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Total Organic Carbon (total + organic_carbon)
Terms modified by Total Organic Carbon Selected AbstractsA simple system for biofilm potential monitoring in drinking waterJOURNAL OF BASIC MICROBIOLOGY, Issue 1 2006Eric Delahaye Dr. SAGEP-EAU DE PARIS produces drinking water for the city of Paris (France). In order to supply a high quality water, one of the main SAGEP's concerns is to monitor the Biofilm Formation Potentials of the produced drinking waters. Biofilm incubators were installed at the outlet of three Water Treatment Plants (WTP). These incubators allowed biofilm formation and quantification in terms of Fixed Total Organic Carbon (FTOC), fixed culturable bacteria (HPC-R2A) and fixed total bacteria. During this study, quantitative differences appeared between the biofilms formed at the outlet of the three WTPs, leading to different classifications of the Biofilm Formation Potentials of the three produced waters, depending on the used parameter for biofilms quantification. This observation underlined the necessity of a multi-parametric approach for the study of biofilms. More generally, our results validated the use of these sturdy stainless steel incubators, highly adapted to industrial field conditions, for the monitoring of Biofilm Formation Potentials in drinking water networks. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A comparative geochemical study of bituminous boat remains from H3, As-Sabiyah (Kuwait), and RJ-2, Ra's al-Jinz (Oman)ARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2005Jacques Connan This paper presents a geochemical analysis of fragments of bituminous amalgam from H3, As-Sabiyah (Kuwait), and RJ-2, Ra's al-Jinz (Oman). The fragments bear barnacles on one side and reed impressions on the other, and are thought to have been part of the coating of reed-bundle boats. The material from H3 dates to between 5300,4900 BC, while that of RJ-2 dates to 2500,2100 BC. Samples from both sites were geochemically compared to archaeological and ethnographic material from Kosak Shamali (northern Syria, c.5000,4400 BC), RH-5 (Oman, 4400,3500 BC) and Baghdad (central Iraq, 1900 AD). The composition of the bituminous amalgams was studied in detail. Rock-Eval Pyrolysis gave a measure of Total Organic Carbon in the samples, and allowed an initial comparison of the data sets using various parameters. Examination of the proportions of soluble and insoluble organic matter allowed an assessment of the quantity of vegetal matter added to the bitumen to make the bituminous amalgam. The composition of the Ra's al-Jinz material was studied using X-Ray Diffraction analysis and thin-section petrography, in order to assess the proportions of various minerals in the bituminous amalgams. It was concluded that the recipe for the bituminous mixture used to coat reed-bundle and wooden boats did not differ significantly from that commonly used to make ,mortar' for architectural purposes in Mesopotamia. Traces of animal fats or fish oils were not found in the analysed Ra's al-Jinz material, in contrast to previous hypotheses regarding the composition of the mixture. Comparison of the gross composition of extractable organic matter (the constituents of pure bitumen, soluble in chloroform or dichloromethane) showed the progressive effects of weathering on the samples. The isotopic composition of the bituminous material from H3 and the other sites was then compared to that of bitumen seeps and crude oils from Mesopotamia, Iran and Oman. The most significant result is that the material from As-Sabiyah originated in Kuwait, at a surface seep at Burgan, while the material from Ra's al-Jinz had a source in northern Mesopotamia. [source] Variations of Microbial Communities and the Contents and Isotopic Compositions of Total Organic Carbon and Total Nitrogen in Soil Samples during Their PreservationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2009Qianye TAO Abstract: Semi-sealed preservation of soil samples at different moisture of 4% and 23%, respectively, was simulated to observe the variations of soil microbial communities and determine the contents and isotopic compositions of the total organic carbon and total nitrogen on the 7th and 30th day, respectively. The results show that during preservation, the quantity of microbial communities tended to increase first and then decrease, with a wider variation range at higher moisture (23%). At the moisture content of 23%, the microbial communities became more active on the 7th day, but less after 30 days, and their activity was stable with little fluctuation at the moisture content of 4%. However, there were no significant changes in the contents and isotopic compositions of the total organic carbon and total nitrogen. During preservation, the responses of soil microbes to the environment are more sensitive to changes in the total nitrogen and organic carbon contents. It is thus suggested that the variations of microbial communities have not exerted remarkable impacts on the isotope compositions of the total nitrogen and total organic carbon. [source] Episodic stream water pH decline during autumn storms following a summer drought in northern SwedenHYDROLOGICAL PROCESSES, Issue 9 2002Hjalmar Laudon Abstract The sources of episodic pH decline in four streams from northern Sweden during the autumn of 1996 were quantified. The events, in which pH dropped by between 1·0 and 2·4 units, were preceded by an extensive summer drought. Total organic carbon, which increased 100% to 160% during peak flow, was the most important driving mechanism of the episodic pH decline. Sulphate, however, was relatively more important during these autumn events than during spring flood. In the sites where past and present anthropogenic