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Organic Matter Concentrations (organic + matter_concentration)
Selected AbstractsContext-dependent effects of freshwater mussels on stream benthic communitiesFRESHWATER BIOLOGY, Issue 6 2006DANIEL E. SPOONER Summary 1. We asked whether unionid mussels influence the distribution and abundance of co-occurring benthic algae and invertebrates. In a yearlong field enclosure experiment in a south-central U.S. river, we examined the effects of living mussels versus sham mussels (shells filled with sand) on periphyton and invertebrates in both the surrounding sediment and on mussel shells. We also examined differences between two common unionid species, Actinonaias ligamentina (Lamarck 1819) and Amblema plicata (Say 1817). 2. Organic matter concentrations and invertebrate densities in the sediment surrounding mussels were significantly higher in treatments with live mussels than treatments with sham mussels or sediment alone. Organic matter was significantly higher in the sediment surrounding Actinonaias than that surrounding Amblema. Actinonaias was more active than Amblema and may have increased benthic organic matter through bioturbation. 3. Living mussels increased the abundance of periphyton on shells and the abundance and richness of invertebrates on shells, whereas effects of sham mussels were similar to sediment alone. Differences in the amount of periphyton growing on the shells of the two mussel species reflected differences in mussel activity and shell morphology. 4. Differences between living and sham mussel treatments indicate that biological activities of mussels provide ecosystem services to the benthic community beyond the physical habitat provided by shells alone. In treatments containing live mussels we found significant correlations between organic matter and chlorophyll a concentrations in the sediment, organic matter concentrations and invertebrate abundance in the sediment and the amount of chlorophyll a on the sediment and invertebrate abundance. There were no significant correlations among these response variables in control treatments. Thus, in addition to providing biogenic structure as habitat, mussels likely facilitate benthic invertebrates by altering the availability of resources (algae and organic matter) through nutrient excretion and biodeposition. 5. Effects of mussels on sediment and shell periphyton concentrations, organic matter concentrations and invertebrate abundance, varied seasonally, and were strongest in late summer during periods of low water volume, low flow, and high water temperature. 6. Our study demonstrates that freshwater mussels can strongly influence the co-occurring benthic community, but that effects of mussels are context-dependent and may vary among species. [source] Anaerobic biodegradation of two-phase olive mill solid wastes and liquid effluents: kinetic studies and process performanceJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2006Rafael Borja Abstract The new two-phase olive oil mills produce three identifiable and separate waste streams, namely (1) the wash waters from the initial cleansing of the fruit, (2) the aqueous solid residues from the primary centrifugation and (3) the wash waters from the secondary centrifugation. As well as offering process advantages, they also consume less water. Therefore the solid residue, two-phase olive mill solid waste (OMSW), has a high organic matter concentration, giving it an elevated polluting load, and cannot be easily handled by traditional technology which deals with the conventional three-phase olive cake. In addition, the new two-phase olive mill effluents (TPOME) are made up of a mixture of effluents (1) and (3), the total volume of TPOME generated being ,0.25 dm3 kg,1 olives processed. This review aims to report the main features and characteristics of two-phase OMSW and TPOME as compared with the classical olive cake and olive mill wastewater (OMW) derived from the three-phase manufacturing process. The advantages and disadvantages of the two-phase decanting process are summarised. The anaerobic digestibility of two-phase OMSW using different influent substrate concentrations is reported. Kinetic studies of anaerobic digestion of two-phase OMSW are also reviewed and summarised, as well as mass balances to predict the behaviour of the reactor and simplified kinetic models for studying the hydrolysis, acidogenic and methanogenic steps of one- and two-stage anaerobic digestion of OMSW. The review also includes the following: assays of anaerobic digestion of wastewaters from the washing of olives, of olive oil and the two together using fluidised beds and hybrid reactors; the kinetics, performance, stability, purification efficiencies and methane yield coefficients. Copyright © 2006 Society of Chemical Industry [source] Factors Affecting Sediment Oxygen Demand in Commercial Channel Catfish PondsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2004James A. Steeby Sediment oxygen demand (SOD) measured in 45 commercial channel catfish ponds in northwest Mississippi using in situ respirometry (N = 167) ranged from 63 to 1,038 mg/m2 per h. Mean SOD in this study (359 mg/m2 per h) was greater than that reported previously for catfish ponds but was similar to SOD in semi-intensive marine shrimp ponds. Nine variables were selected and measured to assess their relative importance in accounting for variation in SOD. Six variables were included in multiple regression models that explained slightly more than half of the variation in SOD. These variables were: dissolved oxygen concentration at the beginning of respirometry incubation:, particulate organic matter concentration in water above the sediment surface: