Barnsjön is a small lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 within the Tyresån Lake System

Tyresån Lake System

Tyresån Lake System is a number of lakes in Sweden with a common basin of 251.5 km2....

 in Tyresö Municipality

Tyresö Municipality

Tyresö Municipality is a municipality in Stockholm County in east central Sweden on the coast of the Baltic Sea. Its seat is located in Bollmora.Most of Tyresö Municipality lies within the Stockholm urban area.-History:...

 south of Stockholm

Stockholm

Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

, Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

.

The lake, situated between the residential areas Trollbäcken

Trollbäcken

Trollbäcken is a district of Tyresö Municipality in Sweden. It is located south of Bollmora along county road 260. Trollbäcken contains almost exclusively detached houses. In the area of Trollbäcken centre , also known as Alléplan, there are some multi-apartment buildings and commercial...

 and Bollmora

Bollmora

Bollmora is the central district and municipal seat of Tyresö Municipality in Sweden. Together with major parts of the other two main districts of Tyresö, Trollbäcken and Old Tyresö, Bollmora forms a conurbation with the Stockholm urban area....

, empties into Lake Tyresö-Flaten through the brook Prästängsdiket. It is regarded as an important local recreational milieu. It is popular for both fishing and bathing.
There are two municipal baths by the lake.

Environmental impact

Barnsjön is a forest lake poor is nutrients. With a low buffering capacity, the lake is sensitive for acid deposits

Acid rain

Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...

 and has an acid

Acid

An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ity at about pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

7. It is therefore regarded as important to avoid contaminations within its catchment area.