The rotten-egg stench that descended on Belmont Shore and surrounding areas caused 450 report calls and reports of headaches and nausea, but air quality investigators suspect a petroleum-laden ship off a Long Beach oil island was its source.
The South Coast Air Quality Management District, which investigates all such complaints, said it received 105 reports in three hours Thursday night, most from Long Beach but some from Seal Beach and Orange County.
AQMD spokesman Sam Atwood said five investigators dispatched the Belmont Shore coast during the harshest of the acrid smell--4 p.m. to 7 p.m.--determined there was no natural gas leak, nor other source at regional refineries.
Given the Long Beach Fire Department's report of 300 or more complaint calls, and the AQMD's, the impact was said by both agencies to be fairly geographically wide. Reports of the rotten egg or sulfur-like stink came from Huntington Beach north, and inland as far as Studebaker and Willow, if not broader.
The incident remains under investigation, Atwood said Friday afternoon. But the most plausible source, he said, is considered one of three ships anchored off the Long Beach oil islands.
"What our investigators concluded is that it appears to be a source offshore, possibly one of three ships that were moored off of the oil islands," Atwood said.
What would the source of the strong, in some instances throat-burning, aroma be coming from on a ship?
"They might do flaring but the source is more likely to be gas that is vented," Atwood explained. "So it could be a ship carrying crude oil or some other petroleum product, with a high sulfur content, and when petroleum c are transferred from a ship onshore or vice versa, just like at a retail gas station, you have to have equipment to capture the vapors.
"And if that equipment was not maintained or operating properly --just speculation -- that could be a cause of odors offshore."
To read more about the Thursday incident click here.
For Patch readers who have noted the sulfur smell and questioned whether the source might be pure sulfur in "a big yellow pile that you might see at a port," Atwood said it is an additive that causes the stench, not the sulfur itself.
"Hydrogen sulfide is in the petroleum products that can produce the rotten egg smell that (people) think of as sulfur," Atwood said. For instance, he said, there was a recent case in which the AQMD took action Sept. 21 against a Phillips. "The rotten egg smell was from hydrogen sulfide and that came from a product stored in one of their tanks."
The same month, another widely-reported incident caused by hydrogen sulfide was the widespread bad odor later linked to nature and the Salton Sea.
Although some people report that the rotten egg smell coming from offshore is not uncommon, Atwood noted that it may not always be the same cause, though it is quite likely may be the same substance.
He noted the following:
In order to assist in detecting leaks (of natural gas), a minute amount of odorant is added to the otherwise colorless and almost odorless gas used by consumers. The odor has also been compared to the smell of rotten eggs, or rotting cabbage, due to the added tert-Butylthiol (t-butyl mercaptan). Sometimes a related compound, thiophane may be used in the mixture.--http://en.wikipedia.org/wiki/Natural_gas
As the AQMD continues its probe into Thursday night's incident, Atwood reminded residents to report any concerns to the 24-hour hot line at: 800-cutsmog.