Source-receptor relationships for wet SO42− and NO3− production

Precipitation chemistry data for the years 1982–1985 from 110 stations distributed across the continental U.S. and southern Ontario Province are used to describe the geographic distributions of SO₄²⁻ and NO₃⁻ in precipitation. Volume-weighted, wet SO₄²⁻ and NO₃⁻ concentrations, averaged over the 4 years of observation by season and annullly, show coherent patterns with maxima in the northeastern U.S. and southeastern Canada about ten times greater than the minima observed in the Intermountain and Pacific Northwest regions.Tests for empirical source-receptor relationships indicate that, in land areas with relatively low emissions of SO₂ and NO_x, the associations between wet SO₄²⁻ concentrations and SO₂ emissions and between wet NO₃⁻ concentrations and NO_x emissions within 560 km of each precipitation chemistry station are weak or nonexistent (r²⩽0.42). The remaining land areas show moderate to strong associations between SO₂ and SO₄²⁻ and NO_x and NO₃⁻ during the spring and summer, but only weak to nonexistent associations during the winter. The associations between emissions and concentrations, e.g. SO₂ and SO₄²⁻, are equally well represented by either a linear or a power law function. However, at the level of aggregation employed, the data do not substantiate a linear-proportional relationship between concentrations and anthropogenic emissions. Furthermore, emissions of SO₂ and NO_x are highly correlated, as are the emissions of RHC and NO_x.     

The relationship between upwind SO2 emissions and SO4– concentrations in precipitation at six sites in the eastern U.S.A.

A method for estimating the upwind SO₂ emissions associated with individual wet SO₄²⁻ deposition events has been developed. The relationship between these estimates and wet SO₄²⁻ concentrations was examined at six Utility Acid Precipitation Study Program Sites (UAPSP) for the 1979–1986 period. Using Spearman correlation coefficients and the Bonferroni experimentwise criterion for statistical significance it was found that upwind emissions and concentrations were significantly related (p < 0.05). However, correlation's were sensitive to site location, time upwind of the emissions and season, and ranged from −0.03 to 0.50. Correlations were weaker at sites located west of the high emission region in the midwestern U.S.A. and stronger at sites further away and to the east of this region. There was a decrease in the strength of the correlations from the warm season to the cold season. It was also found that differences in meteorology between events obscured the relationship between emissions and concentrations. The effects of variations in ambient temperature and precipitation amount on wet SO₄²⁻ concentrations were taken into account by calculating partial correlation coefficients. A higher percentage of the resulting correlations were found to be statistically significant and the differences between sites decreased. This suggested that meteorological variability had a confounding influence on the detection of a link between concentrations and emissions. This influence should be considered when studying source-receptor relationships.     

The impact of Swedish SO2 policy instruments on SO2 emissions 1990–2012

Sulphur dioxide (SO₂) emissions cause acidification and human health problems which are, despite present policy instruments, projected to remain even after 2030 in Europe. Additional instruments are needed to solve the problems, and impact analysis of already used policy instruments would contribute to the development of new effective instruments. We present a study on how much of the decoupling of SO₂ emissions from economic growth 1990–2012 that was due to SO₂ policy instruments in general and to what extent it is possible to estimate the impact of individual instruments. Focus is on Sweden, a country with problems reaching its SO₂-related environmental policy targets and with detailed data available.We applied decomposition analysis combined with an analysis of the chronological development of emission factors and mandated emission limits. Our use of official emission inventory data and publicly available data on the development of SO₂ policy instruments increase the usefulness of our results to policy makers.The results indicate that at least 26–27% (corresponding to ∼35–36 ktonne annually) of the decoupling 1990–2012 was due to SO₂ policy instruments. 4–5% (∼6–7 ktonne) of the decoupling was caused by one environmental permit decision and stricter sulphur emission limit for marine oils. Most of the total impact of SO₂ policy instruments could not be causally connected to an individual instrument, because many events and developments overlap in time.The implications of the results are that: a) SO₂ policy instruments should still be important to reduce SO₂ emissions in many countries; b) a lower boundary total emission impact of SO₂ policy instruments can be estimated, but with current knowledge and data the impacts of individual instruments are rarely possible to estimate. Research on how to increase the precision in total impact estimates of SO₂ policy instruments is needed to improve future impact analyses. More detailed emission inventory data would improve impact analysis of individual instruments.     

