BEIJING, Aug. 20 -- China's State Oceanic Administration (SOA) reported "minute traces" of cyanide in waters near the Tianjin blast site on Thursday.

The cyanide was detected in three out of 16 sampling and monitoring sites set in the harbor basin of Tianjin port and the sea east of Dongjiang port on Wednesday, with the maximum density of 0.00105 mg/L, the SOA said in a statement.

The maximum density was below the 0.005 mg/L cap for first-grade water quality, which is fit for oceanic fishing and protected habitats for rare species.

Also, five sites reported detection of volatile phenol. While three sites' readings are up to water quality standard, the substances monitored at the other two sites are above the first-grade water quality ceiling as the maximum density reached 0.00727 mg/L, the statement said.

However, the administration explained that as long as the density of volatile phenol stays below 0.010 mg/L, the water is fit for industrial and tourism use.

Other marine environmental readings such as the seawater PH, chemical oxygen demand (COD), sulfide and polycyclic aromatic hydrocarbons (PAHs) saw no abnormality, it said.

To prevent harm to the marine environment, the SOA has formed an emergency response plan, prepared bleaching materials and protective outfits and sent ships from the China Coast Guard to the site.

The SOA said on Wednesday that it is keeping closer track of cyanide dissemination with a wider monitoring scope and more sampling sites.

One out of 16 sites reported a density of 0.00103 mg/L of cyanide on Monday and no traces were found on Tuesday, according to the SOA's Wednesday report.