Characterization of carbonic anhydrase II from Chlorella vulgaris in bio-CO2 capture

Carbonic anhydrase II (CA II) can catalyze the reversible hydration reaction of CO₂ at a maximum of 1.4?×?10⁶ molecules of CO₂ per second. The crude intracellular enzyme extract containing CA II was derived from Chlorella vulgaris. A successful CO₂ capture experiment with the presence of calcium had been conducted on the premise that the temperature was conditioned at a scope of 30?C40?°C, that the biocatalyst-nurtured algal growth period lasted 3?days, and that pH ranged from7.5 to 8.5. Ions of K⁺, Na⁺, Ca²⁺, Co²⁺, Cu²⁺, Fe³⁺, Mg²⁺, Mn²⁺, and Zn²⁺ at 0.01, 0.1, and 0.5?M were found to exhibit no more than 30?% inhibition on the residual activity of the biocatalyst. It is reasonable to expect that calcification catalyzed by microalgae presents an alternative to geological carbon capture and sequestration through a chain of fundamental researches carried on under the guidance of sequestration technology.     

纯二氧化碳条件下小球藻固定CO2

微藻固碳已经成为消减温室气体排放的新的研究热点。利用静态吸收方法,考查了通人纯CO2对普通小球藻生长特点、固定CO2效率以及藻液pH值变异的影响。结果表明：通入纯CO2使小球藻生长延滞期显著延长,比普通培养延长10～12d,对其他生长阶段的影响不大;小球藻固定CO2速率可分为2个过程,即物理固碳过程和生物固碳过程,前者在藻细胞延滞期发生,峰值由CO。溶解于培养液造成,后者在藻细胞生长的指数期、稳定期和衰退期发生,峰值由藻细胞指数生长造成,2个过程中,固定CO2速率的变化趋势都是先增大后降低;纯CO2条件下,藻液pH值变化速率高,4d内,藻液即被酸化,随后藻液pH值变化速率逐渐降低,且pH值稳定在适宜水平。因此,采用小球藻固定高浓度CO2时,建议提高接种量并加强培养前期的pH值监测和调控,以保证藻液保持适宜的pH值,并缩短培养时间,提高生物固碳效率。     

Biogeochemical Control of the Coupled CO2–O2 System of the Baltic Sea: A Review of the Results of Baltic-C

Past, present, and possible future changes in the Baltic Sea acid–base and oxygen balances were studied using different numerical experiments and a catchment–sea model system in several scenarios including business as usual, medium scenario, and the Baltic Sea Action Plan. New CO₂ partial pressure data provided guidance for improving the marine biogeochemical model. Continuous CO₂ and nutrient measurements with high temporal resolution helped disentangle the biogeochemical processes. These data and modeling indicate that traditional understandings of the nutrient availability–organic matter production relationship do not necessarily apply to the Baltic Sea. Modeling indicates that increased nutrient loads will not inhibit future Baltic Sea acidification; instead, increased mineralization and biological production will amplify the seasonal surface pH cycle. The direction and magnitude of future pH changes are mainly controlled by atmospheric CO₂ concentration. Apart from decreasing pH, we project a decreasing calcium carbonate saturation state and increasing hypoxic area.     

Development and Demonstration of an Explicit Lumped-Parameter Biofilter Model and Design Equation Incorporating Monod Kinetics

Abstract

Biofiltration is an economical air pollution control (APC) technology, particularly suitable for the treatment of air-streams having high flow rates and low concentrations of volatile organic compounds (VOCs). This technology utilizes enzymatic catalysis at ambient conditions to mineralize such pollutants to CO₂, H₂O, and salts. A pilot-scale study conducted for more than 4 years investigated the development of a new biofiltration technology employing trickle bed air biofilters (TBABs). Following the completion of this experimental study, additional data analysis was performed to develop a simple lumped-parameter biofilter model, assuming first-order kinetics. This model related the observed biofilter performance to the principle independent physical, thermodynamic, and biochemical parameters. The initial model has subsequently been expanded to incorporate Monod kinetics. In this paper, the development and use of the final explicit lumped-parameter biofilter model and design equation, incorporating Monod kinetics, are presented. To facilitate the application of this model, practical procedures are also presented for the determination of VOC solubility, VOC biokinetic Monod parameters, and the maximum practical biofilter inlet VOC concentration.     