Predicted and observed concentrations of SO2, SPM and NOχ over Delhi

Three air pollutants, SO₂, SPM and NO_χ, which are identified as major pollutants in urban cities, have been considered for a comparative study between predicted and observed concentrations of these pollutants at different receptor points over Delhi. A receptor-oriented Gaussian plume model (IITLT) and Climatological Dispersion Model (CDM) have been used to estimate the long term concentration of non-reactive pollutants due to emissions from area and point sources. Modified stability parameters are used for low wind speed and calm intervals. Monthly mean concentrations of these pollutants for the period of November, December and January 1987–1988 have been computed and the results obtained from the two models are found to be close to the observed values for this period. An error analysis of 54 pairs of observed and predicted concentrations show that performances of both the models are highly satisfactory, giving an RMSE of 1.61 for IITLT Model and 1.50 for CDM.     

A long-term (1975–1988) study of atmospheric SO42−: Regional contributions and concentration trends

A long-term study of aerosol SO₄²⁻ concentrations ([SO₄²⁻]) has been conducted at Mayville in the western and Whiteface Mountain in the northeastern New York State. From 1975 to 1988, 2382 daily aerosol samples were collected at Whiteface Mountain using high-volume samplers. Similarly, 1863 samples were collected at Mayville for the 1981–1988 period. Both sites are downwind of large SO₂ sources in the Midwest. Whiteface Mountain is located approximately 600 km to the northeast of Mayville. The [SO₄²⁻] at Mayville were approximately twice that of Whiteface Mountain. The highest concentrations at both locations were observed in summer and the lowest during winter. Photochemical reactions appear to be the primary reason for this behavior. Air trajectories (Hefter model) were used to relate the observed [SO₄²⁻] with the upwind SO₂ source regions. In addition, a method based on V/Se ratios was used to resolve SO₄²⁻ contributions between Midwestern sources and those in the East Coast. Approximately, two-thirds or more of the total SO₄²⁻ at the two sites was derived from the Midwestern emissions. At Whiteface Mountain the [SO₄²⁻] for summer months from 1975 to 1988 suggest a decrease of approximately 3% per year between 1978 and 1988. A similar decrease was also observed in SO₂ emissions.     

Ca2+ and SO42− interactions with dissolved organic matter: Implications of groundwater quality for CKDu incidence in Sri Lanka

It has recently been proposed that recalcitrant dissolved organic carbon(DOC) in groundwater plays a potent etiological role in the peculiar distribution of chronic kidney disease of unknown etiology(CKDu).This study aims to elucidate the interactions of Ca~(2+)and SO_4~(2-)with a model organic fraction of humic acid(SHA) to determine the possible relationship of CKDu incidence with the DOC in drinking water.XPS and FT-IR methods respectively determined the surface functional groups and chemical composition of protonated dissolved organic carbon(HDOC) in a CKDu high-risk zone(HR) of Sri Lanka and in SHA.Higher surface C composition(87.9%) and lower O(11.4%) were observed for HDOC from the HR region than for SHA(C: 73.8%, O: 24.7%).Aromatic C with less Ocontaining functional groups was observed in HDOC.The IR band at 1170 cm~(-1) confirms the formation of organic sulfonate(C–SO_3~-) on SHA.A band at 1213 cm~(-1) due to organic sulfonate in HDOC from the CKDu HR region was also identified.The IR band at 866 cm~(-1) evidenced the formation of CaCO_3 on SHA above pH 7.4.XPS data confirmed the presence of sulfur oxidation states corresponding to SO_3~(2-)and SO_4~(2-)at 168.9 eV and 170.1 eV binding energies,respectively.The binding energies at 347 eV and 351 eV for Ca 2p_(3/2) and Ca 2p_(1/2) eV,respectively, confirmed the bidentate complexation of Ca~(2+)with COO-and sulfonate groups on SHA.The organic sulfonate formed is postulated as a uremic toxicant.     

