Saulwood Lin

Geochemical speciation and risk assessment of heavy metals in the river estuarine sediments—A case study: Mahanadi basin, India

Sequential extraction technique was used to study the mobility and dynamics of operationally determined chemical forms of heavy metals in the sediments and their ecological risk on the biotic species. The results reveal that high environmental risk of Cd, Ni, Co and Pb, are due to their higher availability in the exchangeable fraction. Substantial amount of Cd, Co, Mn, Cu, Zn, Ni and Pb, is observed as carbonate bound, which may result due to their special affinity towards carbonate and their co-precipitation with its minerals. Colloids of Fe-Mn oxides act as efficient scavengers for the heavy metals like Zn, Pb, Cu, Cr, Co, and Ni. Toxic metals like Ni, Pb and Cd are of concern, which occasionally may be associated with adverse biological effects based on the comparison with sediment quality guidelines (SQGs). The risk assessment code (RAC) suggests that the highest mobility of Cd poses a higher environmental risk and also threat to the aquatic biota. Factor analysis reveals that the enrichment of heavy metals in bioavailable fraction is mostly contributed from anthropogenic sources. These contributing sources are highlighted by cluster analysis.

Influence of the Yangtze River and grain size on the spatial variations of heavy metals and organic carbon in the East China Sea continental shelf sediments

Abstract Bulk heavy metal (Fe, Mn, Zn, Cu, Pb, Cd), Al, organic carbon and carbonate concentrations, grain sizes, and δC13 of the organic carbon distributions were studied in sediments collected throughout the East China Sea continental shelf and the Yangtze River Delta. The results demonstrated that terrigenous sediments from the Yangtze River is a dominating factor controlling the spatial variations of heavy metals and organic carbon concentrations on the East China Sea continental shelf. In addition, grain size and recent anthropogenic influences are also major factors modifying the spatial and vertical variations of heavy metals. Large spatial variations with a band type distribution of heavy metals, grain size, organic carbon and carbonate were observed. Higher concentrations of heavy metal and light δC13 of the organic carbon were found primarily in the Deltaic and inner shelf sediments. The band type distribution generally followed the coastline with little variations in the north–south direction. Away from the Delta and inner shelf (west–east direction), most heavy metal concentrations decreased rapidly with the exception of Cd where high concentrations of Cd were also found in the carbonate-rich shelf break sediments. Coarse-grained relict sediments and biogenic carbonate are two primary diluting agents for the fine-grained aluminosilicate sediments from the Yangtze River with high concentrations of heavy metals. Unusually high concentrations of Cu, Pb, and Cd showed both spatially and vertically that more pollution prevention measures are needed in the Yangtze River drainage basin in order to prevent further heavy metal pollution of the East China Sea inner continental shelf.

Consequences and implication of heavy metal spatial variations in sediments of the Keelung River drainage basin, Taiwan

A great deal of effort was enforced to reduce the pollution of the Keelung River in the past 20 years. A set of sediments covering most of the Keelung River drainage basin was analyzed for bulk sediment heavy metal concentrations, grain size content and Pb-210 dating in order to understand the spatial variations of sediment heavy metal contents as well as to evaluate the effectiveness of pollution control. The results showed that anthropogenic pollution and grain size are two of the most important factors in controlling spatial variations of metals in the Keelung River sediments. In addition, little reduction of sediment heavy metal concentrations was observed in the Keelung River drainage basin. Large spatial variations of metals and grain size were observed. High concentrations of zinc, copper, lead and cadmium were found in sediments near the main outlets of the adjacent Da-Wu-Lun Industrial Park and municipal waste drainage systems. Anthropogenic sources of heavy metal have altered the natural sediment heavy metal distributions. Positive linear relationships between aluminum, iron and fine-grained sediments showed that spatial grain size variations controlled the natural aluminum and iron concentrations in sediments. Zinc, copper, lead and cadmium contents were much higher than those measured 15 years ago. The unusually high concentrations of heavy metals, high enrichment factors and their rapid increases with time in Pb-210 dated core showed that the efforts in heavy metal reduction were futile. A proper regulation to prevent further heavy metals from entering into the river is urgently needed.