The influence of engineered Fe2O3 nanoparticles and soluble (FeCl3) iron on the developmental toxicity caused by CO2-induced seawater acidification

An embryo development assay using a common test organism, the edible mussel (Mytilus galloprovincialis), exposed to both Fe₂O₃ nanoparticles and soluble FeCl₃ at 3 acidic pHs, has provided evidence for the following: (1) CO₂ enriched seawater adjusted to pH projections for carbon capture leakage scenarios (CCS) significantly impaired embryo development; (2) under natural pH conditions, no significant effect was detected following exposure of embryos to Fe, no matter if in nano- or soluble form; (3) at pH of natural seawater nano-Fe particles aggregate into large, polydisperse and porous particles, with no biological impact detected; (4) at pH 6 and 7, such aggregates may moderate the damage associated with CO₂ enrichment as indicated by an increased prevalence of normal D-shell larvae when nano-Fe was present in the seawater at pH 7, while soluble iron benefited embryo development at pH 6, and (5) the observed effects of iron on pH-induced development toxicity were concentration dependent.     

不同Ca/P比下碳酸根对磷酸钙沉淀反应回收磷的影响

以模拟污水处理厂污泥厌氧消化液为处理对象,进行磷酸钙沉淀除磷小试实验,考察了不同Ca/P物质的量比下碳酸根(CO2-3)对磷酸钙沉淀反应回收磷的影响;利用扫描电镜(SEM)、X射线衍射仪(XRD)和傅里叶变换红外光谱(FTIR)对沉淀产物进行表征。结果表明,磷酸钙沉淀反应是一个快速过程,CO2-3的存在并未改变这一显著特征。磷酸钙沉淀反应过程中,CO2-3的存在降低了磷的去除率,改变了沉淀物形貌、结构和组分;实验设定范围内,磷酸钙的过饱和度越高,越难形成晶体态羟基磷灰石((Ca5(PO4)3OH,HAP);当pH值为9.0,Ca/P比为1.67时,CO2-3取代HAP晶格中的PO3-4,形成碳磷灰石(CHAP);当pH值为9.0,Ca/P比为3.33和5.01时,CO2-3和PO3-4之间竞争,形成碳酸钙(CaCO3);增大Ca/P能有效提高磷的去除率,降低CO2-3对磷酸钙沉淀反应的抑制作用,但综合考虑实际效果,选择Ca/P比为3.33作为适宜的反应条件。     

Carbon dioxide fluxes over an urban park area

From September 2006 to October 2007 turbulent fluxes of carbon dioxide were measured at an urban tower station (26 m above ground level, z/z_h = 1.73) in Essen, Germany, using the eddy covariance technique. The site was located at the border between a public park area (70 ha) in the south–west of the station and suburban/urban residential as well as light commercial areas in the north and east of the tower. Depending on the land-use two different sectors (park and urban) were identified showing distinct differences in the temporal evolution of the surface-atmosphere exchange of CO₂. While urban fluxes appear to be governed by anthropogenic emissions from domestic heating and traffic (average flux 9.3 μmol m^?2 s^?1), the exchange of CO₂ was steered by biological processes when the park contributed to the flux footprint. The diurnal course during the vegetation period exhibited negative daytime fluxes up to ?10 μmol m^?2 s^?1 on average in summer. Nevertheless, with a mean of 0.8 μmol m^?2 s^?1 park sector fluxes were slightly positive, thus no net carbon uptake by the surface occurred throughout the year.In order to sum the transport of CO₂ a gap-filling procedure was performed by means of artificial neural network generalisation. Using additional meteorological inputs the daily exchange of CO₂ was reproduced using radial basis function networks (RBF). The resulting yearly sum of 6031 g m^?2 a^?1 indicates the entire study site to be a considerable source of CO₂.     

