The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
David L. Sedlak - One of the best experts on this subject based on the ideXlab platform.
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The Speciation and Reactivity of Wastewater-Derived Organic Nitrogen
2004Co-Authors: David L. Sedlak, Elif PehlivanogluAbstract:Nitrogen often is the limiting nutrient for the growth of algae and phytoplankton in estuaries and surface waters in California. To control cultural eutrophication (i.e., excessive growth of algae and plankton related to anthropogenic sources) regulatory agencies often focus on the control of point source discharges, including municipal wastewater effluent. Recent attempts to control cultural eutrophication in Nitrogen-limited systems have focused on the simultaneous control of all forms of inOrganic Nitrogen with the underlying assumption that inOrganic and Organic Nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted using denitrified wastewater effluent samples that contained mainly Organic Nitrogen. The growth assays were performed with a species of algae (Selenastrum Capricornutum) that is commonly used for regulatory compliance monitoring. Results of the study indicate that the wastewater-derived dissolved Organic Nitrogen (DON) is not bioavailable to the algae in the absence of bacteria. However, approximately half of the wastewater-derived Organic Nitrogen was available to the algae in the presence of bacteria during a two-week incubation. In conjunction with the experiments on bioavailability, the nature and properties of wastewater-derived Organic Nitrogen was characterized by measuring concentrations of free and combined amino acids and by subjecting wastewater effluent samples to ultrafiltration. Results of these experiments indicate that most of the wastewater-derived Organic Nitrogen was associated with unidentified compounds that are capable of passing through a 1 kDa ultrafilter. Wastewater-derived Organic Nitrogen also plays an important role in the formation of the carcinogenic disinfection byproduct, N-nitrosodimethylamine (NDMA). NDMA is formed when wastewater effluent is disinfected with chlorine. It also can be formed when surface water or groundwater that has been impacted by wastewater effluent discharges undergoes disinfection in drinking water treatment plants. Recently, concerns associated with NDMA have caused great concern among utilities that practice indirect potable water reuse. Most of the attention to date has focused on the removal of NDMA from the treated wastewater effluent. However, the presence of NDMA precursors also could be a problem if the NDMA precursors in drinking sources are stable after they are discharged because they could result in NDMA formation during drinking water treatment. To assess the stability of NDMA precursors associated with wastewater-derived Organic Nitrogen, NDMA precursor concentrations were measured in effluent samples before and after incubation with bacteria under aerobic conditions. Results of the experiments indicate that the NDMA precursors are stable for at least 30 days. These results suggest that wastewater-derived Organic Nitrogen consists of complex compounds that are not very reactive. However, under certain conditions, wastewater-derived Organic Nitrogen species can serve as a source of nutrients in Nitrogen-limited systems and as disinfection byproduct precursors. The results of this research will be useful in the development of indirect potable water reuse systems and the design of watershed protection plans designed to protect aquatic ecosystems from the effects of cultural eutrophication.
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Bioavailability of wastewater-derived Organic Nitrogen to the alga Selenastrum Capricornutum.
Water research, 2004Co-Authors: Elif Pehlivanoglu, David L. SedlakAbstract:Recent attempts to control cultural eutrophication in Nitrogen-limited systems have focused on the simultaneous control of all forms of Nitrogen with the underlying assumption that inOrganic and Organic Nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted on denitrified wastewater effluent samples, in the presence and absence of bacteria isolated from an effluent-receiving surface water. Bioassay results indicated that wastewater-derived dissolved Organic Nitrogen (DON) is not bioavailable to the algae Selenastrum Capricornutum in the absence of bacteria. However, approximately half of the wastewater-derived Organic Nitrogen was available to the algae in the presence of bacteria during a 2-week incubation. These results suggest that while it is inappropriate to assume that wastewater-derived DON cannot cause cultural eutrophication, it will not cause as much eutrophication as inOrganic Nitrogen. Additional research is needed to develop methods of minimizing the discharge of bioavailable forms of wastewater-derived Organic Nitrogen by wastewater treatment plants.
