Marine life

To overcome these difficulties, drilling fluids are treated with a variety of mud lubricants available from various suppHers. They are mostly general-purpose, low toxicity, nonfluorescent types that are blends of several anionic or nonionic surfactants and products such as glycols and glycerols, fatty acid esters, synthetic hydrocarbons, and vegetable oil derivatives. Extreme pressure lubricants containing sulfurized or sulfonated derivatives of natural fatty acid products or petroleum-base hydrocarbons can be quite toxic to marine life and are rarely used for environmental reasons. Diesel and mineral oils were once used as lubricants at levels of 3 to 10 vol % but this practice has been curtailed significantly for environmental reasons. 

Toxicity to fish is included in the data Hsted in Table 4. Marine life, particularly fish, may suffer damage from spills in lakes and streams. The chlorobenzenes, because they are denser than water, tend to sink to the bottom and may persist in the area for a long time. However, some data indicate that dissolved 1,2,4-trichlorobenzene can be biodegraded by microorganisms from wastewater treatment plants and also has a tendency to slowly dissipate from water by volatilization (34). 

The phthalate esters are one of the most widely used classes of organic esters, and fortunately they exhibit low toxicity (82). Because of the ubiquitous nature of phthalates, many iavestigations have been conducted to determine their toxicides to marine life as well as ia mammals (83—85). Generally, phthalates are not absorbed through the skin and are not very potent when inhaled. The phthalates become less toxic as the alcohol group increases in molecular weight. For example, dimethyl phthalate has an oral LD q (mouse) of 7.2 g/kg, whereas di(2-ethylhexyl) phthalate shows an oral LD q (rat) of greater than 26 g/kg. 

The underlying assumption driving marine natural products chemistry research is that secondary metabolites produced by marine plants, animals, and microorganisms will be substantially different from those found in traditional terrestrial sources simply because marine life forms are very different from terrestrial life forms and the habitats which they occupy present very different physiological and ecological challenges. The expectation is that marine organisms will utilize completely unique biosynthetic pathways or exploit unique variations on well established pathways. The marine natural products chemistry research conducted to date has provided many examples that support these expectations. 

Calcium, as noted above, is the fifth most abundant element in the earth s crust and hence the third most abundant metal after A1 and Fe. Vast sedimentary deposits of CaC03, which represent the fossilized remains of earlier marine life, occur over large parts of the earth s surface. The deposits are of two main... 

Oil Spills. Oil spills occur from oil pipeline leaks, oil tanker accidents, or submarine oil drilling operations. The two major ocean drilling accidents—oil wells blowing out—were the 1969 Santa Barbara Channel spill and the 1979 Yucatan Peninsula spill, in Mexico. The Yucatan spill spewed out more than three million barrels before being capped in 1980. Both caused damage to beaches and marine life, but the smaller Santa Barbara spill was far more devastating because of unfavorable winds following the accident. 

Limestone. This is a sedimentary rock that is formed by the accumulation of organic marine life remains (shells or coral). Its main component is calcium carbonate. Cement rock. This is a sedimentary rock that has a similar composition as the industrially produced cement. 

Resistance to marine organisms. In the case of submarine lines, the coating should not be easily penetrated by marine life, e.g. mussels, borers, barnacles, etc. 

The effect on marine life of such widespread pollution by polymers is significant. Sea turtles, for example, may mistake plastic pellets for food. 

Tetrodotoxin (TTX) and saxitoxin (STX) are potent sodium channel blockers that are found in phylogenetically diverse species of marine life. The wide distribution of TTX and STX has resulted in speculation that bacteria are the source of these toxins. Recently, investigators have reported isolation of marine bacteria, including Vibrio Alteromonas, Plesiomonas, and Pseudomonas species, that produce TTX and STX. This chapter details the methods and results of research to define bacterial sources of TTX and STX. 

Despite these hazards, humans continue to venture beneath the surface of the seas. Adventurers seek to salvage materials from sunken ships. Archaeologists wish to explore ancient seaport sites that have since sunk beneath the waves. Navy Seals practice warfare underwater. Biologists and lovers of nature study marine life in its natural habitat. In addition, hordes of amateur divers pursue this sport for its sheer enjoyment. 

Such a composition reduces friction, permeates drilling mud wall cake, destroys binding wall cake, and reduces differential pressure. Unfortunately, many of such compositions are toxic to marine life. Synthetic PAOs are nontoxic and effective in marine environments when used as lubricants, retum-of-permeabiUty enhancers, or spotting fluid additives for water-based drilling muds. A continuing need exists for other nontoxic additives for water-based drilling muds, which serve as lubricants, retum-of-permeability enhancers, and spotting fluids. 

Ethylhexanol can be epoxidized with 1-hexadecene epoxide. This additive also helps reduce or prevent foaming. By eliminating the need for traditional oil-based components, the composition is nontoxic to marine life, biodegradable, environmentally acceptable, and capable of being disposed of at the drill site without costly disposal procedures [44]. 

Butyl- and phenyltin compounds, particularly the trialkylated forms are very toxic to marine life. The antifouling paints, mainly tributyltin (TBT) but also triphenyltin (TPhT) caused and continue to cause substantial damage because of their slow biodegradation and their accumulation in the biota, notwithstanding a substantial reduction in application through multi-national regulation). 

Shiny silvery metal that is relatively soft in its pure form. Forms a highly resistant oxide coat. Used mainly in alloys, for example, in construction steel. Tiny amounts, in combination with other elements such as chromium, makes steel rustproof and improves its mechanical properties. Highly suited for tools and all types of machine parts. Also applied in airplane turbines. Chemically speaking, the element is of interest for catalysis (for example, removal of nitric oxides from waste gases). Vanadium forms countless beautiful, colored compounds (see Name). Essential for some organisms. Thus, natural oil, which was formed from marine life forms, contains substantial unwanted traces of vanadium that need to be removed. 

MARINE LIFE PROTECTION Acute exposure Total recoverable silver <2.3 pg/L at any time 2... 

To protect important species of marine animals, the U.S. Environmental Protection Agency recommends that total recoverable zinc in seawater should average <58 pg/L and never exceed 170 pg/L for acid-soluble zinc, these values are <86 and 95 pg/L (Table 9.9). As was the case for freshwater biota, there is a growing body of evidence (Table 9.9) demonstrating that many species of marine plants, crustaceans, molluscs, echinoderms, and fish are adversely affected at ambient zinc concentrations between 9 and 50 pg/L, or significantly below the current proposed criteria for marine life protection. 

The proposed criterion for marine life protection of 0.004 pg/L as a 24-h mean, not to exceed 0.09 pg/L at any time (Table 13.6), seems to offer a reasonable degree of protection. But the proposed freshwater criterion of 0.0043 pg/L, 24-h average, not to exceed 2.4 pg/L at any time (Table 13.6), overlaps the range of 0.2 to 3.0 pg/L shown earlier to be harmful to sensitive species of fish and aquatic invertebrates. Accordingly, the maximum permissible freshwater value should... 

---