Environmental Botany Division, Department of Botany, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002, India.
Department of Life and Environmental Science, The Faculty of Science and Technology, Bournemouth University, Talbot Campus, Poole, Dorset BH12 5BB, UK.
Sci Total Environ. 2017 Apr 15;584-585:1221-1229. doi: 10.1016/j.scitotenv.2017.01.186. Epub 2017 Jan 30.
The present study investigates the extent of biotransfer and bioaccumulation of cadmium (Cd), lead (Pb) and zinc (Zn) from fly ash amended soil in mustard (Brassica juncea)-aphid (Lipaphis erysimi)-beetle (Coccinella septempunctata) food chain and its subsequent implications for the beetle. The soil was amended with fly ash at the rates of 0, 5, 10, 20 and 40% (w/w). Our results showed that the uptake of Cd, Pb and Zn from soil to mustard root increased with the increase in fly ash application rates, but their root to shoot translocation was relatively restricted. Increase in chlorophyll content and dry mass of mustard plant on treatments ≥20% even at elevated accumulation of Cd (1.67mgkg), Pb (18.25mgkg) and Zn (74.45mgkg dry weight) in its shoot showed relatively higher tolerance of selected mustard cultivar to heavy metal stress. The transfer coefficient (TC) of Cd from mustard shoot to aphid was always >1, indicating that Cd biomagnified in aphids at second trophic level. But, there was no biomagnification of Cd in adult beetles at third trophic level. Zinc accumulation was 2.06 to 2.40 times more in aphids than their corresponding host shoots and 1.26-1.35 times more in adult beetles than their prey (aphids) on which they fed. Lead was only metal whose TC was <1 at both second and third trophic levels. The elimination of Cd via honeydew of aphids was most efficient as the ratio of metal in honeydew to aphid (ranging from 0.21 to 0.26) was higher than the Pb (0.16 to 0.20) and Zn (0.07 to 0.09). The statistically consistent (p>0.05) biomass and predation rate of predatory beetles indicated that all levels of soil amendments with fly ash did not have any lethal or sub-lethal effects on beetles.
本研究调查了从添加粉煤灰的土壤中，通过芥菜（芥菜）-蚜虫（桃蚜）-甲虫（七星瓢虫）食物链转移和生物积累镉（Cd）、铅（Pb）和锌（Zn）的程度，及其对甲虫的后续影响。土壤以 0、5、10、20 和 40%（w/w）的粉煤灰进行了改良。我们的结果表明，从土壤到芥菜根的 Cd、Pb 和 Zn 的吸收随着粉煤灰施用量的增加而增加，但它们的根到茎叶的转移相对受到限制。即使在 Cd（1.67mgkg）、Pb（18.25mgkg）和 Zn（74.45mgkg 干重）在茎叶中积累量增加的情况下，处理≥20%时芥菜植株的叶绿素含量和干质量增加，表明所选芥菜品种对重金属胁迫具有较高的耐受性。Cd 从芥菜茎叶到蚜虫的转移系数（TC）总是>1，表明 Cd 在第二营养级的蚜虫中生物放大。但是，在第三营养级的成年甲虫中，Cd 没有生物放大。Zn 在蚜虫中的积累量比相应的宿主茎叶高 2.06-2.40 倍，在成年甲虫中比以其为食的猎物（蚜虫）高 1.26-1.35 倍。Pb 是仅在第二和第三营养级 TC<1 的金属。由于蚜虫蜜露中金属与蚜虫的比例（0.21-0.26）高于 Pb（0.16-0.20）和 Zn（0.07-0.09），因此通过蚜虫蜜露去除 Cd 是最有效的。捕食性甲虫的生物量和捕食率统计上一致（p>0.05），表明粉煤灰土壤改良的所有水平对甲虫均无致死或亚致死影响。
