https://www.meas.ncsu.edu/sealevel/publications/Liu_Yangtze_2007_Geomorphology.pdf

Flux and fate of Yangtze River sediment delivered to the East China Sea

The majority of life on Earth--notably, microbial life--occurs in places that do not receive sunlight, with the habitats of the oceans being the largest of these reservoirs. Sunlight penetrates only a few tens to hundreds of meters into the ocean, resulting in large-scale microbial ecosystems that function in the dark. Our knowledge of microbial processes in the dark ocean-the aphotic pelagic ocean, sediments, oceanic crust, hydrothermal vents, etc.-has increased substantially in recent decades. Studies that try to decipher the activity of microorganisms in the dark ocean, where we cannot easily observe them, are yielding paradigm-shifting discoveries that are fundamentally changing our understanding of the role of the dark ocean in the global Earth system and its biogeochemical cycles. New generations of researchers and experimental tools have emerged, in the last decade in particular, owing to dedicated research programs to explore the dark ocean biosphere. This review focuses on our current understanding of microbiology in the dark ocean, outlining salient features of various habitats and discussing known and still unexplored types of microbial metabolism and their consequences in global biogeochemical cycling. We also focus on patterns of microbial diversity in the dark ocean and on processes and communities that are characteristic of the different habitats.

Microbial Ecology of the Dark Ocean above, at, and below the Seafloor

Acid volatile sulfide (AVS)

Distribution and accumulation of heavy metals in the sediments of Kaohsiung Harbor, Taiwan.

Heavy metal contamination in surface sediments of Yangtze River intertidal zone: an assessment from different indexes.

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

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

Sulfate reduction rate, organic carbon and sulfide burial rate; organic carbon, carbonate carbon, and reactive iron contents; grain size; and sedimentation rate were determined in sediments of the southern East China Sea continental slope. The results show high sulfate reduction and pyrite sulfur burial rates in slope areas with high organic carbon and sedimentation rates. Unusually high rates of organic carbon deposition enhance sulfate reduction and pyrite sulfide burial in the region. Both sulfate reduction rates and pyrite sulfur burial rates increased linearly with increasing organic carbon burial rate, indicating that deposition of organic carbon on the slope is the primary controlling factor for pyrite formation. Abundant reactive iron indicated that iron is not limiting pyrite formation. Pyrite is the predominant sulfide mineral; however, acid volatile sulfide constituted up to 50% of total sulfide at some stations. Up to 240 μmol/g of pyrite sulfur and 5 mmol/m 2 /day of sulfate reduction rates were found in the slope sediment. Sulfate reduction rate and pyrite sulfur did not decrease with increasing overlying water depth. High organic carbon burial rates enhanced the sulfate reduction rate and subsequently the rate of pyrite sulfur burial in the slope region. As a result, the southern East China Sea continental slope environment is an efficient pyrite sulfur burial environment.

Sulfate reduction and iron sulfide mineral formation in the southern East China Sea continental slope sediment

Sulfate reduction rates and sedimentation rates were determined in sediments at ten stations on the southern East China Sea continental shelf. The area is characterized by relatively low organic carbon concentration with fast sedimentation rate. Rapid sulfate reduction rates, ranging from 1 to 4 mmol/m 2 /day, were observed. Organic carbon concentration varied from 0.3 to 0.6 wt%. Sedimentation rate varied from 0.2 to 0.7 cm/yr. In addition, normal marine S/C ratios were observed. Up to 96% of pyrite-sulfur was reoxidized before its final burial. Sulfate reduction rate and pyrite-sulfur burial rate increased linearly with increasing organic carbon burial rate, indicating that organic carbon deposition controlled pyrite formation in the East China Sea continental shelf sediments. The organic carbon utilized by the sulfate reduction and its burial represented a significant but relatively small fraction of the primary production in the studied East China Sea region.

Organic carbon deposition and its control on iron sulfide formation of the southern East China Sea continental shelf sediments

Carbon/sulfide/iron relationship and sulfate reduction rate were investigated in the East China Sea continental shelf sediments. The area is characterized by median to high sulfate reduction rate, and high concentrations of iron oxide minerals. Organic carbon was found to be the primary limiting factor for the pyrite formation. Sulfate reduction rate increased with increasing organic carbon concentration. C/S ratio displays a typical normal marine sediment ratio. Low DOP values and abundance of highly reactive iron oxide, ferrihydrite and lepidocrocite, indicate that iron is not limited in the East China Sea continental shelf.

Kuo-Ming Huang

Papers

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

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

Sulfate reduction and iron sulfide mineral formation in the southern East China Sea continental slope sediment

Organic carbon deposition and its control on iron sulfide formation of the southern East China Sea continental shelf sediments

The carbon-sulfide-iron relationship and sulfate reduction rate in the East China Sea continental shelf sediments