Short-term Changes in Seafloor Character due to Flood-Derived Hyperpycnal Discharge: Typhoon Mindulle, Taiwan, July 2004

During Typhoon Mindulle in early July 2004, the Choshui River (central-western Taiwan) discharged similar to 72 Mt of sediment to the eastern Taiwan Strait; peak concentrations were g= 200 g/L, similar to 35%-40% of which was sand. Box-core samples and CHIRP (compressed high-intensity radar pulse) sonar records taken just before and after the typhoon indicate that the hyper-pycnal sediment was first deposited adjacent to the mouth of the Choshui, subsequently resuspended and transported northward (via the Taiwan Warm Current), and redeposited as a patchy coastal band of mud-dominated sediment that reached thicknesses of 1-2 m within megaripples. Within a month most of the mud was gone, probably continuing its northward transit, but more mud appeared in late August in response to Typhoon Aere. Following autumn and winter storms, the entire nearshore area was again sand dominated by early spring.

Occurrences of Green Oyster and Heavy Metals Contaminant Levels in the Sien- San Area, Taiwan

An abnormal increase of copper concentrations was observed in both the oyster tissues and sediments of the Sien-San coastal area in the north-western part of Taiwan. As much as 200 and 5000 ppm of copper was found in sediments and oysters. These excessive concentrations of copper were introduced to the coastal area within a short period of about 4 yr. Copper concentrations increased 50 and 100-fold respectively in oyster tissues and sediments. The green oyster phenomenon occurred as a result of these rapid increases in metal concentrations. The appearance of green oysters and the abnormal concentrations of copper demonstrated that the Sien-San coastal area is undergoing a drastic change as a result of copper pollution. This pollution problem represents a serious threat to the local fishing community.

Distribution of terrigenous lipids in marine sediments off northeastern Taiwan

Surface sediments on the continental margin off northeastern Taiwan have been analyzed for terrigenous lipids including n-alkanes, n-fatty alcohols, and sterols. Marine input to the sediments is particularly low based on the average n-C17/n-C29 alkane and n-C16/n-C28 fatty alcohol ratios, 0.15±0.13 and 0.13±0.06, respectively; this may be due to the fact that marine lipids are more prone to degradation than terrestrial ones. The study area has the highest plant wax n-alkane contribution (average carbon preference index 3.9±1.2) among the coastal marine areas surrounding Taiwan; lateral particle transport from the southern East China Sea shelf and river runoff from the east Taiwan coast are considered to be the major contributors. The distributions of plant wax n-alkane and n-alkanol concentrations normalized to total organic carbon (TOC) in the study area generally show maximum values on the upper slope of the southernmost Okinawa Trough, but not for phytosterols. Linear regression of TOC versus plant wax n-alkane concentrations show a weak relationship (r=0.64, p=0.001), and an even weaker relationship (r=0.42, p=0.05) between TOC and plant wax n-fatty alcohol concentrations is found. This could be attributed to several factors: (1) a complex input (not a point source) of terrigenous organic matter to the study area, (2) TOC also including marine organic matter, (3) temporal variations in river flow due to flooding, and (4) different rates of degradation for TOC and individual biomarkers. However, in spite of those factors, TOC and phytosterol concentrations are positively linearly correlated (r=0.85, p<0.001), implying that the dilution of phytosterols in terrigenous organic carbon with marine organic carbon with or without the phytosterols follows a nearly constant ratio, which is remarkable. In addition, the predominant source of diploptene in the sediments does not appear to be of higher plant origin.

Records of submarine natural hazards off SW Taiwan

Abstract In the past few years, large earthquakes and torrential rain hit southern Taiwan and induced severe submarine hazards off the SW coast. Marine sediments (turbidites) provide valuable records with which to study and understand the formation of these submarine geo-hazards. The Pingtung Earthquake (two major events (ML=7.0) plus many aftershocks), on 26 December 2006, triggered turbidity currents that severed submarine cables in the Fangliao and Gaoping submarine canyons. This caused significant economic loss. In addition to earthquake activity, typhoons and torrential rains that induced flooding are also important mechanisms responsible for the formation of turbidites. On 8–9 August 2009 Typhoon Morakot brought heavy rains to southern Taiwan, causing serious landslides and flooding on land. The typhoon also caused submarine cable breaks in the Gaoping Canyon. All such events are likely to be recorded in the marine sediments of the canyon system, and by analysing these records we may be able to reconstruct the history of past earthquakes and floods in the region. Chirp sonar profiles, in conjunction with core analysis, including X-ray radiographs, grain size and 210Pb analysis, are used to identify the sources, transport and deposition of the turbidites (or hyperpycnite) and to reconstruct the history of earthquakes and flooding in the study area. Results indicate that these submarine hazards are not only related to earthquake and floods but that the unique geological and hydrological setting also plays an important role in the initiation of these submarine geo-hazards.

