Chow Y N, Lee L K, Zakaria N A, Foo K Y
River Engineering and Urban Drainage Research Centre (REDAC), Universiti Sains Malaysia, Nibong Tebal, Malaysia.
School of Industrial Technology, Universiti Sains Malaysia, Gelugor, Malaysia.
Front Plant Sci. 2021 Feb 23;12:609396. doi: 10.3389/fpls.2021.609396. eCollection 2021.
Nickel, a micronutrient essential for plant growth and development, has been recognized as a metallic pollutant in wastewater. The concentration of nickel ions in the water course, exceeding the maximum tolerable limit, has called for an alarming attention, due to the bioaccumulative entry in the water-plant-human food chain, leaving a burden of deteriorative effects on visible characteristics, physiological processes, and oxidative stress response in plants. In this work, the renewable utilization of nickel electroplating industrial wastewater effluent (0, 5, 10, 25, 50, and 100%) as a viable source of irrigation water was evaluated using a hydroponic cultivation system, by adopting and as the plant models, in relation to the physical growth, physiological and morphological characteristics, photosynthetic pigments, proline, and oxidative responses. The elongation of roots and shoots in and was significantly inhibited beyond 25 and 5% of industrial wastewater. The chlorophyll-, chlorophyll-, total chlorophyll, and carotenoid contents, accompanied by alterations in the morphologies of xylem, phloem, and distortion of stomata, were recorded in the industrial wastewater-irrigated groups, with pronounced toxicity effects detected in . Excessive proline accumulation was recorded in the treated plant models. Ascorbate peroxidase (APX), guaiacol peroxidase (POD), and catalase (CAT) scavenging activities were drastically altered, with a profound upregulation effect in the POD activity in and both POD and APX in , predicting the nickel-induced oxidative stress. Conclusively, the diluted industrial wastewater effluent up to the optimum concentrations of 5 and 25%, respectively, could be feasibly reused as a renewable resource for and irrigation, verified by the minimal or negligible phytotoxic implications in the plant models. The current findings have shed light on the interruption of nickel-contaminated industrial wastewater effluent irrigation practice on the physical and biochemical features of food crops and highlighted the possibility of nutrient recycling via wastewater reuse in a sustainable soilless cultivation.
镍作为植物生长发育所必需的一种微量营养素，却被视为废水中的金属污染物。由于镍离子在水 - 植物 - 人类食物链中的生物累积性进入，导致水道中镍离子浓度超过最大耐受限度，这已引起了人们的高度警觉，因为它会给植物的可见特征、生理过程以及氧化应激反应带来一系列恶化影响。在这项研究中，采用水培种植系统，以生菜和番茄作为植物模型，评估了镍电镀工业废水流出物（0%、5%、10%、25%、50%和100%）作为可行灌溉水源的可再生利用情况，涉及植物的物理生长、生理和形态特征、光合色素、脯氨酸以及氧化反应。当工业废水含量超过25%和5%时，生菜和番茄的根与茎的伸长受到显著抑制。在工业废水灌溉组中，记录到叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量发生变化，同时伴有木质部、韧皮部形态改变以及气孔扭曲，在生菜中检测到明显的毒性效应。在处理过的植物模型中记录到脯氨酸过度积累。抗坏血酸过氧化物酶（APX）、愈创木酚过氧化物酶（POD）和过氧化氢酶（CAT）的清除活性发生了剧烈变化，生菜中的POD活性以及番茄中的POD和APX活性均有显著上调，预示着镍诱导的氧化应激。总之，分别将工业废水流出物稀释至最佳浓度5%和25%时，可以作为生菜和番茄灌溉的可再生资源进行可行的再利用，这在植物模型中表现为最小或可忽略的植物毒性影响，从而得到验证。目前的研究结果揭示了镍污染的工业废水流出物灌溉对粮食作物物理和生化特征的影响，并强调了在可持续无土栽培中通过废水再利用实现养分循环的可能性。