deposition were believed to be the main source of sulphate in stream water, sulphate contributed less than 0·3 pH units to the pH decline. In catchments where natural sources of sulphate are known to be important, sulphate contributed up to 0·6 units of pH decline. The export of sulphate during the episodes was two to nine times higher than what was expected from deposition only. The drought preceding the study episodes resulted in some of the lowest ground water levels during the 1990s in that region. The large export of sulphate was probably due to oxidation of natural sulphate bearing minerals in the soil and/or previously deposited sulphate driven by the low ground water level preceding the episodes. Copyright © 2002 John Wiley & Sons, Ltd. [source] HYDROCARBON POTENTIAL OF THE LATE CRETACEOUS GONGILA AND FIKA FORMATIONS, BORNU (CHAD) BASIN, NE NIGERIAJOURNAL OF PETROLEUM GEOLOGY, Issue 4 2010B. Alalade The hydrocarbon potential of possible shale source rocks from the Late Cretaceous Gongila and Fika Formations of the Chad Basin of NE Nigeria is evaluated using an integration of organic geochemistry and palynofacies observations. Total organic carbon (TOC) values for about 170 cutting samples range between 0.5% and 1.5% and Rock-Eval hydrogen indices (HI) are below 100 mgHC/gTOC, suggesting that the shales are organically lean and contain Type III/IV kerogen. Amorphous organic matter (AOM) dominates the kerogen assemblage (typically >80%) although its fluorescence does not show a significant correlation with measured HI. Atomic H/C ratios of a subset of the samples indicate higher quality oil- to gas-prone organic matter (Type II-III kerogens) and exhibit a significant correlation with the fluorescence of AOM (r2= 0.86). Rock-Eval Tmax calibrated against AOM fluorescence, biomarker and aromatic hydrocarbon maturity data suggests a transition from immature (<435°C) to mature (>435°C) in the Fika Formation and mature to post-mature (>470°C) in the Gongila Formation. The low TOC values in most of the shales samples limit their overall source rock potential. The immature to early mature upper part of the Fika Formation, in which about 10% of the samples have TOC values greater than 2.0%, has the best oil generating potential. Oil would have been generated if such intervals had become thermally mature. On the basis of the samples studied here, the basin has potential for mostly gaseous rather than liquid hydrocarbons. [source] Electrochemical Detection of Arsenic(III) in the Presence of Dissolved Organic Matter (DOM) by Adsorptive Square-Wave Cathodic Stripping Voltammetry (Ad-SWCSV)ELECTROANALYSIS, Issue 4 2008Tsanangurayi Tongesayi Abstract This study has demonstrated that As(III) can be electrochemically detected and quantified in the presence of fulvic acid (FA) and dissolved organic matter (DOM). This eliminates the need to remove DOM prior to measurement of As(III) in environmental samples. Apart from reducing analysis time and the cost of the analysis, this could be potentially useful for the development of electrochemical methods for the detection and measurement of As(III) onsite. Both synthetic samples in which FA was added and a real sample with 22.16,mg/L total organic carbon (TOC) were analyzed. [source] Evaluation of factors influencing membrane performanceENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2005Weihua Peng Abstract Three commercial water treatment membranes, TFC-S (Koch membranes, San Diego, CA), ESPA1, and NTR7450 (Hydranautics, San Diego, CA), were tested under various physical and chemical conditions to investigate their fouling behaviors. It was found that TFC-S always displayed the greatest rate of flux decline, ESPA1 displayed a mild trend in flux decline, and NTR7450 presented a nearly stable flux. Multivariable regression models showed that the flux decline rates for TFC-S and ESPA1 were controlled by the initial permeate flux, whereas their initial (that is, instantaneous) foulings were controlled by the interaction between permeate drag and electrostatic repulsions. Feed bacteria concentration also contributed to the initial fouling of ESPA1 as a result of cell deposition on the membrane surface. NTR7450 showed an initial decline in flux followed by a steady flux, and its initial fouling was significantly affected by feed water total organic carbon (TOC) arising from the initial accumulation of colloidal organic particles on the surface. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Influence of soil type and organic matter content on the bioavailability, accumulation, and toxicity of ,-cypermethrin in the springtail Folsomia candidaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2010Bjarne Styrishave Abstract The influence of organic matter (OM) content on ,-cypermethrin porewater concentrations and springtail Folsomia candida accumulation was investigated in two soils with different levels of organic matter, a forest soil with a total organic carbon (TOC) content of 5.0% (OM,=,11.5%) and an agricultural soil with a TOC content of 1.3% (OM,=,4.0%). Also, the effects of ,-cypermethrin concentrations in soil and pore water and the influence of soil aging on springtail reproduction were investigated. Springtail reproduction was severely affected by increasing ,-cypermethrin in soil with 1.3% TOC; the median effective concentration value (EC50) was estimated to 23.4,mg/kg (dry wt). Reproduction was only marginally affected in the soil with 5.0% TOC, and no EC50 value could be estimated. However, when expressing ,-cypermethrin accumulation as a function of soil ,-cypermethrin concentrations, no difference was found between the two soil types, and no additional ,-cypermethrin uptake was observed at soil concentrations above approximately 200,mg/kg (dry wt). By using solid-phase