The contamination of heavy metals in various environmental matrices is a major concern to many researchers and requires attention due to their detrimental impacts on the environment and humans as well. This research was carried out to investigate heavy metal levels in soils of some selected sites along the Vaisigano river in Upolu, Samoa. The soil samples were also analysed for physicochemical parameters such as pH, Electrical Conductivity, Moisture Factor, Cation Exchange Capacity (CEC), Organic Carbon, Nitrogen, Phosphorus, and Soil texture. The mean concentrations of heavy metals at the Lelata site were 0.19 ± 0.05 mg/kg (Pb), 0.37 ± 0.45 mg/kg (Mn), 0.15 ± 0.02 mg/kg (Zn) and 0.56 ± 0.42 mg/kg (Cu). The mean concentrations of heavy metals at the Alaoa site were 0.13 ± 0.03 mg/kg (Pb), 0.42 ± 0.51 mg/kg (Mn), 0.16 ± 0.03 mg/kg (Zn) and 0.45 ± 0.43 mg/kg (Cu). The heavy metal concentrations from both sites were lower than the permissible levels given by the World Health Organization (WHO). The Geo-accumulation pollution index (I(geo)) of heavy metals in the Lelata site was Cu > Mn > Pb > Zn and from the Alaoa site was Cu > Pb > Zn > Mn.

Organochlorine pesticides (OCPs) are one of the most important persistent organic pollu‐ tants (POPs) which pose threats to ecosystems and human health. The twelve so-called POPs; nine of which are organochlorine pesticides. The two organochlorine pesticides (HCH and dieldrin) were used in or arise from industry mainly for agriculture purposes. Sediments serve as both a source and a removal mechanisms for contaminants to and from rivers and streams and as a means of contaminant transport downstream. Sediment also provides habitat for benthic biota and can be in the food web around rivers and stream, and some organisms such as fish are consumed by people and birds (Brasher & Anthony, 1998; Laabs et al., 2002). Although the residue levels of the chlorinated com‐ pounds in the environments have considerable declined in the past 20 years, recent work has depicted that chlorinated pesticides could be detected in the range of 0.03-25.17 ngg-1 (dry weight) (Chang & Doong, 2006; Zhou et al., 1994).

Coral reefs are deteriorating worldwide due to various stresses, including pollution of hazardous chemicals such as antifouling chemicals. Occurrence and impacts of a new antifouling biocide Irgarol-1051 (2-methylthio-4-tert- butylamino -6-cyclopropylamino -s-triazine) have been studied in coral reef waters around Okinawa Islands, Japan. The average concentration of Irgarol detected at commercial and fisheries Ports was 24.70 ± 9.88 ng/L. In Naha Bay, the average concentration of Irgarol was 10.00±12.98 ng/L. The average level detected around the Ports has already approaches the environmental risk limit for the marine organisms. Irgarol was detected in waters at the frequency of 92.3 % (24/26) of the total samples collected during two sampling campaigns (September and December, 2007) at the Ports. In Naha Bay, Irgarol was detected by 40.5 % (17/42) of the total water samples collected monthly from Sep., 2007 to Feb., 2008, indicating that Irgarol is widely detected along the coastal shorelines of Okinawa Island. The eco- toxicological study revealed that the rate of photosynthesis in the coral Galaxea fascicularis was significantly reduced by 18 % and 121 % relative to control when the corals were exposed to 1000 and 10,000 ng/L of Irgarol, respectively. The calcification rate dropped by 98.3 % relative to control when the corals were exposed to 10,000 ng/L of Irgarol. The results of the present study report the wide occurrence of new antifouling biocide Irgarol around coastal areas of Okinawa Island. However, the contamination does not pose serious threat on the photosynthesis and calcification of corals under short term exposure (96 h).

ABSTRACT Organic pollutants have detrimental effects on the environment. In this study we evaluated the current status of contamination with organochlorine pesticides (OCPs), organo-tin compounds (OTCs), and polychlorinated biphenyls (PCBs) in the waters in and around Okinawa Island, Japan. Possible toxicological effects of these pollutants on marine life including corals are also discussed. Concentrations of total OCPs in river water were in the range of 1.02–56.4 ng liter−1. Among the OCPs, α-BHC, β-BHC, and aldrin were common in river water. OTCs detected in 30 samples of seawater were (mean ±SD) monobutyl tin (MBT), 0.44 ±0.75 ng (Sn) liter−1; dibutyl tin (DBT), 1.32 ±2.70 ng (Sn) liter−1; tributyl tin (TBT), 0.72 ±2.90 ng (Sn) liter−1; monophenyl tin (MPhT), 0.04 ±0.42 ng (Sn) liter−1; diphenyl tin (DPhT), 0.007 ng (Sn) liter−1; and triphenyl tin (TPhT), 0.013 ng (Sn) liter−1. Highest concentrations of TBT, 28.5 ng (Sn) liter−1 for water and 172 ng (Sn) g−1 dry weight for sediment, were detected in samples from Itoman Port. Concentrations of total PCBs were 0.05–0.28 ng liter−1 in open ocean and from 1.59 to 2.48 ng liter−1 in coastal waters. Overall, this study shows that the coral reef ecosystems and their adjacent environments around Okinawa Island are contaminated by toxic organic contaminants (OCPs, OTCs, and PCBs). Levels of these contaminants detected in some sites have exceeded the Environmental Quality Target (EQT), which may pose a risk to health of marine life.