organic carbon concentration at the immediate sediment-water interface (flocculent or F-layer) combined with the upper 2 cm of sediment (S-layer); organic carbon concentration in the mature (M) underlying sediment layer: water temperature: and total depth of accumulated sediment. Sediment oxygen demand was most sensitive to changes in dissolved oxygen concentration in the overlying water, particulate organic matter concentration in the water, and the concentration of organic carbon in the combined flocculent and upper sediment (F+S) layer. Models for SOD in this research predict that the mass of sediment below the upper 2-cm surface layer on average contributes only ,20% of total SOD. Stratification and normal daily fluctuation of dissolved oxygen concentration in eutrophic culture ponds likely limit expression of sediment oxygen demand. Maintaining aerobic conditions at the sediment-water interface will minimize accumulation of organic matter in pond sediment. [source] Damage to DNA in Bacterioplankton: A Model of Damage by Ultraviolet Radiation and its Repair as Influenced by Vertical Mixing ,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2000Yannick Huot ABSTRACT A model of UV-induced DNA damage in oceanic bacterioplankton was developed and tested against previously published and novel measurements of cyclobutane pyrimidine dimers (CPD) in surface layers of the ocean. The model describes the effects of solar irradiance, wind-forced mixing of bacterioplankton and optical properties of the water on net DNA damage in the water column. The biological part includes the induction of CPD by UV radiation and repair of this damage through photoreactivation and excision. The modeled damage is compared with measured variability of CPD in the ocean: diel variation in natural bacterioplankton communities at the surface and in vertical profiles under different wind conditions (net damage as influenced by repair and mixing); in situ incubation of natural assemblages of bacterioplankton (damage and repair, no mixing); and in situ incubation of DNA solutions (no repair, no mixing). The model predictions are generally consistent with the measurements, showing similar patterns with depth, time and wind speed. A sensitivity analysis assesses the effect on net DNA damage of varying ozone thickness, colored dissolved organic matter concentration, chlorophyll concentration, wind speed and mixed layer depth. Ozone thickness and mixed layer depth are the most important factors affecting net DNA damage in the mixed layer. From the model, the total amplification factor (TAF; a relative measure of the increase of damage associated with a decrease in ozone thickness) for net DNA damage in the euphotic zone is 1.7, as compared with 2.1,2.2 for irradiance weighted for damage to DNA at the surface. [source] Context-dependent effects of freshwater mussels on stream benthic communitiesFRESHWATER BIOLOGY, Issue 6 2006DANIEL E. SPOONER Summary 1. We asked whether unionid mussels influence the distribution and abundance of co-occurring benthic algae and invertebrates. In a yearlong field enclosure experiment in a south-central U.S. river, we examined the effects of living mussels versus sham mussels (shells filled with sand) on periphyton and invertebrates in both the surrounding sediment and on mussel shells. We also examined differences between two common unionid species, Actinonaias ligamentina (Lamarck 1819) and Amblema plicata (Say 1817). 2. Organic matter concentrations and invertebrate densities in the sediment surrounding mussels were significantly higher in treatments with live mussels than treatments with sham mussels or sediment alone. Organic matter was significantly higher in the sediment surrounding Actinonaias than that surrounding Amblema. Actinonaias was more active than Amblema and may have increased benthic organic matter through bioturbation. 3. Living mussels increased the abundance of periphyton on shells and the abundance and richness of invertebrates on shells, whereas effects of sham mussels were similar to sediment alone. Differences in the amount of periphyton growing on the shells of the two mussel species reflected differences in mussel activity and shell morphology. 4. Differences between living and sham mussel treatments indicate that biological activities of mussels provide ecosystem services to the benthic community beyond the physical habitat provided by shells alone. In treatments containing live mussels we found significant correlations between organic matter and chlorophyll a concentrations in the sediment, organic matter concentrations and invertebrate abundance in the sediment and the amount of chlorophyll a on the sediment and invertebrate abundance. There were no significant correlations among these response variables in control treatments. Thus, in addition to providing biogenic structure as habitat, mussels likely facilitate benthic invertebrates by altering the availability of resources (algae and organic matter) through nutrient excretion and biodeposition. 5. Effects of mussels on sediment and shell periphyton concentrations, organic matter concentrations and invertebrate abundance, varied seasonally, and were strongest in late summer during periods of low water volume, low flow, and high water temperature. 