Test and Evaluation of Four Fire Resistant Booms at OHMSETT

During the period of 22 August–12 October 1998, seven commercial fire booms were involved in burn testing at the US Coast Guard Fire and Safety Test Detachment Facility in Mobile, Alabama in accordance with the proposed protocol, American Society for Testing and Materials-F20. Four of the seven booms survived the test sequence and were shipped from Mobile, Alabama to the Minerals Management Service’s OHMSETT facility for additional tests including first loss, gross loss, tow speed, oil loss rate, and critical tow speed. The four booms showed the same trend in response to various wave conditions; the long sinusoidal waves improved containment performance and the short choppy waves degraded performance. One of the four booms achieved slightly higher first and gross oil loss rate tests. One boom demonstrated superior stability at high tow speeds. The results of this test report are consistent with the evaluation of fire booms that had been previously tested at OHMSETT, but also show a slight increase in performance. The tests indicate that the existing fire booms can contain oil in currents up to 1 knot and in various wave conditions after being exposed to multiple burns. This information will be used by the Coast Guard to develop policies and procedures for the in situ burning (ISB) of oil during a spill.     

Quantitative analysis of shore-line protection by boom arrangements

The objective of this paper is to quantitatively analyze the arrangement of booms to improve their effectiveness in protecting natural resources. The boom arrangements tested were parallel booms placed at angles of 60°, 90°, and 120° to the shore-line. It was found that the angle between the shoreline and the parallel booms was effective in the range of 45° and 75° for all velocities. The arrangement that was found to be particularly effective was principally a set of three parallel booms placed at an angle of 60° to the shore-line with cylinders placed along the center-line.The open channel experiment was carried out for four different flow velocities, ranging from 0.2 to 0.7 knot. For each speed the position of the parallel booms and the size of the cylinders were changed. Cylinder sizes varied from 4.5 to 7.5 cm. A volume analysis was performed to determine the volume of oil contained. The variation of the length scales for the position of the parallel booms and the size of the cylinders were used to determine the optimum position for the parallel booms and the optimum cylinder diameter for each velocity. A relationship of effectiveness vs U₂/gR was found which displayed a maximum. This relationship was tested experimentally with random parameters, and verified. With a particular velocity U, the graph may be used to find the optimum radius R for the cylinders to be used. The maximum in the relationship can be explained as follows: for cylinders with smaller diameters the effectiveness increases with increase in diameter because of the increased contribution of the centrifugal forces. A maximum is reached because of the physical relationship between the cylinder diameter and the channel width.     

Second Phase Evaluation of a Protocol for Testing a Fire Resistant Oil Spill Containment Boom

Most response plans for in situ burning of oil at sea call for the use of a fire-resistant boom to contain the oil during a burn. Presently, there is no standard method for the user of fire-resistant boom to evaluate the anticipated performance of different booms. The American Standard for Testing Materials (ASTM) F-20 Committee has developed a draft standard, `Standard Guide for in situ Burning of Oil Spills on Water: Fire-Resistant Containment Boom'; however, the draft provides only general guidelines and does not specify the details of the test procedure. Utilizing the guidelines in the draft standard, a second series of experiments was conducted to evaluate a protocol for testing the ability of fire-resistant booms to withstand both fire and waves.     

Evaluating a Protocol for Testing a Fire-Resistant Oil-Spill Containment Boom

Most response plans for in situ burning of oil at sea call for the use of a fire-resistant boom to contain the oil during a burn. Presently, there is no standard method for the user of a fire-resistant boom to evaluate the anticipated performance of different booms. The ASTM F-20 committee has developed a draft standard, “Standard Guide for in situ Burning of Oil Spills on Water: Fire-Resistant Containment Boom”; however, the draft provides only general guidelines and does not specify the details of the test procedure. Utilizing the guidelines in the draft standard, a series of experiments were conducted to evaluate a protocol for testing the ability of fire-resistant booms to withstand both fire and waves.     

Dynamic modelling of oil boom failure using computational fluid dynamics

The common response to an oil spill on water is to contain the oil with booms and recover it with skimming devices. In some situations, however, the booms cannot hold the oil and the oil will escape underneath the boom due to hydrodynamic forces. Computational fluid dynamics (CFD) is a powerful modelling tool combining fluid dynamics and computer technology. We have utilized a commercial CFD program, Fluent, to simulate the oil-water flow around a boom. The studies accurately model channel experiments conducted in recent years. The studies show that the flow patterns around booms are modified by the presence of oil and, therefore, suggest that towing and wave-conformity tests of booms will not be meaningful unless they are undertaken with the presence of oil.     

