Tamotsu Oomori

Venting of carbon dioxide-rich fluid and hydrate formation in mid-okinawa trough backarc basin.

Carbon dioxide-rich fluid bubbles, containing approximately 86 percent CO2, 3 percent H2S, and 11 percent residual gas (CH4 + H2), were observed to emerge from the sea floor at 1335- to 1550-m depth in the JADE hydrothermal field, mid-Okinawa Trough. Upon contact with seawater at 3.8�C, gas hydrate immediately formed on the surface of the bubbles and these hydrates coalesced to form pipes standing on the sediments. Chemical composition and carbon, sulfur, and helium isotopic ratios indicate that the CO2-rich fluid was derived from the same magmatic source as dissolved gases in 320�C hydrothermal solution emitted from a nearby black smoker chimney. The CO2-rich fluid phase may be separated by subsurface boiling of hydrothermal solutions or by leaching of CO2-rich fluid inclusion during posteruption interaction between pore water and volcanogenic sediments.

Distribution coefficient of Mg2+ ions between calcite and solution at 10–50°C

The distribution coefficient (λMg) of Mg2+ ions between calcite and solution was found to be 0.012 ± 0.001 (10°C), 0.014 ± 0.001 (15°C), 0.019 ± 0.001 (25°C), 0.024 ± 0.001 (30°C), 0.027 ± 0.001 (35°C) and 0.040 + 0.003 (50°C). This indicates a remarkable dependence on temperature. The effect of the Mg2+/Ca2+ molar ratio in a parent solution on λMg for calcite is small, where the molar ratio lies in the range 0.04-2. However, the λMg value for aragonite tends to decrease with increasing Mg2+/Ca2+ ratio in the parent solution. The largest Mg content of calcite in the Ca(HCO3)2-Mg2+ → calcite system is around 2 mol% in the temperature range 10–50°C. Neither homogeneous nor heterogeneous distribution laws hold for aragonite precipitation, and the temperature effect on the coprecipitation of Mg2+ ions with aragonite is very small.

Culture-Dependent and -Independent Characterization of Microbial Communities Associated with a Shallow Submarine Hydrothermal System Occurring within a Coral Reef off Taketomi Island, Japan

ABSTRACT Microbial communities in a shallow submarine hydrothermal system near Taketomi Island, Japan, were investigated using cultivation-based and molecular techniques. The main hydrothermal activity occurred in a craterlike basin (depth, ∼23 m) on the coral reef seafloor. The vent fluid (maximum temperature, >52°C) contained 175 μM H2S and gas bubbles mainly composed of CH4 (69%) and N2 (29%). A liquid serial dilution cultivation technique targeting a variety of metabolism types quantified each population in the vent fluid and in a white microbial mat located near the vent. The most abundant microorganisms cultivated from both the fluid and the mat were autotrophic sulfur oxidizers, including mesophilic Thiomicrospira spp. and thermophilic Sulfurivirga caldicuralii. Methane oxidizers were the second most abundant organisms in the fluid; one novel type I methanotroph exhibited optimum growth at 37°C, and another novel type I methanotroph exhibited optimum growth at 45°C. The number of hydrogen oxidizers cultivated only from the mat was less than the number of sulfur and methane oxidizers, although a novel mesophilic hydrogen-oxidizing member of the Epsilonproteobacteria was isolated. Various mesophilic to hyperthermophilic heterotrophs, including sulfate-reducing Desulfovibrio spp., iron-reducing Deferribacter sp., and sulfur-reducing Thermococcus spp., were also cultivated. Culture-independent 16S rRNA gene clone analysis of the vent fluid and mat revealed highly diverse archaeal communities. In the bacterial community, S. caldicuralii was identified as the predominant phylotype in the fluid (clonal frequency, 25%). Both bacterial clone libraries indicated that there were bacterial communities involved in sulfur, hydrogen, and methane oxidation and sulfate reduction. Our results indicate that there are unique microbial communities that are sustained by active chemosynthetic primary production rather than by photosynthetic production in a shallow hydrothermal system where sunlight is abundant.

Active hydrothermal mounds in the Okinawa Trough backarc basin, Japan

Abstract Dive studies by the “SHINKAI 2000” were made in September, 1984 and July, 1986 in the central axial rift of the Middle Okinawa Trough, a possible active backarc basin in a nascent stage. Hydrothermally active mounds were discovered on a small knoll (27°34.4′N, 127°08.6′E) directly south of the area where a high heat flow (higher than 1 W/m2) had been observed previously. The largest mound, 5–6 m high and 15–25 m wide, has several peaks and ridges, along which yellow materials are exposed. Shimmering water was noted at several places on the yellow materials. The rest of the mound is thinly covered by brown materials. The temperature of the ejecting water was higher than that of the ambient seawater by 2–3°C, and a 40 cm long thermometer inserted into the mound recorded a temperature of 20–50°C. Analysis of the ejected water showed a methane content of about 200 nl/kg. It is possible that further dive studies will reveal larger scale hydrothermal activity in the area.

