Assessing causes of recent organic carbon losses from cropland soils by means of regional-scaled input balances for the case of Flanders (Belgium)

Several recent reports on cropland soil organic carbon (SOC) stock changes throughout Europe indicate a general continuing loss of SOC from these soils. As most arable soils in Europe are not in an equilibrium situation because of past changes in land-use and management practices, shifts in both have been suggested to drive this decline of SOC stocks. A lack of data has prevented the unambiguous verification of the contribution of these factors to SOC loss. First, this study focused on recent evolutions in management options for SOC sequestration in Flanders and showed that despite such practices have increased since 1990, their current contribution is still limited. Strikingly, their expansion is at odds with the reported general losses of SOC (−0.48 t OC ha⁻¹ year⁻¹ on average). We used very detailed datasets of livestock numbers, N-application rates and cropping surfaces to calculate regional shifts in input of effective OC from animal manure application, cereal straw incorporation and crop residue incorporation which amounted to −0.094, −0.045 and −0.017 t OC ha⁻¹ year⁻¹, respectively. Shifts in management were identified to have potentially brought about but a third of the recent loss of SOC in the study area, although for central West-Flanders and the Eastern border of Flanders larger impacts of management were observed. This study suggests other influences such as land-use change and climate change to be involved as well. We estimated that another 10%–45% of the loss of SOC could potentially be attributed to land-use changes from grassland to cropland during the 1970–1990 period and about 10% to the observed temperature increase. While being a regional-scaled case study, these findings may be relevant to other European regions in particular (Denmark, The Netherlands, North-West Germany, Brittany and the North-West of France, the Po-valley in Italy and parts of England), with similar climate and intensity of agriculture, and where comparable trends in farming management may well have taken place.     

Carbon sequestration potential of organic agriculture in northern Europe – a modelling approach

Decline in carbon content in agricultural soils contributes both to climate change and to soil fertility problems. The CENTURY element dynamics simulation model was tested and adapted for Northern European agricultural conditions using long-term datasets from Askov experimental farm in southern Denmark. The part of the model dealing with decomposition was tested in isolation using a bare fallow experiment and it could predict soil organic matter levels with high accuracy. In the cropping experiments predictions were less accurate. The crop production was not accurately predicted. Predictions were more accurate on loamy than on sandy soils. The model was used to predict the effect of conversion to organic agriculture on carbon sequestration as soil organic matter. It predicted an increase in soil organic matter during the first 50 years of about 10–40 g C m^–2 y^–1, and a stable level after about 100 years. The use of grass-clovers in the rotation and as cover crops was particularly important for the increase in organic matter.     

Potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the tropics

Losses of carbon (C) stocks in terrestrial ecosystems and increasing concentrations of greenhouse gases in the atmosphere are challenges that scientists and policy makers have been facing in the recent past. Intensified agricultural practices lead to a reduction in ecosystem carbon stocks, mainly due to removal of aboveground biomass as harvest and loss of carbon as CO₂ through burning and/or decomposition. Evidence is emerging that agroforestry systems are promising management practices to increase aboveground and soil C stocks and reduce soil degradation, as well as to mitigate greenhouse gas emissions. In the humid tropics, the potential of agroforestry (tree-based) systems to sequester C in vegetation can be over 70 Mg C ha^–1, and up to 25 Mg ha^–1 in the top 20 cm of soil. In degraded soils of the sub-humid tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha^–1 y^–1 above continuous maize cropping. Soil C accretion is linked to the structural development of the soil, in particular to increasing C in water stable aggregates (WSA). A review of agroforestry practices in the humid tropics showed that these systems were able to mitigate N₂O and CO₂ emissions from soils and increase the CH₄ sink strength compared to cropping systems. The increase in N₂O and CO₂ emissions after addition of legume residues in improved fallow systems in the sub-humid tropics indicates the importance of using lower quality organic inputs and increasing nutrient use efficiency to derive more direct and indirect benefits from the system. In summary, these examples provide evidence of several pathways by which agroforestry systems can increase C sequestration and reduce greenhouse gas emissions.     

