The Environmental Protection Agency collected sediment samples on September 3, 2010 in coastal Louisiana and "three samples found nickel in exceedance of chronic aquatic benchmarks, and one sample found both nickel and vanadium in exceedance of chronic aquatic benchmarks." (See update at bottom)
Near Grand Isle on 09/03/2010: Nickel @ 22.7 mg/kg [ppm1] in sediment:
Near Bay Chaland on 09/03/2010: Nickel @ 19.3 mg/kg [ppm1] in sediment (Massive fishkill occurred at Bayou Chaland):
Why is Vanadium a problem? According to Food Quality News:
The UK Food Standard Agency's Expert Group on Vitamins and Minerals (EVM) reached a similar opinion in 2003, determining overexposure to vanadium could cause cramps, loosened stools, 'green tongue' as well as fatigue and lethargy.
In vivo studies indicate vanadium could adversely affect male and female reproduction as well as infant development.
Why is nickel a problem? According to the Centers for Disease Control:
The Department of Health and Human Services (DHHS) has determined that nickel metal may reasonably be anticipated to be a carcinogen and that nickel compounds are known human carcinogens.
The CDC also said:
A lot of nickel released into the environment ends up in soil or sediment where it strongly attaches to particles containing iron or manganese. Under acidic conditions, nickel is more mobile in soil and might seep into groundwater.
Metal Concentrations in Soils and Sediments in Southwest Louisiana, James N. Beck; Joseph Sneddon, Analytical Letters, Volume 33, Issue 10 2000:
Abstract: The coastal zone of Louisiana provides a “living laboratory” to investigate the mechanisms of transport, deposition, and dissolution of trace metals into this fragile environment. Common trace metals determined and their range of concentrations in soil and sediments are... iron (0.6-2.1 %) [6,000-21,000 ppm], manganese (200-600 ppm).
Is this amount of Fe and Mn along the coast considered higher than other areas? According to the Louisiana State AgCenter, Iron levels above 4.5 ppm and Manganese levels above 4.0 ppm are considered high. The iron levels along the coast are over 1,000 times higher than what LSU considers high.
The report continued:
Manganese- Manganese deficiencies are uncommon in Louisiana. Where they occur, they resemble iron deficiencies. Manganese toxicity is a common problem in the state. It is caused by low soil pH (highly acidic soil). It can be corrected by liming the soil to a pH of 5.5 or higher.
Such high levels of manganese and iron in the soil, combined with highly acidic ph levels, indicate that the high nickel content observed by the EPA will be "more mobile in soil and might seep into groundwater."
Update: While compiling information for this report, the EPA website has changed. It now says "two samples with nickel in exceedance of chronic aquatic benchmarks" instead of "three samples found nickel in exceedance of chronic aquatic benchmarks, and one sample found both nickel and vanadium in exceedance of chronic aquatic benchmarks."