Saltwater Environments Research Articles

New Airport Distribution System with Closed-Loop Circuit - Remote Operation and Monitoring

Unique distribution design to accommodate load growth for an airport facility features an economic approach to sectionalizing and supervisory control. A distribution vacuum interrupter switch with automatic controls provides low-cost light-duty breaker functions to upgrade the existing facility. Unusual equipment mounting positions, particularly high-voltage switchgear hung from hallway ceilings, save valuable space and construction costs. A new ring main bus arrangement with central dispatch and control is described. The design is geared to provide maximum continuity for a system whose XLP cables are exposed to a salt water environment.

Meren Field-An Engineering Review

Summary This paper describes the engineering process required to formulate a comprehensive plan to deplete eight major oil reservoir units in the Meren field simultaneously. The multidisciplined effort involved computed log analyses, core analyses, material-balance studies, cross-sectional simulation studies, and simulation of certain reservoirs. Computer simulation of candidate reservoirs indicated that the injection of water increased recovery to a greater extent than the injection of gas. The studies also verified that the reservoirs may be treated as homogeneous units. Primary recovery was calculated to be 38% of the original oil in place (OOIP). The engineering study recommended that 200,000 B/D seawater be injected into the eight major reservoir units. Water injection would increase recovery from the Meren field by 121.7 million bbl oil. Ultimate recovery for the reservoir candidates would be increased to 48% of the oil in place (OIP). Introduction The Meren field is located in federal offshore waters off Bendel State, Nigeria. The water depth in the field varies from 48 to 60 ft. The field is owned jointly by the Nigerian Natl. Petroleum Corp. (NNPC) and Gulf Oil Co. (Nigeria) Ltd. (GOCON). The field was discovered in 1965, with first production occurring in Sept. 1968. Fifty-seven wells have been drilled in the field, three of which are dry holes. As of July 1, 1980, the field had produced 347,194,961 STB oil, 321,545,190 Mcf gas, and 10, 123, 132 bbl water. The continued pressure decline during the producing life of the field prompted an in-depth investigation into the remaining potential. All major reservoirs in the field were found to have very low maximum efficient rates (MER's) in relation to the quantity of remaining reserves. The worst-case reservoir (Reservoir G1-G2/A) was found to have a producing life extending to the year 2010 at an MER of 4,000 BOPD. The installation of some type of pressure-maintenance project would accelerate field depletion to within a reasonable time frame. A feasibility study was initiated on the Meren field in 1978 to determine the potential for improving the recovery. The study is reported in a companion paper (see Page 2095). A generalized plan to deplete all candidate reservoirs in the Meren field simultaneously evolved early in the study. This type of field-depletion scheme appeared to offer a practical remedy to the following problems.The field production platforms and most of the well jackets had been set in the late 1960's and early 1970's in an offshore saltwater environment. Life of the physical plant was estimated to be approximately 30 years. Corrosion over such an extended time would require the replacement of the in-place field equipment.The individual reservoir MER's were too low to permit depletion of the majority of the reserves from the field within this physical-plant lifetime limit.The injection of water into the reservoirs in a sequential manner would increase recovery. but field life more than likely would extend beyond plant life.The value of the reserves would be negligible if they were discounted back to time of production.The installation of additional equipment in the Field would require the setting of another platform. The capital requirements for a large injection station were not appreciably greater than those for a moderate-size injection station. This paper describes the process of coupling the investigation into the rock and fluid characteristics of the field with field performance data. The product of these efforts was a plan to deplete all of the major reservoirs in Meren field effectively and simultaneously. JPT P. 2105^

Containment area sizing for disposal of dredged material

Procedures are given for containment area sizing for retention of suspended solids based on the settling characteristics of the dredged material. Separate sizing procedures for freshwater and saltwater sediments provide for determination of the respective surface area or detention time required to accomodate continuous dredged material disposal. Procedures are given for the laboratory testing required to obtain data for sediment characterization, containment area sizing, and estimates of storage capacity required. These procedures can also be used for designing containment areas for other slurries having high suspended solids concentrations. Settling tests performed in a 20-cm-diam column were found to be satisfactory for defining dredged material settling behavior. Settling behavior in the freshwater environment was best described by a flocculent settling test, while behavior in a saltwater environment was best described by a zone settling test. The same settling columns were used for both tests withonly minor procedural changes. Procedures are presented for designing new containment areas for suspended solids retention and for evaluating the suspended solids retention potential of existing containment areas during planned disposal activities.