Oxidation of Cr(Ⅲ) on birnessite surfaces: The effect of goethite and kaolinite

Oxidation of Cr(Ⅲ) by manganese oxides may pose a potential threat to environments due to the formation of toxic Cr(Ⅵ) species. At present, it was still unclear whether the extent of Cr(Ⅲ) oxidation and fate of Cr(Ⅵ) would be changed when manganese oxides co-exist with other minerals, the case commonly occurring in soils. This study investigated the influence of goethite and kaolinite on Cr(Ⅲ) oxidation by birnessite under acidic p H condition(p H 3.5)and background electrolyte of 0.01 mol/L Na Cl. Goethite was found not to affect Cr(Ⅲ)oxidation, which was interpreted as the result of overwhelming adsorption of cationic Cr(Ⅲ) onto the negatively-charged birnessite(point of zero charge(PZC) 3.0) rather than the positively-charged goethite(PZC = 8.8). However, more Cr(Ⅵ) would be retained by the surface with the increase in addition of goethite because of its strong ability on adsorption of Cr(Ⅵ) at low p H. Moreover, either Cr(Ⅲ) oxidation or distribution of the generated Cr(Ⅵ)between the solid and solution phases was not affected by kaolinite(PZC 3.0), indicating its low affinity for Cr species. Reactions occurring in the present mixed systems were suggested, which could be partly representative of those in the soils and further indicates that the mobility and risk of Cr(Ⅵ) would be decreased if goethite was present.     

The interplay between knowledge and governance: Insights from the governance of recreational boating in the Dutch Wadden Sea area, 1981–2014

Through shifts toward interactive and participatory forms of environmental governance, knowledge dynamics may come into play that differ from those of traditional forms of policy-making. This paper investigates how shifts of environmental governance and knowledge are related. In order to do so, it reconstructs the development of the governance of recreational boating in the Dutch Wadden Sea on the empirical basis of interviews, document analysis, and a focus group. Moreover, it analyzes this development by means of an analytical framework that combines governance modes, knowledge systems and knowledge–governance interfaces. Our results show that in the last decades partly an accumulation and partly a sequence of various governance arrangements concerning recreational boating has occurred; this has entailed a shift from predominantly centralized governance to a combination of governance modes with a stronger emphasis on decentralized, interactive and self-governance. This shift has occurred together with an increasing prominence of qualitative local knowledge, stakeholders’ knowledge, and the integration of various forms of knowledge. Furthermore, a shift has taken place toward more participatory knowledge–governance interfaces. Our analysis suggests that environmental governance and knowledge are interconnected in various ways: the regulatory and epistemic aspects of environmental issues are bound up with each other, and governance and knowledge are coproduced and mutually constitutive. Key lessons from this analysis are that room for experimentation is an important factor in improving environmental governance, and that increasing stakeholder involvement in governance implies that new modes of jointly creating and exchanging knowledge may need to be taken into account.     

The effect of interaction between Bacillus subtilis DBM and soil minerals on Cu(Ⅱ) and Pb(Ⅱ) adsorption

The effects of interaction between Bacillus subtilis DBM and soil minerals on Cu(Ⅱ)and Pb(Ⅱ)adsorption were investigated.After combination with DBM,the Cu(Ⅱ)and Pb(Ⅱ)adsorption capacities of kaolinite and goethite improved compared with the application of the minerals independently.The modeling results of potentiometric titration data proved that the site concentrations of kaolinite and goethite increased by 80%and 30%,respectively after combination with DBM.However,the involvement of functional groups in the DBM/mineral combinations resulted in lower concentrations of observed sites than the theoretical values and led to the enhancement of desorption rates by NH_4NO_3 and EDTA-Na_2.The DBM-mineral complexes might also help to prevent heavy metals from entering DBM cells to improve the survivability of DBM in heavy metal-contaminated environments.During the combination process,the extracellular proteins of DBM provided more binding sites for the minerals to absorb Cu(Ⅱ)and Pb(Ⅱ).In particular,an especially stable complexation site was formed between goethite and phosphodiester bonds from EPS to enhance the Pb(Ⅱ)adsorption capacity.So,we can conclude that the DBM–mineral complexes could improve the Cu(Ⅱ)and Pb(Ⅱ)adsorption capacities of minerals and protect DBM in heavy metal-contaminated environments.     

