Mujeeb Amtul, Aziz Irfan, Ahmed Muhammad Zaheer, Shafiq Sheraz, Fatima Sadia, Alvi Sofia Khalique
Dr. Muhammad Ajmal Khan Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi 75270, Pakistan.
Dr. Muhammad Ajmal Khan Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi 75270, Pakistan.
Sci Total Environ. 2021 Aug 10;781:146715. doi: 10.1016/j.scitotenv.2021.146715. Epub 2021 Mar 25.
Coastal wetlands primarily serve as natural sinks of trace metals and their importance for phytoremediation is well known at global level. There are some reports on trace metal availability in soil sediments of the Karachi coast but studies on accumulation and translocation to harvestable (Shoot) parts among halophytes of the littoral zones have not been conducted. Hence, phytoremediation potential of six naturally existing halophytes (Aeluropus lagopoides, Arthrocnemum macrostachyum, Atriplex stocksii, Avicennia marina, Cressa cretica and Suaeda fruticosa) was assessed for cleaning metal (Mn, Zn, Pb and Cr) polluted soils of the Karachi coast. Seasonal (winters, pre and post-monsoon summers) and spatial (three littoral zones: viz., site - I: Sandspit, site - II: Do-Dariya/Clifton and site - III: Korangi creek) variations in soil and plant metals of the Karachi coast were studied. Soil Zn, Pb and Cr were generally higher in winters, Mn and organic matter in summers (7-11%) while pH values ranged between 7.15 and 7.5 in all seasons at site - III. All tested species had potential for cleaning Pb through their harvestable part (shoots) with A. stocksii as prominent candidate (16 mg kg) at site - I. Cressa cretica emerged as exclusive candidate for Zn phytoremediation (96 mg kg) at site - I, while S. fruticosa, A. macrostachyum and A. lagopoides showed bioaccumulation in pre-monsoon summers at site II. Aeluropus lagopoides with higher Mn in post monsoon summers (62 at site - III and 53 mg kg at site - II) and Cr (7.1 mg kg at site - II and 14 mg kg at site - III) appeared exclusive bioindicator with potential of for cleaning all metals (Mn, Zn, Pb and Cr) at different sites. Metal bioaccumulation at study sites appeared species specific and varied seasonally among tested halophytes.
沿海湿地主要作为痕量金属的天然汇，其在植物修复方面的重要性在全球范围内广为人知。关于卡拉奇海岸土壤沉积物中痕量金属有效性已有一些报道，但尚未对滨海带盐生植物中痕量金属向可收获（地上部分）部位的积累和转运进行研究。因此，评估了六种天然存在的盐生植物（獐毛、盐节木、海滨藜、白骨壤、小花十字花和灌木碱蓬）对卡拉奇海岸受金属（锰、锌、铅和铬）污染土壤的植物修复潜力。研究了卡拉奇海岸土壤和植物金属的季节性（冬季、季风前和季风后夏季）和空间（三个滨海带：即地点I：沙嘴、地点II：多达里亚/克利夫顿和地点III：科兰吉溪）变化。地点III所有季节的土壤锌、铅和铬含量通常在冬季较高，锰和有机质在夏季较高（7 - 11%），而pH值在7.15至7.5之间。所有测试物种都有通过其可收获部分（地上部分）清除铅的潜力，地点I的海滨藜是突出候选者（16毫克/千克）。小花十字花是地点I锌植物修复的唯一候选者（96毫克/千克），而灌木碱蓬、盐节木和獐毛在地点II的季风前夏季表现出生物积累。季风后夏季锰含量较高（地点III为62，地点II为53毫克/千克）且铬含量较高（地点II为7.1毫克/千克，地点III为14毫克/千克）的獐毛似乎是不同地点清除所有金属（锰、锌、铅和铬）的唯一生物指示物。研究地点的金属生物积累表现出物种特异性，且在测试的盐生植物中随季节变化。