The technology windows-of-opportunity for marine oil spill response as related to oil weathering and operations

This paper identifies and estimates time periods as ‘windows-of-opportunity’ where specific response methods, technologies, equipment, or products are more effective in clean-up operations for several oils. These windows have been estimated utilizing oil weathering and technology performance data as tools to optimize effectiveness in marine oil spill response decision-making. The windows will also provide data for action or no-action alternatives. Crude oils and oil products differ greatly in physical and chemical properties, and these properties tend to change significantly during and after a spill with oil aging (weathering). Such properties have a direct bearing on oil recovery operations, influencing the selection of response methods and technologies applicable for clean up, including their effectiveness and capacity, which can influence the time and cost of operations and the effects on natural resources.The changes and variations in physical and chemical properties over time can be modeled using data from weathering studies of specific oils. When combined with performance data for various equipment and materials, tested over a range of weathering stages of oils, windows-of-opportunity can be estimated for spill response decision-making. Under experimental conditions discussed in this paper, windows-of-opportunity have been identified and estimated for four oils (for which data are available) under a given set of representative environmental conditions. These ‘generic’ windows have been delineated for the general categories of spill response namely: (1) dispersants, (2) in situ burning, (3) booms, (4) skimmers, (5) sorbents, and (6) oil-water separators. To estimate windows-of-opportunity for the above technologies (except booms), the IKU Oil Weathering Model was utilized to predict relationships—with 5 m s⁻¹ wind speed and seawater temperatures of 15°C.The window-of-opportunity for the dispersant (Corexit 9527^®) with Alaska North Slope (ANS) oil was estimated from laboratory data to be the first 26 h. A period of ‘reduced’ dispersibility, was estimated to last from 26–120 h. The oil was considered to be no longer dispersible if treated for the first time after 120 h. The most effective time window for dispersing Bonnic Light was 0–2 h, the time period of reduced dispersibility was 2–4 h, and after 4 h the oil was estimated to be no longer dispersible. These windows-of-opportunity are based on the most effective use of a dispersant estimated from laboratory dispersant effectiveness studies using fresh and weathered oils. Laboratory dispersant effectiveness data cannot be directly utilized to predict dispersant performance during spill response, however, laboratory results are of value for estimating viscosity and pour point limitations and for guiding the selection of an appropriate product during contingency planning and response. In addition, the window of opportunity for a dispersant may be lengthened if the dispersant contains an emulsion breaking agent or multiple applications of dispersant are utilized. Therefore, a long-term emulsion breaking effect may increase the effectiveness of a dispersant and lengthen the window-of-opportunity.The window-of-opportunity of in situ burning (based upon time required for an oil to form an emulsion with 50% water content) was estimated to be approximately 0–36 h for ANS oil and 0–1 h for Bonnie Light oil after being spilled. The estimation of windows-of-opportunity for offshore booms is constrained by the fact that many booms available on the market undergo submergence at speeds of less than 2 knots. The data suggest that booms with buoyancy to weight ratios less than 8:1 may submerge at speeds within the envelope in which they could be expected to operate. This submergence is an indication of poor wave conformance, caused by reduction of freeboard and reserve net buoyancy within the range of operation. The windows-of-opportunity for two selected skimming principles (disk and brush), were estimated using modeled oil viscosity data for BCF 17 and BCF 24 in combination with experimental performance data developed as a function of viscosity. These windows were estimated to be within 3–10 h (disk skimmer) and after 10 h (brush skimmer) for BCF 17. Whereas for BCF 24, it is within 2–3 d (disk skimmer) and after 3 d (brush skimmer).For sorbents, an upper viscosity limit for an effective and practical use has in studies been found to be approximately 15,000 cP, which is the viscosity range of some Bunker C oils. Using viscosity data for the relative heavy oils, BCF 17 and BCF 24 (API gravity 17 and 24), the time windows for a sorbent (polyamine flakes) was estimated to be 0–4 and 0–10 d, respectively. With BCF 24, the effectiveness of polyamine flakes, was reduced to 50% after 36 h, although it continued to adsorb for up to 10 d. For BCF 17, the effectiveness of polyamine flakes was reduced to 50% after 12 h, although it continued to adsorb for up to 4 d. The windows-of-opportunity for several centrifuged separators based upon the time period to close the density gap between weathered oils and seawater to less than 0.025 g ml⁻¹ (which is expected to be an end-point for effective use of centrifugal separation technology), were estimated to be 0–18 (ANS) and 0–24 h (Bonnie Light) after the spill. Utilizing the windows-of-opportunity concept, the combined information from a dynamic oil weathering model and a performance technology data base can become a decision-making tool; identifying and defining the windows of effectiveness of different response methods and equipment under given environmental conditions. Specific research and development needs are identified as related to further delineation of windows-of-opportunity.     

