Biological cycle and accumulation of lanthanum in the forage-mushroom-soil system
Rare earth elements ( REE) and their compounds have been widely applied in agronomic and medical fields for many years. The bioinorganic chemical research of REE in the past few years indicates that REE play important roles in the promotion of photosynthesis, root absorption, and regulation of hormone and nitrogen metabolism. There was an increasing interest in the bioaccumulation processes of rare earth elements ( REEs) due to the wide application of REEs in a variety of non-nuclear industries and agriculture, resulting in possible environmental contamination. Investigations into the bioaccumulation characteristics of REEs have been carried out in recent years as sensitive techniques such as inductively coupled plasma-mass spectrometry (ICP-MS) and neutron activation analysis ( NAA) have became available. Despite extensive studies on REE uptake and transport in plants, few studies have been carried out on the REE fractionation in the soil plant system via laboratory experiments. However, little attention has been paid to the REE fractionation and migration in the multi-link food chain. In this study, three cultivation experiments were carried out, including the pot experiments of Digitaria smutsii cultivation with La fertilizer and mushroom residue fertilizer, and the experiment of Pleurotus eryngii cultivation using La-applied forages as medium. The distribution and biological concentration of lanthanum ( La) in the forage-mushroom-soil system were discussed. The results showed that the trend of La adsorption of D. smut.sii were root ＞ leaf ＞ stem. La concentration in all organs of forage increased with the increase of La application rate. La relative content of roots in La application treatments rose significantly , increasing by 10. 76％ -31. 37％ compared with the control. The yield of P. eryngii fruitbodies with the La application treatment increased by 16. 10％ compared with that of the no-La application treatment, but there was no significant difference between them. The trend of La adsorption of P. eryngii were pileus ＞ stipe. There was no significant difference in the La concentration of P. eryngii between the La application treatment and the control. La concentration in fruitbodies were 0. 7 mg/kg or so, lower than the critical limit of rare plant food standards in China (2 mg/kg). The results also showed that the bioaccumulation coefficients of La by D .smutsii increased with increasing La dose, and that the bioaccumulation coefficient of root was the highest, ranging between 0. 443 and 0. 580. Except for the high-dose La treatment( M4 ) , there was no significant difference about the bioaccumulation coefficients of La by leaf and stem among the other treatments, but that of root obviously varied. The results of P. eryngii cultivation with Laapplied forage showed that there was no significant difference about the bioaccumulation coefficients of La by pileus and stipe. But La bioaccumulation coefficients of the control were 2. 45-2. 61 times of that of the La application treatment. This explained that the La bioavailability in forage was lower to P. eryngii. The results of D. smutsii cultivation with residues showed that there were no significant difference about La bioaccumulation coefficients among different treatments. This study revealed that reuse efficiency of exogenous La gradually decreased after several biological cycles. Only a small amount of lanthanum was absorbed by living organisms, most of the La elements still remained in the environment.
国家科技期刊平台
NSTL
万方数据
维普