microextraction (SPME), it could be demonstrated that ,-cypermethrin porewater concentrations were higher in the soil with low organic matter (LOM) content than in the soil with high organic matter (HOM) content. Furthermore, a clear relationship was found between ,-cypermethrin concentrations in springtails and porewater. Soil aging was not found to exert any effect on ,-cypermethrin toxicity toward springtails. The study indicates that the springtail's accumulation of ,-cypermethrin and reproduction is governed by ,-cypermethrin porewater concentrations rather than the total ,-cypermethrin concentration in soil. Environ. Toxicol. Chem. 2010;29:1084,1090. © 2010 SETAC [source] Agricultural soils spiked with copper mine wastes and copper concentrate: Implications for copper bioavailability and bioaccumulation,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Rosanna Ginocchio Abstract A better understanding of exposure to and effects of copper-rich pollutants in soils is required for accurate environmental risk assessment of copper. A greenhouse experiment was conducted to study copper bioavailability and bioaccumulation in agricultural soils spiked with different types of copper-rich mine solid wastes (copper ore, tailing sand, smelter dust, and smelter slag) and copper concentrate. A copper salt (copper sulfate, CuSO4) that frequently is used to assess soil copper bioavailability and phytotoxicity also was included for comparison. Results showed that smelter dust, tailing sand, and CuSO4 are more likely to be bioavailable and, thus, toxic to plants compared with smelter slag, concentrate, and ore at equivalent total copper concentrations. Differences may be explained by intrinsic differences in copper solubilization from the source materials, but also by their capability to decrease soil pH (confounding effect). The copper toxicity and bioaccumulation in plants also varied according to soil physicochemical characteristics (e.g., pH and total organic carbon) and the available levels of plant nutrients, such as nitrogen, phosphorus, and potassium. Chemistry/mineralogy of mine materials, soil/pore-water chemistry, and plant physiological status thus should be integrated for building adequate models to predict phytotoxicity and environmental risk of copper. [source] A field validation of two sediment-amphipod toxicity testsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Steven P. Perraro Abstract A field validation study of two sediment-amphipod toxicity tests was conducted using sediment samples collected subtidally in the vicinity of a polycyclic aromatic hydrocarbon (PAH)-contaminated Superfund site in Elliott Bay (WA, USA). Sediment samples were collected at 30 stations with a 0.1 m2 grab from which subsamples were taken for sediment toxicity testing and geochemical and macrofaunal analyses. Standard 10-d sediment-amphipod toxicity tests were conducted with Rhepoxynius abronius and Leptocheirus plumulosus. Sediments were analyzed for 33 PAHs, pentachlorophenol, polychlorinated biphenyls, acid-volatile sulfide, simultaneously extracted metals (Cd, Cu, Zn, Pb, Ni), total organic carbon, and grain size. Sediment temperature, oxygen-reduction potential, water depth, and interstitial water salinity were also measured. Polycyclic aromatic hydrocarbons, quantified as total PAH toxic units (TUPAH), were confirmed to be an important common causal agent of the changes in the two toxicity test (% survival R. abronius, % survival L. plumulosus) and five macrofaunal community (number of species, S; numerical abundance, A; total biomass, B; Swartz's dominance index, SDI; Brillouin's index, H) endpoints. Two other macrofaunal community metrics (the complement of Simpson's index, 1 , SI, and McIntosh's index, MI) were less sensitive to TUPAH than the two toxicity test endpoints. The sensitivities of R. abronius and L. plumulosus to TUPAH were statistically indistinguishable. Field validations were conducted by testing the association between or among each toxicity test endpoint, each of seven macrofaunal community metrics (S, A, B, SDI, H, 1 , SI, MI), and TUPAH by (1) Spearman's coefficient of rank correlation, (2) Kendall's coefficient of concordance, (3) G tests of independence, and (4) regression analysis. Some field validations based on multivariable tests of association (e.g., points 2 and 3) among toxicity test, field, and stressor endpoints produced false positive results. Both toxicity test endpoints were validated as indicators of changes in S, A, SDI, and H by all the methods tested. The resolution power of the relationships between the laboratory toxicity test and macrofaunal field endpoints was low (, three classes) but sufficient to discriminate ecologically important effects. We conclude that standard sediment-amphipod toxicity tests are ecologically relevant and that, under the proper conditions, their results can be used for lab-to-field extrapolation. [source] Three lines of evidence in a sediment toxicity evaluation for hexachlorobutadieneENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2000Phyllis C. Fuchsman Abstract Three approaches were used in a site-specific sediment toxicity evaluation for hexachlorobutadiene (HCBD), a chemical not previously tested for toxicity in sediment. The results of a sediment dilution study, spiked sediment toxicity tests, and a probabilistic model based on equilibrium partitioning theory were used to estimate ecological effects thresholds for HCBD in sediments of a Gulf Coast estuary. Twenty-nine sediment samples, including 11 undiluted samples and six dilution series, were tested for toxicity under estuarine conditions (10%0 salinity) using Hyalella azteca and Leptocheirus plumulosus. Site sediment was used as diluent, and all samples were assayed for a range of