Carbon sequestration in soil aggregates under different crop rotations and nitrogen fertilization in an inceptisol in southeastern Norway

Effects of crop rotation and fertilization (nitrogen and manure) on concentrations of soil organic carbon (SOC) and total soil nitrogen (TSN) in bulk soil and in soil aggregates were investigated in a long-term field experiment established in 1953 at Ås, Norway. The effect of these management practices on SOC sequestration was estimated. The experiment had three six-course rotations: (I) continuous spring grain, (II) spring grain for 3 years followed by root crops for 3 years, and (III) spring grain for 2 years followed by meadow for 4 years. Three fertilizer treatments compared were: (A) 30–40 kg N ha^–1; (B) 80–120 kg N ha^–1; and (C) a combination of B and 60 Mg farmyard manure (FYM) ha^–1. All plots received a basal rate of PK fertilizer. Soil samples from these treatments were collected in autumn 2001 and analyzed for aggregate size, SOC and TSN concentrations. There were significant increases in 0.6–2 mm and < 0.6 mm aggregate size fractions, and reduction in the 6–20 mm and the > 20 mm sizes for rotation III only. There were also significant differences among rotations with regard to water stable aggregation. The order of increase in stability was II < I < III. Fertilizer treatment had no effect on aggregation or aggregate size distribution, but there was a slight tendency of increased stability with the application of FYM. Aggregate stability increased with increasing concentration of SOC (r2 = 0.53). The SOC and TSN concentrations in bulk soil were significantly higher in rotation III than in rotations II and I. Application of FYM increased SOC and TSN concentrations significantly in the 0–10 cm soil depth, but there were few significant differences between fertility treatments A and B. There was a trend of increase in concentration of SOC and TSN with decreasing aggregate size, but significant differences in these parameters in different aggregate size fractions were found only in few cases. The SOC and TSN concentrations were higher in >0.25 mm than in < 0.25 mm aggregates. The SOC sequestration rate was 77–167 kg SOC ha^–1 yr^–1 by increasing the N rate and 40–162 kg SOC ha^–1 yr^–1 by applying FYM. The SOC sequestration rate by judicious use of inorganic fertilizer was the greatest in the grain–meadow rotation, while that by application of FYM was the greatest in the all grain rotation.     

Thermodynamic and transport property models for carbon capture and sequestration (CCS) processes with emphasis on CO2 transport

Carbon capture and sequestration (CCS) is one of the most promising technologies for the reduction of carbon dioxide (CO₂) concentration in the atmosphere, so that global warming can be controlled and eventually eliminated. A crucial part in the CCS process design is the model that is used to calculate the physical properties (thermodynamic, transport etc.) of pure CO₂ and CO₂ mixtures with other components.     

Carbon dioxide sequestration through novel use of ion exchange fibers (IX-fibers)

Electrical power generation and metal removal processes are practiced globally and share two common attributes that make them ideal candidates to be incorporated in a novel carbon dioxide sequestration scheme using ion exchange fibers (IX-fibers). First, the softening of boiler feed water used in power generation and the removal of metals from finishing wastewaters often employs the use of ion exchange for the purpose of selective separation. Second, both processes represent significant point source CO₂ emissions. This investigation demonstrated that using IX-fibers it is possible to sequester a portion of the CO₂ produced in these practices as carbonate alkalinity during the regeneration step of both the water softening and the trace heavy metal removal processes. Weak acid IX-fibers were used for hardness removal while hybrid cation exchange fibers (HCIX-F) loaded with hydrated Zr(IV) oxide (HZO) were used to remove toxic heavy metals such as zinc, cadmium and copper. IX-fibers offer the unique capability to use and consume CO₂ during the efficient regeneration of IX-fibers, whereas commercial ion exchange resins are not amenable to regeneration with CO₂. A much shorter intraparticle diffusion path length in cylindrical IX-fibers as compared to resin beads is the underlying reason for a highly efficient regeneration of the fibers. In addition to sequestering carbon dioxide, no hazardous or aggressive chemicals/brine solutions are present in the regenerant wastes as compared with traditional ion exchange processes.     

Revegetation of eroded land and possibilities of carbon sequestration in Iceland

Carbon (C) sequestration within the context of the Kyoto protocol of the United Nations Framework Convention on Climate Change has great potential as an incentive for combating land degradation and desertification. Desertification continues to be a major threat to Iceland's natural resources. Revegetation in Iceland can both reduce C in the atmosphere by fixing C in vegetation and soil, and also reduce C emission by preventing further ecosystem damage, vegetation degradation and subsequent soil erosion. The sequestration potential in Iceland lies in the available land area and in the soil properties. Iceland has vast areas where vegetation can be enhanced or restored (10 000–45 000 km²), and the Andic nature of Icelandic soils tends to immobilize C. In the year 2001 the Soil Conservation Service worked on revegetation of roughly 13 000 ha or 130 km², resulting in C sequestration of about 8000–14000 Mg C in 2001. Reclamation of degraded land through changed land use, and/or seeding and fertilizing can promote sustainable development and healthier ecosystems, increase biological diversity and soil fertility, in addition to mitigating climate change through C sequestration.     

