Английский язык

Acidification of the Soil

The critical load, the ability of the soil to resist is sooner or later used up and it becomes acidified. The following may be said to be the worst effects:

Plant nutrients are leached out. The ability of plants to take up nutrientsdiminishes when the availability of base cations in the soil, such as magnesium, calcium, and potassium, is reduced. Forest growth can be affected, and some sensitive plant species possibly eliminated. It is estimated that the content of easily available base cations in the soil of southern Sweden os declining at a rate of 1-2 % per annum.

Poisonous metals are freed. Aluminium ions, which are poisonous to plant’s root systems, are freed through the weathering of the soil at lower pH-values. As the soil becomes more acid, the mobility of many heavy metals also increases. In acidified soil, it is likely that uptake by the plantsof cadmium, zink, manganese, and nickel, to mention a few, is increased.

Phosphates become bound. Plants also suffer indirectly when the concentrations of dissolved aluminium increased. Alumimiun ions have the ability to bind phosphate, which is an important nutrient and make it less easily available. The effect of an insufficiency of phicphate i moreover heightened when the process of decomposition becomes slowed down in the soil as a result of acidification. Some other important nutrients besides phosphate, such as molybdenum, boron, and selenium, also become less easily available to plants when the soil is acidified.

Up to the early 1980’s, most soil scientists believed belived it to be unlikely that the soil would be affected by acidification. There are parts of Europe where the soil has a large content of easily weathred minerals, enabling it to accept great amounts of acid without becoming acidified. But where the soil minerals weather less easily, as in Scandinavia, the resistance to acidification is low. The amount of acidific deposition that the various types of soil can accepr without becoming acidified, vries in Europe. Continuous sampling in Sweden has shown that the pH value of the soil has decreased by 0.3 to 1.0 units in only a few decades. The drop has not  only taken place in the upper layers, but also far down into the mineral soil. The store of base cations available to plants has on the average been halved in forty years.

До начала 1980-х годов большинство исследователей почвы считали маловероятным воздействие окисления на почву. Есть части Европы, где почва имеет большое содержание легко переносимых минералов, что позволяет ей принимать большое количество кислоты, не будучи окисленной. Но там, где минералов в почве не хватает, как в Скандинавии, устойчивость к окислению низкая. Количество окисленного осаждения, которое могут принять различные типы почв, не становясь окисленными, наблюдается в Европе. 

1. Where have the effects of acidification on freshwater life been most evident?

2. why does the number of phytoplankton rapidly diminish?

1. ability – disability;

2. acceleration – deacceleration

3. acidification – deacidification 

4. appearance –disappearance

5. aquation – disaquation

1. to eliminate; d

2. conclusion; c

3. capacity; b

4. to compound; a

5. available; e a. to combine;

B. MATCH THE WORDS WITH THEIR DEFINITIONS:

1. leakage; c

2. nutrient; a

1. The ability of the soil (to withstand, to resist, to oppose) is sooner or later used up.

2. Alumnium ions are (vindictive, toxic, poisonous) to plants’ root system.

3. Plants (suffer, endure, undergo) when the concentration of dissolved aluminium increase.

B. MARK THE STATEMENTS AS TRUE (T) OR FALSE (F). CORRECT THE FALSE STATESMENTS: 

6. The ability of plants to take up nutrients is reduced when the availability of base cations in the soil diminishes. (T)

7. Aluminium ions are poisonous very useful to plants’ root systems.(F)

1 Отмечается большая утечка азота с лесных угодий в Нидерландах, Дании, северной Германии.

2. Ионы алюминия обладают способностью связывать фосфат, который является важным питательным веществом, и делать его менее доступным.

3. Большинство ученых считают маловероятным, что на почву повлияет окисление.