Marine Chemistry Lecture 1

Connections in Earth Systems

Hydrosphere, atmosphere, and lithosphere connections involve a complex interplay of various elements and processes that shape our planet's systems:

• Organic Ligands: These are compounds that can form complexes with metal ions and play a significant role in biogeochemical cycles.

• Reductants: Important reductants include CO2, NO, (CH3)2S, SO2, and others which are key in chemical reactions that reduce other compounds or species in the environment.

• Precipitation Processes: Precipitation is crucial for replenishing water sources and supporting terrestrial and aquatic ecosystems.

• Key Atmospheric Processes: Chemical interactions involving compounds such as HCl and CO from industrial activities, including evaporator plants, are essential for understanding atmospheric chemistry and its impacts on environmental health.

• Formation of Soils and Weathering Processes: Soil formation is influenced by weathering of rocks, contributing to the habitat for vegetation and affecting nutrient cycling.

• Importance of Humus and Products of Detritus: Humus enhances soil fertility through organic matter decomposition, facilitating nutrient availability for plants.

• Role of Fresh Waters and Algae in Photosynthesis: Freshwater systems and algae contribute significantly to photosynthesis, capturing CO2, and releasing oxygen, essential for life.

Temporal and Spatial Scales of Oceanic Processes

Scales of Space and Time:

• Ocean Mixing Times: The mixing time of ocean waters is approximately on the scale of 1000 years, indicating the slow movement and turnover within ocean basins.

• Atmosphere Mixing Times: In contrast, atmospheric mixing times are much shorter, approximately 1 year, reflecting the dynamic nature of the atmosphere.

• Reference: Bacosa et al., 2015

Overview of Ocean Chemistry

Key Concepts:

• Composition: Understanding the matter and energy involved in ocean chemistry is crucial for marine science.

• Transport: Studying the types and scales (both spatial and temporal) of transport mechanisms in ocean water is vital for comprehending ocean dynamics.

• Transformation: Focusing on processes of speciation, reaction, and exchange highlights how chemical substances change and interact.

• Human Impact: It is important to note that marine pollution, often stemming from land-based activities, significantly affects ocean ecosystems.

• The Overarching Field: The study of ocean chemistry encompasses a wide range of interdisciplinary approaches to understand the oceans' chemical properties and processes.

Chemical Oceanography Techniques

Water Collection Methods:

• Rosettes: Devices used to collect water samples at various depths to study chemical composition.

• Tow-fish: Equipment to gather data while being towed behind a vessel, useful for surface and subsurface measurements.

• Collection of Major Ions: Determining the concentration of major ions is vital for understanding salinity and chemical balance in ocean waters.

Tools for Ocean Charting:

• Bottles: Simple water sampling devices.

• CTD Devices (Conductivity, Temperature, Depth): Instruments that measure temperature and salinity at various depths, providing critical data for ocean studies.

Trace Elements and Sample Collection

Trace Element Sampling:

• Utilizing Titanium-plastic rosettes (often referred to as "Fish") is essential for high-precision trace metal sampling.

• Reference: Jeandel 2024; NIOZ

Sediment Collection Techniques

Sediment Collection Methods:

• Sediment Cores: Collecting long cylindrical samples of sediment to analyze historical environmental changes.

• Methods include:-

  • Plastic Liners

  • Corers: Devices to penetrate sediment layers and retrieve samples.

  • Drilling Ships: Vessels specifically designed for deep-sea drilling and sample collection.

• Techniques include:

  • Box Core: Captures surface sediments.

  • Megacore: Collects multiple cores from a single drop.

  • Multicore: Similar to Megacore but specialized for discrete sampling.

• Utilized Vessel: JOIDES Resolution, known for its research capabilities in ocean drilling and sediment retrieval.

Understanding Past Conditions through Proxies

Proxy Definitions:

• A proxy is a measurable characteristic that indicates a harder-to-measure characteristic or quantity, essential for reconstructing past environmental conditions.

• Examples of proxy archives include:

  • Sediments: Layers of sediment can provide historical climate and ecological records.

  • Biogenic Minerals: Microscopic evidence of past biological activity.

  • Fossilized Morphologies: Examination of fossils helps to understand ancient ecosystems.

  • Ice: Ice core samples preserve atmospheric gas compositions over millennia.

• References: Girard (2014), phys.org, EOS, British Antarctic Survey

Analytical Chemistry Techniques in Ocean Studies

Examples of "Wet" Chemistry:

• Titration: A quantitative chemical analysis method for measuring salinity and oxygen levels.

• Spectrophotometry: Utilized for analyzing concentrations of substances like nitrate, nitrite, and phosphate in water samples.

• Fluorometry: Method for detecting ammonium and chlorophyll concentrations in aquatic environments.

• Chromatography and Mass Spectrometry: Advanced techniques for detailed chemical analysis of ocean samples.

Observing Oceanic Distributions

Three-Dimensional Distributions:

• Specific reference: AI_D [nmol/kg] levels from GEOTRACES data, crucial for mapping chemical distributions in ocean waters.

Sensor Technologies and Ocean Observations

Key Deployment Methods:

• Satellite observations and communications are critical for far-reaching data gathering about oceanographic conditions.

• Implementation of GOOS (Global Ocean Observing System) provides essential data for ocean monitoring.

  • GOOS Delivery Areas: Focus on real-time ocean status and maintaining quality management. Categories include:

    • Archived Data

    • Real-time Operational Data

    • Climate Health Monitoring

    • Ship-based Measurements: Meteorological and oceanographic measurements conducted from research vessels.

    • Tsunami and Tropical Moored Buoys

    • HF Radars and Drifting Buoys: Used for ocean current data collection.

    • Profiling Floats like Argo: Important for gathering deep and biogeochemical measurements.

Summary of GOOS Observation Tools

Observational Tools List:

• Argo Profiling Floats: Essential for time series sites via OceanSITES, allowing continuous data collection over time.

• Drifting Buoys: Integral for real-time ocean measuring, coordinated by the Data Buoy Cooperation Panel (DBCP).

• Moored Buoys and Tsunami Buoys: Categorized under DBCP for continuous monitoring of oceanographic conditions.

• Ship Observations Team (SOT): Focuses on ship-based meteorological and oceanographic measures to gather vital data on ocean dynamics.

• GO-SHIP: Conducts repeated transects to gather consistent oceanographic data across different times, crucial for understanding changes in ocean chemistry and biology.

This comprehensive set of notes covers the major themes and methodologies in chemical oceanography, focusing on the interconnectedness of Earth's systems, advanced techniques for ocean sampling and observation, and the significant role of proxies in understanding past oceanic conditions, all of which are essential for fostering a deeper understanding of oceanic and climatic processes.