The Effects Of Simulated Acid Rain On Cation Releases Characteristics In Red Soils Collected From Southern Anhui

Soil acidification caused by acid rain(acidic precipitation) has been a globalenvironmental problem.The soil property is directly effected by soil acidification,whichlead to nutrient element loss,soil deterioration,Aluminum and heavy metal elementactivation and plant poisoning,causing environmental problems.This paper chose redsoil as research subject collected from southern Anhui,which has a very widedistribution in acid rain areas of China.The effects of simulated acid rain on red soilacidification and the leaching of base ions and Al were studied by a laboratory leachingexperiment on simulated acid rain. The result showed as follows:(1)The red soil pH ranged from4.62to4.88.Exchangeable aluminum accounts fora large proportion of Acidic,more than80%.Red soil, a kind of acid sensitive soil withlow buffer capacity,about23.4-25.2mmol/kg, easily leads to acidification under A longperiod of Simulated acid rain leaching.red soil buffer capacity is obviously affected bysoil pH,base saturation percentage(BS%) and cation exchange capacity(CEC).(2)Cation Releases is closely related to simulated acid rain pH and leachingamount. Expect Na,Leached nutrients from the tested soil decreased in the order Ca＞Mg＞K.Cumulative release amount was increasing along with amount and acidity ofsimulated acid rain,Ca and Mg played a major role during cations buffering.(3)Mineral weathering and Al activation was directly affected by the acidity ofsimulated acid rain.under the same leaching amount condition.At pH2.0the releaseamounts of Al, increased significantly with the strengthened.a little Al release at the pH＞3.0and mass Al only release at the pH below3.0, Al had a declining release abilitywith the undergoing eluviation. With an increase of the leaching amount of acid rain,faintly acid rain also led to the release of Al. (4) Red soil had buffer capacity under simulated acid rain,which was related withsoil property and simulated rain strength. Leaching solution pH maintained at a highlevel under pH≥3of the simulated acid, which illustrated that red soil had kind of acidcapacity under the range of acid strength.but, leaching solution pH value decreasedsharply under pH2.0simulated acid rain, and finally reached a lower level andmaintain stability, which meant the original red buffer system is broken,and a newacid-base has established; After a long leaching period under pH>5simulated acid rainred soil pH rose slightly; but red soil pH decreased under pH<5simulated acid rainleaching series,especially red soil pH reached a minimum value under pH2.0simulatedacid rain,the soil exchangeable acidity increased rapidly, as well as the proportion ofexchangeable aluminum.In addition, the amount of exchangeable cations reduced,whichmeant minerals weathering by acid rain leaching and base cations were wash away withsimulated acid rain leaching.