Soil organic carbon sequestration in tropical areas. General considerations and analysis of some edaphic determinants for Lesser Antilles soils

Some general notions on soil organic carbon (SOC) sequestration and the difficulties to evaluate this process globally are presented. Problems of time- and space- scales are emphasized. SOC erosion, which is generally difficult to evaluate in relation to land use changes, is discussed in detail. Different aspects of SOC sequestration on the Lesser Antilles are presented for a wide range of soil types. Comparisons between soils revealed that the SOC stocks in the Lesser Antilles are highly dependent upon the mineralogy: higher stocks for allophanic (ALL) soils than for low activity clay (LAC) and high activity clay (HAC) soils. But in terms of potential of SOC sequestration (pSeq-SOC, differences between permanent vegetation and continuous cultivation situations), there are no differences between ALL and LAC soils (22.9 and 23.3 tC. ha⁻¹, respectively). On the other hand, the potentials of SOC sequestration were higher for HAC soils (30.8 – 59.4 tC. ha⁻¹, with the higher levels in the less Mg- and Na-affected Vertisol). Sheet erosion is a serious problem for Vertisol with high Mg and Na on exchange complex, causing high dispersability of fine elements. Thus, the lower SOC levels in these soils may be partly due to erosion losses. Laboratory incubations have shown that 37 – 53% of the protected SOC in these soils was located in aggregates larger than 0.2 mm. The effect of agricultural practices on SOC sequestration was studied for the Vertisols. Intensification of pastures led to higher plant productivity and higher organic matter restitutions and SOC sequestration. The gain was 53.5 and 25.4 tC. ha⁻¹ for the low and high-Mg Vertisol, respectively (0–20 cm layer). SOC sequestration with pastures also depends upon the plot history with lower mean annual increase in SOC for the initially eroded (1.0 gC . kg⁻¹ soil . yr⁻¹) than for the non-degraded (1.5 gC . kg⁻¹ soil . yr⁻¹) Vertisol. Loss of SOC in a pasture-market gardening rotation was 22.2 tC . ha⁻¹ with deep (30–40 cm) and 10.7 tC . ha⁻¹ with surface (10–15 cm) tillage. It was unclear whether the differences in SOC losses were due to mineralization and/or to erosion. This revised version was published online in June 2006 with corrections to the Cover Date.     

Investigation of the pH effect of a typical host rock and buffer solution on CO2 sequestration in synthetic brines

Carbon dioxide sequestration in deep saline aquifers is a critical component of long-term storage options. It is suggested that the precipitation of mineral carbonates is mostly dependent on brine pH and is favoured above a basic pH of 9.0. However, brine pH will drop to acidic values once CO₂ is injected into the brine. Therefore, there is a need to raise brine pH and maintain it stable. Synthetic brines were used here instead of natural brines because of the difficulty in obtaining and storing natural brines. Therefore, experiments were conducted to prepare a series of synthetic brines and to compare their suitability to natural brines for carbon sequestration firstly. A typical host rock (Oriskany rock) and a buffer solution (NaCl/NaHCO₃) were selected to buffer brine pH. In a subsequent step, studies were conducted to correlate how brine samples respond in the presence of the host rock or the buffer solution at realistic reservoir temperatures (40 and 100 °C) and pressures (1160 and 1500 psi) for CO₂ storage. The results show that synthetic brines prepared can be used as analogues as natural brines for carbon sequestration studies in terms of chemical composition and pH response. Both XRD and SEM/EDS analyses confirmed the presence of mineral carbonates in the CO₂-rock-brine and the CO₂-buffer-brine experiments. However, the amount of carbonates precipitated from the CO₂-buffer-brine reactions is nearly 18 times larger than that formed from the CO₂-rock-brine experiments. ICP-MS studies also verified that there was only 4% reduction in Ca concentration in solution after the CO₂-rock-brine studies, while the concentrations of Ca and Sr decreased by 90% during the CO₂-buffer-brine experiments.     