Sorption characteristics of cyromazine and its metabolite melamine in typical agricultural soils of China

A myriad of physical, chemical, and biological processes controls the fate of organic contaminants in soils. The knowledge of bioavailability of a contaminant in soil can be useful to conduct environmental risk assessment. We conducted batch equilibrium experiments to investigate the sorption of cyromazine (CA) and its metabolite melamine (MA) onto five typical soils of China belonging to suborders Ali-Perudic Ferrosols, Udic Argosols, Gleyic-Stagnic Anthrosols, Ustic Cambosols, and Udic Isohumosols. Results showed that sorption of CA and MA onto soils was linear, as indicated by the Freundlich and Langmuir models. Different sorption behaviors of CA and MA were observed on the five agricultural soils, with lgK _f values (Freundlich model) of 1.6505–2.6557 and 1.632–2.549, respectively. Moreover, the K _f values for CA and MA were positively correlated with soil organic matter (r?=?0.989, r?=?0.976) and significantly negatively correlated with pH (r?=??0.938, r?=??0.964). The free energy of sorption of CA and MA ranged from ?20.8 to ?23.0 kJ mol^?1 and ?20.8 to ?22.8 kJ mol^?1, respectively, suggesting that the sorption of CA and MA onto the soils is primarily a physical process.     

UTILIZATION OF AGRICULTURAL WASTE CORN COB FOR THE PREPARATION OF CARBON ADSORBENT

In the present study, a series of activated carbons were prepared from agricultural waste corn cob by chemical and physical activations with potassium hydroxide (KOH)/potassium carbonate (K₂CO₃) and carbon dioxide (CO₂). The effect of process variables such as impregnation ratio, impregnation time, activation temperature and soaking time of CO₂ was studied in order to relate these preparation parameters with the physical properties of final carbon products. The resulting activated carbons were characterized by nitrogen adsorption[ch-[chdesorption isotherms at 77 K. The surface areas and pore volumes of carbons were estimated by the BET equation, the Langmuir equation and the t-plot method. Under the experimental conditions investigated, the main parameters in the activation of corn cob were found to be the impregnation ratio and activation temperature. The soaking time of CO₂ is another important variable, which had a strong effect on the pore volume development. The BET surface area and total pore volume were as large as about 2000 m²/g and about 1.0 cm³/g, respectively. This study showed that the activation of agricultural waste corn cob with KOH/K₂CO₃ and CO₂ was suitable for the preparation of large-surface-area activated carbons.     

Diurnal changes in photosynthetic parameters of Populus tremuloides, modulated by elevated concentrations of CO2 and/or O3 and daily climatic variation

The diurnal changes in light-saturated photosynthesis (Pn) under elevated CO₂ and/or O₃ in relation to stomatal conductance (g_s), water potential, intercellular [CO₂], leaf temperature and vapour-pressure difference between leaf and air (VPD_L) were studied at the Aspen FACE site. Two aspen (Populus tremuloides Michx.) clones differing in their sensitivity to ozone were measured. The depression in Pn was found after 10:00 h. The midday decline in Pn corresponded with both decreased g_s and decreased Rubisco carboxylation efficiency, Vc_max. As a result of increasing VPD_L, g_s decreased. Elevated [CO₂] resulted in more pronounced midday decline in Pn compared to ambient concentrations. Moreover, this decline was more pronounced under combined treatment compared to elevated CO₂ treatment.The positive impact of CO₂ on Pn was relatively more pronounced in days with environmental stress but relatively less pronounced during midday depression. The negative impact of ozone tended to decrease in both cases.     