Summary of Development and Field Testing of the Transrec Oil Recovery System

This paper summarizes the development, field testing and performance evaluation of the Transrec oil recovery system including the Framo NOFO Transrec 350 skimmer and multi-functional oil spill prevention and response equipment and presents performance data, not published before, from full-scale experimental oil spills in the North Sea from 1981 to 1990. The rare data provides useful information for evaluation of mechanical clean-up capabilities and efficiency, in particular, for responders who are using this equipment in many countries around the world.The development of the Transrec oil recovery system represents one of the most comprehensive efforts funded to date by the oil industry in Norway to improve marine and open ocean oil spill response capabilities. The need for improvements was based upon early practical user experience with different oil recovery systems, and test results from experimental oil spills in the North Sea.The result of the development efforts increased: (1) skimmer efficiency from approximately 15–75% (it reached 100% under favorable environmental conditions); (2) oil emulsion recovery rate from approximately 20–300 m³/h; (3) recovery system efficiency from approximately 15–85% in 1.5 m significant wave height; (4) oil emulsion thickness from approximately 15–35 cm; (5) weather-window for mechanical recovery operations from 1.5 to 3.0 m significant wave height; (6) capability for transfer of recovered oil residue to shuttle tankers in up to 4 m significant wave height and 45 knot winds; (7) capability for operations at night.The new Transrec oil recovery system with the special J-configuration virtually eliminated skimming operation downtime, and damage to booms and equipment failures that had been caused by oil spill response vessel (OSRV) problems with maintaining skimming position in the previous three-vessel oil recovery system with the boom towed in U-configuration. The time required to outfit OSRVs dropped from approximately 30–<1 h, reducing time from notification to operation on site by more than 24 h.Improvement in oil recovery resulted in the acceptance of a new oil spill preparedness and response plan. The new plan reduced the need for oil recovery systems from 21 to 14, towing vessels in preparedness from 42 to 18, and personnel on stand-by from 135 to 70, which subsequently reduced the total contingency and operational costs by almost 50%. These cost reductions resulted from lower contingency fees for personnel, fewer towing vessels on stand-by, less expensive open ocean training and exercises, less equipment and reduced storage space to lease, and simplified equipment maintenance.     

Aluminium: The Need for a Re-Evaluation of Its Toxicity and Solubility in Mature Forest Stands

Aluminium (Al) is a key element in critical loadcalculations for forest. Here, we argue for re-evaluating theimportance of Al. Effects of two levels of enhanced Alconcentrations and lowered Ca:Al ratios in the soil solutionin a field manipulation experiment in a mature spruce stand(1996–1999) on tree vitality parameters were tested. Inaddition, Al solubility controls were tested. Various loads ofAl were added to forest plots by means of an irrigationsystem. Potentially toxic Al concentrations and criticalratios of Ca to inorganic Al were established. The ratio of Cato total Al was not a suitable indicator for unfavourableconditions for plant growth. No significant effects on crowncondition, tree growth and fine root production were observedafter three years of treatment. In 1999, foliar Mg content inthe highest Al addition treatment had declined significantly.This agreed with the known response to Al stress of seedlingsin nutrient solution experiments. No support was found forusing the chemical criterion Ca:Al ratio in soil solution,foliar and root tissue as an indicator for forest damage dueto acidification. Al solubility was considerably lower thanimplied by the assumption of equilibrium with gibbsite,particularly in the root zone. The gibbsite equilibrium iscommonly used in critical load models. Substitution of thegibbsite equilibrium with an Al-organic matter complexationmodel to describe Al solubility in soil water may have largeconsequences for calculation of critical loads. The resultsindicate that critical load maps for forests should bereconsidered.     