Quantifying the effect of soil organic matter on indigenous soil N supply and wheat productivity in semiarid sub-tropical India

A field experiment was conducted on a loamy sand soil for six years to quantify the effect of soil organic matter on indigenous soil N supply and productivity of irrigated wheat in semiarid sub-tropical India. The experiment was conducted by applying different combinations of fertilizer N (0–180 kg N ha⁻¹), P (0–39 kg P ha⁻¹) and K (0–60 kg K ha⁻¹) to wheat each year. For the data pooled over years, fertilizer N together with soil organic carbon (SOC) and their interaction accounted for 75% variation in wheat yield. The amount of fertilizer N required to attain a yield goal decreased as the SOC concentration increased indicating enhanced indigenous soil N supply with an increase in SOC concentration. Besides SOC concentration, the soil N supply also depended on yield goal. For a yield goal of 4 tons ha⁻¹, each ton of SOC in the 15 cm plough layer contributed 4.75 kg N ha⁻¹ towards indigenous soil N supply. An increase in the soil N supply with increase in SOC resulted in enhanced wheat productivity. The contribution of 1 ton SOC ha⁻¹ to wheat productivity ranged from 15 to 33 kg ha⁻¹ across SOC concentration ranging from 3 to 9 g kg^-1 soil. The wheat productivity per ton of organic carbon declined curvilinearly as the native SOC concentration increased. The change in wheat productivity with SOC concentration shows that the effect of additional C sequestration on wheat productivity will depend on the existing SOC concentration, being higher in low SOC soils. Therefore, it will be more beneficial to sequester C in soils with low SOC than with relatively greater SOC concentration. In situations where the availability of organic resources for recycling is limited, their application may be preferred in soils with low SOC concentration. The results show that an increase in C sequestration will result in enhanced wheat productivity but the increase will depend on the amount of fertilizer applied and the existing fertility level of the soil.     

Influence of reduced graphene oxide (rGO) on phase development and porosity of SiOC/rGO ceramic composites

Ceramic materials based on silicon oxycarbide (SiOC) and reduced graphene oxide (rGO) were produced by polymer pyrolysis and evaluated in terms of phase development and porosity. Carbonaceous phase, initially prepared from graphite oxide, was incorporated into silicone dihydroxy terminated in different amounts (0, 5, 15 and 25 wt%) and submitted to pyrolysis at 1500 °C to obtain SiOC/rGO ceramics. Higher ceramic yields and more thermally stable materials were obtained after rGO addition, whose results were associated to the chemical interaction degree between rGO and polymer structure. C_graphite and SiC phases were generated in rGO-containing ceramics and a mixture of α- and β-SiC was achieved from 15 wt% rGO, enhancing their crystallinity with increasing of rGO content. Porosity features were influenced by the carbonaceous phase amount and different rGO-polymer interaction degrees. SiOC/rGO ceramics demonstrated desirable structural characteristics for future investigations in electrical and/or electrochemical applications.     

Factors affecting organic carbon dynamics in soils of Nepal/Himalayan region – a review and analysis

We reviewed the factors and processes relevant to C (Carbon) stocks and dynamics in the soils of Hindu Kush-Himalayan region (HKH) in general, and Nepal in particular. Included in this paper are reviews of land use change, soil types, erosion, soil fertility status, land management and other pertinent information in relation to the SOC (Soil Organic Carbon) stock, dynamics and sequestration. Watershed degradation in the HKH region appears to be a serious problem affecting the SOC pool, which may be primarily attributed to deforestation, land use changes, forest degradation, soil erosion and fertility decline. Soils under degraded forest and grazing land and red soils were reported to have less than 1% SOC; however, well managed forests have considerably higher organic matter (SOC = 4%) levels than those cleared for cultivation. Our estimates show that both the soil and SOC losses are site specific, being as high as 256 kg C ha^–1 y^–1. Estimated net CO₂ losses from the erosion displaced SOC varied between <1 and 42 kg C ha^–1 y^–1 depending on initial SOC content and soil erosion rates in the specific sites. The land cover changes in the past 18 years in the two Nepalese watersheds, Mardi and Fewa, may have resulted in net loss of SOC stock (29% losses for Mardi and 7% losses for Fewa) compared to land cover in the base year (1978). The processes contributing to C pool, fluxes and sequestration are inadequately studied, and particularly in the HKH region, there is a lack of data on several essential aspects needed for estimating soil C fluxes and C sequestration potential. Systematic soil survey and long term experiments are needed on dominant soil types and land use systems of the HKH region for developing the database on soil fertility and SOC relationships to site specific management practices. Future research should focus upon generating data on spatial and temporal variation, depth distribution, quantification of various pools, and transport/translocation of SOC, as well as the establishment of soil/SOC databases, in relation to specific land use and management practices.     