The growth response of Alternanthera philoxeroides in a simulated post-combustion emission with ultrahigh [CO2] and acidic pollutants

Although post-combustion emissions from power plants are a major source of air pollution, they contain excess CO₂ that could be used to fertilize commercial greenhouses and stimulate plant growth. We addressed the combined effects of ultrahigh [CO₂] and acidic pollutants in flue gas on the growth of Alternanthera philoxeroides. When acidic pollutants were excluded, the biomass yield of A. philoxeroides saturated near 2000 μmol mol⁻¹ [CO₂] with doubled biomass accumulation relative to the ambient control. The growth enhancement was maintained at 5000 μmol mol⁻¹ [CO₂], but declined when [CO₂] rose above 1%, in association with a strong photosynthetic inhibition. Although acidic components (SO₂ and NO₂) significantly offset the CO₂ enhancement, the aboveground yield increased considerably when the concentration of pollutants was moderate (200 times dilution). Our results indicate that using excess CO₂ from the power plant emissions to optimize growth in commercial green house could be viable.     

Influence of transport and trends in atmospheric CO2 at Lampedusa

The study of the CO₂ 15-year records at Lampedusa (35° 31′N, 12° 37′E) is presented in this work. Short- and long-term CO₂ variability has been investigated. No significant diurnal variations are observable thus remarking the background character and representativeness of the observation site. The CO₂ long-term trend shows a mean linear growth rate (GR) of 1.9 ppm yr^?1. The periodic behaviour of the time series has been analysed and the mean seasonal cycle amplitude has been found to be 8.72 ppm. The seasonal cycle amplitude shows a marked interannual variability. The lowest value of the seasonal cycle amplitude has been detected in 2003, in concomitance with the strong anomalous heat wave recorded in Europe. CO₂ GR behaviour has been related to global processes such as El Niño Southern Oscillation (ENSO) and global temperature (T_g). The influence of ENSO event on GR is remarkable only during 1998. CO₂ GR curve shows peaks in the periods 1995, 2001 and 2005 (1.9, 3.7, 3.2 ppm yr^?1 respectively) that are characterized by high T_g values and by intense biomass burning events. The anomalous decrease in the GR during the warm 2003 has been attributed to changes in the atmospheric circulation regime. Evaluation of the influence of transport on CO₂ variability has been carried out using backward air-mass trajectory analysis and highlights the effect of the regional distribution of sources and sinks. The industrial activities and forests located in the Eastern European and Russian sector strongly affect the CO₂ mixing ratio. The CO₂ content of air-masses originating from this region is influenced in summertime by the high efficiency of the vegetation sink while in the winter period prevails the effect of industrial emissions.     

Effects of high atmospheric CO2 concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source

We examined root hydraulic conductivity (L_p) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO₂ and inorganic nitrogen (N) sources. We found marked interspecific differences in L_p responses to high CO₂ ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO₂ effects on root water transport may be coupled to leaf area responses under nitrate (NO₃⁻), but not ammonium (NH₄⁺) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO₂ levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO₂, N deposition, and ecohydrology.     

A new perspective to environmental degradation: the linkages between higher education and CO2 emissions

Although there have been many studies, focusing on basic determinants of carbon dioxide emissions (CO₂), the effect of higher education, which has the potential to be an important determinant of CO₂, has been neglected. The paper aims to display the potential mechanisms between higher education and CO₂ and expand the environmental economics literature. In the paper, the trade-off between higher education and CO₂ is tested by autoregressive distributed lag (ARDL) during the period 1983–2017 in Turkey. Results denote that cointegration exists and an increase in higher education negatively affects CO₂. We also find that economic growth and energy consumption positively affect CO₂ both in the long run and short run. Vector error correction model (VECM) reveals that higher education, economic growth, energy consumption, trade openness, and exchange rates are the causes of CO₂ in the long run. Also, energy consumption and economic growth are the causes of CO₂ in the short run. Therefore, higher education can be used to overcome environmental problems.

