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2. Sorpcia a desorpcia herbicídu MCPA v pôdach a sedimentoch

Creator:
Hiller, Edgar, Sirotiak, Maroš, Zemanová, Lenka, and Bartaľ, Mikuláš
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
sorption, desorption, herbicide, MCPA, soil, sorpcia, desorpcia, herbicíd, and pôda
Language:
Slovak
Description:
We investigated the sorption-desorption behaviour of acid herbicide MCPA (4-chloro-2-methylphenoxy acetic acid) in five soils (denoted as A1-5), three bottom sediments (S1-3) and in two river sediments (L1-2) at two initial concentrations in aqueous solution - C0 = 0.5 and 10 mg L-1. Sorption and desorption of MCPA was measured by a batch equilibrium technique using analytical pure MCPA. There was no significant influence of the initial concentration of MCPA on its equilibrium distribution between soil/sediment and aqueous solution. The difference between distribution coefficient KD at C0 = 0.5 mg L-1 and KD at C0 = 10 mg L-1 was found only in the case of one bottom sediment (S2). Simple regression analysis between KD at C0 = 0.5 and 10 mg L-1 and soil/sediment properties indicated that the most important property which determined the variation in MCPA sorption is organic carbon (r = 0.885** and r = 0.921***, respectively). Similarly, the desorption of MCPA was inversely proportional to organic carbon content of the soils and sediments used (r = -0.821* and r = -0.888**). These observations showed that sorption-desorption behaviour of MCPA in soils and sediments was primarily controlled by organic components of the geosorbents used. Overall, the sorption extent of MCPA in soils and sediments was low (Psorp ≈ 5 - 53 %; KD = 0.131 - 2.827 L kg-1) and desorption extent was relatively high (Pdes ≈ 11 - 52 %), especially in soils and sediments with the lower organic carbon content. The experimental results and calculated values of groundwater ubiquity score GUS and relative leaching potential index RLPI imply that MCPA is very mobile in all soils and has high potential to contaminate groundwater. and Laboratórnymi metódami sme skúmali sorpčno-desorpčné správanie herbicídu MCPA (kyselina 4-chlór2-metyl fenoxyoctová) s kyslým charakterom (pKa = 3,07) v 5 vzorkách pôd (A1-5), v 3 vzorkách dnových sedimentov (S1-3) a v 2 vzorkách riečnych sedimentov (L1-2) pri dvoch koncentráciách vo vodnom roztoku - 0,5 a 10 mg l-1. Počiatočná koncentrácia MCPA vo vodnom roztoku nemala vplyv na jeho rozdelenie medzi pôdu/sediment a vodný roztok, iba v prípade 1 vzorky dnového sedimentu (S2) bol zistený rozdiel v rozdeľovacích koeficientoch KD. Sorbované množstvo MCPA v sledovaných pôdach a sedimentoch priamo úmerne záviselo od celkového obsahu organického uhlíka. Podobne, vodou desorbované (extrahované) množstvo MCPA z pôd a sedimentov vyjadrené v % (Pdes) nepriamo úmerne záviselo od celkového obsahu organického uhlíka. Tieto pozorovania dokumentujú, že sorpčno-desorpčné správanie MCPA v pôdach a sedimentoch je primárne kontrolované organickými zložkami sledovaných geosorbentov. Celkovo bol sorbovaný podiel MCPA v pôdach a sedimentoch nízky (Psorp ≈ 5-53 %; KD = 0,131-2,827 l kg-1) a desorbované množstvo relatívne vysoké (Pdes ≈ 11-52 %), zvlášť v pôdach a sedimentoch s nižším obsahom organického uhlíka. Experimentálne výsledky a vypočítané hodnoty GUS (Groundwater Ubiquity Score) a RLPI (Relative Leaching Potential Index) poukazujú na výraznú pohyblivosť MCPA v pôdach a vysokú tendenciu MCPA preniknúť do podzemných vôd.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public