The evaluation of some photochemical smog reaction mechanisms—III. Dilution and emissions effects

The effects of dilution and emissions on the performance of four widely-used photochemical smog reaction mechanisms are examined, using newly available experimental data from the CSIRO outdoor smog chambers. It is found that the Caltech, CB-XR and CB-IV mechanisms overpredicted the smog produced (SP) maximum associated with the dilution by 14–29% when the dilution rate was 22% h⁻¹ and by 53–73% when the rate was 55% h⁻¹. The CB-III mechanism underpredicted the maximum by 17% at the lower dilution rate (when the cumulative light flux was moderate), but agreed with the observations at the higher dilution rate (when the cumulative light flux was high). Five emissions experiments were conducted at moderate to very high HC/NO_x ratios (8.3–51.0). When HC were injected during the light-limited regime the rate of formation of SP increased markedly; when NO was injected in this regime there was less effect (a slight decrease in slope). When HC were injected during the NO_x-limited regime there was a gradual decline in SP concentration, but when NO was injected during the NO_x-limited regime there was a dramatic increase in SP, leading to a second light-limited regime and a second NO_x-limited regime. When both HC and NO_x were injected during the light-limited regime, marked increases in slope occured after each injection. The Caltech model gave good to excellent agreement with the data. In one experiment it overestimated the final SP by 8%. The CB-III model performed next best, sometimes in excellent agreement with the data, but at other times underpredicting the final SP by 14–18%. The CB-XR and CB-IV models underpredicted the final SP for most of the experiments by up to 38%.     

Contribution of industrial and developing countries to the atmospheric CO2 concentrations: — impact of the Kyoto protocol

The UN Framework Convention on Climate Change and the Kyoto protocol made under the Convention, aim at controlling the greenhouse gas emissions and their concentrations in the atmosphere. The contributions of fossil fuel use in industrial and developing countries to the atmospheric CO₂ concentration are calculated using estimates for emission developments and a simple carbon cycle model. The contribution of the industrial countries to the CO₂ concentration increase, above the preindustrial level, is estimated to be about 50 ppm in 1990 if only the emissions from fossil fuels are considered. The contribution from developing countries is about 15 ppm. The contribution from industrial countries would increase by about 20 ppm between 1990 and 2010 if no emission reductions were assumed and by about 15 ppm in the considered rather strict reduction scenario. According to the Kyoto protocol the emissions from industrial countries should be reduced by 5.2% from the 1990 level in about 20 years. This development of the emissions would cause a concentration increase of 18 ppm. The concentration increase due to developing countries between 1990 and 2010 would be about 15 ppm. In order that the present global increase rate of CO₂ concentration 1.5 ppm/a would not be exceeded, steeper reductions than those made in Kyoto should be agreed. Increasing global emissions and slow removal of CO₂ from the atmosphere makes it difficult to reach the ultimate objective of the Climate Convention, the stabilisation of the atmospheric concentration.     

The future of global warming: will it be emissions control or environmental damages?

This paper explores the role of risk perceptions in influencing public policy related to global warming. It solves for the optimal paths for emissions, abatement and investment in pollution-eliminating research by incorporating perceived risks into public decision making. It also compares the impact of differential risk perceptions on international collaboration on carbon abatement. Key findings are that the perception of risks related to environmental damages and technological breakthroughs plays an important role in determining the level of mitigation efforts. A high level of perceived risk of environmental damages discourages investment in pollution-eliminating research as there are few benefits from eliminating pollution after damages are realized. Other options that allow for sequestering carbon from the atmosphere may still remain viable. Another key finding is that when it comes to effort sharing between nations, differential mitigation efforts are primarily caused due to the differences in abatement technology, benefits from emissions and research capabilities. However, such differences could be accentuated or mitigated depending upon the differences in risk perception of developed and developing countries.     

The effect of freezing on the composition of supercooled droplets—I. Retention of HCl,HNO3, NH3 and H2O2

Experiments were done to check on the possibility that cloud droplets might, during freezing, lose acidity by evolution of HCl or HNO₃, lose NH₃ or lose dissolved H₂O₂. A spray of droplets with average diameter 39μm was produced by an ultrasonic transducer. The droplets acquired a temperature between −8 and −12°C and fell onto an ice surface, where they froze. Appropriate analytical techniques were applied to compare the composition of the frozen droplets with that of the sprayed liquid. It was found that the four chemical species studied were totally retained in the ice after freezing.     