用海泡石处理采油废水

用海泡石吸附法处理采油废水,考察了处理时间、海泡石加入量和采油废水pH对采油废水COD去除率的影响,并通过正交实验优化了采油废水处理工艺条件。通过正交实验得到的采油废水处理最佳工艺条件为：处理时间6h,粒径为150μm的海泡石加入量200g／L,采油废水pH9。在该条件下处理采油废水,COD去除率达到91％,处理后出水的COD为34．71mg／L,小于GB8978-1996（（污水综合排放标准》中的一级标准（60mg／L）。     

Geotechnical characterization of a Municipal Solid Waste Incineration Ash from a Michigan monofill

A field and laboratory geotechnical characterization study of a Municipal Solid Waste Incineration Ash disposed of at the Carleton Farms monofill in Michigan was performed. Field characterization consisted of field observations, collection of four bulk samples and performance of shear wave velocity measurements at two locations. Laboratory characterization consisted of basic geotechnical characterization, i.e., grain size distribution, Atterberg limits, specific gravity tests, compaction tests as well as moisture and organic content assessment followed by direct shear and triaxial shear testing. The test results of this investigation are compared to results in the literature. The grain size distribution of the samples was found to be very similar and consistent with the grain size distribution data available in the literature, but the compaction characteristics were found to vary significantly. Specific gravities were also lower than specific gravities of silicic soils. Shear strengths were higher than typically reported for sandy soils, even for MSWI ash specimens at a loose state. Strain rate was not found to impact the shear resistance. Significant differences in triaxial shear were observed between a dry and a saturated specimen not only in terms of peak shear resistance, but also in terms of stress–strain response. In situ shear wave velocities ranged from 500 to 800 m/s at a depth of about 8 m, to 1100–1200 m/s at a depth of 50 m. These high shear wave velocities are consistent with field observations indicating the formation of cemented blocks of ash with time, but this “ageing” process in MSWI ash is still not well understood and additional research is needed. An improved understanding of the long-term behavior of MSWI ash, including the effects of moisture and ash chemical composition on the ageing process, as well as the leaching characteristics of the material, may promote unbound utilization of the ash in civil infrastructure.     

Flammability Properties of Virgin and Recycled Polycarbonate (PC) and Acrylonitrile–Butadiene–Styrene (ABS) Recovered from End-of-Life Electronics

Acrylonitrile–Butadiene–Styrene (ABS), Polycarbonate (PC) and their alloys are widely used in automotive industry, computer and equipment housings. With increasing disposal of end-of-life electronic equipment, there is also an increased demand for recycling of these materials so that they do not pose environmental challenge as solid waste. One of the recycling approaches is mechanical recycling of these thermoplastics where recycled plastic is melt blended with virgin materials to obtain a high quality product. Besides obtaining desirable mechanical properties, such blends should also conform to fire safety standards. In this work, a series of blends were prepared using PC and ABS recovered from discarded computers and virgin materials using a twin-screw extruder. Their flammability properties were evaluated using burner flammability tests and Ohio State University (OSU) release rate tests. It was found that the extinguishing time, burning extent and weight loss appears to progressively decrease with the addition of both virgin or recycled PC to virgin or recycled ABS. It was also seen that the addition of the 70% of PC, virgin or recycled, to ABS virgin or recycled, appears to significantly decrease heat release and smoke evolution. The results of this study indicate that recycled polycarbonate can be used as an additive for virgin or recycled ABS, as a means of giving flame resistance to ABS in high-value applications. This result is significant when related to the result obtained by a separate study indicating that up to 25% of recycled material can be used without degradation of mechanical properties in the presence of 15% short glass fiber reinforcement.     