Effect of frequency and environment on fatigue-crack propagation of SA533B-1 steel

The effects of a decrease in the frequency of cyclic loading on the fatigue-crack propagation characteristics of SA533B-1 steel in various environments were investigated. Frequency levels of 10 Hz, 1.0 Hz and 0.1 Hz were employed in laboratory air, distilled water and a 3.5% NaCl solution. As the loading frequency was decreased, statistically significant increases in the fatigue-crack growth rates ( da/ dN) for the distilled water and salt water environments, as compared to those measured in laboratory air, were observed. These increases in growth rates were limited to certain ranges of stress intensity range ( ΔK) values depending upon the frequency level being tested. A hydrogen embrittlement mechanism is proposed to explain the increase in growth rates based upon a fractographic analysis.

Effect of salinity on methylation of mercury.

Monomethyl and dimethylmercury are potent neurotoxins subject to biomagnification in food webs. This fact was tragically demonstrated by the Minamata and Niigata poisoning incidents in Japan in which 168 persons who ate seafood from mercury polluted waters were poisoned, 52 fatally. Shortly after these two incidents, work conducted in freshwater environments demonstrated the microbial conversion of inorganic and phenylmercury compounds to mono- and di-methylmercury. Consideration of some fragmentary evidence from the literature, however, indicates that the rate and the significance of microbial methylation of mercury in freshwater and saltwater environments may not be the same. A demonstrated relationship between mercury methylation rates and water salinity would greatly influence our thinking about mercury pollution effects in marine versus freshwater environments. Since we were unable to locate published reports on this subject, we are investigating the influence of salinity on the rate of mercury methylation in an estuarine sediment.

Composição isotópica de carbono e oxigênio de conchas de pelecípodos do litoral brasileiro e seu significado ambiental

Carbon and oxygen isotopic compositions have been determined on modern pelecypod shells and ancient pelecypod shells whose ages had been measured by the radiocarbon method. The modern shells collected along the Brazilian coastline in order to identify possible isotopic composition trends in the shells of the pelecypods living along this coastline. The ancient pelecypod shells were collected mostly from the Cananéia-Iguape coastal plain (State of Sao Paulo). The isotopic composition ratios of these samples can be correlated with sea-level fluctuations during the Holocene, whose transgressive and regressive phases left their own typical isotopic compositions imprinted on these shells. Some samples of freshwater pelecypod shells were also analysed to establish the limites of δC13 and δO18 in fluviatile and lacustrine environments. The analytical results showed that isotopic composition can be used to distinguish between pelecypod shells in freshwater environments from those in saltwater environments, as previously has been verified elsewhere. This fact demonstrates that biological control of the isotopic fractionation mechanisms may be overriden by environmental controls.