The purpose of this study was to assess exposure of four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in drinking water of Okinawa Island and Samoa. Trihalomethanes compounds were determined in the drinking water samples that were collected from the selected consumption sites and treatment plants of both Okinawa and Samoa in 2003–2004. The Chatan and Nishihara Water Treatment Plants (Okinawa) uses both ozonation and chlorination for primary and secondary disinfection. For Samoa Water Treatment Plants only chlorination is used as primary disinfection. Results showed that the mean concentration of trihalomethanes from treatment plants in Okinawa ranged from 0.30 ± 1.81 ⧎g/L to 11 ± 2.68 ⧎g/L and from the consumption sites ranged from 2.08 ± 0.32⧎g/L to 19.39 ± 100 ⧎g/L. In comparison, the mean concentration of trihalomethanes from the treatment plants in Samoa ranged from 226 ± 81.2 ⧎g/L to 267 ± 92.3 ⧎g/L and from the consumption sites were in the ranges 212 ± 101 ⧎g/L to 387 ± 125 ⧎g/L. Brominated compounds were commonly seen in all samples collected in Okinawa. Among the trihalomethanes compounds, chloroform was the common detected trihalomethanes in the samples collected from Samoa. The trihalomethanes levels in all samples collected in Okinawa and Samoa were generally below the guideline values in Japan, but some samples displayed levels which exceeded the level of Japan Water Quality and WHO Standards for chlorinated and brominated compounds.

The contamination of organochlorine pesticides (OCPs) from the selected rivers in Okinawa Island was investigated to estimate the current status of pollution in water, plants and surface sediments in these rivers. The Aja River, Asato River, Houtoku River, Kokuba River and Okukubi River were selected for this study. The concentration of the total pesticides were in the range of 0.94-231.8 ng/L in river water, 0.006–191.6 ng/L dry weight in river sediments and 0.001–55.8 ng/L dry weight in plants. Among the OCPs, ΣHCB of α-BHC,β-BHC and Aldrin were the common detected compounds in river water. The α-BHC, Aldrin and Dieldrin were the most frequent detected compounds in river sediments and α-BHC and Dieldrin were the common OCPs detected in plants. Aldrin, Dieldrin and ΣHCB were in abundance. Various contamination patterns between the selected river water, sediments and plants were observed. Aja River, Asato River and Houtoku River were contaminated with α,β,δ,γ- BHC, Aldrin and Dieldrin (water and sediments) whereas the main OCPs in Kokuba River and Okukubi River were Dieldrin (plants) The OCPs levels in all rivers were generally below guideline values in Japan, but some sites displayed levels which exceeded the EC and WHO Standards for Aldrin, Dieldrin and α,β-BHC.

We investigated eight organochlorine pesticides (OCPs) in the rivers of southern part of Okinawa Island, Japan, from July to September 2005. The mean concentration for Sigma BHC (alpha,beta,gamma,delta-BHC) in four rivers was 25.67 +/- 58 ngL(-1)(mean +/- SD). The highest concentration of BHC detected in water samples was 49.10 ngL(-1). Other OCPs such as Aldrin, Dieldrin, Heptachlor epoxide (Isomer B) and Methoxychlor were also detected in most water samples with their mean concentrations of 6.96 +/- 80, 4.33 +/- 59.9, 3.16 +/- 55 and 2.01 +/- 57.6 ngL(-1). Within the monitoring period, the concentration of OCPs increases in July and August (Aldrin, alpha-BHC and beta-BHC). The possible sources of these OCPs might be the effluents and dusts from residential areas and agricultural activities. The levels of OCPs in rivers in southern part of Okinawa were generally below the guideline values in Japan. This preliminary documentation of OCPs in river waters from southern part of Okinawa Island revealed that the rivers are lightly contaminated and suggesting more monitoring studies in order to protect the health of aquatic systems and accompanied life.