organic and inorganic chemicals. A logistic relationship was observed between HCBD concentrations and organism response, and nonlinear regression explained approximately 90% of the observed variation in amphipod survival as a function of HCBD. Spiked sediment toxicity test results generally agreed with the results of the dilution study, demonstrating the causality of the observed concentration,response relationship. Effects thresholds were estimated as HCBD concentrations corresponding to 80% amphipod survival. The most conservative effects thresholds from the spiked sediment and dilution studies were 0.63 mg/kg normalized to 1% total organic carbon (mg/kg1%OC) for H. azteca and 1.4 mg/kg1%OC for L. plumulosus. Aquatic LC50s for 10 species and a measured acute,chronic ratio from the published literature were used to predict a distribution of sediment effects thresholds for HCBD, with 10th and 90th percentile values of 2.6 and 45 mg/kg1%OC, respectively. The predicted and observed sediment effects thresholds thus agreed relatively well, although the H. azteca and L. plumulosus test results from this study seem to be somewhat more conservative than the majority of published aquatic toxicity test results. [source] Evaluation of methods to remove ammonia interference in marine sediment toxicity tests,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000James A. Ferretti Abstract Ammonia naturally accumulates to high concentrations in nonsurficial marine sediments. It can also interfere and confound interpretation of toxicity from persistent anthropogenic chemicals in tests with laboratory amphipods. Renewal of overlying water has become a standardized procedure to decrease pore-water ammonia. Our objective was to propose an alternative technique for decreasing pore-water ammonia concentrations. Sediment samples with ammonia concentrations of 70 and 155 mg/L were purged of toxic concentrations in pore-water ammonia using the existing procedure of performing two renewals of overlying water per day. A thin-layer technique, which involved increasing the sediment surface area during the purging period, decreased the ammonia concentration by as much as 4.5-fold faster than the conventional purging protocol. Minimal decreases in concentrations of polycyclic aromatic hydrocarbons, heavy metals, and total organic carbon were found among all the purging techniques. Toxicity tests with the marine amphipod Ampelisca abdita suggest that minimizing the time required to purge a sediment of ammonia is critical in maintaining the integrity of the sample. The thin-layer purging technique appears to be an effective method of decreasing pore-water ammonia concentrations in sediments before laboratory toxicity testing with amphipods. [source] Determination of refractory organic matter in marine sediments by chemical oxidation, analytical pyrolysis and solid-state 13C nuclear magnetic resonance spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2008J. M. De La Rosa Summary Seeking to quantify the amount of refractory organic matter (ROM), which includes black carbon-like material (BC), in marine sediments, we have applied a two-step procedure that consists of a chemical oxidation with sodium chlorite of the demineralized sediments followed by integration of the aromatic C region in the remaining residues by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The efficacy for lignin removal was tested by analytical pyrolysis in the presence of tetramethyl ammonium hydroxide (TMAH). Riverine, estuarine and offshore marine sediment samples were collected from the southwest Atlantic coast of Spain, a site of geological and environmental interest. Measured contents of BC-like material ranged between 3.0 and 45.7% of the total organic carbon. Greater relative BC contents were found in riverine sediments close to urban areas, which show an elevated input of anthropogenic organic material. The contents of BC-like material in offshore marine sediments (5.5,6.1%) were similar to those previously reported for these kinds of samples. However, NMR and pyrolysis-GC/MS of the isolated ROM reveals that abundant refractory aliphatic organic material remains in most of the marine samples after chlorite oxidation. We suggest that this pool of aliphatic carbon may play an important role as a stable carbon pool within the global C cycle. [source] The turnover of carbohydrate carbon in a cultivated soil estimated by 13C natural abundancesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2006D. Derrien Summary Understanding the chemical composition of soil organic matter (SOM) requires the determination of the dynamics of each class of compounds. We measured the dynamics of carbon in neutral carbohydrates by use of natural 13C labelling in an experimental wheat and maize sequence extending over 23 years. The isotopic composition of individual neutral monosaccharides was determined in hydrolysed particle-size fractions by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) of trimethylsilyl (TMS) derivatives. The sensitivity in terms of 13C/12C ratios ranged between 1 and 2, depending on the monosaccharide. The age distribution of neutral sugar carbon was very similar to that of total soil carbon. Particulate organic matter (POM) was characterized by the predominance of glucose and xylose of vegetal origin. In POM >,200 µm, the mean age of sugar-C (5 years) was slightly less than that of total carbon (7 years). Xylose was younger than glucose. The fine fraction 0,50 µm contained mainly glucose, arabinose, galactose, xylose, fucose and mannose, which had predominantly microbial origins. The mean age of carbohydrate carbon in the fraction 0,50 µm was between 60 and 100 years and was similar to that of total organic carbon (OC). No difference in the age of