CHM and PHY Analysis of Seawater Test 2

What is chlorophyll a?

the primary green pigment that enables plants and such to perform photosynthesis

What region does chlorphyll absorb light in?

PAR - violet/blue and orange/red regions

Structural difference between clorophyll a and b

a has a methyl on porphyrin and b has an aldehyde on the ring

What happens to chlorphyll in the presence of light or acid?

Describe chlorophyllin manufacuring.

Magnesium is replaced with copper.

Describe blanching.

Describe regreening. What color is the new compound?

Describe pheophyinization.

Why do we measure chlorohyll a?

to estimate the biomass of plankton in various areas and over a period of time

What is the relationship btwn concentration of chlorophyll a and plankton biomass?

Global patterns of chlorophyll abundance.

Higher in the northern hemisphere and in some coastal regions. Also more abundant as you get closer to land.

How does chlorophyll change with time?

High in the spring and summer and low in the fall and winter

What does chlorophyll pigments convey about algal groups?

Draw a graph of absorbance vs wavelength for the different types of chlorophyll. Label the peak wavelengths.

What are the typical concentrations of chlorophyll a in the atlantic? Upwelling areas? Near shore? Cape fear estuary?

Pros and cons of florescence

What are the methods for measuring chlorophyll a?

fluorescence and absorbance

Pros and cons of absorbance

How does a fluorescence analysis work?

Filter sample to take out particulates and freeze until further analysis. Acetone is added to the sample which is then sonicated for 15 min and centrifuged for 5 minutes. The sample is then ready for fluorescence.

relationship between light attenuation and chlorophyll

proportional

relationship between carbonate and calcification

proportional

relationship between pH and CO2, why?

inverse, more CO2 reacts with water to produce H2CO3 which dissociates into H+ and HCO3, thus increasing the pH

What is a conservative property and what are some examples?

it changes only through mixing and addition/removal of material, not through temp. or pressure. examples: salinity, chloride, sodium, total alkalinity

What is a non-conservative property and what are some examples?

what contributes most to total alkinity?

carbonate concentration

what are the major components of total alkalinity

HCO3, CO3, B(OH)4, OH, H+, and HSO4

What happens to total alkalinity when we add CO2 or CaCO3?

CO2 does not change the alkalinity, CaCO3 will change

How is nitrogen cycled through marine environments?

fixation, nitrification, assimilation, and denitrification

How is phosphorous cycled through marine environments?

weathering of rocks, uptake by marine organisms, and sedimentation on the ocean floor

How is silicon s cycled through marine environments?

through diatoms via dissolution and precipitation

What are the general sampling and preservation protocols nutrients in marine samples?

• Use nutrient-free containers

• Filter to remove particulates

• preserve through freezing and chemical preservation

• paper storage

How do nutrients enter seawater?

naturally via riverine input, upwelling, and atmospheric deposition, enriching marine ecosystems

How are nutrients removed from seawater?

through phytoplankton uptake, sedimentation of organic matter, and microbial denitrification

What is eutrophication? What causes it?

Human activities like agricultural runoff and wastewater discharge

What are the redfield and atkinson and smith ratios mean? What is the limiting reactant? What is the common limiting reactant in oceans and coral reefs and why?

The ratios represent that ratio of carbon, nitrogen, and phosphorus needed to support the primary production and synthesis of new biomass. The limiting reactant represents the nutrient that gets used up first, limiting further production. In oceans, it is typically nitrogen due to denitrication and in coral reefs , it is typically phosphorous due to CaCO3 absorbs phosphorous.

What is the redfield ratio? The Atkinson and Smith ratio?

C:N:P of 106:16:1 and 500:30:1

How does the concentration of nitrates and phosphates change with depth? Why?

Generally, the concentration of nitrates and phosphates increase with depth up until a point and then the concentrations remains the same. This is because phytoplankton are more abundant near the surface, in which they takeup nitrate and phosphates for growth and production. As the depth increases, there is less phytoplankton to do this and dead organic matter sinks, releasing the nutrients.

How does the concentration of dissolved oxygen change with depth? Why?

Dissolved oxygen concentration decreases with depth because oxygen is produced from photosynthesis by the phytoplankton which is more abundant at the surface. Also, oxygen enters the water through exchange with the atmosphere. At lower depths, there is less photosynthesis and organisms consume oxygen through cellular respiration.

Explain the different parts of the marine nitrogen cycle.

1) nitrogen fixation: nitrogen-fixing bacteria converts atmospheric nitrogen (N2) to ammonia or ammonium available for organisms to use

2) nitrification: phytoplankton convert ammonia/ammonium (PON/DON) to nitrate

3) assimilation: phytoplankton takeup dissolved inorganic nitrogen (nitrite/nitrate)

4) denitrification: nitrate is converted to nitrogen gas in low oxygen conditions

5) upwelling: nitrate from deep waters is brought to the surface

6) ammonification: dead matter is broken up and nitrogen is converted to ammonia

Is the nitrification process a reduction or oxidation? Why?