Elif Pehlivanoglu - One of the best experts on this subject based on the ideXlab platform.
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The Speciation and Reactivity of Wastewater-Derived Organic Nitrogen
2004Co-Authors: David L. Sedlak, Elif PehlivanogluAbstract:Nitrogen often is the limiting nutrient for the growth of algae and phytoplankton in estuaries and surface waters in California. To control cultural eutrophication (i.e., excessive growth of algae and plankton related to anthropogenic sources) regulatory agencies often focus on the control of point source discharges, including municipal wastewater effluent. Recent attempts to control cultural eutrophication in Nitrogen-limited systems have focused on the simultaneous control of all forms of inOrganic Nitrogen with the underlying assumption that inOrganic and Organic Nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted using denitrified wastewater effluent samples that contained mainly Organic Nitrogen. The growth assays were performed with a species of algae (Selenastrum Capricornutum) that is commonly used for regulatory compliance monitoring. Results of the study indicate that the wastewater-derived dissolved Organic Nitrogen (DON) is not bioavailable to the algae in the absence of bacteria. However, approximately half of the wastewater-derived Organic Nitrogen was available to the algae in the presence of bacteria during a two-week incubation. In conjunction with the experiments on bioavailability, the nature and properties of wastewater-derived Organic Nitrogen was characterized by measuring concentrations of free and combined amino acids and by subjecting wastewater effluent samples to ultrafiltration. Results of these experiments indicate that most of the wastewater-derived Organic Nitrogen was associated with unidentified compounds that are capable of passing through a 1 kDa ultrafilter. Wastewater-derived Organic Nitrogen also plays an important role in the formation of the carcinogenic disinfection byproduct, N-nitrosodimethylamine (NDMA). NDMA is formed when wastewater effluent is disinfected with chlorine. It also can be formed when surface water or groundwater that has been impacted by wastewater effluent discharges undergoes disinfection in drinking water treatment plants. Recently, concerns associated with NDMA have caused great concern among utilities that practice indirect potable water reuse. Most of the attention to date has focused on the removal of NDMA from the treated wastewater effluent. However, the presence of NDMA precursors also could be a problem if the NDMA precursors in drinking sources are stable after they are discharged because they could result in NDMA formation during drinking water treatment. To assess the stability of NDMA precursors associated with wastewater-derived Organic Nitrogen, NDMA precursor concentrations were measured in effluent samples before and after incubation with bacteria under aerobic conditions. Results of the experiments indicate that the NDMA precursors are stable for at least 30 days. These results suggest that wastewater-derived Organic Nitrogen consists of complex compounds that are not very reactive. However, under certain conditions, wastewater-derived Organic Nitrogen species can serve as a source of nutrients in Nitrogen-limited systems and as disinfection byproduct precursors. The results of this research will be useful in the development of indirect potable water reuse systems and the design of watershed protection plans designed to protect aquatic ecosystems from the effects of cultural eutrophication.
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Bioavailability of wastewater-derived Organic Nitrogen to the alga Selenastrum Capricornutum.
Water research, 2004Co-Authors: Elif Pehlivanoglu, David L. SedlakAbstract:Recent attempts to control cultural eutrophication in Nitrogen-limited systems have focused on the simultaneous control of all forms of Nitrogen with the underlying assumption that inOrganic and Organic Nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted on denitrified wastewater effluent samples, in the presence and absence of bacteria isolated from an effluent-receiving surface water. Bioassay results indicated that wastewater-derived dissolved Organic Nitrogen (DON) is not bioavailable to the algae Selenastrum Capricornutum in the absence of bacteria. However, approximately half of the wastewater-derived Organic Nitrogen was available to the algae in the presence of bacteria during a 2-week incubation. These results suggest that while it is inappropriate to assume that wastewater-derived DON cannot cause cultural eutrophication, it will not cause as much eutrophication as inOrganic Nitrogen. Additional research is needed to develop methods of minimizing the discharge of bioavailable forms of wastewater-derived Organic Nitrogen by wastewater treatment plants.
