Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its ...role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August–September 2008) and dry (March–April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m−3 and 0.11–0.56 μg-N m−3 in total suspended particles samples and between 0.08 and 0.54 mg-N l−1 and 0.02–1.3 mg-N l−1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year−1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.
•TDN atmospheric deposition induced primary productivity to the Cariaco basin could replace 20% and 40% of C and N removed by sediment burial, respectively.•Anthropogenic sources of N could contribute to 30% of TDN atmospheric deposition in the basin.•Reduced DON (gas + particles) could represent a significant fraction of the bulk N deposition in the basin.
Protection scheme testing using a power system model Jodice, J.A.; Giuliante, A.T.
Conference proceedings - Canadian Conference on Electrical and Computer Engineering,
1996, Letnik:
2
Conference Proceeding, Journal Article
This paper describes a new method for testing relay schemes and relay panels. The new procedure is based on a power system model that is used to simulate different events selected according to the ...application. Events are played back through power system simulators that also monitor scheme performance. The advantages of the method are briefly discussed. The authors describe the method in more detail, and then describe the INSITE expert system to monitor the power system and the components in it to watch for changes in system operation.
A directional wave detector relay capable of fulfilling the high-speed or ultrahigh-speed (UHS) protection requirements for EHV and UHV transmission lines is described. The results of combining ...directional wave detection with a sequential measurement distance relay and a sensitive ground overcurrent unit are discussed. Multiple functions operating in series and parallel enhance the security and dependability by mutual support whereby the inherent strengths of each measurement technique are used to improve the characteristics of others. Solutions for difficult application problems are presented. In addition, economic considerations are noted for increased power transfer and reduced circuit breaker costs.
Treatment of xanthoma of the Achilles tendon has up until the present been based on partial or total surgical resection of the affected tendon. Because of the different results of surgical treatment ...our study was aimed at using clinical and ultrasound data to reveal the effectiveness of hypocholesteremic medical therapy in 39 cases of tendinous xanthoma.
An introduction is presented to the trial use standard ANSI/IEEE C37.90.2, Withstand Capability of Relay System to Radiated Electromagnetic Interference from Transceivers. This introduction provides ...background information on the need for the standard, a summary of the withstand test parameters and procedures, and some of the comments which have been made on the standard. Misoperations experienced, effects of RFI (radio-frequency interference) on static relay circuitry, failure modes, and test parameters are discussed
An histological and E.M. study has been performed on rat's intestinal tract resection to evaluate CO2 laser effects. Necrotic effect of laser is evident up to 120 micron. While the intestinal tissue ...results normal at 480 micron from resection line. Muscular and fibrous components appear more resistant to damage while E.M. presents a new organization of its components forming a new compact and continue tissue. This new organization may be involved in the protection of the subepithelial spaces, and may have an important role in intestinal anastomosis scar process.
An introduction is presented to the trial use standard ANSI/IEEE C37.90.2, Withstand Capability of Relay System to Radiated Electromagnetic Interference from Transceivers. This introduction provides ...background information on the need for the standard, a summary of the withstand test parameters and procedures, and some of the comments which have been made on the standard. Misoperations experienced, effects of RFI (radio-frequency interference) on static relay circuitry, failure modes, and test parameters are discussed.< >
Concentrations of water soluble organic nitrogen (WSON) were determined in atmospheric total suspended particles (TSP) collected between September of 2005 and May of 2006, in an urban continental ...(Caracas, 10 deg 29' 09'' N, 66 deg 53' 48'' W), an urban coastal (Catia la mar, 10 deg 35' 47'' N, 67 deg 01' 45'' W), a sub-urban coastal (Osma, 10 deg 32' N, 67 deg 28' W), a suburban continental (Altos de Pipe, 10 deg 23' 41'' N, 63 deg 59' 10'' W), a pristine coastal (Isla de Aves, 15 deg 40' N, 63 deg 36' W) and a pristine continental (La Gran Sabana National Park, 5 deg 41' 30'' N, 61 deg 34' 20'' W) areas of Venezuela. TSP samples were collected using a Hi-Vol airborne particle sampler. TSP were impacted on a fiberglass filter pretreated under 400 deg C for 4 hours to minimize organic nitrogen contamination. Ultra sound water extractions of the sample filters were performed and their NH4+, NO2- and NO3- concentrations were determined by ion exchange liquid chromatography. The water extracts were UV digested and the nitrogen inorganic ions were analyzed after the UV exposure. WSON concentrations were calculated by the difference between the inorganic nitrogen concentrations before and after UV digestion. Ninety five percent of the aerosol samples collected in the suburban and pristine areas showed a WSON concentration range from 0.03 to 0.6 mug/m3 whereas in urban areas the range was 0.21 to 1.09 mug/m3. These concentration values are on the same order of magnitude than the previously found in other tropical and subtropical areas. The contribution of aerosol WSON to the total soluble nitrogen in the coastal urban, sub-urban and pristine areas ranged from 23 to 67%, while in Caracas was smaller (38+/-8%, n=5). Therefore, aerosol WSON provides an important source of nitrogen to these pristine and suburban ecosystems, which could potentially have implications on the nutrient cycling. There was a statistically significant linear correlation between the aerosol WSON and the water soluble inorganic nitrogen (WSIN) for the urban coastal, sub-urban and pristine zones (R2= 0.81, n=22). This correlation could be explained by a possible source of secondary water soluble organic aerosols derived by the reaction between biogenic volatile organic compounds (VOCs), such as isoprene, and nitrogen oxides (NOx) present in the atmosphere of these regions. Such correlation was not found in Caracas, possibly due to the fact that in this city the major source of VOCs is fossil fuel combustion which produces mostly non soluble aliphatic VOCs. These compounds could most likely produce low water soluble secondary organic nitrogen aerosols.
