What was Redfield known for?

phytoplankton stoichiometry/ratio

Which one of these was NOT an important topic in the paper?

nitrogen fixation & annamox reactions

Is nitrogen fixing important?

No, there's an overabundance of N.

Marine Microorganisms and Global Nutrient Cycling

A solution is a mixture in which one or more substances are uniformly distributed in another substance. Solutions can be mixtures of liquids, solids, or gases. For example, plasma, the liquid part of blood, is a very complex solution. It is composed of many types of ions and large molecules, as well as gases, that are dissolved in water. A solute (SAHL-YOOT) is a substance dissolved in the solvent. The particles that compose a solute may be ions, atoms, or molecules. The solvent is the substance in which the solute is dissolved. For example, when sugar, a solute, and water, a solvent, are mixed, a solution of sugar water results. Though the sugar dissolves in the water, neither the sugar molecules nor the water molecules are altered chemically. If the water is boiled away, the sugar molecules remain and are unchanged. Solutions can be composed of various proportions of a given solute in a given solvent. Thus, solutions can vary in concentra- tion. The concentration of a solution is the amount of solute dis- solved in a fixed amount of the solution. For example, a 2 percent saltwater solution contains 2 g of salt dissolved in enough water to make 100 mL of solution. The more solute dissolved, the greater is the concentration of the solution. A saturated solution is one in which no more solute can dissolve. Aqueous (AY-kwee-uhs) solutions—solutions in which water is the solvent—are universally important to living things. Marine microorganisms spend their lives immersed in the sea, an aqueous solution. Most nutrients that plants need are in aqueous solutions in moist soil. Body cells exist in an aqueous solution of intercellu- lar fluid and are themselves filled with fluid; in fact, most chemical reactions that occur in the body occur in aqueous solutions. Copyright © by Holt, Rinehart and Winston. All rights reserved. Liquid water Solid water Ice (solid water) is less dense than liquid water because of the structure of ice crystals. The water molecules in ice are bonded to each other in a way that creates large amounts of open space between the molecules, relative to liquid water. FIGURE 2-12 solvent from the Latin solvere, meaning “to loosen” Word Roots and Origins CHEMISTRY OF LIFE 43 ACIDS AND BASES One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base? Ionization of Water As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change: one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into two ions of opposite charge: H2O ∏ H OH The OH ion is known as the hydroxide ion. The free H ion can react with another water molecule, as shown in the equation below. H H2O ∏ H3O The H3O ion is known as the hydronium ion. Acidity or alkalin- ity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution. If the number of hydronium ions in a solution equals the number of hydroxide ions, the solution is said to be neutral. Pure water contains equal numbers of hydro- nium ions and hydroxide ions and is therefore a neutral solution. Acids If the number of hydronium ions in a solution is greater than the number of hydroxide ions, the solution is an acid. For example, when hydrogen chloride gas, HCl, is dissolved in water, its mol- ecules dissociate to form hydrogen ions, H, and chloride ions, Cl, as is shown in the equation below. HCl ∏ H Cl These free hydrogen ions combine with water molecules to form hydronium ions, H3O. This aqueous solution contains many more hydronium ions than it does hydroxide ions, making it an acidic solution. Acids tend to have a sour taste; how- ever, never taste a substance to test it for acidity. In concentrated forms, they are highly corrosive to some materials, as you can see in Figure 2-13. Bases If sodium hydroxide, NaOH, a solid, is dissolved in water, it dissociates to form sodium ions, Na, and hydroxide ions, OH, as shown in the equation below. NaOH ∏ Na OH Copyright © by Holt, Rinehart and Winston. All rights reserved. Eco Connection onnection Acid Precipitation Acid precipitation, more commonly called acid rain, describes rain, snow, sleet, or fog that contains high levels of sulfuric and nitric acids. These acids form when sulfur dioxide gas, SO2, and nitrogen oxide gas, NO, react with water in the atmosphere to produce sulfuric acid, H2SO4, and nitric acid, HNO3. Acid precipitation makes soil and bodies of water, such as lakes, more acidic than normal. These high acid levels can harm plant and animal life directly. A high level of acid in a lake may kill mollusks, fish, and amphibians. Even in a lake that does not have a very elevated level of acid, acid precipitation may leach aluminum and magnesium from soils, poisoning water- dwelling species. Reducing fossil-fuel consump- tion, such as occurs in gasoline engines and coal-burning power plants, should reduce high acid levels in precipitation. Sulfur dioxide, SO2, which is produced when fossil fuels are burned, reacts with water in the atmosphere to produce acid precipitation. Acid precipitation, or acid rain, can make lakes and rivers too acidic to support life and can even corrode stone, such as the face of this statue. FIGURE 2-13 44 CHAPTER 2 This solution then contains more hydroxide ions than hydronium ions and is therefore defined as a base. The adjective alkaline refers to bases. Bases have a bitter taste; however, never taste a substance to test for alkalinity. They tend to feel slippery because the OH ions react with the oil on our skin to form a soap. In fact, commercial soap is the product of a reaction between a base and a fat. pH Scientists have developed a scale for comparing the relative con- centrations of hydronium ions and hydroxide ions in a solution. This scale is called the pH scale, and it ranges from 0 to 14, as shown in Figure 2-14. A solution with a pH of 0 is very acidic, a solution with a pH of 7 is neutral, and a solution with a pH of 14 is very basic. A solution’s pH is measured on a logarithmic scale. That is, the change of one pH unit reflects a 10-fold change in the acidity or alkalinity. For example, urine has 10 times the H3O ions at a pH of 6 than water does at a pH of 7. Vinegar, has 1,000 times more H3O ions at a pH of 3 than urine at a pH of 6, and 10,000 times more H3O ions than water at a pH of 7. The pH of a solution can be measured with litmus paper or with some other chemical indicator that changes color at various pH levels. Buffers The control of pH is important for living systems. Enzymes can function only within a very narrow pH range. The control of pH in organisms is often accomplished with buffers. Buffers are chemi- cal substances that neutralize small amounts of either an acid or a base added to a solution. As Figure 2-14 shows, the composition of your internal environment—in terms of acidity and alkalinity— varies greatly. Some of your body fluids, such as stomach acid and urine, are acidic. Others, such as intestinal fluid and blood, are

