Abstract

Compared to noncalcareous soils, data on the soil-to-plant transfer of heavy metals and their response to sewage sludge (SS) in calcareous soils with diverse properties are limited. Cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) transfer from soil to cabbage (Brassica oleracea L. var. capitata) under greenhouse conditions in 30 diverse soils amended with two types of sewage sludge (non-spiked and spiked with heavy metals) were investigated. Three transfer factors were calculated for heavy metals in three treated soils including control soils (CS), soils treated with non-spiked SS (NSS), and soils treated with spiked SS (PSS). The bio-concentration factor of heavy metals from soil to root (BCF_Roots) in cabbage in three treatments was as follows: CS: Pb > Cu > Co > Zn > Ni; NSS: Pb > Co > Cu ≥ Zn > Ni; and PSS: Pb > Cd > Zn > Co > Cu > Ni. The same order was found for the bio-concentration factor of heavy metals from soil to shoots (BCF_Shoots) in PSS, and in CS and NSS treatments except that the position of Co, Cu, and Zn was changed. Based on the heavy metals translocation from plant roots to shoots, Cd, Cu, and Zn were the heavy metals that posed the highest risk due to the higher shoot content in all treatments, whereas Ni and Pb posed relatively lesser risk. Generally, the percentage of sand and silt in BCF_Roots and BCF_Shoots was quite effective for Co, Ni, and Zn and it seems that soil texture is an important variable in heavy metals bioavailability. In conclusion, our findings highlight the significance of using SS to increase cabbage growth in soils contaminated with heavy metals. Furthermore, cabbage may be a good choice for phytoremediation of heavy metal-contaminated calcareous soils in terms of soil remediation.

Novelty statement In recent years, sewage sludge production has increased as well as related waste disposal strategies because of the increasing population and growing demand for agricultural products. Sewage sludge utilization as a low-cost fertilizer has spread in some parts of Iran and the world. On the other hand, unnecessary and unproductive use of sewage sludge results in the accumulation of heavy metals in soils, adding them to food and the potential risk to human health. Currently, work on the transfer of heavy metals from soil to plant after soil treated with sewage sludge has focused on the bioavailability of heavy metals using specific extractants. The assessment of the transfer of heavy metals from soil to different parts of plants using sewage sludge has been less studied. In this study, the transfer of heavy metals (Cd, Co, Cu, Ni, Pb, and Zn) from several soils (30 soils samples) having diverse physical and chemical properties to the tissues of the cabbage plant in control soils, and two types of sewage sludge (nonspiked and spiked with heavy metals) were investigated. The novelty of this study is that the measured bio-concentration factor of heavy metals from soil to root and from soil to shoot and translocation of heavy metals from plant roots to shoots and correlations between these parameters and soil properties are reported for the first time in diverse calcareous soils.

摘要

与非钙质土壤相比，关于重金属从土壤到植物的转移及其对具有不同性质的钙质土壤中的污水污泥 (SS) 的反应的数据是有限的。镉（Cd），钴（Co），铜（Cu），镍（Ni），铅（Pb），并从土壤锌（Zn）转移到甘蓝（甘蓝L.变种实蝇）下在30多样温室条件研究了用两种类型的污水污泥（未掺入和掺入重金属）改良的土壤。计算了三种处理土壤中重金属的三个转移因子，包括对照土壤 (CS)、非加标 SS (NSS) 处理的土壤和加标 SS (PSS) 处理的土壤。重金属从土壤到根的生物富集因子（BCF _Roots) 3 种处理白菜含量如下： CS：Pb > Cu > Co > Zn > Ni；NSS：Pb > Co > Cu ≥ Zn > Ni；和 PSS：Pb > Cd > Zn > Co > Cu > Ni。除了Co、Cu和Zn的位置发生变化外，PSS、CS和NSS处理中重金属从土壤到芽（BCF_芽）的生物富集因子的顺序相同。根据重金属从植物根部转移到地上部，Cd、Cu 和 Zn 是风险最高的重金属，因为在所有处理中地上部含量较高，而 Ni 和 Pb 的风险相对较小。一般而言，BCF _Roots和 BCF _Shoots中沙子和淤泥的百分比对 Co、Ni 和 Zn 非常有效，而且土壤质地似乎是重金属生物有效性的重要变量。总之，我们的研究结果强调了在受重金属污染的土壤中使用 SS 促进卷心菜生长的重要性。此外，在土壤修复方面，卷心菜可能是重金属污染钙质土壤植物修复的不错选择。

新颖性声明 近年来，由于人口增加和对农产品的需求不断增长，污水污泥产量以及相关的废物处理策略有所增加。污水污泥作为低成本肥料的利用已经在伊朗和世界的一些地区普及。另一方面，污水污泥的不必要和非生产性使用会导致重金属在土壤中积累，将它们添加到食物中并对人类健康构成潜在风险。目前，在用污水污泥处理土壤后，重金属从土壤转移到植物的工作集中在使用特定提取剂的重金属的生物利用度上。使用污水污泥评估重金属从土壤转移到植物不同部位的研究较少。在本研究中，重金属（Cd、Co、Cu、Ni、Pb、和 Zn) 从具有不同物理和化学性质的几种土壤（30 个土壤样品）到对照土壤中的甘蓝植物组织，以及两种类型的污水污泥（未掺入和掺入重金属）进行了研究。本研究的新颖之处在于首次报道了重金属从土壤到根部和从土壤到地上部的生物富集因子以及重金属从植物根部到地上部的易位以及这些参数与土壤性质之间的相关性。多样的钙质土壤。