     

Investigation of uranium binding forms in selected German mineral waters

Cryogenic time-resolved laser-induced fluorescence spectroscopy was successfully used to identify uranium binding forms in selected German mineral waters of extremely low uranium concentrations (<2.0 μg/L). The measurements were performed at a low temperature of 153 K. The spectroscopic data showed a prevalence of aquatic species Ca₂UO₂(CO₃)₃ in all investigated waters, while other uranyl–carbonate complexes, viz, UO₂CO_3(aq) and UO₂(CO₃)₂ ^2?, only existed as minor species. The pH value, alkalinity (CO₃ ^2?), and the main water inorganic constituents, specifically the Ca²⁺ concentration, showed a clear influence on uranium speciation. Speciation modeling was performed using the most recent thermodynamic data for aqueous complexes of uranium. The modeling results for the main uranium binding form in the investigated waters indicated a good agreement with the spectroscopy measurements.     

填料塔中Na_2CO_3吸收高浓度H_2S的传质特性

在填料吸收塔中考察了Na2CO3溶液吸收高浓度H2S气体的气液传质特性。通过测量填料塔进出口气体中H2S浓度计算了Na2CO3溶液吸收高浓度H2S气体的总体积传质系数(KGa),并研究了进气流速、吸收液流量、吸收温度和吸收液浓度对KGa的影响。结果表明,KGa随Na2CO3浓度、吸收液流量的增加而增加,随吸收温度、进气流速的升高而降低;在高浓度H2S吸收过程中液相传质阻力不能忽略。     

Silica-Enhanced Sorbents for Dry Injection Removal of SO2 from Flue Gas

Novel silica-enhanced lime sorbents were tested in a bench-scale sand-bed reactor for their potential for SO₂ removal from flue gas. Reactor conditions were 64°C (147°F), relative humidity of 60 percent [corresponding to an approach to saturation temperature of 10°C (18°F)], and inlet SO₂ concentration of 500 or 1000 ppm. The sorbents were prepared by pressure hydration of CaO or Ca(OH)₂ with siliceous materials at 100°C (101 kPa) [212°F (14.7 psi)] to 230°C (2793 kPa) [446°F (405 psi)] for 15 min to 4 h. Pressure hydration fostered the formation of a sorbent reactive with SO₂ from fly ash and Ca(OH)₂ in a much shorter time than did atmospheric hydration. The conversion of Ca(OH)₂ in the sand-bed reactor increased with the increasing weight ratio of fly ash to lime and correlated well with B.E.T. surface area, increasing with increasing surface area. The optimum temperature range for the pressure-hydration of fly ash with Ca(OH)₂ was between 110 and 160°C (230 and 320 °F). The pressure hydration of diatomaceous earth with CaO did not offer significant reactivity advantages over atmospheric hydration; however, the rate of enhancement of Ca(OH)₂ conversions was much faster with pressure hydration. Scanning electron microscope (SEM) and x-ray diffraction studies showed solids of different morphology with different fly ash/lime ratios and changing conditions of pressure hydration.     

Stomatal uptake of O3 in aspen and aspen-birch forests under free-air CO2 and O3 enrichment

Rising atmospheric carbon dioxide (CO₂) may alleviate the toxicological impacts of concurrently rising tropospheric ozone (O₃) during the present century if higher CO₂ is accompanied by lower stomatal conductance (g_s), as assumed by many models. We investigated how elevated concentrations of CO₂ and O₃, alone and in combination, affected the accumulated stomatal flux of O₃ (AFst) by canopies and sun leaves in closed aspen and aspen-birch forests in the free-air CO₂-O₃ enrichment experiment near Rhinelander, Wisconsin. Stomatal conductance for O₃ was derived from sap flux data and AFst was estimated either neglecting or accounting for the potential influence of non-stomatal leaf surface O₃ deposition. Leaf-level AFst (AFst_l) was not reduced by elevated CO₂. Instead, there was a significant CO₂ × O₃ interaction on AFst_l, as a consequence of lower values of g_s in control plots and the combination treatment than in the two single-gas treatments. In addition, aspen leaves had higher AFst_l than birch leaves, and estimates of AFst_l were not very sensitive to non-stomatal leaf surface O₃ deposition. Our results suggest that model projections of large CO₂-induced reductions in g_s alleviating the adverse effect of rising tropospheric O₃ may not be reasonable for northern hardwood forests.     