Lide 1: Introduction to Bioreactor A bioreactor is a vessel used for growing microorganisms, plant or animal cells Provides controlled conditions for biological reactions Maintains optimum pH, temperature, oxygen, and nutrients Widely used in fermentation, enzyme, vaccine, and antibiotic production Ensures sterile and aseptic environment Scale ranges from laboratory to industrial production Slide 2: Basic Design Requirements of a Bioreactor Must be constructed with non-toxic, corrosion-resistant materials Should allow effective mixing and mass transfer Provision for sterilization (in situ sterilization) Must maintain uniform temperature and pH Easy sampling without contamination Should support scalability and automation Slide 3: Materials Used in Bioreactor Construction Stainless steel (SS-316) for industrial bioreactors Glass for laboratory-scale bioreactors Plastic (polycarbonate) for disposable bioreactors Materials must withstand heat and pressure Should be smooth to prevent microbial attachment Resistant to chemicals and cleaning agents Slide 4: Main Parts of a Bioreactor Vessel: holds the culture medium and microorganisms Agitator (impeller): provides mixing Sparger: supplies sterile air Baffles: prevent vortex formation Sensors: monitor pH, temperature, dissolved oxygen Ports: used for inoculation, sampling, and feeding Slide 5: Agitation System Ensures uniform mixing of nutrients and cells Improves oxygen transfer rate Common impellers: Rushton turbine, marine propeller Speed controlled by motor Prevents settling of cells Affects shear stress on cells Slide 6: Aeration System Supplies oxygen for aerobic fermentation Air introduced through sparger Types of spargers: ring, nozzle, sintered Maintains dissolved oxygen concentration Air is filtered for sterility Essential for high cell density cultures Slide 7: Temperature and pH Control Temperature controlled by heating/cooling jackets pH maintained using acid or alkali addition Sensors continuously monitor parameters Automated control systems used Ensures optimal microbial growth Prevents enzyme denaturation Slide 8: Foam Control System Foam formed due to protein and agitation Excess foam reduces oxygen transfer Mechanical foam breakers used Chemical antifoam agents added Foam sensor detects foam formation Maintains efficient fermentation Slide 9: Types of Bioreactors – Based on Mode of Operation Batch bioreactor Fed-batch bioreactor Continuous bioreactor Choice depends on product type Widely used in industrial fermentation Controls productivity and yield Slide 10: Batch Bioreactor All nutrients added at the beginning No addition or removal during process Simple and easy to operate Low risk of contamination Used for antibiotics and enzymes Limited control over nutrient depletion Slide 11: Fed-Batch Bioreactor Nutrients added during fermentation Prevents substrate inhibition High product yield Widely used in industrial fermentation Allows better control of growth rate Used in insulin and enzyme production Slide 12: Continuous Bioreactor Fresh medium continuously added Culture removed at same rate Maintains steady-state conditions High productivity Risk of contamination is high Used in wastewater treatment and SCP production Slide 13: Types of Bioreactors – Based on Design Stirred tank bioreactor Airlift bioreactor Bubble column bioreactor Packed bed bioreactor Fluidized bed bioreactor Photobioreactor Slide 14: Stirred Tank Bioreactor (STR) Most commonly used bioreactor Mechanical agitation using impellers Suitable for aerobic fermentation Excellent mixing and oxygen transfer Used for bacteria and fungi Easy scale-up Slide 15: Airlift Bioreactor Mixing achieved by air circulation No mechanical agitator Low shear stress Energy efficient Suitable for shear-sensitive cells Used in wastewater treatment Slide 16: Bubble Column Bioreactor Air bubbles provide mixing Simple design and low cost No moving parts Limited mixing efficiency Used for microbial fermentation Suitable for large-scale operations Slide 17: Packed Bed Bioreactor Contains immobilized cells or enzymes Substrate flows through packed matrix High cell density Used in continuous processes Limited oxygen transfer Used in enzyme and wastewater treatment Slide 18: Fluidized Bed Bioreactor Immobilized particles kept in suspension Better mass transfer than packed bed Reduced clogging Suitable for continuous operation Used in biotransformations Higher operational complexity Slide 19: Photobioreactor Designed for photosynthetic organisms Provides light source Used for algae and cyanobacteria Controls light, CO₂, and temperature Used in biofuel and pigment production Can be tubular or flat-plate design Slide 20: Applications of Bioreactors Production of antibiotics and vaccines Enzyme and organic acid production Single cell protein production Wastewater treatment Biofertilizer and biopesticide production Biopharmaceutical manufacturing