carbon between the individual monosaccharides was found. The POM fraction 50,200 µm had an intermediate signature and turnover. Considering the typical lability of carbohydrates, the relatively great age of carbohydrate carbon may be explained by physical or chemical protection from degradation, as well as by recycling of soil organic matter carbon by soil microbes. [source] Assessing macroinvertebrate metrics for classifying acidified rivers across northern EuropeFRESHWATER BIOLOGY, Issue 7 2010S. JANNICKE MOE Summary 1. The effects of acidification on ecological status of rivers in Northern Europe must be assessed according to the EU Water Framework Directive (WFD). Several acidification metrics based on macroinvertebrates already exist in different countries, and the WFD requires that they be comparable across northern Europe. Thus, we compiled macroinvertebrate monitoring data from the U.K. (n = 191 samples), Norway (n = 740) and Sweden (n = 531) for analysis against pH. 2. We tested new and existing acidification metrics developed nationally and used within the Northern Geographical Intercalibration Group. The new metrics were based on the acidification sensitivity of selected species and are proposed as a first step towards a new common indicator for acidification for Northern Europe. 3. Metrics were assessed according to responsiveness to mean pH, degree of nonlinearity in response and consistency in responses across countries. We used flexible, nonparametric regression models to explore various properties of the pressure,response relationships. Metrics were also analysed with humic content (total organic carbon above/below 5 mg L,1) as a covariate. 4. Most metrics responded clearly to pH, with the following metrics explaining most of the variance: Acid Water Indicator Community, Number of ephemeropteran families, Medin's index, Multimetric Indicator of Stream Acidification and the new metric ,Proportion of sensitive Ephemeroptera'. 5. Most metrics were significantly higher in humic than in clear-water rivers, suggesting smaller acidification effects in humic rivers. This result supports the proposed use of humic level as a typological factor in the assessment of acidification. 6. Some potentially important effects could not be considered in this study, such as the additional effects of metals, episodic acidification and the contrasting effects of natural versus anthropogenic acidity. We advocate further data collection and testing of metrics to incorporate these factors. [source] Lability of organic carbon in lakes of different trophic statusFRESHWATER BIOLOGY, Issue 6 2009A. P. OSTAPENIA Summary 1. We used first-order kinetic parameters of biological oxygen demand (BOD), the constant of aerobic decomposition (k) and the asymptotic value of BOD (BODult), to characterise the lability of organic carbon pools in six lakes of different trophic state: L. Naroch, L. Miastro and L. Batorino (Belarus), L. Kinneret (Israel), L. Ladoga (Russia) and L. Mendota (U.S.A.). The relative contributions of labile and refractory organic carbon fractions to the pool of total organic carbon (TOC) in these lakes were quantified. We also determined the amounts of labile organic carbon within the dissolved and particulate TOC pools in the three Belarus lakes. 2. Mean annual chlorophyll concentrations (used as a proxy for lake trophic state) ranged from 2.3 to 50.6 ,g L,1, labile organic carbon (OCL = 0.3BODult) from 0.75 to 2.95 mg C L,1 and k from 0.044 to 0.14 day,1. 3. Our data showed that there were greater concentrations of OCL but lower k values in more productive lakes. 4. In all cases, the DOC fraction dominated the TOC pool. OCL was a minor component of the TOC pool averaging about 20%, irrespective of lake trophic state. 5. In all the lakes, most (c. 85%) of the DOC pool was refractory, corresponding with published data based on measurements of bacterial production and DOC depletion. In contrast, a larger fraction (27,55%) of the particulate organic carbon (POC) pool was labile. The relative amount of POC in the TOC pool tended to increase with increasing lake productivity. 6. Long-term BOD incubations can be valuable in quantifying the rates of breakdown of the combined particulate and dissolved organic carbon pools and in characterising the relative proportions of the labile and recalcitrant fractions of these pools. If verified from a larger number of lakes our results could have important general implications. [source] Effects of hydrogeomorphic region, catchment storage and mature forest on baseflow and snowmelt stream water quality in second-order Lake Superior Basin tributariesFRESHWATER BIOLOGY, Issue 5 2003Naomi E. Detenbeck SUMMARY 1. In this study we predict stream sensitivity to non-point source pollution based on the non-linear responses of hydrological regimes and associated loadings of non-point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5,10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second-order streams grouped as follows: three in each region × catchment storage × mature forest class. 2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid-growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio. 3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class. 