# The Effects of Plasma-Activated Water on Heavy Metals Accumulation in Water Spinach
###### Abstract
Research on direct and indirect plasma treatments of several vegetable species with DBD was conducted by [PERSON] et al., who found that the germination of seeds was improved, although the efficiency depended on the species [12]. [PERSON] et al. proved that the polysaccharides of a mutant strain of _Ganoderma lingzhi mycelia_ increased by 25.6% after treatment with atmospheric DBD non-thermal plasma [7]. Another similar study by [PERSON] et al. included the application of a pulsed high-voltage electrical stimulation to cultivation mushrooms at 50-130 kV, where the fruiting body formation increased by 1.3-2 times [9]. Plasma-treated water or plasma-activated water (PAW) is produced by applying plasma to water in order to generate active oxygen molecules and excited OH radicals. Atomic oxygen and nitrogen generated in gaseous plasma could transfer into liquid and be easily converted into other reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as nitrates (NO3\({}^{-}\)), nitrites (NO2\({}^{-}\)), and hydrogen peroxides (H2O2) in the solution. Air is considered to be the most abundant processing gas at low cost, and acts as a great source of oxygen (O2) and nitrogen (N2) with ultraviolet radiation and other chemical species in liquids. PAW is a mixture of high biochemically reactive solution of an acidic condition due to the changes in oxidation-reduction potential (ORP), electrical conductivity (EC), and the formation of RON and RNS [13; 14]. [PERSON] et al. evaluated the potential application of plasma treatment of tap-water (PATW) produced by cold atmospheric pressure DBD for improving agricultural quality [15]. The study revealed that the formation of nitrite, nitrate, ammonium ions (NH4\({}^{+}\)), and H2O2 in the water could induce and enhance crop growth, and that the consumption of bicarbonate ions could promote seedling growth. The length of the seedlings increased by 34% and 128.4% after 3 and 6 days of PATW treatment. The production of reactive species using plasma-activated water could change or affect the seeds both physically and chemically. [PERSON] et al. reviewed the relevant research on PAW and indicated that the physical and chemical properties of PAW are related to the acidity, conductivity, redox potential, and concentration of ROS and RNS in the water, which affects microorganisms [14; 16]. In addition, [PERSON] et al. suggested that PAW has a synergistic effect on food disinfection and can also promote the growth of seed seedlings [14]. The increment in the proportion of nitrate and nitrite ions in PAW may be the actual reason for the improvement in plant growth. Soaking seeds in PAW can play an antibacterial role and can also promote seed germination and plant growth. PAW may be used to increase crop yields and confront drought environmental conditions [12; 14]. Several previous studies in the literature have proven the efficiency of plasma treatment for improving the germination and growth rate of plant species. Hence, this research focuses on assessing the application of non-thermal plasma in decreasing the heavy metal accumulation of vegetables planted in contaminated soil by initiating the growth of the vegetables.