Oxidation because the nitrogen atoms are losing electrons to the oxygen atoms.

Explain the different parts of the phosphorous nitrogen cycle.

1) fish, zooplankton, and phytoplankton release organic and inorganic phosphates

2) plants take up inorganic and some organic phosphorous

3) phosphorous is absorbed by sediment and is eventually released upon decomposition

What is the full speciation of nitrication?

NH4+ —> NH2OH —> N2O —> NO2- —> NO3-

What is the full speciation for denitrication?

NO3- —> NO2- —> N2O —> N2O —> NO —> N2

How does nutrient abundance change with seasonal changes? Why?

In the winter time, upwelling brings nutrients to the surface amidst the decrease of plant growth at the surface. In the spring, more sunlight brings more organisms to consume the nutrients available. In the summer, there is increased stratification due to the thermocline, minimizing the upwelling of deep-water nutrients. In the fall, the cooling temperatures minimize the stratification. Therefore, generally, the surface nutrients are higher in fall and winter than spring and summer.

General steps for measuring the concentration of marine nutrients.

1) Collect samples in clean polyethelene bottles

2) prepate reagents depending on nutrient

3) For nitrate, pass sample through cadmium collumn and measure absorbance at 543 nm. For phosphorous, measure absorbance at 885 nm.

4) run blanks and make calibration curve

5) use calibration curve to calculate concentration

how does a continuous flow analyzer work? What are its advantages?

Water samples are continuously pumped through narrow tubes. Chemical reagents are added to the samples which react with the nutrients, producing a colored solution. A colorimeter or spectrophotometer measures the color intensity and calculates the nutrient concentration.

Advantages: high throughput, consistent nutrient measurement, minimal sample handling

What nutrients are ideally measured through calorimetry?

phosphate and ammonium

Advantages of spectrophotometric techniques for nutrient measuremnts.

high specificity and sensitivity in nutrient quantification

Explain the role of nitrate, phosphate, and silicate in marine primary production

• nitrate: phytoplankton growth

• phosphate: energy transfer and nucleic acid formation

• silicate: diatoms to build silica-based cell walls

significance of DOC in the ocean

• largest organic carbon reservoir

• energy source for marine microbes

• interacts with nitrogen and phosphorous cycles and oxygen dynamics

• carbon sequestering to regulate atmospheric CO2

• effects trace metal speciation and light absorption

what does DOM, DOC, CDOM, DON, DIC, DIN, TDN, POM, POC, and PON stand for?

Does the lower, middle, or upper estuaries tend to have the most DOC? Why?

The upper estuaries typically have the most DOC because its higher influence of terrestrial organic matter from the freshwater input. The TOM dissolved in the water, increasing the amount of DOC in the water. There is less TOM in the seawater areas.

From smallest to largest, what are the different carbons pools on earth?

particulate organic matter < sediments < atmosphere < ocean DOC < land biota < soil carbonate < soil humus < ocean DIC

What are the main sources of DOC to the oceans?

• river input

• atmospheric deposition

• porewater diffusion

• biological production (excretion)

Explain how DOC is cycled in the ocean.

1) DOC is put into the ocean through rain, runoff, the atmosphere, and biological production.

2) UV radiation can break down DOC and DIC like CO2.

3) Microorganisms release DOC only to be taken up again by other microorganisms and some will release as CO2 through cellular respiration.

4) Some DOC will be transported into deep waters.

How does DOC change with depth? Why?

DOC decreases with depth up until around 500 meters in which is slowly increases. The DOC is highest at the surface because phytoplankton produce and release organic carbon. The decrease occurs as a result of decreased phytoplankton and the consumption of organic matter by bacteria. The overall low but slight increase in DOC in deep waters occurs as a result of the movement of DOC to deep waters.

what is the global distribution of DOC in the ocean? Why?

DOC is most abundant in warmer waters, centered around the equator and less abundant in colder waters near the poles. This trend is as a result of the differences of biological production

How old are marine DOC surface and deep waters? Why the difference?

1300 yrs old and 4100-6000 yrs old. Surface DOC cycles at a faster rate than deep ocean DOC cycles.

What are the general steps to analyzing DOC?

1) Collect sample

2) filter

3) acidify filtrate

4) store in airtight glass vials

5) use a High-Temperature Catalytic Oxidation (HTCO) analyzer - sample is sparged w/ carrier gas to remove inorganic carbon

6) organic carbon is oxidized to CO2 and measured using a Non-Dispersive Infrared (NDIR) detector and converted to DOC concentration based on calibration curves

What is the difference between conservative and non-conservative mixing in terms of DOC?

With conservative mixing, the concentration changes as a result of the changing water mass. This would result in a linear relationship with salinity. The concentration change due to non-conservative mixing because DOC is being added or removed during mixing. To determine which is occurring, one must measure the DOC and salinity and determine the type of relationship.