Fire Effects on Carbon and Nitrogen Budgets in Forests

Estimates of C and N loss by gasification during a wildfire in a Jeffrey pine (Pinus Jeffreyii [Grev. and Balf.]) forest in Little Valley, Nevada are compared to potential losses in more mesic forests in the Integrated Forest Study (IFS). In Little Valley, the fire consumed the forest floor, foliage, and an unknown amount of soil organic matter, but little standing large woody material. On an ecosystem level, the fire consumed approximately equal percentages of C and N (12 and 9%, respectively), but a considerably greater proportion of aboveground N (71%) than C (21%). Salvage logging was the major factor in loss, and C lost from the site will not be replenished until forest vegetation is established and succeeds the current shrub vegetation. N₂ fixation by Ceanothus velutinus [Dougl.] in the post-fire shrub vegetation appears to have more than made up for N lost by gasification in the fire over the first 16 yr, and may result in long-term increases in C stocks once forest vegetation takes over the site. N loss from the fire equaled > 1,000 years of atmospheric N deposition and > 10,000 years of N leaching at current rates. Calculations of C and N losses from theoretical wildfires in the IFS sites show similar patterns to those in Little Valley. Calculated losses of N in most of the IFS sites would equal many centuries of leaching. Conceptual models of biogeochemical cycling in forests need to include episodic events such as fire.     

Effects of Temperature and Relative Humidity on Polylactic Acid Plastic Degradation

Three high molecular weight (120,000 to 200,000 g mol^–1) polylactic acid (PLA) plastic films from Chronopol (Ch-I) and Cargill Dow Polymers (GII and Ca-I) were analyzed for their degradation under various temperature and relative humidity (RH) conditions. Two sets of plastic films, each containing 11 samples, were randomly hung in a temperature/humidity-controlled chamber by means of plastic-coated paper clips. The tested conditions were 28, 40, and 55°C at 50 and 100% RH, respectively, and 55°C at 10% RH. The three tested PLA films started to lose their tensile properties when their weight-average molecular weight (M _w) was in the range of 50,000 to 75,000 g mol^–1. The average degradation rate of Ch-I, GII, and Ca-I was 28,931, 27,361, and 63,025 M _w/week, respectively. Hence, GII had a faster degradation rate than Ch-I and Ca-I under all tested conditions. The degradation rate of PLA plastics was enhanced by the increase in temperature and relative humidity. This trend was observed in all three PLA plastics (Ca-I, GII, and Ch-I). Of the three tested films, Ch-I was the first to lose its mechanical properties, whereas Ca-I demonstrated the slowest loss, with mechanical properties under all tested conditions.     

Concentrations,Cumulative Exposure and Critical Levels of Ozone in Ireland

Concentrations of tropospheric ozone(O₃) and exceedance of critical levels to vegetationhave been investigated and mapped for Ireland. Hourlyozone concentration data (1995–1997) at 7 sevenmonitoring stations and the CORINE landcover database,supported by a Geographical Information System, wereused. AOT40 (Accumulated exposure Over a Threshold of 40ppb) was calculated for daylight hours for each station,and mapped using surface interpolation. Average O₃concentrations vary from year to year, and were estimatedto be 28 ppb, 26 ppb and 24 ppb for 1995, 1996 and 1997respectively. Ozone concentrations show a large diurnalvariation, with a maximum in the afternoon and a minimumat night-time. The critical level for crops and (semi-)natural vegetation was exceeded in all years examined.The highest exceedance occurred in 1995, where thecritical level was exceeded for almost 35% of the mappedarea. Approximately 15% and 1% of the mapped area wasexposed to exceedance levels during 1996 and 1997respectively. The maximum cumulative exposures (AOT40)were approximately 5000, 3890 and 3230 ppbh in 1995, 1996and 1997 respectively. The critical level for forests wasnot exceeded during the period of investigation.     

Peanut hull pellets as a single use sorbent for the capture of Cu(II) from wastewater

This paper investigates the ability of peanut hulls and peanut hull pellets to adsorb copper from dilute aqueous metal ion solutions in batch and fixed bed systems. The kinetics of copper uptake onto the media have been investigated in batch systems and the influence of pH and particle size on the rate and extent of copper capture determined. The Langmuir and Freundlich isotherm theories were determined; the Langmuir model was found to best represent the equilibrium isotherm data. In normalized kinetic tests at least 75% of copper removal occurred within the first 20 min; 92% removal was effected within the first 50 min. The rate of uptake was optimum within the pH range 5-7.5, and media capacities remained relatively constant at a pH above 4.0. Bench-scale column studies were performed using peanut hull pellets. The overall capacity of pelletized peanut hulls was higher than for unmodified peanut hulls. Due to their demonstrated ability for Cu(II) uptake and favorable structural characteristics, pelletized peanut hulls could gain use as a low-cost, once-through biomass filter medium for copper-bearing waste streams.     