A TIDAL SIMULATION SYSTEM FOR ESTUARINE ECOSYSTEM RESEARCH

ABSTRACT This paper describes a system for simulating tidal movements in an enclosed salt-water (estuarine) environment. This Tidal Simulation System (TSS) can be programmed to deliver various tide levels on variable cycles, and can record system performance analog data output on strip charts. Employing a variable-speed centrifugal pump, a system of pneumatic valves actuated by a central timing device, a pressurization subsystem, and a special piping manifold, the system controls flow through a branched array of submerged outlet pipes which prevent disruption of surface water and oil films, and prevent disturbance of bottom sediments. The system has undergone extensive operation tests in the Ecosystem Research Laboratory of the Mississippi State University Research Center, situated at the NASA National Space Technology Laboratory (NSTL) at Bay St. Louis, Mississippi, and has been used to simulate tides in two pairs of ponds which were employed on an Environmental Protection Agency contract to study the fate and effect of oil in the aquatic environment of the Gulf Coast Region. The salinity of the ponds ranged from 6 to 12 parts per thousand (‰), and the composition of the plankton population changed with salinity and paralleled changes observed in the estuarine area of the south-central Gulf area. Several effects of low level oil pollution, not found in laboratory studies, were observed during the course of an eleven-month study.

Clostridium botulinumin aquatic environments in Great Britain and Ireland

Mud samples from aquatic environments in many parts of Great Britain and Ireland were collected, mainly in 1975 and 1976, and examined for Clostridium botulinum. The samples were taken from lakes, ponds, reservoirs, marshes, mudflats, streams, rivers and canals, and the sampling areas included a number of bird refuges and reserves. Of 554 samples 194 (35.0%) were positive and 167 (30.1%), 19 (3.4%), 6 (1.1%) and 15 (2.7%) contained types B, C, D and E respectively; 13 (2.3%) contained more than one type. Each type demonstrated was found in both fresh-and salt-water environments. Type B was widespread; types C, D and E were demonstrated in widely separated areas in England and Wales, and type C was found in both the north and south of Scotland. The results were compared with those reported earlier in respect of surveys in the London area, the Norfolk Boads and the Camargue (France).

Frequency, Stress Ratio, and Potential Effects on Fatigue Crack Growth of HY130 Steel in Salt Water

AbstractFatigue crack growth rates over wide ranges of stress intensities (from threshold to nearly critical stress intensity) were measured on HY130 steel in 3.5% sodium chloride aqueous solution at several cyclic frequencies, stress ratios, and potentials. The growth rates are compared with reference data measured in laboratory air. The growth rate curves for both environments can be approximated by two linear sections converging at low stress intensity ranges to the same threshold, which depends only on the stress ratio. The upper parts of the lines with lower slopes converge again to the point where maximum stress intensity approaches its terminal value. As a result, the maximum environmental acceleration of crack growth appears at intermediate stress intensities, and it increases with decreasing frequency and potential. Data indicate a relatively low susceptibility of HY130 steel to corrosion fatigue. With increasing stress ratio R the fatigue crack growth threshold is shifted to lower stress intensity ranges by the same amount in both air and salt water environments. The effect of R on growth rate can be introduced into a power law expression.

Effect of composition on the mechanical and stress-corrosion behaviour of Al-Zn-Mg alloys

Mechanical properties of a range of alloys based upon the AI-4.5Zn-2.5Mg composition have been studied both in air and in a salt water environment. Correlation of microstructural information with alloy composition and with mechanical test data shows that zinc additions have the greater hardening influence, while stress-corrosion cracking is more sensitive to the magnesium content.

Consistency of Stress Corrosion Cracking Behavior of Uranium Alloys in Three Environments

Abstract The consistency of stress corrosion cracking (SCC) behavior of U-2%Mo, U-3/4%Ti, U-3/4% Quad (U-0.71Mo-0.75Nb-0.81Zr-0.46Ti), and U-3/4% Quint (U-0.84Mo-0.75Nb-0.86Zr-0.16V-0.44Ti) has been studied in three environments: (1) moist air, (2) salt contaminated moist air, and (3) salt water. Time-to-failure for four-point bend specimens decreased as the environment changed from moist air to salt contaminated moist air to salt water for all the alloys except U-3/4%Ti, in which no cracking in salt water was observed during the time of the test. Fracture modes for the four alloys were predominantly quasi-cleavage, although some intergranular fracture was observed in salt water environments.

