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study & questions

This is a discussion on study & questions within the Advanced Freshwater Discussion forums, part of the Freshwater Fish and Aquariums category; --> i hope to use this thread to get feedback if i'm understanding things right --- in high pH iron is removed (i think around ...

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Old 03-22-2014, 01:23 PM   #1
 
study & questions

i hope to use this thread to get feedback if i'm understanding things right

---

in high pH iron is removed (i think around 8.0 all iron is removed - those notes are at home, i'm not :(

i have notes on the most basic of redox, only enough to understand it's got some value (still learning)
-sounds interesting to get into :)

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iron, in a high redox environment (tends to coincide with high pH environments)
-converts iron from ferrous iron(2+) into ferric iron(3+) (i still don't understand this about iron, so i'm just going with it) which is not soluble, and falls out of suspension

this leaves out rust, but at the moment i'm not concerned

in a low O2 environment, (eg. anoxic substrate) iron may be converted back into ferrous form, and be returned to the nutrient cycle.

---

leaves me with more questions than answers, but sharing and curious if i got that much right at the moment
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Old 03-22-2014, 03:15 PM   #2
 
Redox potential and pH do not correlate with eachother. pH deals with hydrogen ions, redox is electrons. You can have high pH and low redox, you can have low pH and high redox. Some molecules can have pH dependent redox potentials

Iron changes form under oxidizing conditions because it of how its electrons are arranged. An oxidizing environment has a higher number of electrons present. This changes energy requirements for many compounds and allows them to take an oxidized state. Every chemical change effects the physical properties of that chemical. For iron the +3 oxidized state is mostly insoluble because it looses that attraction it had to the water molecules. Redox has an effect on many chemicals and compounds other then iron as well.

The first thing to come to terms with flear is chemical and biological systems are dynamic. There are usually no straight lines and always more questions then answers.
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Old 03-22-2014, 03:43 PM   #3
 
so redox and pH correlations are coincidental, got it, ... (still need to learn more)

i red that before but tried to overly simplify it :(

i could ask all kinds of questions on that iron 3+ vs iron 2+ relating to redox and pH, ... but it would really be frustrating for everyone if the answer was on the next page, ... back to reading. this will be one of those questions i'll wait till i'm done the book and either have the answer or not, ... but better to read first instead of get distracted.
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Old 03-22-2014, 03:56 PM   #4
 
"High levels of dissolved O2 can inhibit photosynthesis."

does this mean pearling is bad ? (it looks neat, never thought beyond that)

needs more water circulation ?
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Old 03-23-2014, 07:38 AM   #5
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Hello Flint:
Photosynthesis is the process by which plants, some bacteria, and some protistans use the energy from sunlight to produce sugar, which cellular respiration converts into ATP, the "fuel" used by all living things. The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll. Most of the time, the photosynthetic process uses water and releases the oxygen
We can write the overall reaction of this process as:
6H2O + 6CO2 ----------> C6H12O6+ 6O2
Most of us don't speak chemicalese, so the above chemical equation translates as:
six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen

oxygean is a by-product and not used in photosynthesis
I would not worry about pearling dissolved oxygen on leaves, my plastic plants pearl dissolved oxygen all the time.
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Old 03-23-2014, 11:15 AM   #6
 
not related to study

aside from toxicity levels (without actually being toxic, just present in quantities too high)

animals and plants just poop out what they don't use don't they ? (yes, generalized)
(or whatever it's called with plants and bacteria do this)

---

-back to study (having a difficult time today - but working on it)
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Old 03-23-2014, 12:14 PM   #7
 
Quote:
Originally Posted by Flear View Post
"High levels of dissolved O2 can inhibit photosynthesis."

does this mean pearling is bad ? (it looks neat, never thought beyond that)

needs more water circulation ?
The only natural scenario where high or supersaturated levels of dO2 happen would be in a very high photosynthesis environment where O2 production is in considerable excess of the systems O2 demand and O2 diffusion into the atmosphere. Basically its not highly common and would be temporary and localized if it does happen. Circulation would help but you need to realize there isn't much water movement in natural heavy planted waters. Its not going to have much effect on the plants since its a issue of their production. Photosynthesis is energy input. They can still respire under high O2, after all respiration requires oxygen. Simply because light is present doesn't mean a plant has to only photosynthesize. Too much light will also inhibit photosynthesis, tho the actual levels depend on the plant species. Everything that is a variable to plant growth... nutrients, light, environmental conditions all have ideal levels and can be too high or two low. But this is all relative to a specific species, which leads on to the basis of resource competition between species.