The impact of grassland ploughing on CO2 and N2O emissions in the Netherlands

The contribution of ploughing permanent grassland and leys to emissions of N₂O and CO₂ is not yet well known. In this paper, the contribution of ploughing permanent grassland and leys, including grassland renovation, to CO₂ and N₂O emissions and mitigation options are explored. Land use changes in the Netherlands during 1970–2020 are used as a case study. Three grassland management operations are defined: (i) conversion of permanent grassland to arable land and leys; (ii) rotations of leys with arable crops or bulbs; and (iii) grassland renovation. The Introductory Carbon Balance Model (ICBM) is modified to calculate C and N accumulation and release. Model calibration is based on ICBM parameters, soil organic N data and C to N ratios. IPCC emission factors are used to estimate N₂O-emissions. The model is validated with data from the Rothamsted Park Grass experiments. Conversion of permanent grassland to arable land, a ley arable rotation of 3 years ley and 3 years arable crops, and a ley bulb rotation of 6 years ley and one year bulbs, result in calculated N₂O and CO₂ emissions totalling 250, 150 and 30 ton CO₂-equivalents ha^–1, respectively. Most of this comes from CO₂. Emissions are very high directly after ploughing and decrease slowly over a period of more than 50 years. N₂O emissions in 3/3 ley arable rotation and 6/1 ley bulb rotation are 2.1 and 11.0 ton CO₂-equivalents ha^–1 year^–1, respectively. From each grassland renovation, N₂O emissions amount to 1.8 to 5.5 ton CO₂-equivalents ha^–1. The calculated total annual emissions caused by ploughing in the Netherlands range from 0.5 to 0.65 Mton CO₂-equivalents year^–1. Grassland renovation in spring offers realistic opportunities to lower the N₂O emissions. Developing appropriate combinations of ley, arable crops and bulbs, will reduce the need for conversion of permanent pasture. It will also decrease the rotational losses, due to a decreased proportion of leys in rotations. Also spatial policies are effective in reducing emissions of CO₂ and N₂O. Grassland ploughing contributes significantly to N₂O and CO₂ emissions. The conclusion can be drawn that total N₂O emissions are underestimated, because emissions from grassland ploughing are not taken into account. Specific emission factors and the development of mitigation options are required to account for the emissions and to realise a reduction of emissions due to the changes in grassland ploughing.     

利用活性炭处理铬黑T实验室废液的试验研究

选用活性炭对低浓度铬黑T实验室模拟废液进行脱色处理,通过活性炭用量、活性炭浓度,搅拌时间、pH值等变量,进行脱色率的试验.通过设计正交实验选出的最佳脱色条件为:活性炭用量1000mg/L,搅拌时间100min,铬黑T质量浓度15mg/L,pH为2.试验证明在此条件下进行脱色,脱色率都达到90%以上.     

Effects of Carbon Fillers on Crystallization Properties and Thermal Conductivity of Poly(phenylene sulfide)

Differential scanning calorimetry and polarized optical microscopy methods were used to investigate the crystallization behavior and isothermal crystallization kinetics of poly(phenylene sulfide) (PPS)/carbon nanotube (CNT) and PPS/CNT/carbon fiber (CF) composites. In this article, the influences of CNT and CF on PPS crystallization behavior are explained. The thermal conductivity properties of composites were studied using the laser flash method. The results show that CNT increased crystallization temperature and rate and thermal conductivity greatly improved at 8 wt.% CNT content. In addition, the crystallization and thermal performance of PPS are significantly improved via synergistic effects of CNT and CF in the composites.     

Effects of Multi-Walled Carbon Nanotube (MWCNT) Content on Physical Properties and Cell Structure in Ethylene Vinyl Acetate Copolymer (EVA)/MWCNT Nanocomposite Foams

Melt compounding is used to mix ethylene-vinyl acetate copolymer (EVA) and multi-walled carbon nanotube (MWCNT). Then the obtained EVA/MWCNT mixtures were foamed using a chemical blowing agent. Without any modification of MWCNT, a significant improvement of the tensile properties was observed for the EVA/MWCNT foams. With increasing the MWCNT content to 10 phr, the average cell size decreases to 36 µm due to the higher melt viscosity and the average cell density increases to 10.5 × 10⁶ cell/cm³ due the heterogeneous nucleation. To investigate the possible applications for static dissipative purpose, the surface resistivity of EVA/MWCNT foams was also investigated.     