Hydrothermal plumes at the Rodriguez triple junction, Indian ridge

Water column anomalies of light transmission, Mn, Fe, Al and CH4 concentrations were searched in the central, southeastern and southwestern Indian Ridge segments centered on the Rodriguez Triple Junction (RTJ) (∼25°32′S, ∼70°02′E), for the purpose of locating hydrothermally active areas, in July to August 1993. We found an active zone in the central Indian Ridge segment (25°18–20′S) approximately 12 miles north of the RTJ, where significant hydrothermal plumes were observed at 2,200–2,400 m depth. Intensive tow-yo observations using a CTD rosette multi-sampling system equipped with a transmissometer revealed that the plumes show temporal as well as spatial variations. Discrete water samples within the plumes were enriched in Mn, Fe, and CH4, with maximum concentrations of 9.8 nM, 40.2 nM and 3.3 nM, respectively. Judging from the spatial and chemical characteristics of the plumes, especially from transmission anomalies andC/H4Mn ratios, we speculate that the hydrothermal venting site might be not in the rift valley but on the eastern off-axis zone, several miles distant from the rift valley.

Distribution of pesticides and bisphenol A in sediments collected from rivers adjacent to coral reefs

To investigate the deteriorating health of coral reefs in Okinawa, Japan, natural sediment samples were analyzed for diuron, Irgarol 1,051, chlorpyrifos, and bisphenol A (BPA) which are hazardous to corals. Samples were analyzed by solid-phase extraction (SPE) followed by high-performance liquid chromatography with tandem mass spectrometry (LC-MS-MS). Although diuron and chlorpyrifos usage is only well recorded for farms and not for cities, these chemicals were detected in both rural and urban areas. Additionally, diuron concentration in urban areas was in some cases higher than in rural areas, which might be caused by greater consumption of these chemicals in home gardens in city areas. Irgarol 1051 was detected in downstream river areas, which are situated far from the source sites such as pier or fishery harbor (0.6-3.2 km). This result suggested that Irgarol 1051 could be transported from the river mouths to the sampling sites during flood tides. High BPA concentrations were associated with urban areas (<1.2-22.0 microg kg(-1)), while low concentrations were associated with rural areas (nd-6.8 microg kg(-1)). The river sediments under study are delivered to coral reefs in large quantity through runoff caused by typhoons and other heavy rains. The highly hazardous chemicals are carried into coral reefs on these sediments. Therefore, these hazardous chemical substances may already be influencing the coral reefs.

Carbonic Anhydrase in Calcified Endoskeleton: Novel Activity in Biocalcification in Alcyonarian

Carbonic anhydrase (CA) is a key enzyme in the chemical reaction of living organisms and has been found to be associated with calcification in a number of invertebrates including calcareous sponges, but until now no direct evidence has been advanced to show CA activity in alcyonarian corals. However, it is essential to understand the role of CA in the process of biocalcification in alcyonarian. Here we describe the novel activity of CA and its relationship to the formation of calcified hard tissues in alcyonarian coral, Lobophytum crassum. We find that two CA proteins, which were partially purified by electro-elution treatment, can control the morphology of CaCO3 crystals and one of them is potentially involved in the process of biocalcification. Previously, we isolated CA from the total extract of alcyonarian, and further, we report here a single protein, which has both calcium-binding and CA activities and is responsible for CaCO3 nucleation and crystal growth. This matrix protein inhibited the precipitation of CaCO3 from a saturated solution containing CaCl2 and NaHCO3, indicating that it can act as a negative regulator for calcification in the sclerites of alcyonarians. The effect of an inhibitor on the enzyme activity was also examined. These findings strongly support the idea that carbonic anhydrase domain in alcyonarian is involved in the calcification process. Our observations strongly suggest that the matrix protein in alcyonarian coral is not only a structural protein but also a catalyst.

Contamination by organochlorine pesticides from rivers

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.

Detection and ecological threats of PSII herbicide diuron on coral reefs around the Ryukyu Archipelago, Japan

a Department of Chemistry, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan b Okinawa Prefectural Institute of Health and Environment, 2085 Ozato Ozato Nanjo, Okinawa 901-1202, Japan c Water Quality Control Office, Okinawa Prefectural Bureau, 1-27 Miyagi, Chatan, Okinawa 904-0113, Japan d WWF Japan, Minato-ku, Shiba 3-1-14, Tokyo 105-0014, Japan e Department of Sciences, The State University of Zanzibar, Tanzania

Occurrence of tributyltin compounds and characteristics of heavy metals

Surface sediment samples were collected from Tanzanian major commercial ports and studied for the distribution and behavior of tributyltin (TBT) compounds and heavy metals. The content of TBT in sediments ranged from ND-3670 ng (Sn) g1dry wt (1780 ± 1720) (Mean ± SD) at Zanzibar and from ND-16700 ng (Sn)g1 dry wt (4080 ± 7540) at Dar es Salaam ports, respectively. Maximum TBT levels were detected inside the both ports. Metabolic degradation of butyltin compounds (BTCs) showed that MBT + DBT > TBT %, this may be attributed by the warm ambient water and intense sunlight in the tropical regions. A sequential extraction procedure was undertaken to provide detailed chemical characteristics of heavy metals in the sediments. The procedure revealed that about 50% of Fe in the both ports is in immobile fraction (residual fraction) while other metals; Cd, Cu, Ni, Co, Zn, Pb, and Mn were mostly found in exchangeable or carbonate fractions and thus can be easily remobilized and enter the aquatic food chain. This paper provides basic information of TBT compounds contamination and chemical characteristics of heavy metals in the marine ecosystem in Tanzania. To our knowledge, this is the first documentation of Organotin compounds (OTCs) in marine environments in East Africa and suggests the importance of further detailed OTCs studies in other sub-Saharan Africa regions