Russian to English Law/Patents Environment & Ecology Assessment of environmental impact + calculation of charges

The term is from a document title stating the following:

Расчет суммы платы ***по объекту негативного воздействия***

then there is a table listing (inter alia) the type of pollutant, measurement units, a set limit of allowed emissions, actual level of emissions (both within and exceeding the set limits), a fee rate per ton, surcharges (different indices and multiples) and the actual amount of charges to be paid.

Now I am struggling with 2 things here:

(a) the "по" bit - which (in my understanding) is basically a classification BY the type of pollutant; and

(b) the actual English term for "объект негативного воздействия" - which (again, in my understanding) is not the object of exposure (such as air, water, etc.) but, based on the contents of the table, is the TYPE of pollutant that is regarded as something having adverse environmental impact. I was thinking along the lines of "source" but cannot tie it in with "adverse impact" so that it Googles properly.

In addition "объект негативного воздействия" is also used to denote a type of waste (in a similar table relating to volumes of industrial waste storage and disposal)

Any help/advice would be much appreciated!