Dixon L.K.,Mote Marine Laboratory |
Murphy P.J.,HydrO Inc. |
Becker N.M.,Mote Marine Laboratory |
Charniga C.M.,Mote Marine Laboratory
Harmful Algae | Year: 2014
The project "EcoHAB: Karenia Nutrient Dynamics in the Eastern Gulf of Mexico" (NOAA EcoHAB grant NA06NOS4780246) was designed to simultaneously quantify a wide variety of nutrient sources which can support the nearly annual blooms of Karenia brevis in the estuarine and coastal waters of west central Florida. Estuarine outflows and water column stocks of nutrients have been previously demonstrated to be insufficient to support the observed cell densities (>106cellL-1) which K. brevis can achieve. Nutrients released from sediments, however, are a nutrient source common to offshore, coastal, and estuarine environments. Prior regional measurements were generally lacking, particularly in coastal waters. Dark-only nutrient fluxes from the sediments were directly measured using large (65L, 0.27m2), in situ, opaque, stirred chambers deployed over 5-8h. Stations were located in coastal waters, a lagoonal system, and in the lower portions of two major estuaries, Tampa Bay and Charlotte Harbor, and were sampled during the fall of 2007-2009. Field procedures included triplicate chambers at each station and a water column control. Fluxes were quantified for dissolved oxygen, and dissolved ammonium, nitrate-nitrite, urea, total nitrogen, orthophosphorus, total phosphorus, and silica. Fluxes were dominated by dissolved silica (900-13,800μmolm-2d-1), ammonium (430-3360μmolm-2d-1) and ortho-phosphorus (50-1200μmolm-2d-1) and were greater than literature values which had been previously incorporated in local ecological modeling efforts. Based on literature growth rates and on cell complement data, the measured sediment flux of nutrients could have provided up to 300% of P requirements, and up to 100% of N requirements of 50,000cellsL-1 of K. brevis, modified by water depth. Flux values, derived from dark incubation and applied to Karenia cells only, likely represented an upper boundary of sediment contributions to Karenia nutrient budgets. Density stratifications common to upwelling coastal plumes and migratory behavior of K. brevis would have increased the percentage of supply afforded by sediment flux. Despite ammonium to ortho-phosphorus ratios in sediment flux substantially less than Redfield, ammonium flux provided a larger fraction of growth needs due to low levels of water column DIN concentrations (averaging 1.0μmolL-1). Fluxes enriched in P were consistent with bulk sediment P and the P-enriched geology of the region, and would have complemented N supplied by common nitrogen fixers such as Trichodesmium sp. © 2014 Elsevier B.V.
Bloch H.P.,Hydro Inc |
Bluse B.,Hydro Inc
Hydrocarbon Processing | Year: 2011
Starting with the late 1980s, considerable consolidation and re-shuffling has affected the pump industry. Some of the big name pump producers, the "legacy manufacturers," have vanished from the scene. As their process pumps age and undergo repairs, component geometry needs to be restored. New and improved metallurgies must be selected. Asset optimization requires upgrading the weak-link components and optimizing hydraulic efficiencies. Traditional restoration and merely doing routine maintenance by quick fixes are rarely the wisest course of action. That said, this overview and a recent case history deal with pumps in the 100-kW and larger size categories. It is in these sizes that the loss of legacy brand experience makes itself felt. Some original equipment manufacturers (OEMs) are no longer staffed with primarily experienced personnel, and there are repercussions. At times the now often less knowledgeable OEM employees are, in some instances, ill-equipped to work with the owner-operator of these pumps. In contrast, a few competent pump repair shops (CPRSs) are diligently nurturing CPRS-owner/user cooperation. However, smart owner-operators realize that essential non-OEM capabilities must be defined. Surveys are made to define pre-repair and anticipated post-repair mechanical reliability and hydraulic efficiency achievements. Such surveys represent the first stage in a critically important sequence of interactions between the CPRS and the pump owner or customer. All culminate in combining expert repairs with substantial upgrading so as to reduce the risk of incurring repeat failures.
Hydro Inc. | Date: 2012-01-31
Pumps for machines; pump impellers; valves for pumps; valves being parts of machines.