6. Our study demonstrates that freshwater mussels can strongly influence the co-occurring benthic community, but that effects of mussels are context-dependent and may vary among species. [source] Development of a membrane-assisted hybrid bioreactor for ammonia and COD removal in wastewatersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2005Vinka Oyanedel Abstract A new membrane-assisted hybrid bioreactor was developed to remove ammonia and organic matter. This system was composed of a hybrid circulating bed reactor (CBR) coupled in series to an ultrafiltration membrane module for biomass separation. The growth of biomass both in suspension and biofilms was promoted in the hybrid reactor. The system was operated for 103 days, during which a constant ammonia loading rate (ALR) was fed to the system. The COD/N-NH4+ ratio was manipulated between 0 and 4, in order to study the effects of different organic matter concentrations on the nitrification capacity of the system. Experimental results have shown that it was feasible to operate with a membrane hybrid system attaining 99% chemical oxygen demand (COD) removal and ammonia conversion. The ALR was 0.92 kg N-NH4+ m,3 d,1 and the organic loading rate (OLR) achieved up to 3.6 kg COD m,3 d,1. Also, the concentration of ammonia in the effluent was low, 1 mg N-NH4+ dm,3. Specific activity determinations have shown that there was a certain degree of segregation of nitrifiers and heterotrophs between the two biomass phases in the system. Growth of the slow-growing nitrifiers took place preferentially in the biofilm and the fast-growing heterotrophs grew in suspension. This fact allowed the nitrifying activity in the biofilm be maintained around 0.8 g N g,1 protein d,1, regardless of the addition of organic matter in the influent. The specific nitrifying activity of suspended biomass varied between 0.3 and 0.4 g N g,1 VSS d,1. Copyright © 2004 Society of Chemical Industry [source] Temporal and spatial patterns based on sediment and sediment,water interface characteristics along a cascade of reservoirs (Paranapanema River, south-east Brazil)LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2005Adriana Jorcin Abstract Physical and chemical characteristics of the sediments in a cascade of eight reservoirs located in the Paranapanema River (south-east Brazil) were analysed during two consecutive years during summer (January), autumn (April), winter (July) and spring (October) of 2000 and 2001, respectively. The granulometric texture, organic matter content and nutrient concentration (total nitrogen and phosphorus) were determined in the superficial sediment of 19 sampling stations, as well as the temperature, dissolved oxygen, pH, conductivity and redox potential in the bottom layer of the water column. Seasonal and spatial changes were observed for both years, especially for organic matter and nutrient concentrations. Three different areas could be identified along the river, which corresponded to the upper, middle and lower Paranapanema basin. The first area was characterized by an increase of nutrients and organic matter in the sediments and a decrease of temperature and dissolved oxygen in the downstream direction. The second one represented a region where fluctuations in nutrient and organic matter concentrations and a reduction in dissolved oxygen were observed. In the third area, there was an increase in nutrient and organic matter in the sediments and also an increase in temperature and dissolved oxygen towards the river mouth. The results of the principal components analysis, using water and sediments variables, showed the ordination of sampling stations by periods: wet (January,April) and dry (July,October) during 2000. This pattern was also verified during 2001, but with slight changes, probably due to the increase in the rains which would have produced certain homogenization effects along the river. [source] Trophic state, fish community and intensive production of salmonids in Alicura Reservoir (Patagonia, Argentina)LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 4 2001P. F. Temporetti Abstract The Governments of the Provinces located in Patagonia, Argentina, promote the intensive breeding of salmonids in the Andean Patagonian region. Although annual production is low (450 ton ha,1 year,1), some effects are significant. Waste produced by salmonid breeding (feed losses, faeces and excretion) increases nutrient and organic matter concentrations, which cause modifications of water quality, sediments and biota. A consequent risk is the elevation of eutrophication levels. Possible changes in water composition, sediments, algae and wild fish populations were studied. Sites affected by fish farming showed increased nutrient concentration, and phytoplankton and periphyton biomass. Chlorophyll a was similar at both sites (affected and unaffected by fish farm sites). Sediments clearly reflect fish farm waste inputs: total phosphorus and organic matter increased 12-fold and fourfold, respectively. The species present in the gill-net catches were the autochthonous Percichthys trucha, Odontesthes hatcheri, Diplomystes viedmensis, and the introduced salmonids Oncorhynchus mykiss, Salmo trutta, Salmo salar sebago and Salvelinus fontinalis. About 50% of the total catch was salmonids. A major portion of the catch per unit weight was composed of rainbow trout, followed by perch. The catch per unit weight obtained for this reservoir agrees with the range of values previously determined (Quiros 1990) for Patagonian reservoirs. Compared with previous studies by Freyre et al. (1991), a variation in catch composition exists. This consists mainly of an increase in the numbers and condition of O. mykiss and a decrease in P. trucha. Presence of fish that escaped from hatcheries, recognizable by their eroded fins, was observed; particularly in a sampling station near the fish cage systems. Variations in catches could be caused by cyclical changes in fish populations (Wooton 1991), by direct and indirect effects of intensive fish farming, or by a combination of both events, and can only be understood through long-term studies of catch variation. [source] | |||||||||||||