Method of preventing corrosion and fouling by marine growth

On May 28, 1974, a United States Patent Application, Serial No. 473,691, was filed on a new process for preventing corrosion in steel substrates subjected to marine environments, and for preventing bio‐fouling so common in those situations. The patent application also applies to other substrates which have only the bio‐fouling problem but may not be subject to corrosion, such as fibreglass, plastics, etc. In December, 1976, this patent was issued with essentially all claims requested, with the exception of the application to ship's hulls. During the prosecution of the case in the US Patent Office, several wording changes were required by the examiner in an attempt to limit the claims of the patent and, as a result, a continuation‐in‐part is being filed to further expand the use to other than just “marine” environments, which is defined as applying only to salt water environments. The continuation‐in‐part will also cover the applications to boilers for prevention of scale corrosion, fresh water applications, and the applications specifically directed to heat exchanges and underwater drilling apparatus. As more applications are discovered with experience, further patent applications are to be filed.

Red cell carbonic anhydrase levels in flounders, Platichthys flesus L., from salt water and fresh water

1. 1. Carbonic anhydrase levels in flounder red cells were unchanged by adaptation to salt or fresh water. 2. 2. Two major red cell isoenzymes were found in flounder red cells after electrophoresis. These patterns were identical in all fish studied, whether from salt or fresh water environments. Thus no inherited or adaptive changes were observed. 3. 3. Both flounder red cell carbonic anhydrase isoenzymes split a range of ester substrates. Activity was abolished with acetazolamide.

Fatigue-Crack Growth in an X-65 Line-Pipe Steel at Low Cyclic Frequencies in Aqueous Environments

The effects of salt and distilled water environments on fatigue-crack growth rates have been evaluated for an X-65 line-pipe steel. Tests were conducted over a frequency range between 10 and 0.01 Hz, under conditions of cathodic potential and free corrosion. A distinct pattern in the functional dependence of growth rates on ΔK and frequency has been found. Maximum environmental enhancement of growth rates was 50 times that of air at a cathodic potential of −1.04V, and 10 times that of air at a free-corrosion potential of −0.68V. In each case it occurred at the lowest frequency and at relatively high values of ΔK. Hydrogen embrittlement and the two-stage cracking process are examined as the main mechanisms of growth acceleration.

Uptake and binding of labeled corticosterone by the salt gland of the duck ( Anas platyrhynchos)

Tritiated corticosterone was injected ip into young mallard ducks and the birds were sacrificed at various time intervals thereafter up to 3 hr. There were no differences in rate of change in the concentration of tritium in the blood and salt glands of these animals. Following perfusion, however, the rate of change in the glands was much slower than that of the blood, indicating that the glands take up and retain significant amounts of labeled material and that true uptake and retention probably cannot be demonstrated in salt glands without removal of the radioactivity in the blood. Pretreatment with dexamethasone did not significantly inhibit the in vivo uptake of radioactivity by salt glands of birds maintained on a freshwater regimen, but did inhibit isotope retention by 72% in ducks previously adapted to hypertonic saline in their drinking water. In addition, cytosols from salt glands bound over 12 and 33 times more radioactivity in vitro than did the hippocampus and hypothalamus, respectively. These studies indicate that the salt glands of euryhaline birds take up, retain, and appear to selectively bind labeled material after injection of tritiated corticosterone. The data suggest that the salt gland is most likely a glucocorticoid target organ and that exposure to a salt water environment probably stimulates enhanced synthesis of steroid receptors in salt glands.

