A study of the role of micrometeorological conditions on uptake of 3,4-dichloroaniline in maize

Abstract

<p>3,4-dichloroaniline (3,4-DCA) is a hardly biodegradable and hydrolysable compound, characterized as a persistent pollutant for water, soil and sediment and highly toxic for living organisms. In this work, the impact of different micrometeorological conditions on uptake of 3,4-DCA was investigated in maize (Zea mays L.) plants grown hydroponically. For this purpose, seedlings of a uniform vigor were developed in appropriate nutrient solution supplied with an initial amount of 3,4-DCA (growth solution) under controlled high light (HL) and low light intensity (LL) conditions and under high (HH) and low relative humidity (LH) conditions in the combinations of HL/HH, LL/HH and HL/LH. Plants grown under HL/LH were replenished with the initial amount of 3,4-DCA after 48 h from the application of the growth solution (AGS). The measurements which took place were related to the uptake of 3,4-DCA and of growth solution by plants. Also, the fresh weight of plants was measured. Results showed that maize was capable of removing noticeably high amounts of 3,4-DCA (up to three quarters of the initial amount) from the growth solution after completion of the first 24 h period from AGS, irrespective of micrometeorological conditions. It was also demonstrated that almost the whole available amount of 3,4-DCA was removed from the growth solution after a 48 h period from AGS under HL/LH. Plants under these conditions removed a significantly higher volume of growth solution compared to the HH conditions, irrespective of measurement time. The significant increase of the 3,4-DCA uptake (almost the whole available amount) by maize plants which were replenished with this compound under LH compared to HH, indicated a considerable capability of these plants to remove high concentrations of 3,4-DCA from the growth solution after 72 h from AGS. The fresh weight of maize plants under the examined micrometeorological conditions did not change significantly in the majority of the cases, as regards to different micrometeorological conditions. On the contrary, this plant parameter was significantly higher in 3rd compared to 1st measurement day in all examined conditions. The increase of 3,4-DCA uptake rates by maize plants grown under low relative humidity conditions, 72 hrs from AGS, could be associated with the expected acceleration of the plants transpiration rates and with the plant growth rate, as expressed by the fresh weight, as in these conditions plants remove considerably high volume of growth solution. The information obtained from the aforementioned results on plant uptake of 3,4-DCA in maize plants could be a first step in designing suitable management practices such as phytoremediation strategies which might reduce environmental pollution.</p>