An intensive two-week study of an urban CO2 dome in Phoenix,Arizona, USA

Atmospheric CO₂ concentrations were measured prior to dawn and in the middle of the afternoon at a height of 2 m above the ground along four transects through the metropolitan area of Phoenix, Arizona on 14 consecutive days in January 2000. The data revealed the existence of a strong but variable urban CO₂ dome, which at one time exhibited a peak CO₂ concentration at the center of the city that was 75% greater than that of the surrounding rural area. Mean city-center peak enhancements, however, were considerably lower, averaging 43% on weekdays and 38% on weekends; and averaged over the entire commercial sector of the city, they were lower still, registering 30% on weekdays and 23% on weekends. Over the surrounding residential areas, on the other hand, there are no weekday–weekend differences in boundary-layer CO₂ concentration. Furthermore, because of enhanced vertical mixing during the day, near-surface CO₂ concentrations in the afternoon are typically reduced from what they are prior to sunrise. This situation is additionally perturbed by the prevailing southwest-to-northeast flow of air at that time of day, which lowers afternoon CO₂ concentrations on the southern and western edges of the city still more, as a consequence of the importation of pristine rural air. The southwest-to-northeast flow of air also sometimes totally compensates for the afternoon vertical-mixing-induced loss of CO₂ from areas on the northern and eastern sides of the city, as a consequence of the northeastward advection of CO₂ emanating from the central, southern and western sectors of the city. Hence, although complex, the nature of the urban CO₂ dome of Phoenix, Arizona, is readily understandable in terms of basic meteorological phenomena and their interaction with human activities occurring at the land/air interface.     

Short-term effect of increasing nitrogen deposition on CO2, CH4 and N2O fluxes in an alpine meadow on the Qinghai-Tibetan Plateau,China

An increasing nitrogen deposition experiment (2 g N m^?2 year^?1) was initiated in an alpine meadow on the Qinghai-Tibetan Plateau in May 2007. The greenhouse gases (GHGs), including CO₂, CH₄ and N₂O, was observed in the growing season (from May to September) of 2008 using static chamber and gas chromatography techniques. The CO₂ emission and CH₄ uptake rate showed a seasonal fluctuation, reaching the maximum in the middle of July. We found soil temperature and water-filled pore space (WFPS) were the dominant factors that controlled seasonal variation of CO₂ and CH₄ respectively and lacks of correlation between N₂O fluxes and environmental variables. The temperature sensitivity (Q₁₀) of CO₂ emission and CH₄ uptake were relatively higher (3.79 for CO₂, 3.29 for CH₄) than that of warmer region ecosystems, indicating the increase of temperature in the future will exert great impacts on CO₂ emission and CH₄ uptake in the alpine meadow. In the entire growing season, nitrogen deposition tended to increase N₂O emission, to reduce CH₄ uptake and to decrease CO₂ emission, and the differences caused by nitrogen deposition were all not significant (p < 0.05). However, we still found significant difference (p < 0.05) between the control and nitrogen deposition treatment at some observation dates for CH₄ rather than for CO₂ and N₂O, implying CH₄ is most susceptible in response to increased nitrogen availability among the three greenhouse gases. In addition, we found short-term nitrogen deposition treatment had very limited impacts on net global warming potential (GWP) of the three GHGs together in term of CO₂-equivalents. Overall, the research suggests that longer study periods are needed to verify the cumulative effects of increasing nitrogen deposition on GHG fluxes in the alpine meadow.