Marine Mammals-Whales

Marine Science Midterm

Marine and Coastal Processes.What are the hazards that usually occur along marine and coastal areas? Coastal processes, such as waves, tides, sea level changes, crustal movement, and storm surges will result to coastal erosion, submersion, and saltwater intrusion. Coastal Erosion. Coastal erosion is the wearing down of the coastlines by the movement of wind and water. It is not a constant process; instead, the rate of erosion depends on other events such as cyclones. When cyclones occur along coastal areas, the winds and waves carry the sediment away from the shoreline. Shorelines play an important role to society. They are used in transportation, fishing, and tourism. Therefore, preventing coastal erosion is of utmost priority. There are three main classifications of stabilizing the shoreline: hard stabilization, soft stabilization, and retreat. 1. Hard stabilization is done by building structures that will slow down the erosion on areas that are prone to erosion. Examples of hard stabilization structures are jetties, sea walls, and breakwaters. Though they may slow down the erosion in one area, it may hasten the erosion in other areas. 2. Soft stabilization includes the process of beach nourishment, wherein sand from an offshore location is brought to an area with a receding shoreline. It does not make use of structures like the ones used in hard stabilization. 3. Retreat is the option taken by residents near areas where coastal erosion is already severe. At this point, the authorities no longer attempt to save the shoreline but rather limit the amount of human interference in the area. Submersion. Coastal erosion happens because of the interaction of the winds and waves on the shoreline. Submersion, on the other hand, happens because of the changes in the sea level, specifically, when it rises dangerously above the normal level. This is all due to the increase in the global temperature, which, in turn, melts the glacial deposits and increases the overall sea level. Another factor that may cause submersion is the vertical movement of the plates. Landmasses can be uplifted, which can also cause changes in the sea level. It can also be caused by tsunamis and storm surges. Submersion will most likely occur in reclaimed lands. These are the areas that were originally part of oceans, riverbeds, or lakebeds. They are low-lying flatlands, so even a small rise in sea level can cause great damage on the land. To prevent this from happening not only in reclaimed lands but also in coastal areas, a hard stabilization technique is used. Sea walls are built along the coastline to protect the land from being easily flooded. Aside from sea walls, dikes can also help prevent flooding. The government can also upgrade the infrastructures built in coastal areas, regenerate mangroves, or relocate the people. There are also other proposed strategies to mitigate coastal submersion, such as imposing of setback policies and construction regulations and creating adaptive plans for coastal management. Saltwater Intrusion. In coastal areas where there is an interaction between saltwater and fresh water, saltwater intrusion is one of the hazards that are evident in that area. Saltwater intrusion is the movement of saltwater into the freshwater aquifer. The natural flow is that the fresh water, which is less dense, moves towards the denser saltwater. But if the fresh water is being withdrawn faster than it is being replenished, then there will be a change in pressure and saltwater intrusion will occur.There are a few ways of preventing saltwater intrusion. One is to stop using the well where fresh water has been depleted and let the groundwater replenish naturally via the water cycle. The other method is to build two wells: a pumping well-built farther inland and an injection well-built closer to the coast. Using the injection well, fresh water is pumped into the aquifer to prevent the saltwater from intruding. The different marine and coastal hazards often occur in the Philippines, being an archipelago with the longest coastline. Manila Bay is one of the coastal areas of the Philippines that is facing various threats from both natural and anthropological causes. Saltwater intrusion occurs due to uncontrolled withdrawal of groundwater to be used by residential, commercial, and industrial areas built around the bay. It is also frequently flooded due to poor drainage systems and improper disposal of waste. Since Manila Bay is shared by four coastal provinces, four noncoastal provinces, and the National Capital Region, each local government unit and national agencies need to collaborate in planning, developing, and managing its marine and coastal resources. And it is not only Manila Bay but other parts as well, for as long as they are in coastal areas, hazards will mostly likely occur if not immediately addressed.

Marine erosion

Marine Mammals

Marine Heatwaves

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