Uptake and sequestration of ouabain and other cardiac glycosides inDanaus plexippus (Lepidoptera: Danaidae): Evidence for a carrier-mediated process

Larvae ofDanaus plexippus feed almost exclusively on milkweed species of the genusAsclepias, whose characteristic secondary metabolites are cardiac glycosides (CGs). Aposematic last-instar larvae were fed with ouabain and other cardiac glycosides of differing polarities. Time course experiments show that ouabain is sequestered in the integument within 48 hr after feeding, whereas midgut tissue and hemolymph function as transient CG storage compartments. About 63% of ouabain was transferred from larvae to the butterflies, whereas 37% of ouabain was lost with larval and pupal exuviae and with the meconium. The main sites of storage in imagines are wings and integument. If mixtures of CGs are fed toD. plexippus larvae, differential sequestration can be observed: The polar ouabain contributes 58.8% of total CGs, followed by digitoxin (19.6%), oleandrin (10.6%), digoxin (4.9%), digoxigenin (4.6%) and proscillaridin A (1.5%). Thus, uptake and sequestration must be selective processes. Uptake of [³H]ouabain in vitro by isolated larval midguts was time-, pH-, and temperature-dependent and displayed an activation energy of 49 kJ/mol. Furthermore, the in vitro uptake of ouabain was inhibited (probably competitively) by the structurally similar convallatoxin. These data provide first evidence that ouabain uptake does not proceed by simple diffusion but with the aid of a carrier mechanism, which would explain the differential cardenolide uptake observed in living larvae.     

The Effect of Ozonation and Filtration on AOC (Assimilable Organic Carbon) Value of Water from Eutrophic Lake

The effects of applying ozone into the source water of Cheng-Ching Lake Water Works (CCLWW) on the analysis of AOC (assimilable organic carbon) were compared in the laboratory and pilot-scale tests. CCLWW takes its raw water from an eutrophic lake. A pilot plant, established in CCLWW in southern Taiwan, was performed to improve the quality of water obtained by the former treatment processes. The direct application of ozone to the source water of CCLWW is called the pre-O₃ process. The post-O₃ process involves the treatment of effluent with ozone through a sand filter, following other treatments, including pre-O₃, coagulation and sedimentation. In a laboratory test, a 0.45 μm membrane filter was used to replace the facility of filtration for a sand filter. AOC_Total comprises AOC_P17 and AOC_NOX, which were determined using the P. fluorescens strain P17 and the Spirillum species strain NOX, respectively. During over 2 years' sampling in eutrophic lake, it revealed that AOC_P17 contributed substantially to AOC_Total. However, the filtrate from the source water obtained by filtering through a 0.45 μm membrane filter had an AOC_Total much lower than that of the source water, especially for the considerable decrease of AOC_P17. Also, the AOC value in source water is increased with algae number but not with NPDOC (non-purgeable dissolved organic carbon). This result indicated that algae numbers existing in the eutrophic lake might affect the analysis of AOC. Following the pre-O₃ process at the pilot-scale plant, the AOC_P17 was markedly lower than that of the source water, and AOC_NOX was slightly higher than that of the source water. However, when post-O₃ was added to the effluent from a sand filter at the pilot-scale plant, AOC_NOX exceeded that before post-O₃, while AOCP17 differed slightly from that before post-O₃. Apparently, this difference may be due to the algae number existing in the water samples. These results were verified by applying ozone to the source water, and to filtrate obtained by filtering through a 0.45 μm membrane filter in a lab-scale test, respectively.     

Effects of Different Carbon Sources and NaBr-KCI on Synthesis of Ti(C,N)

Ti(C,N) was synthesized with the starting materi-als of 76.9% titania white and 23.1% carbon black (graphite or activated carbon),or 40% titania white and 60% amylum,with or without 10% NaBr-KCI,dry moulding and carbon embedded firing at 1 300 ℃ and 1 400 ℃ for 3 h,respectively.Phase composition and microstructure of the synthesized Ti (C,N) were analyzed by XRD,SEM and EPMA.Effects of different carbon sources and NaBr-KCl on the synthesis of Ti (C,N) were investigated.The results show that:(1) Ti (C,N) can be synthesized by using carbon black,graphite,activated carbon or amylum as carbon source separately;(2) Additive NaBr-KCI is more fa-vorable for accelerating the carbothdrmal reduction reac-tion using carbon black or amylum as carbon source;(3) In the presence of NaBr-KCl,particle size of the synthesized Ti (C,N) is 5-8 μm using carbon black as carbon source fired at 1 300 ℃ for 3 h,while that is only 1-3 μm using graphite,activated carbon or amy-lum fired at 1 400 ℃ for 3 h.