Pearling happens under the right conditions. Flow certainly does have an effect. The layer of water on the leaves is the first thing to get super saturated. Any object in water will have drag on the water moving around it. This means where the leaves and water meet will have the slowest water movement. On the other hand pearling doesn't mean the water is super saturated. It could just be an effect of circulation and diffusion. If the plant is producing O2 faster then it can dissolve into the water it will pearl regardless of O2 content of the water.
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Old 03-23-2014, 01:27 PM   #8
 
slight distraction from studies

correct me if i'm wrong, ...

is redox related to oxygen or potential chemical energy ? (i'm thinking the later)

everything i'm readings talks about oxygen, (current text), ... but also talks about the potential energy gained in reactions...

(i wish i had a bigger list)... things like fluorine, cobalt, gold, chlorine all have higher energy values that oxygen
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Old 03-23-2014, 02:34 PM   #9
 
Quote:
Originally Posted by Flear View Post
correct me if i'm wrong, ...

is redox related to oxygen or potential chemical energy ? (i'm thinking the later)

everything i'm readings talks about oxygen, (current text), ... but also talks about the potential energy gained in reactions...

(i wish i had a bigger list)... things like fluorine, cobalt, gold, chlorine all have higher energy values that oxygen
As far as we care in this situation redox is related to oxygen. An oxic environment pushes towards oxidation (Ammonia to nitrate as we know). Anoxic the energy potential is different and pushes towards reduction (nitrate to ammonia). Oxygen is common and is an oxidizer, there are many other oxidizers but in a biological system oxygen is the main one. Flourine are chlorine are both oxidizers and they are both highly toxic to biological systems.

Potential energy varies widely and is specific to each reaction and changes based on environmental conditions and fluxes. I'm not sure what you mean by other ions having higher energy values.... Its not to say they don't, but there are a couple different types of energy when talking about chemistry. Potential energy is the stored energy in a molecule or system. There is also activation energy which is what is required to initiate the reaction. If activation energy can not be met the reaction will not happen unless it is somehow reduced. This doesn't matter if potential energy is high or not. Not all reactions result in an energy gain, especially biological ones. Photosynthesis requires energy input, that mostly being sunlight but some comes from the plant as well. The energy input drives the synthesis of sugars. The sugars are now stored energy for the plant. Only when it respires and breaks down the sugars it made does it get energy out of them.
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Old 03-24-2014, 07:15 AM   #10
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Hello Mikaila31
“An oxic environment pushes towards oxidation (Ammonia to nitrate as we know). Anoxic the energy potential is different and pushes towards reduction (nitrate to ammonia).” I am not disagreeing with you but only asking a question would not a anoxic environment tend to reduce nitrate to a form of nitrogen gas completing the nitrogen cycle instead of ammonia restarting the nitrogen cycle which is an oxygen intense process.

“Photosynthesis requires energy input, that mostly being sunlight but some comes from the plant as well. The energy input drives the synthesis of sugars. The sugars are now stored energy for the plant. Only when it respires and breaks down the sugars it made does it get energy out of them” again I am not disagreeing with you but I thought that oxygen (respiration) is produced by photosynthesis during the light dependent reaction creating ATP’s glucose sugars are created during the light independent reaction using CO2 the calvin-benson cycle and not part of plant respiration.
In #7 “Any object in water will have drag on the water moving around it. This means where the leaves and water meet will have the slowest water movement” are you talking about the unstirred area that is sometimes called the boundary layer in fluid dynamics created by friction.

I have been learning up.
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