A monitoring-modeling approach to SO42 − and NO3− secondary conversion ratio estimation during haze periods in Beijing, China

SO_4~(2-) and NO_3~- are important chemical components of fine particulate matter(PM_(2.5)),especially during haze periods.This study selected two haze episodes in Beijing,China with similar meteorological conditions.A monitoring-modeling approach was developed to estimate the secondary conversion ratios of sulfur and nitrogen based on monitored and simulated concentrations.Measurements showed that in Episode 1(24th–25th October,2014),the concentrations(proportions)of SO_4~(2-) and NO_3~- reached 35.1μg/m~3(14.9%) and 55.0μg/m~3(22.9%),while they reached 14.4μg/m~3(9.3%) and 59.1μg/m~3(38.1%)in Episode 2(26th–27th October,2017).A modeling system was applied to apportion Beijing's SO_4~(2-) and NO_3~- in primary and secondary SO_4~(2-)/NO_3~- emitted from local and regional sources.Thus,secondary conversion contributions considering the local and regional level were defined.The former primarily focused on Beijing atmospheric oxidation ability and the latter mainly considered the existence form of Beijing SO_4~(2-)/NO_3~- under the regional transport impacts.Finally,secondary oxidation ratios were estimated through combining secondary conversion contribution coefficients for simulated and monitored concentrations.At regional level,sulfur oxidation ratios in polluted(clean)days during two sampling periods were0.57–0.72(0.07–0.52)and 0.74–0.80(0.08–0.61),nitrogen oxidation ratios were 0.20–0.29(0.05–0.15)and 0.34–0.38(0.02–0.29),indicating that atmospheric oxidation was enhanced when considering regional transport through 2014–2017.At the local level,sulfur oxidation ratios were 0.66–0.71(0.04–0.48)in haze(clean)days,while nitrogen oxidation ratios were0.16–0.29(0.02–0.16).The atmospheric oxidation ability markedly increased in PM_(2.5)pollution days,but changed only slightly between the two periods.     

Treated wastewater irrigation effect on soil, crop and environment： Wastewater recycling in the loess area of China

A study was carried out at the Loess Plateau in Dongzhi,China,to test the feasibility of using secondary treatment sewage effluent and to determine whether the water quality would then meet the recommended irrigation norm.Seven crops,including celery,wheat, maize,millet,apples,rapeseed and yellow beans,were tested in the study.Physical and chemical properties of the soil,crop yield and quality and leachate at different soil depths were measured.In most cases,the quality of the crops that made use of treated sewage was not distinctively different from those that did not use treated sewage.However,yields for the former were much higher than they were for the latter.Leachates at different soil depths were analyzed and the results did not show alarming levels of constituents.For a period of approximately 14 months,the treated sewage irrigation had no significant effect on the loess soil and no cases of illness resulting from contact with the treated sewage were reported.With treated sewage irrigation,a slight increase in the organic content of the soil was observed.     

Evaluation on abundance or deficiency of avai- lable trace elements in soil of middle area in China and the effect of applying trace element fertilizer

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Reaction of monoterpenes with ozone,sulphur dioxide and nitrogen dioxide—gas-phase oxidation of SO2 and formation of sulphuric acid

Teflon bag experiments were carried out in the dark in order to study the gas-phase reactions of selected monoterpenes with O₃ in the presence of SO₂ (β-pinene) as well as in the presence of SO₂/NO₂ (α-pinene, β-pinene, limonene). Emphasis was given in identifying the main reaction products and in quantifying the H₂SO₄ aerosol formed. Apart from the H₂SO₄ aerosol no other S containing compounds could be detected.It was found that the reaction of β-pinene with O₃, SO₂ and NO₂ leads mainly to 6,6-dimethyl-bicyclo [3.1.1] heptan-2-one (nopinone), the α-pinene-O₃-SO₂-NO₂-reaction produced 2′,2′-dimethyl-3-acetyl cyclobutyl ethanal (pinonaldehyde). The reaction of limonene with O₃-SO₂-NO₂ leads mainly to an unidentified product with a molecular weight M⁺ 134. In addition to the above-mentioned volatile products, the formation of organic nitrates could be established by means of gas chromatography-mass spectrometry.The yield of H₂SO₄ in the system β-pinene/O₃/SO₂ varies between 0.13 and 0.44 depending on the initial conditions, e.g. humidity. In the system terpene/O₃/SO₂/NO₂ the yield of H₂SO₄ for α-pinene (after 1 h reaction time) was 0.01–0.03, for β-pinene (2 or 4 h reaction time) 0.07–0.13 and for limonene (1 h reaction time) 0.02–0.09.     

The effect of coupling coagulation and flocculation with membrane filtration in water treatment： A review

Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane Bio-Reactor (MBR) technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology (BAT) for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.