"... Pearl Harbor is one of the largest sheltered harbors in the USA and the only harbor wholly owned and controlled by the U.S. Navy. The facility contains numerous maintenance service facilities and has been the site of continuous Navy operations for more than 50 years. Previous investigations by Navy contractors have analyzed sediment samples from the harbor and found tributyltin, a single PCB (Aroclor 1254), significant levels of total PAHs, and several phthalates (plasticizers). Other samples contained low levels of DDT degradation products. Chlorinated pesticides were not detected. Significant amounts of total sulfides were also detected in most sediment samples indicating anaerobic biological activity. Ammonia was also found in most sediment samples. Detectable concentrations of several metals (arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc) were also found. TCLP analyses for the same metals found all below reporting limits. Despite the presence of all these chemicals, the water column has not been found to be highly toxic (less than allowable) and fish tissues were not such that specific advisories were required or adverse biological effects were expected. This indicates that not all of the chemicals are bioavailable. Additionally, in 1996 there was a oil spill of 16,000 gallons (bunker fuel oil No. 6) in a stream near its mouth into the harbor from a Chevron oil pipeline that passes through to a nearby electric-power generating plant. The heavy oil initially sank and most was recovered. No other oil spills have been reported in the area. All of these findings can be expected from such a large harbor facility which has been in service for as many years and has serviced as many vessels in as many different maintenance facilities. The Pearl Harbor sediment and associated water column are ideal sources of "real" samples for conducting research into rapid and easy immunochemical techniques (suitable for field use) for extraction, identification, and quantification of toxic organic chemicals for both pollutant monitoring and assessment of bioavailability. ..."
Most dry cargo containers are steel boxes weighing between two tonnes and four tonnes, and are constructed to be weather-proof, rather than watertight. If empty they sink as a result of water ingress. If full, they may float for a while: air trapped in the cargo may hold a box on the surface until the cargo becomes waterlogged.
Containers are rarely watertight. Most have small openings and distortions. However, if 11 kg of seawater per hour entered a 20’ container, it would take some 57 days it to sink; and some 183 days for a 40’ container! These times may be considerably shortened by the in-water deterioration of seals, but this does indicate that floating containers can remain a hazard to shipping for some time.
Our information is that most containers do in fact sink. This may be due to the effects of poor maintenance, the fact that a container is a fragile object not intended to fend off a boarding sea, the initial distortions as the container breaks free, the subsequent impact with the ocean and the battering of loose cargo.
In rough weather, boxes may be smashed up by the waves. With up to 20 tonnes of cargo moving inside, the containers soon tend to lose their structural integrity. Refrigerated boxes and tank containers create the greatest threat, because of their inherent buoyancy, but because of their high value, from $25,000 to $70,000 each it makes it worthwhile for companies to build in tracking devices. Such containers may in any case be easier to spot with the naked eye or by radar.
Unfortunately, when a container or containers are lost overboard, there is rarely a news release and the fact is seldom publicised by the shipping company. The loss is only revealed to those in a need to know situation i.e. the shipowner, the exporter and importer, and the insurer.
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