Iron Sulfide and Carbonate Mineral Diagenesis in Baffin Bay, Texas

ABSTRACT In anoxic sediments, bacterially-mediated sulfate reduction can play a major role in both carbonate and sulfide mineral diagenesis. In order to understand better the complex interrelationships involved in these diagenetic processes, diagenesis of iron sulfide and carbonate minerals was studied in the poorly-sorted siliclastic-dominated sediments from Baffin Bay, Texas. The production of pyrite dominantly takes place in the top 20 cm of sediment. A good correlation (r2 = 0.76) is observed between the total inorganic sulfur (TRS) content of the sediments and the percentage of the sediment that is fine-grained ( 0.8) degrees of Fe pyritization, and elevated C/S ratios compared to normal marine sediments indicate that reactive iron probably limits sulfide burial in sediments from this region containing more than about 1 wt. % organic carbon. A major ( 10 fold) increase in CO2 driven by sulfate reduction is closely related to a large decrease in dissolved calcium in the upper 1 m of sediment. The major decrease in dissolved calcium is probably due to the precipitation of calcium carbonate. Dolomite was observed in these sediments, and favorable conditions for its formation are present. However, a detrital origin for the dolomite cannot be ruled out.

Solubility and complexing of Ni in the system NiO-H2O-HCl

Abstract The solubility of bunsenite (NiO) in Cl-bearing fluids in the range of 450°–700°C, 1–2 kbar was determined using the Ag + AgCl acid buffer technique. Based on the results of the experiments, it is concluded that the associated NiCl 0 2 complex is the dominant Ni species in the fluid over the entire temperature-pressure range investigated. The temperature dependence of the equilibrium constant for the reaction NiO ( s ) + 2 HCl 0 ( aq ) = NiCl 0 2 ( aq ) + H 2 O is given by log K = −4.17(±0.55) + 4629(±464)/ T ( K ) at 1 kbar, and log K = −4.75(±0.91) + 5933(±756)/ T ( K ) at 2 kbar. The calculated difference in standard state Gibbs free energy of formation between NiCl 0 2 and 2HCl 0 in kcal is G 0 ( NiCl 0 2 ) − 2 G 0 ( HCl 0 ) = −20.77(±2.22) + 0.03264(±0.0026) T ( K ), at 1 kbar and G 0 ( NiCl 0 2 ) − 2 G 0 ( HCl 0 ) = −25.01(±1.35) + 0.03264(±0.0016) T ( K ) at 2 kbar. Comparison of the solubilities of Ni end-member minerals with those of Ca, Mn, Fe, and Mg indicates that nickel minerals generally are the least soluble at a given temperature and pressure. The relatively low solubility of Ni end-member minerals, combined with the relatively low concentration of Ni in most rocks, should result in a quite low mobility of Ni in hydrothermal fluids.

HIGH-RESOLUTION SEISMIC IMAGES OF THE FORMOSA RIDGE OFF SOUTHWESTERN TAIWAN WHERE “HYDROTHERMAL” CHEMOSYNTHETIC COMMUNITY IS PRESENT AT A COLD SEEP SITE

A high-resolution seismic reflection survey was conducted during the NT07-05 cruise over the Formosa Ridge offshore southwestern Taiwan where strong and continuous bottom simulating reflections (BSR) have been observed. Previous seafloor pictures taken from a deep-towed camera indicate that there are some chemosynthetic colonies. During the NT07-05 cruise, not only large and dense chemosynthetic communities were confirmed at the plume site, ROV Hyper Corresponding author: Phone: +886 2 33661387 Fax +886 2 23660881 E-mail: csliu@ntu.edu.tw. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, CANADA, July 6-10, 2008.