4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity. [source] Role of lakes for organic carbon cycling in the boreal zoneGLOBAL CHANGE BIOLOGY, Issue 1 2004Grete Algesten Abstract We calculated the carbon loss (mineralization plus sedimentation) and net CO2 escape to the atmosphere for 79 536 lakes and total running water in 21 major Scandinavian catchments (size range 437,48 263 km2). Between 30% and 80% of the total organic carbon that entered the freshwater ecosystems was lost in lakes. Mineralization in lakes and subsequent CO2 emission to the atmosphere was by far the most important carbon loss process. The withdrawal capacity of lakes on the catchment scale was closely correlated to the mean residence time of surface water in the catchment, and to some extent to the annual mean temperature represented by latitude. This result implies that variation of the hydrology can be a more important determinant of CO2 emission from lakes than temperature fluctuations. Mineralization of terrestrially derived organic carbon in lakes is an important regulator of organic carbon export to the sea and may affect the net exchange of CO2 between the atmosphere and the boreal landscape. [source] Spatial and temporal dynamics of methane emissions from agricultural sources in ChinaGLOBAL CHANGE BIOLOGY, Issue 1 2001Peter H. Verburg Summary Agricultural activities contribute significantly to the global methane budget. Agricultural sources of methane are influenced by land-use change, including changes in agricultural area, livestock keeping and agricultural management practices. A spatially explicit inventory of methane emissions from agriculture is made for China taking the interconnections between the different agricultural sources into account. The influence of land-use change on methane emissions is studied by linking a dynamic land-use change model with emission calculations. The land-use change model calculates changes in rice area and livestock numbers for a base-line scenario. Emissions are calculated for 1991 based on land-use statistics and for 2010 based on simulated changes in land-use patterns. Emissions from enteric fermentation and manure management are based on emission factors, while emissions from rice paddies involve the calculation of total organic carbon added to rice paddy soils and assume that a constant fraction is emitted as methane. Spatial patterns of emissions are presented for the different sources. For the land-use scenario considered it is expected that total methane emissions from agricultural sources in China increase by 11% while the relative contribution of rice fields to the emission decreases. Emissions from manure management are expected to become more important. These results indicate that agencies should anticipate changes in source strengths as a consequence of land-use changes when proposing mitigation strategies and future national greenhouse gas budgets. [source] Arsenic in Glacial Aquifers: Sources and Geochemical ControlsGROUND WATER, Issue 4 2005Walton R. Kelly A total of 176 wells in sand-and-gravel glacial aquifers in central Illinois were sampled for arsenic (As) and other chemical parameters. The results were combined with archived and published data from several hundred well samples to determine potential sources of As and the potential geochemical controls on its solubility and mobility. There was considerable spatial variability in the As concentrations. High concentrations were confined to areas smaller than 1 km in diameter. Arsenic and well depth were uncorrelated. Arsenic solubility appeared to be controlled by oxidation-reduction (redox) conditions, especially the presence of organic matter. Geochemical conditions in the aquifers are typically reducing, but only in the most reducing water does As accumulate in solution. In wells in which total organic carbon (TOC) was below 2 mg/L and sulfate (SO42,) was present, As concentrations were low or below the detection limit (0.5 ,g/L). Arsenic concentrations >10 ,g/L were almost always found in wells where TOC was >2 mg/L and SO42, was absent or at low concentrations, indicating post,SO42,reducing conditions. Iron (Fe) is common in the aquifer sediments, and Fe oxide reduction appears to be occurring throughout the aquifers. Arsenic is likely released from the solid phase as Fe oxide is reduced. [source] Influence of Emergent and Submerged Macrophytes on the Structure of Planktonic Ciliate Communities in Shallow Freshwater Lakes (Eastern Poland)INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2008Tomasz Mieczan Abstract Data from two shallow macrophyte-dominated lakes (Eastern Poland) sampled with standardized methods, were evaluated in order to examine the effects of various stands of macrophytes in predicting protozooplankton community structure. Differences in macrophyte structure led to two distinct groups of habitats having different patterns of ciliate distribution. The first group consists of two vegetated habitats of sparse stem density and of the open water zone, and the second of submerged macrophyte species, which were more dense and complex. The number of significant correlations was different in the studied habitats. In central zones of macrophyte habitats the number of ciliates had the strongest correlation with concentrations of total organic carbon and Ptot. On the other side in the border zone a significant correlation between the number of ciliates and the chlorophyll a concentration was found. