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Climate Change: Coastal Marine Ecosystems
Published in Yeqiao Wang, Atmosphere and Climate, 2020
Jennifer P. Jorve, Rebecca L. Kordas, Kathryn M. Anderson, Jocelyn C. Nelson, Manon Picard, Christopher D. G. Harley
Climate change is caused by anthropogenic emissions of greenhouse gases such as carbon dioxide (CO2), which will soon reach the highest atmospheric concentration in tens of millions of years .[2] The rise in CO2 concentrations since the industrial revolution are 100-1000 times faster than at any point in the past 420,000 years, and these rates of increase are expected to accelerate by a factor of 2-6 by the year 2100.[3] Although one of the most widely publicized repercussions of greenhouse gas emissions is the predicted 2-3°C increase in average air and ocean temperatures over the next 100 years,[2] several additional changes will occur in the ocean. For example, excess CO2 reacts with seawater to increase the concentration of hydrogen ions (i.e., reduce pH) and reduce the concentration of carbonate ions, which are a key building block for calcified shells and skeletons. This suite of changes in ocean chemistry is known as "ocean acidification." The acidity of the surface ocean (the uppermost ocean layer where mixing due to a combination of temperature changes, waves, and currents acts to homogenize chemical conditions) has already increased by 30%, and may increase up to 150% by the end of this century.[2] Additional factors
A brief introduction to the marine environment
Published in Mark Zacharias, Jeff Ardron, Marine Policy, 2019
Understanding of the structure and function of the oceans is foundational to their effective management. For example, an understanding of ocean temperature and ocean chemistry is fundamental to comprehending the impacts of greenhouse gas emissions on marine environments (e.g. sea level rise, ocean acidification). This knowledge also contributes to evaluating opportunities to either mitigate (reduce) greenhouse gas emissions or adapt (respond to) to climate change. Another example is the need to understand how deep-seabed mining may affect marine environments. This requires knowledge of the oceanographic, physiographic and biological structures and processes that contribute to the ecological health of the deep-sea and associated communities.
Water and the Hydrosphere
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Humans have had major impacts on ocean chemistry near ocean margins because of polluted runoff and industrial effluent. On a global scale, however, the oceans contain too much water for human impacts to be seen. An exception to this is a slight increase in acidity; over the past 150 years, the average ocean pH has decreased from 8.25 to 8.14 due primarily to increased CO2 in the atmosphere, which dissolves in the oceans, producing carbonic acid.
Design of deep-sea chemical data collector for the seafloor observatory network
Published in Marine Georesources & Geotechnology, 2022
Bin Lv, Jie Chen, Hai-lin Liu, Chao Liu, Zhao-wen Zhang, Xiao-nan Zhang, Hao Gao, Yu-long Cai
The scientific instrument node of the marine chemical data collector includes a domestic independently developed optical dissolved oxygen sensor, a deep-sea methane sensor, a chlorophyll sensor, a turbidity sensor, and a colored dissolved organic matter (CDOM) sensor. This paper introduces the design and experimental verification process of the Marine chemical data collector and analyzes the results of the sea trial in Jiaozhou Bay, Qingdao. Note that the interface resources of the existing seafloor in-situ monitoring data collectors are limited. Hence they need to be specially designed according to the unique power supply and communication interfaces of the connected sensors. Interfaces also lack the functions of fault diagnosis and emergency treatment. The innovation of the designed marine chemistry data collector is the ability to self-diagnose the faults of the power supply, data transmission, and interface status of the system connected with various sensors. Furthermore, this system can apply emergency fault treatment. The energy communication interface between the data collector and the sensor is versatile and installed in plug-and-play mode. The control and data acquisition system of the ocean chemistry observation platform is also provided with a redundant backup design. Therefore, the power supply and communication of sensors are always guaranteed by the availability of a second link.
Red crust: evidence for an early Paleozoic oceanic anoxic event
Published in Australian Journal of Earth Sciences, 2020
N. Langsford, T. Raimondo, J. Jago
Although oceans were mostly oxic in Ediacaran and early Paleozoic times, numerous workers (e.g. Canfield et al., 2008; Jin et al., 2014; Poulton & Canfield, 2011; Sperling et al., 2015; Wang, Chen, Yan, Wei, & Xiang, 2012) have found geochemical evidence for episodes of ocean anoxia during this period. Poulton and Canfield (2011) have termed such states of anoxia as ‘ferruginous’, where oxygen levels are sufficiently low to allow elevated Fe2+ levels in ocean waters. These events reflect major perturbations in ocean chemistry. When ferruginous waters were introduced into shallow-water marine environments, they may have affected biological development at local to regional scales, especially during the early Paleozoic, a time of rapid biological evolution (e.g. Chen et al., 2015; Zhuravlev & Wood, 1996). In particular, the increased Fe2+ would be available to iron-oxidising chemolithotrophic bacteria, which may form distinctive stratigraphic horizons containing abundant ferrimicrobialites. Such horizons are a signature of ferruginous incursions and provide direct sedimentological and biological information as to their duration, extent and paleo-ecological effects, at scales ranging from mm-thick laminae to stratigraphic intervals several metres thick.
Relationship between geoacoustic properties and chemical content of submarine polymetallic crusts from offshore Brazil
Published in Marine Georesources & Geotechnology, 2020
Arthur Ayres Neto, Vanessa Alves da Costa, Clara Pinto Ferreira Maia Porto, Thais Cristina Vargas Garrido, Jean-Pierre Hermand
Among PMCs, ferromanganese crusts have the simplest mineralogy and are composed predominantly of manganese oxide and a variety of non-crystalline iron oxyhydroxides. They also contain minor amounts of detrital minerals, such as quartz and feldspar. Crusts thicker than 60 mm often contain phosphorous-enriched layers formed from sea water long after the crusts have precipitated (Hein and Koschinsky 2013). Given this economic potential, especially for critical high-technology metals such as Pt, Cu, Ni, Co and Rare Erath and Ytrium (REY) (Bau et al. 2014; ECORIS/GEOMAR 2014), PMCs have elicited a lot of global attention from both the public and private sectors. However, most research so far has focused on the chemical and mineralogical constitutions of PMCs and not on their physical properties. Zhang et al. (2012) explored REE enrichment in ferromanganese nodules and PMCs of the East Pacific Basin and concluded that the complex structural history of an area defines the number of active hydrothermal zones. That study found that the expansion of the East Pacific Ridge favored the occurrence of a large number of active hydrothermal zones and extensive areas of submarine basalts, weathering of which provides the source material for nodule growth in the Clarion-Clipperton area. In contrast, fine-scale variation in PMC geochemistry is dependent on local environmental conditions, such as regional seawater chemistry, suggesting that the geochemical signature of PMCs can be used to infer temporal changes in ocean chemistry (Wen, De Carlo, Li 1997).