We’re rewarding the question askers & reputations are being recalculated! Read more.

Hot answers tagged

21

As always: It Depends. Assuming enough water and sunshine, crop growth rate boils down to the concept of limiting nutrients. These may be: nitrogen (via ammonia or nitrates), phosphorous (via phosphates), potassium, and sometimes others. In typical continental settings (i.e. subduction related vulcanism), lavas may be enriched in potassium and phosphorous ...


6

Like many things in Earth Science, the answer is, "It depends." In this case it depends on the composition of the soil and the contaminant you are talking about. Climate, particularly the amount of precipitation, can also have an effect. Septic systems are primarily designed to promote aerobic conditions and aerobic bacteria to degrade organic compounds ...


5

The effects of Coriolis in rivers and estuaries are more subtle than in the open ocean. Coriolis tends to be a second or third order process in fast-moving and relatively small systems like rivers. On the other hand, when the residual flow in an estuary is considered, then that process tends to be slow and persistent and the effects of Earth's rotation (...


5

The climate impacts of CO2 are not constrained to the location they are emitted, but rather the whole globe will feel the effects. CO2 is a long-lived molecule that takes 100+ years to convert or deposit. The troposphere, though, only takes months to mix. There are longer times for mixing between the north/south hemispheres, (e.g. over a year), but it is ...


4

Yes, they have many impacts: They provide a substrate for algae to grow and they can have whole ecosystems under them. You might think that such substrate is transient because it is melting, but Arctic and Antarctic waters are often below zero degrees Celsius, therefore, freshwater ice doesn't melt. You can find many articles about such ecosystems (here is ...


4

Coral die because of coral bleaching, a process in which the symbiotic algae living in the coral (which give the coral its colour), leave the coral host. Bleaching can occur for a variety of reasons, but the ones that relate to a warming climate are: Ocean acidification caused by dissolution of carbon dioxide in the water. Thermal stress. According to this ...


3

David LeBauer is correct in saying that there are 'allometric equations' to estimate the leaf biomass, but they only refer to small experimental plots in such places as Hawaii, Japan, Singapore and Malaysia. The number of species involved is a few dozen at most. As 'N9ZN' points out, trying to develop generalizations would be a titanic task, and essentially ...


3

The ecological footprint is the impact of a person or community on the environment, expressed as the amount of land required to sustain their use of natural resources. A global hectare (gha) from Wikipedia: One global hectare represents the average productivity of all biologically productive areas (measured in hectares) on earth in a given year. and... ...


3

This book is based on Australian experience, some of it may be relevant of North American wildfires. I read it ten years ago. Paul Collins, Burn - The Epic Story of Bushfire in Australia, Allen & Unwin, 2006, ISBN 9781741750539, ISBN 1 74175 053 9. Part 4, titled: The Great Fire Debates, has three chapters (9 to 11); 09 To burn or not to burn 10 ...


3

A weed is just a plant where you do not want it. Totally a matter of context. Tumbleweeds are non-native, introduced centuries ago. I assume you mean the invasive species of plants that have been spread by humans and are disrupting ecologies throughout most of the world Until recently, these plants we consider weeds were limited in their range to home ...


3

As a rule no, while sulfur and nitrogen compounds from industrial and vehicle exhaust have an immediate impact and a relatively fast deposition cycle and thus are extremely location sensitive carbon dioxide is relatively long lived in the atmosphere and too plentiful in discharge to be heavily effected by the environment of discharge, assuming direct ...


3

I disagree with the statement that flood-plain basalts don't make fertile soils. The most fertile soils in southeast Australia are on the Victorian volcanic plains. The soils of the Deccan Plateau of India are considered very fertile. There are very fertile soils formed on the Columbia River basalts of eastern Washington state and Oregon as far as the ...


3

Plants follow the law of the minimum. There's a ratio at which nutrients occur in plant matter. If it can't get those amounts, it will be limited by the one nutrient that falls below the ratio. Let's say a plant wants to grow 123 grams of biomass. It needs 106g of carbon, 16g of nitrogen, and 1 g of Phosphorous (this is called the Redfield ratio, and it ...


2

Drying out of North Africa is likely the result of something far more local. I've never heard of the either the Tibetan Plateau or the growing Himalaya as causing changes to Africa's monsoons and always understood the connection between Milankovich cycles and the consequences of glaciation. According to this study, which modelled weather patterns of the time:...


2

You can always weigh the biomass of the (global) ecosystem in metric tons, or any other unit, even when this mass would not be constant. I don't see a reason why the total biospheric mass should be constant (maybe because it reached a saturation limit long ago) on short timescales. On long/geological timescales it is certainly not, as the available carbon, ...


2

The problem about rain water catchment is, that it prevents ground water from being formed, thus depleting these ressources and making them unavailable during droughts. Plus, ground water tends to be cleaner than rain water as far as I know - provided there's no fracking or subterranean atomic waste storage around.


2

Rain water is still one of the most cleanest water sources available. There may be some ancient underground aquifers that have clean uncontaminated water. One issue with rain water is that atmospheric moisture - part of the water cycle - needs to condense on aerosols in the atmosphere before it can develop into rain. With the amount of pollution humans are ...


2

Two things to think about: Nitrous oxide is extremely scarce in the atmosphere, less than 1 ppm. Compare with carbon dioxide that (unfortunately) is now greater than 400 ppm. Also consider the lifetime of the gases in the atmosphere: nitrous oxide has a much shorter lifetime than carbon dioxide. If we'd stop emitting greenhouse gases now, nitrous oxide ...


2

There isn't enough nitrous oxide in the atmosphere to make a major contribution to global warming, which in some ways is a pity, because we'd all bee in a much jollier mood if there was (N2O is sometimes known as laughing gas). It also depletes the ozone layer if it gets up that high, though depleting ozone at ground level, where it is harmful, is a good ...


1

According to @AllInOne from the comments: This is currently what a project in New York City is trying to do. Their listed goal on wikipedia is to get one billion live oysters in New York Harbor by 2035. According to their website, they do this because of the following reasons: Oysters have a remarkable ability to filter nitrogen pollution from water ...


1

I think the reason you were marked wrong is because your text book is using the term "climate" loosely. The deterioration of vegetation will result in desert encroachment ... which in turn can cause a change in local climate. After all, if you create more desert, you have changed the local climate, right? However, it takes many years to define a climate ...


1

Slash and burn has been used in North America and still is at times. I see regular field burning near me where fields are particularly rocky and tilling if impractical for the crops grown. It also occurs when there is intrusions of some noxious weeds that are controllable through fire as effectively and much cheaper than chemical controls. In general, I ...


1

Dry season It is easy to burn things in the dry season, not so much where it is wet. Eastern North America generally qualifies as wet, certainly in the winter, less so in the summer. This isn't to say that you CAN'T do slash and burn where it is wet, since it is done in rainy Papua New Guinea an the Amazon, but it makes more sense as a strategy when there ...


1

The currents run counterclockwise. That's why the Humboldt Current cools the Pacific coast of South America, because the water is coming from the "six o'clock" position in the Antarctica. But in the Northern Hemisphere, the "six o'clock" position is warm water near the equator, which warms Oregon and Washington. In the northern hemisphere, the cold Labrador ...


1

SWAT model has a pretty good technical and theoretical documentation on their website : http://swat.tamu.edu/documentation/ Regarding the conceptual logic, SWAT is based on sub-watershed discretization. Inside these, it defines Hydrological Response Units (similar slope, land use and soil). Then, you simplify it on the basis of the HRU heterogeneity, you ...


Only top voted, non community-wiki answers of a minimum length are eligible