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Diclofenac removal from water by ozone and photolytic TiO2 catalysed processesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Juan F. García-Araya Abstract BACKGROUND: The aim of this work was to establish the efficiency of single ozonation at different pH levels (5, 7 and 9) and with different TiO2 photolytic oxidizing systems (O2/UV-A/TiO2, O3/UV-A/TiO2 or UV-A/TiO2) for diclofenac removal from water, with especial emphasis on mineralization of the organic matter. RESULTS: In the case of single ozonation processes, results show fast and practically complete elimination of diclofenac, with little differences in removal rates that depend on pH and buffering conditions. In contrast, total organic carbon (TOC) removal rates are slow and mineralization degree reaches 50% at best. As far as photocatalytic processes are concerned, diclofenac is completely removed from the aqueous solutions at high rates. However, unlike single ozonation processes, TOC removal can reach 80%. CONCLUSION: In single ozonation processes, direct ozone reaction is mainly responsible for diclofenac elimination. Once diclofenac has disappeared, its by-products are removed by reaction with hydroxyl radicals formed in the ozone decomposition and also from the reaction of diclofenac with ozone. In the photocatalytic processes hydroxyl radicals are responsible oxidant species of diclofenac removal as well as by-products. Copyright © 2010 Society of Chemical Industry [source] Effect of loading rate on TOC consumption efficiency in a sulfate reducing process: sulfide effect in batch cultureJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2008Citlali García-Saucedo Abstract BACKGROUND: The sulfate reducing process (SRP) was analyzed in order to identify factors that diminish the effectiveness of the SRP during wastewater treatment. The effect of different sulfate loading rates (SLR, 290 to 981 mg SO4 -S L,1d,1) and lactate at a stoichiometric C/S ratio of 0.75 on SRP was studied in an upflow anaerobic sludge blanket (UASB) reactor. The effect of sulfide concentration (0 to 200 mg sulfide-S L,1) on SRP in batch culture was evaluated. RESULTS: When the SLR was increased, the total organic carbon (TOC) and sulfate consumption efficiencies decreased from 93% ± 3 to 66% ± 2 and 60% ± 5 to 45% ± 4, respectively. Acetate and propionate were accumulated. Microbial analysis showed the presence of microorganisms related with the SRP, fermentation and methanogenesis. In batch culture, when lactate and sulfate were present, SRP and fermentation were observed. When sulfide was added only SRP was observed. At concentrations higher than 150 mg sulfide-S L,1 the efficiencies, yields and specific consumption rates (q) decreased. CONCLUSION: Based on the sulfide-S/volatile suspended solid ratio, it was found that the decrease in efficiency and accumulation of acetate and propionate in the UASB reactor was not related to sulfide inhibition but to the q of acetate and propionate, which were up to 11 times lower than lactate. Copyright © 2008 Society of Chemical Industry [source] An overview of the application of Fenton oxidation to industrial wastewaters treatmentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2008P Bautista Abstract This review provides updated information on the application of the Fenton process as an advanced oxidation method for the treatment of industrial wastewaters. This technology has been used in recent decades as a chemical oxidation process addressed to meet a variety of objectives including final polishing, reduction of high percentages of organic load in terms of chemical oxygen demand or total organic carbon and removal of recalcitrant and toxic pollutants thus allowing for further conventional biological treatment. The efficiency and flexibility of this technology has been proven with a wide diversity of effluents from chemical and other related industries or activities, including pharmaceutical, pulp and paper, textile, food, cork processing, and landfilling among others. Copyright © 2008 Society of Chemical Industry [source] Reductive decolourization and total organic carbon reduction of the diazo dye CI Acid Black 24 by zero-valent iron powderJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Ming-Chin Chang Abstract In this study, wastewater contaminated by colour and total organic carbon from the diazo dye CI Acid Black 24 was successfully removed by reductive decolourization with zero-valent iron powder. The effects on decolourization of experimental variables such as iron dosage, initial dye concentration, pH and dissolved oxygen level were evaluated. The best removal efficiencies for decolourization of 99.7% and total organic carbon of 57.4% were obtained with an initial dye concentration of 25.0 mg L,1 and iron dosage of 200.0 g L,1. Moreover, the decolourization rates followed pseudo-first-order kinetic equations with respect to dye concentration. The colour removal efficiency was simultaneously dependent on iron dosage and various initial dye concentrations, although the colour and total organic carbon removal efficiencies linearly increased with increased iron dosage, reaching a maximum at 100.0 g L,1. A contour plot was developed to illustrate the 3D relation of removal efficiencies with initial dye concentration and iron dosage. For wastewater with a concentration range from 25 to 100 mg L,1 CI Acid Black 24 the suggested ideal operation conditions are 100.0 g L,1 iron dosage, pH 2-4, normal oxygen concentration of 5-7 mg L,1 and reaction time of 30-60 min. Copyright © 2006 Society of Chemical Industry [source] Enhancement in mineralization of some natural refractory organic compounds by ozonation,aerobic biodegradationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006Devendra P Saroj Abstract Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry [source] Biological treatment of saline wastewaters from marine-products processing factories by a fixed-bed reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2002Neji Gharsallah Abstract Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30,g,dm,3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish-processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000,mg,COD,dm,3 day,1. Under low OLR (250,mg,COD,dm,3 day,1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000,mg,COD,dm,3 day,1. © 2002 Society of Chemical Industry [source] Kinetics of Solids Leaching During Rehydration of Particulate Dry VegetablesJOURNAL OF FOOD SCIENCE, Issue 3 2004A. MARABI ABSTRACT: Air-dried and freeze-dried carrots were rehydrated in a computerized mixing