Survey of Organic Chemical Contaminants In Water, Sediment and Biota of the Hanalei River,
Island of Kauai, Hawaii, December 2001

Final Report CERC-8335-FY03-31-01

Columbia Environmental Research Center - USGS

November 12, 2002
Carl Orazio, Principal Investigator

The following is the summary of the final report, prepared for the Hanalei Heritage River Program. Please contact us if you would like to see the full report.

Background

Intense agricultural and tourism-related activities are potential sources of chemical contamination of the Hanalei River. This study was undertaken to determine the occurrence of organochlorine pesticides, priority pollutant PAHs, alkylated PAHs, aliphatic hydrocarbons (petroleum oil residues), select non-polar organic chemicals, and trace elements at sites upstream and downstream of potential sources. The distribution of contaminants in bed sediments, surface waters, crabs, clams, and fish was determined to allow potential routes of exposure to be evaluated. The majority of chemicals chosen for this investigation are toxic organic chemicals and trace elements/metals that are persistent and ubiquitous in the environment. The results of this study indicate that concentrations of semivolatile aliphatic hydrocarbons, PAHs, PCBs, organochlorine pesticides, certain hydrophobic organics, and metals are very low in the Hanalei River. In most cases, the organic contaminants were below the limits of detection.

Current Level of Contamination in the Hanalei River

The reason these organic chemicals are quite low in the Hanalei River is likely a combination of factors: the amount of chemical used in the Hanalei watershed and the fate of the chemical once in the river system. Residues of chlordanes and dieldrin (aldrin degradant) are likely due to past use to control termites (prior to 1988 ban in chlordane use in the US). Chlordane is quite stable in the soil environment and continues to be transported for years from soils near treated buildings into the watershed (17-18). The fate of an organic chemical is dependent primarily upon its physicochemical properties and the nature of the river (such as flow rate, storm events, organic carbon, sediment quality). Rain events that dramatically raise the river discharge in a matter of hours from its baseline of around 2 m3/s to over 100 m3/s rapidly flush the river of any recently deposited bed sediments. In February 1995, a flood event moved an estimated 260 metric tons of sediment into Hanalei Bay (19). Although such an event may remove contaminated sediment from the river, transport of sediment onto the Bay's coral has the potential to deliver sediment-associated contaminants, in addition to smothering the coral.

Aliphatic petroleum oils spilled into water or released from boat engines dissolve to a limited extent, with a larger insoluble portion rising to the surface of the water. Aliphatic hydrocarbons are microbially degraded relatively rapidly (as compared to PAHs and organochlorine pesticides). Higher molecular weight aliphatic hydrocarbons (heavy weight oil) may bind to suspended and bed sediments. In the Hanalei River, it is expected that concentrations of hydrocarbon residues in the water are reduced by factors such as river flow rate, degradation, volatilization from the water, and simple dilution. However, an increase in the amount of petroleum hydrocarbons released into the river could overcome these factors, raising residues to detectable levels.

Comparison of Hanalei River Contaminant Levels in Other Hawaiian Streams
And Evaluation of Potential Adverse Ecological Effects

Levels of dieldrin, chlordane, DDE and DDT in the fish and sediments of the Hanalei River are less than 1 mg/kg in all cases, hundreds to 1000 times lower than levels found in urban streams on the Island of Oahu. Furthermore, Hanalei River levels of these and other organochlorine pesticides are below Canadian Sediment Quality Guidelines- Probable Effect Level (CSQG PEL) and New York State Department of Environmental Conservation's (NYSDEC) wildlife guidelines (20-21). Chronic exposure of aquatic biota to levels above the CSQG PEL are expected to result in frequent adverse effects. The NYDEC sets levels for protection fish-eating birds and mammals.

In 1998, USGS sampled selected streams on Oahu and found levels of chlordane and dieldrin in bed sediment and fish tissue to exceed guidelines for the protection of birds that eat fish and sediment-dwelling biota (22). Levels of dieldrin from urban sites (Manoa, Nuuanu, Kaneohe) were between 50-300 mg/kg (dry wt basis), well above the CSQG PEL of 6.7. Fish tissue residues of dieldrin from these same sites ranged as high as 1200 mg/kg (wt wet basis), well exceeding the NYSDEC wildlife guideline of 120 mg/kg for fish. Waikele River, an agricultural area stream on Oahu, and a conservation stream (Waihee), had no dieldrin detected in the fish or sediment. Chlordane levels in the urban sediments were 10-40 times the CSQG PELA. Urban fish chlordane levels ranged from about 300-1900 mg/kg, in cases exceeding the NYSDEC PEL of 500 mg/kg. Chlordane levels in agricultural and conservation stream sediments and fish were reported as being below 5 mg/kg. DDT contaminants were highest in streams near agriculture, in cases exceeding the NYSDEC PEL of 200 mg/kg.

The concentrations of PAHs in the Hanalei River bed sediments were less than levels found in urban areas of Oahu (23). Phenanthrene, fluoranthene, chrysene, pyrene, benzo[a]anthracene and benzo[a]pyrene concentrations of 1400, 1800, 1000, 1600, 770, and 780 mg/kg, respectively, were reported in sediments of Kalauao Stream at Moanalua Road. Other streams had levels of PAHs ranging from <50 mg/kg to several hundred mg/g. One of the triplicate aliquots of the Hanalei downstream sediment had concentrations of 190, 132, 94,180, 65, and 63 of these PAHs, respectively. It is interesting to note that the ratio of these PAHs in the Kalauao is: 1.8 | 2.3 | 1.3 | 2.1 | 1.0 | 1.0, while the Hanalei sediment was 3.0 | 2.1 | 1.5 | 2.9 | 1.0 | 1.0. These quite similar patterns are indicative of similar source type. Benzo[a]pyrene is present and the ratio of several PAHs indicate a pyrogenic source.

Brief Summary of Toxic Metals, Arsenic and Selenium Investigation

The analysis of metals and toxic elements is presented in detail as a separate attached report: CERC-8335-FY02-32-14. The following is a very brief summary of the results: Excluding the one high lead (Pb) value mentioned in the report (#25546), the elemental water concentrations were less than the EPA Freshwater Criterion Continuous Concentrations (CCC) for chromium, iron, nickel, copper, zinc, arsenic, selenium and lead (USEPA 1999). The aluminum CCC of 87 ng/mL was exceeded in water samples at all sites, however, all Hanalei water samples were unfiltered, so the resulting Al levels may have been due to soil particulates in the water. Levels of metals, arsenic, and selenium in the sediment, water, clams, crabs, and fish were below probable effects levels. Elements present in downstream samples were indicative of the elemental composition of seawater. See the complete report of the inorganic investigation for full interpretation and discussion of the results.

Levels of arsenic, selenium, and mercury and other toxic metals in the Hanalei River sediments seem to be indicative of natural levels in fresh and estuarine waters of Hawaii. Trace elements in stream bed sediments from selected streams on the Island of Oahu, 1998, 2000 show levels similar to or above those found in the Hanalei River (23). Mercury levels on Oahu were reported to range from 0.06- 0.2 mg/g, indistinguishable from the Hanalei River sediments at the upstream and downstream sites, which ranged from 0.025- 0.09. Levels of arsenic and selenium were also similar to Oahu sediment levels.