Absorption and transport of ferritin and exogenous horseradish peroxidase in the opisthonephric kidney of the sea lamprey

The tubular nephrons in the opisthonephric kidney of the sea lamprey, Petromyzon marinus L., were demonstrated to absorb and transport exogenous protein. The proximal convoluted segment is the major site of protein absorption from the tubular lumen and the process involved is similar to that described for the proximal convoluted segment in the kidneys of other vertebrates. The lateral intercellular spaces are a possible channel for the transport of intact proteins in this segment. The cilated neck segment, the intermediate segment, and the collecting segment demonstrate only limited involvement with protein tracers and likely are not involved in the absorption of protein from the glomerular filtrate. A substantial involvement of the distal segment with the absorption and transport of protein is suggested. Diffusion of tracers from the peritubular capillaries and sinusoids through the basement membrane into the lateral intercellular spaces and smooth vesicles of cells in both the proximal and distal segments indicates that retrograde transport likely occurrs. This also demonstrates that the cytoplasm of these cells contains a complex endomembranous system continuous with the plasma membrane. The significance of these findings is discussed in relation to possible functions of the kidney in osmoregulation of the sea lamprey in both freshwater and saltwater environments.

Blood oxygen capacities of eels acclimated to fresh-, brackish- and salt-water environments

1. Groups of American eels, Anguilla rostrata, were acclimated to three environmental salinities and their blood oxygen capacities determined. 2. The brackish-water group exhibited the highest mean oxygen capacity and weight-specific oxygen capacity. 3. Highly significant differences ( P < 0·001) were demonstrated between the oxygen capacities of the freshwater and marine groups and between the brackish water and marine groups. A significant difference was not observed between the freshwater and brackish-water eels. 4. Weight-specific blood oxygen capacities for the three groups exhibited an inverse relationship with body weight. 5. The American eel, under different salinity regimes, shows a relationship between oxygen capacity and hematocrit, which appears to be altered by ambient salinity. 6. The lower oxygen capacities and hematocrits observed in the salt water-acclimated eels suggests that the yellow eel is programmed for a freshwater and/or brackish-water existence and that acclimation to higher salinities disrupts its normal blood—oxygen relationships.

Absorption and transport of exogenous protein in the archinephric duct of the opisthonephric kidney of the sea lamprey, Petromyzon marinus L.

1. The epithelium of the archinephric duct in the opisthonephric kidney of the sea lamprey, Petromyzon marinus, has the ability to absorb small quantities of exogenous protein. It is doubtful however, whether the epithelium performs this function in normal protein loads. 2. The lateral intercellular spaces demonstrate a capacity for bidirectional transport of these tracers, suggesting that the intercellular spaces may play a role in the transport of solutes. Energy for this process may be provided by mitochondria-rich cells within the epithelium. 3. These results are discussed in relation to the capability of the sea lamprey to osmoregulate in freshwater and saltwater environments.

Subcritical crack growth under sustained load

Compact tension specimens of annealed Ti-4 Al-3 Mo-l V were exposed under sustained load for periods of up to 8 days to determine the effects of initial stress intensity and test environment on subcritical crack growth. Crack growth occurred by a tunneling process with no surface crack extension until just prior to final rapid failure. Crack growth in vacuum or moist air environments occurred at stress intensities as low as 40 pct of the fracture toughness, and there was no evidence of a threshold stress intensity below which crack growth would not occur. Specimens tested in salt water behaved similarly at stress intensities of greater than about 60 pct of the fracture toughness, but showed crack arrest at lower stress intensities. At lower stress intensities, resistance to crack growth in a saltwater environment was superior to that in vacuum or moist air. Subcritical crack growth was readily identified on the fracture surface after exposure in all three environments through the presence of numerous cleavage-like facets. A critical strain concept, with crack growth occurring as a result of creep processes, can be used to explain the results.

Fatigue and Corrosion-Fatigue Crack Propagation in Intermediate-Strength Aluminum Alloys

Fatigue crack propagation studies were conducted on a variety of intermediate-strength aluminum alloys under high stress-intensity range cycling (ΔK &gt; 10 ksiin.). Tests were conducted in ambient room air and in 3.5-percent NaCl saltwater environments. Data are presented on log-log coordinates in terms of fatigue crack growth rate (da/dN) as a function of the stress-intensity factor range (ΔK). Comparisons are made among similar crack propagation data for steel and titanium alloys.