There is also evidence that life itself can contribute to mass extinctions. When the eventually , organisms that could not survive or thrive around oxygen (called ) . When anoxic conditions appeared, particularly when existed, the anaerobes could abound once again, and when thrived, usually arising from ocean sediments, they . Since the ocean floor had already become anoxic, the seafloor was already a dead zone, so little harm was done there. The hydrogen sulfide became lethal when it rose in the and killed off surface life and then wafted into the air and near shore. But the greatest harm to life may have been inflicted when hydrogen sulfide eventually , which could have been the final blow to an already stressed ecosphere. That may seem a fanciful scenario, but there is evidence for it. There is fossil evidence of during the Permian extinction, as well as photosynthesizing anaerobic bacteria ( and ), which could have only thrived in sulfide-rich anoxic surface waters. Peter Ward made this key evidence for his , and he has implicated hydrogen sulfide events in most major mass extinctions. An important aspect of Ward’s Medea hypothesis work is that about 1,000 PPM of carbon dioxide in the atmosphere, which might be reached in this century if we keep burning fossil fuels, may artificially induce Canfield Oceans and result in . Those are not wild-eyed doomsday speculations, but logical outcomes of current trends and , proposed by leading scientists. Hundreds of already exist on Earth, which are primarily manmade. Even if those events are “only” 10% likely to happen in the next century, that we are flirting with them at all should make us shudder, for a few reasons, one of which is the awesome damage that it would inflict on the biosphere, including humanity, and another is that it is entirely preventable with the use of technologies .
Hydroponics is a method of growing plants without soil. Plants are simply placed in water with the necessary chemicals. As plants are deprived of support from the ground, they will fall down. To support the plants, an inert material like expanded clay pebbles is used in a pot in the tank (figure 5). Before inserting a plant in a hydroponic system, you must carefully remove all soil from the roots otherwise bacteria will putrefy them.
For many houseplants you can use tap water. Though, particularly for vegetables, it is advised to add appropriate nutrients. This cultivation method has the advantages of both requiring less frequent waterings and using very little water. With this system you can grow nearly any houseplant or vegetable. Hydroponics is useful also to show what nutrition plants need.
1 - Place some houseplants in hydroponics.
2 - Try hydroponics with vegetables and find the suitable nutrients.
Hydroponics in the Classroom
Growing plants without soil
To teach orphaned children how to grow their own food with hydroponics (gardening that uses very little water).
Organic Greenhouse Vegetable Production
Internet keywords: hydroponics classroom.
Where Do Bacteria That Carry Out Chemosynthesis
are an organism that requires organic substrates to get its carbon for growth and development. Some are strictly aerobic, but many are facultative anaerobes (they can survive in either the presence or absence of oxygen).
Heterotrophic Bacteria are generally found in most over the counter aquarium cycling products (especially "Sludge Removers") due to their portability and quick activity.
Heterotrophs can be either gram-positive (ex: Bacillus) or gram-negative (ex: Pseudomonas) which in the case of Pseudomonas many gram negative aquarium treatments (such as Kanamycin) can be effective against Pseudomonas while not harming true Autotrophic nitrifying bacteria.
Another point is growth (which is why Heterotrophic bacteria are favored for cycling products); nitrifying (Autotrophic) bacteria will double in population every 15-24 hours under optimal growth conditions. Heterotrophic bacteria, on the other hand, can reproduce in as little as 15 minutes to 1 hour.
Unfortunately research has shown that up to one million times more of these heterotrophic bacteria are required to perform a comparable level of ammonia conversion that is attained by true autotrophic nitrifying bacteria, in part due to the fact of Heterotrophic Bacteria to convert many organics into food.
The use of Heterotrophic Bacteria to cycle an aquarium (or pond) can result in a bio environment that does not contain the necessary Autotrophic nitrifying bacteria to rapidly adapt to changes in bio load either from added fish, wastes, or similar; thus often resulting in sudden spikes in ammonia or nitrites when these Heterotrophic bacteria cycling products are not added in a timely or regular schedule!The other danger is cloudy water.
For this reason products that contain only Heterotrophic Bacteria such as "Hagen Cycle" or even the popular Eco-Complete planted substrate SHOULD BE AVOIDED in some aquariums!
Low pH and Nitrification ;
Nitrification involving AOB & NOB bacteria is different at pH levels of above 7.0 versus below 6.0.
Toxic Ammonia (NH3) changes to ammonium under 6.0 and ammonium (non toxic NH4) switches back to toxic NH3 over 7.0
until the nitrification process re-establishes itself at the higher pH
The cause of this change in the nitrification process is still not clearly understood.
From the above article and quote, I would postulate that a change in Heterotrophic bacteria along with possible Redox Reactions or lack there of (a low pH below 6.0 is very oxidizing with little/no reduction which for this reason alone is not a healthy environment.
As well, Autotrophic bacterial adaptations may be part of this process and why there is an interruption in nitrification from changes in pH and between NH3 & NH4.
Since typical real world aquarium environments invariably are going to contain Heterotrophic bacteria (from fish food waste, etc.) and these tests seemed to lock out these Heterotrophic bacteria (using only ammonium chloride), this bacterium might be part of the cause.
During the nitrification process carbonates are used by the aquarium or pond to counter acids produced during nitrification (or other organic breakdown), however without an adequate KH (even for Amazon River Fish such as Discus or German Rams), subtle or even sudden changes in pH can occur that affects the nitrogen cycle
Keeping a low pH/KH can be a double edged sword where by a simple procedure such as a water change with slightly higher pH water can result in an immediate conversion of ammonium (NH4) to deadly ammonia (NH3) with disastrous results.
This low pH, poor nitrifying environment also easily allows for the growth of pathogenic Fungi/Saprolegnia and a depressed Redox balance.