Eugenio Sanhueza - One of the best experts on this subject based on the ideXlab platform.
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Soluble Organic Nitrogen in Venezuelan rains
Tellus B: Chemical and Physical Meteorology, 2004Co-Authors: Milexi Pacheco, Loreto Donoso, Eugenio SanhuezaAbstract:We present data which show that soluble Organic Nitrogen (SON) is an important component of tropical continental rains, especially in remote unpolluted sites where it represents up to 90% of the total soluble Nitrogen. The inclusion of SON wet deposition in the N budget significantly increases the N nutrient input to the soil vegetation reservoir of Venezuelan ecosystems.
Mechthild Tegeder - One of the best experts on this subject based on the ideXlab platform.
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Transporters for uptake and allocation of Organic Nitrogen compounds in plants
FEBS Letters, 2007Co-Authors: Doris Rentsch, Susanne Schmidt, Mechthild TegederAbstract:Nitrogen is an essential macronutrient for plant growth. Following uptake from the soil or assimilation within the plant, Organic Nitrogen compounds are transported between organelles, from cell to cell and over long distances in support of plant metabolism and development. These translocation processes require the function of integral membrane transporters. The review summarizes our current understanding of the molecular mechanisms of Organic Nitrogen transport processes, with a focus on amino acid, ureide and peptide transporters.
Yuuya Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Water-soluble and water-insoluble Organic Nitrogen in the dry and wet deposition
Atmospheric Environment, 2019Co-Authors: Kiyoshi Matsumoto, Keisuke Sakata, Yuuya WatanabeAbstract:Abstract The simultaneous observation of the water-soluble and water-insoluble Nitrogen species in the wet deposition, dry deposition, aerosols, and gas phase was conducted for 1 year at an urban site in Japan to clarify the deposition amount and mechanisms of the Organic Nitrogen species from the atmosphere. The wet deposition amounts of the water-soluble Organic Nitrogen (WSON) and water-insoluble Organic Nitrogen (WION) were 0.331 and 0.081 mgN m−2 day−1, respectively, on average, which occupied about 80% and 20% of the Organic Nitrogen (ON) and about 20% and 5% of the total Nitrogen (TN) in the wet deposition, respectively. Organic Nitrogen compounds, especially WSON, significantly contributed to the Nitrogen deposition through the wet process. The dry deposition amounts of the WSON and WION were 0.042 and 0.050 mgN m−2 day−1, respectively, on average, which occupied about 46% and 54% of the ON and about 28% and 33% of the TN in the dry deposition, respectively. Compared to the wet process, Organic Nitrogen compounds, especially the WION, more significantly contributed to the Nitrogen deposition through the dry process. The dry deposition amount of the WSON and WION contributed about 11% and 38% of their total (wet + dry) deposition, respectively. A significant fraction of the WSON deposition was derived from the dry process, but a large portion of the WSON deposition can be explained by the wet process. A larger contribution of the dry process to the atmospheric deposition was found for the WION deposition, although the wet process was an important deposition pathway even for the WION. The wet deposition amount of the WSON was strongly influenced by the WSON concentration in the rainwater, and would be affected by the uptake of the WSON into the rainwater in the upper atmosphere. The wet deposition amount of the WION was strongly affected by the uptake of the WION in the aerosols with diameters larger than 10 μm (PM>10) in the surface atmosphere. A higher scavenging ratio was found for the WSON than for the WION, which supports these uptake processes. The dry deposition amount of the WSON was affected by the concentration of the gaseous basic WSON, whereas that of the WION was strongly influenced by the WION concentration in the PM>10, which are supported by the measurements of these Organic Nitrogen species in the aerosols and gas phase and the estimates of their deposition velocities from the resistance model.