be characteristic of phytoplankton under all degrees of N limitation, and, as such, may be useful as an “all or nothing” index of the nitrogen status of natural waters. There is some indication that the index may be useful in determining both the form of and the degree of N limitation as well.     

Toxic effects of enrofloxacin on Scenedesmus obliquus

In this article, the toxic effects of Enrofloxacin (ENFX) on Scenedesmus obliquus were studied, through investigating the growth, photosynthetic pigments, and protein contents. The possible toxic mechanisms of ENFX were analyzed by determining the superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, proline content, and superoxide anion (O ₂ ^? ) generation rate. Results showed that the growth of algae was inhibited by ENFX and the 50% effective concentration (EC₅₀) values for 24, 48, 72, and 96 h of ENFX were 88.39, 63.86, 45.10, and 59.16 mg·L^?1, respectively. After treated with ENFX for 96 h, the contents of photosynthetic pigments decreased with the increase of ENFX concentration, the content of soluble protein and the activity of SOD increased and then decreased, and the generation rate of superoxide anion (O ₂ ^? ) increased continually. The contents of MDA and proline changed little in lower ENFX concentration groups, but increased rapidly when treated with higher concentration groups. These results suggested that ENFX affected the growth of S. obliquus, and the main toxicity mechanism was that algal cells generated the reactive oxygen species under ENFX stress, and then the reactive oxygen species (ROS) induced the oxidation damages of biologic macromolecules and changed the biomembrane permeability further.     

Suppression of inhibition of substrate photodegradation by scavengers of hydroxyl radicals: the solvent-cage effect of bromide on nitrate photolysis

In this paper we show that bromide scavenges the ^·OH radicals formed upon photolysis of nitrate, before they leave the solvent cage. Bromide can thus inhibit the in-cage recombination between ^·OH and ^·NO₂. The consequence is an increased generation of ^·NO₂ and nitrite and of Br₂ ^?· + ^·OH, compared to ^·OH alone in the absence of bromide. We show that this effect compensates for the lower reactivity of Br ₂ ^?· compared to ^·OH toward certain organic substrates, e.g. phenol and tryptophan. Our findings could lead to a deep revision of the present views of the role of bromide in saltwater photochemistry.     

Pollution characteristics of particulate matters emitted from outdoor barbecue cooking in urban Jinan in eastern China

To understand the pollution characteristics of particulate matter emitted from outdoor barbecue cooking in eastern China, measurements of the PM_2.5 mass concentration, the number concentration of particles with a diameter of 0.01 to 1.0 μm, and the particle size distribution from 0.3 to 25 μm were carried out at seven barbecue restaurants in urban Jinan. The average PM_2.5 mass concentration and sub-micron particle number concentrations at a distance of 1 m from the grills were 250 to 1083 μg/m³ and 0.90 × 10⁵ to 2.23 × 10⁵ cm^–3, respectively, which were much higher than those in the ambient air of the urban area. Compared to the ambient atmosphere, barbecue cooking emitted very high levels of particles with a larger increase in the concentrations of super-micron particles than that of sub-micron particles. The super-micron particle number concentrations at the barbecue restaurants were 10 to 100 times higher than those observed in the ambient urban atmosphere. The barbecue smoke had a significant effect on the particle concentrations in the surrounding region. Both mass and number concentrations of particles exhibited maximum values immediately near the barbecue grills and often reached a peak at a distance of 10 to 15 m. The removal efficiency of a range hood for the cooking particles was tested in an indoor kitchen. The range hood effectively cleaned the particulate matter pollution caused by cooking with a removal efficiency larger than 80%. Therefore, the use of a range hood is recommended for outdoor barbecue restaurants coupled with a smoke purifier to clean the emitted high concentrations of particles.

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Stabilitätsverhalten von ausgewählten anorganischen Spurenstoffen in Niederschlagsproben

The stability of H⁺, NH ₄ ⁺ , and PO ₄ ^3? ions in rainwater samples was in vestigated under different conditions cf storage and transport. Microbiological and physicochemical processes account for changes. Suppression of microbiological activities in deposition networks using conventional analyses may be achieved by adding AgCl-powder and by cooling to +4 °C.