anyone please explain detaily what is meant by gradient such as concentration gradient?

Answer 1

Gradient, out of context of your question, is the change from less to more or more to less. Such as a yard or roads "grade" is the slope up or down over a given distance.
The term "concentration gradient", in context of your question, is the change of the concentration (or numbers) of the biological species of which you are observing.
In other words, it is the measurement of the change of individuals within a species over a given period of time.
If you are studying the change in the number of mustangs in a set area of BLM (bureau of land management) lands, over a 5 year period of time, you are documenting what the concentration gradient is, for those given parameters.
good luck and congratulations on worthwhile goals.

Answer 2

A gradient is the change in something between less and more. It's usually applied to something else; for instance "the effect of salt concentration on freezing temperature of water, measured along a concentration gradient of 0.01 % salt to 99.99 % salt" would involve taking measurements of the freezing temp. at various salt concentrations and then plotting them on a graph with one axis being the salt concentration and the other the temp. You could then draw a line showing roughly how the temp changes as you go from high to low concentration or vice-versa. The concentration would be measured along a gradient. Or you could measure salt concentration in sea water as you approach a river mouth. The change in concentration vs. distance from the river would be a concentration gradient.