Stomatal Conductance Measurement for Toxicity Assessment in Zero-Effluent Constructed Wetlands: Effects of Landfill Leachate on Hydrophytes

Abstract

In this research, we explore for the first time the use of leaf stomatal conductance (gs) for phytotoxicity assessment. Plants respond to stress by regulating transpiration. Transpiration can be correlated with stomatal conductance when the water vapor pressure gradient for transpiration is constant. Thus, our working hypothesis was that the gs measurement could be a useful indicator of the effect of toxic compounds on plants. This lab-scale study aimed to test the measurement of gs as a phytotoxicity indicator. Our model plants were two common hydrophytes used in zero-effluent constructed wetlands for treating landfill leachate. The toxic influence of two types of leachate from old landfills (L1, L2) on common reed (Phragmites australis (Cav.) Trin. ex Steud.) and sweet flag (Acorus calamus L.) was tested. The gs measurements correlated well with plant response to treatments with six solutions (0 to 100%) of landfill leachate. Sweet flag showed higher tolerance to leachate solutions compared to common reed. The estimated lowest effective concentration (LOEC) causing the toxic effect values for these leachates were 3.94% of L1 and 5.76% of L2 in the case of reed, and 8.51% of L1 and 10.44% of L2 in the case of sweet flag. Leachate L1 was more toxic than L2. The leaf stomatal conductance measurement can be conducted in vivo and in the field. The proposed approach provides a useful parameter for indicating plant responses to the presence of toxic factors in the environment.

Micro- and Macroelements Content of Plants Used for Landfill Leachate Treatment Based on Phragmites australis and Ceratophyllum demersum

“…The containers thus prepared (with the P. australis and C. demersum seedlings) were completed with the landfills leachate from the four facilities. The series for each landfill consisted of solutions with increasing concentrations: from 0% (tap water), through 6.25%, 12.5%, 25% and 50% to 100% [49]. The leachate exposure lasted for another 14 days [32,50,51].…”

Enhanced leachate phytodetoxification test combined with plants and rhizobacteria bioaugmentation

“…In addition, it is necessary to conduct testing before applying phytotreatment or phytoremediation to determine the effect of contaminants on plants using phytotoxicity tests [ 155 ] The plants Scirpus grossus and Cyperus rotundus used in the tempeh industrial wastewater treatment can be accepted for about 25% of the waste content [ 105 ]. Various types of plants are used in phytotoxicity, such as Phragmites australis , Acorus calamus [ 27 ], Chrysopogon zizanoides [ 43 ]. [ 135 ] using Sinapsis alba L. and Lemna minor L. as bioindicators to measure the toxicity of leachate.…”

Changes of a Landfill Leachate Toxicity as a Result of Treatment With Phragmites australis and Ceratophyllum demersum–A Case Study

“…The reduction of municipal waste landfilling has recently become increasingly important. However, even after major changes in waste management and closure of some landfills, management of leachate from these facilities will still remain a challenge (Białowiec et al, 2019).…”