system, and the medium was analyzed for sugar content with high-performance liquid chromatography (HPLC) and for total organic carbon (TOC). Leaching of solids was significant at very short rehydration time. Understanding the mechanism of the leaching process could provide information required for simulation. TOC values were significantly higher than those derived by HPLC, indicating that other organic components were extracted. The difference between TOC and HPLC values varied with time, indicating the existence of a different mass transfer rate. Sugars and TOC values followed an exponential behavior. Quantifying solids leaching is important for modeling and simulation of the rehydration process and for product optimization. [source] PETROLEUM POTENTIAL, THERMAL MATURITY AND THE OIL WINDOW OF OIL SHALES AND COALS IN CENOZOIC RIFT BASINS, CENTRAL AND NORTHERN THAILANDJOURNAL OF PETROLEUM GEOLOGY, Issue 4 2006H. I. Petersen Oil shales and coals occur in Cenozoic rift basins in central and northern Thailand. Thermally immature outcrops of these rocks may constitute analogues for source rocks which have generated oil in several of these rift basins. A total of 56 oil shale and coal samples were collected from eight different basins and analysed in detail in this study. The samples were analysed for their content of total organic carbon (TOC) and elemental composition. Source rock quality was determined by Rock-Eval pyrolysis. Reflected light microscopy was used to analyse the organic matter (maceral) composition of the rocks, and the thermal maturity was determined by vitrinite reflectance (VR) measurements. In addition to the 56 samples, VR measurements were carried out in three wells from two oil-producing basins and VR gradients were constructed. Rock-Eval screening data from one of the wells is also presented. The oil shales were deposited in freshwater (to brackish) lakes with a high preservation potential (TOC contents up to 44.18 wt%). They contain abundant lamalginite and principally algal-derived fluorescing amorphous organic matter followed by liptodetrinite and telalginite (Botryococcus-type). Huminite may be present in subordinate amounts. The coals are completely dominated by huminite and were formed in freshwater mires. VR values from 0.38 to 0.47%Ro show that the exposed coals are thermally immature. VR values from the associated oil shales are suppressed by 0.11 to 0.28%Ro. The oil shales have H/C ratios >1.43, and Hydrogen Index (HI) values are generally >400 mg HC/g TOC and may reach 704 mg HC/ gTOC. In general, the coals have H/C ratios between about 0.80 and 0.90, and the HI values vary considerably from approximately 50 to 300 mg HC/gTOC. The HImax of the coals, which represent the true source rock potential, range from ,160 to 310 mg HC/g TOC indicating a potential for oil/gas and oil generation. The steep VR curves from the oil-producing basins reflect high geothermal gradients of ,62°C/km and ,92°C/km. The depth to the top oil window for the oil shales at a VR of ,0.70%Ro is determined to be between ,1100 m and 1800 m depending on the geothermal gradient. The kerogen composition of the oil shales and the high geothermal gradients result in narrow oil windows, possibly spanning only ,300 to 400 m in the warmest basins. The effective oil window of the coals is estimated to start from ,0.82 to 0.98%Ro and burial depths of ,1300 to 1400 m (,92°C/km) and ,2100 to 2300 m (,62°C/km) are necessary for efficient oil expulsion to occur. [source] SOURCE ROCK PROPERTIES OF LACUSTRINE MUDSTONES AND COALS (OLIGOCENE DONG HO FORMATION), ONSHORE SONG HONG BASIN, NORTHERN VIETNAMJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2005H. I. Petersen Oligocene lacustrine mudstones and coals of the Dong Ho Formation outcropping around Dong Ho, at the northern margin of the mainly offshore Cenozoic Song Hong Basin (northern Vietnam), include highly oil-prone potential source rocks. Mudstone and coal samples were collected and analysed for their content of total organic carbon and total sulphur, and source rock screening data were obtained by Rock-Eval pyrolysis. The organic matter composition in a number of samples was analysed by reflected light microscopy. In addition, two coal samples were subjected to progressive hydrous pyrolysis in order to study their oil generation characteristics, including the compositional evolution in the extracts from the pyrolysed samples. The organic material in the mudstones is mainly composed of fluorescing amorphous organic matter, liptodetrinite and alginite with Botryococcus-morphology (corresponding to Type I kerogen). The mudstones contain up to 19.6 wt.% TOC and Hydrogen Index values range from 436,572 mg HC/g TOC. From a pyrolysis S2 versus TOC plot it is estimated that about 55% of the mudstones'TOC can be pyrolised into hydrocarbons; the plot also suggests that a minimum content of only 0.5 wt.% TOC is required to saturate the source rock to the expulsion threshold. Humic coals and coaly mudstones have Hydrogen Index values of 318,409 mg HC/g TOC. They are dominated by huminite (Type III kerogen) and generally contain a significant proportion of terrestrial-derived liptodetrinite. Upon artificial maturation by hydrous pyrolysis, the coals generate significant quantities of saturated hydrocarbons, which are probably expelled at or before a maturity corresponding to a vitrinite reflectance of 0.97%R0. This is earlier than previously indicated from Dong Ho Formation coals with a lower source potential. The composition of a newly discovered oil (well B10-STB-1x) at the NE margin of the Song Hong Basin is consistent with contributions from both source rocks, and is encouraging for the prospectivity of offshore half-grabens in the Song Hong Basin. [source] | ||||||||||||||||||||||