R&D Users Guide to the Ohmsett Oil Spill Response Test Facility

Ohmsett – the National Oil Spill Response Test Facility, is the world's largest tow/wave tank designed to evaluate the performance of equipment that detects, monitors and clears up oil spills under environmentally safe conditions. Ohmsett is the only facility capable of testing and training with oil, using full-scale response equipment.     

Transpiration in Black Willow Phytoremediation Plots as Determined by the Tree‐Trunk Heat Balance Method

Plant transpiration is a critical process that affects the water balance in phytoremediation plots. The desired effect is to remove contaminated water from the soils through the plant metabolism. Thus, the transpiration rate can be a major component in modeling the groundwater flow and solute transport for a phytoremediation project and ultimately can determine the time expected to achieve remedial goals. Two phytoremediation plots of black willows (Salix nigra) were planted during October 1996 over separate,shallow groundwater plumes at a site in southeastern Louisiana. Concentrations of less than 10 mg/l of the herbicide bentazon were present in the shallow groundwater. Field experiments were developed and performed during the 1998 and 1999 growing seasons to measure sap flow as an indicator of plant transpiration. The tree‐trunk heat balance method was used to measure sap flow. Sap flow was indexed to the cross‐sectional area of the stem, and the sum of the available stem area for each plot was used to calculate the monthly water use in each plot. Daily water use in the plots averaged between 6 to 13 l/day/m² during the periods tested in 1998 and 1999. By applying growth‐rate observations with the daily water use, annual water use at tree plot maturity was estimated to be 3.6×10⁶ l/year in Plot 1 and 11.39×10⁶ l/year in Plot 2. Application of these data will allow groundwater modeling to be performed to measure the effectiveness of phytoremediation and to predict closure of remediation at the test site. © 2001 John Wiley & Sons, Inc.     

The Reduction of Stranded Oil by In Situ Shoreline Treatment Options

The Svalbard Shoreline Field Trials quantified the effectiveness of sediment relocation, mixing, bioremediation, bioremediation combined with mixing, and natural attenuation as options for the in situ treatment of oiled mixed-sediment (sand and pebble) shorelines. These treatments were applied to oiled plots located in the upper beach at three experimental sites, each with different sediment character and wave-energy exposure. Systematic monitoring was carried out over a 400-day period to quantify oil removal and to document changes in the physical character of the beach, oil penetration, oil loading, movements of oil to the subtidal environment, biodegradation, toxicity, and to validate oil-mineral aggregate formation.The results of the monitoring confirmed that sediment relocation significantly accelerated the rate of oil removal and reduced oil persistence where oil was stranded on the beach face above the level of normal wave activity. Where the stranded oil was in the zone of wave action, sediment relocation accelerated the short-term (weeks) rate of oil loss from the intertidal sediments.Oil removal rates on a beach treated by mechanical mixing or tilling were not significantly higher than those associated with natural recovery. However there is evidence that mixing/tilling may have enhanced microbial activity for a limited period by increasing the permeability of the sediment.Changes in the chemical composition of the oil demonstrated that biodegradation was significant in this arctic environment and a bioremediation treatment protocol based on nutrient enrichment effectively doubled the rate of biodegradation. However, on an operational scale, the success of this treatment strategy was limited as physical processes were more important in causing oil loss from the beaches than biodegradation, even where this oil loss was stimulated by the bioremediation protocols.     

An exposure index for oiled shorelines

Wave action is the most effective natural cleaning agent of oiled shorelines. Therefore, the degree of exposure of a shoreline to wave action dictates how quickly that shoreline will be cleaned by natural processes. In the absence of recorded wave data, a simplified exposure index, tested on the shorelines of Prince William Sound, Alaska oiled during the Exxon Valdez oil spill, can be used to predict potential cleansing by wave action. Wind gauge data correlated with three effective fetch distances measured perpendicular to and at 45° to the shoreline are used to calculate the exposure index. In Prince William Sound, both biological and geomorphological criteria for exposure to waves agreed with the readings calculated for the index. Surface oil on the exposed shorelines was removed quickly during the first storm season. Sheltered coasts were cleaned more slowly. This technique should also work well for other partially enclosed water bodies.