RESUMEN
This study evaluated the reliability of portable X-ray fluorescence (pXRF) in Pb2+adsorption kinetics and isotherm experiments using soybean straw biochar. The research aimed to compare pXRF results with those obtained through traditional atomic absorption spectrometry (AAS). Soybean straw biochar, produced at 400 °C, was employed as the adsorbent for Pb2+. The efficiency of adsorption was assessed using Langmuir and Freundlich models. The kinetics of Pb2+adsorption was analysed through pseudo-first-order and pseudo-second-order models. The pseudo-second-order model described the kinetics of Pb2+adsorption on biochar better than the pseudo-first order model. Importantly, the pXRF technique demonstrated comparable results to those of AAS, making it a reliable and resource-efficient method for studying Pb2+kinetics. The results of the isotherm analyses fit the Langmuir model, indicating a desirable and irreversible adsorption of Pb2+on biochar. PXRF measurements on biochar allowed simultaneous observations of Pb2+adsorption and K+and Ca2+desorption, highlighting ionic exchange as the primary adsorption mechanism. In conclusion, our results showcased the applicability of pXRF for Pb+2adsorption studies in biochars, offering a valuable alternative to traditional methods. The findings contribute to the understanding of biochar as an effective adsorbent for heavy metals, emphasizing the potential of pXRF for cost-effective and efficient environmental research. In this study, we present a novel and detailed procedure that will allow other researchers to continue their studies on Pb2+adsorption on biochar or similar matrices, significantly reducing the resources and time used and enabling the simultaneous study of the behavior of other ions participating in the process.
Asunto(s)
Carbón Orgánico , Glycine max , Plomo , Adsorción , Reproducibilidad de los Resultados , Espectrometría por Rayos XRESUMEN
Plants associated with mycorrhizal fungi has the ability to establish on metal-contaminated soils playing an important role in phytoremediation programs. The objective of this study was to examine the presence of arbuscular mycorrhizal fungi (AMF) (spores density, diversity, indicator species, and root colonization) and dark septate endophytic fungi (DSE fungal root colonization) in three metal accumulator plants (Sorghum halepense, Bidens pilosa, and Tagetes minuta) growing in soils with high Pb content. The Pb content in AMF spores and plant biomass were also assessed. Rhizosphere soil samples were taken from the three dominant plant species at six study sites surrounding the abandoned Pb smelter and one uncontaminated site. The three studied plants were colonized by AMF and DSE fungi. A total of 24 AMF morphospecies were present in the Pb-contaminated areas. The AMF indicator species in the control site (non-contaminated area) was Funneliformis mosseae and in the most contaminated site were Gigaspora decipiens and Denticustata biornata. There was an increase in mycorrhizal variables such as the number of AMF vesicles, spore number, Pb content in AMF spores and plant biomass and DSE colonization (in Sorghum) with increasing soil Pb contamination, but a decrease in AMF diversity and richness was found. For upcoming soil restoration projects, it is crucial to understand the mycorrhizal fungi as well as the plant community that has adapted to the highly contaminated environment.
Asunto(s)
Micobioma , Micorrizas , Plomo , Esporas Fúngicas , Suelo , Raíces de Plantas/microbiología , Microbiología del SueloRESUMEN
The principal impediment for Pb uptake by plants is the Casparian strip in roots. It prevents metals reaching the xylem, thereby hampering translocation to the aerial organs. In the root apices, young root cells have thin cell walls and the Casparian strip is not completely developed, which could facilitate Pb uptake by roots at these vulnerable points. However, as the phytotoxic effects of Pb reduce root growth and enhance suberization, entry of Pb into the plant is avoided. We propose that the application of root growth promotors could be an important complement in the phytoextraction of Pb from polluted soils, due to their effects on produced biomass, Pb toxicity, and root exudate production. A greenhouse experiment was carried on to evaluate the auxin application effect on the Pb uptake of Bidens pilosa and Tagetes minuta. These species were sensitive to auxins, but the phytotoxic effect of Pb was not reversed by this treatment. Root exudates capable of extracting Pb were produced only when the species were grown in highly polluted soils, indicating a behavioral response to Pb exposure which is desirable for phytoremediation.
Asunto(s)
Bidens/efectos de los fármacos , Ácidos Indolacéticos/farmacología , Plomo/metabolismo , Reguladores del Crecimiento de las Plantas/farmacología , Contaminantes del Suelo/metabolismo , Tagetes/efectos de los fármacos , Bidens/metabolismo , Biodegradación Ambiental , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Tagetes/metabolismoRESUMEN
Polluted agricultural soils are a serious problem for food safety, with phytoremediation being the most favorable alternative from the environmental perspective. However, this methodology is generally time-consuming and requires the cessation of agriculture. Therefore, the purpose of this study was to evaluate two potential phytoextractor plants (the native species Bidens pilosa and Tagetes minuta) co-cropped with lettuce growing on agricultural lead-polluted soils. The concentrations of Pb, as well as of other metals, were investigated in the phytoextractors, crop species, and in soils, with the potential risk to the health of consumers being estimated. The soil parameters pH, EC, organic matter percentage and bioavailable lead showed a direct relationship with the accumulation of Pb in roots. In addition, the concentration of Pb in roots of native species was closely related to Fe (B. pilosa, r = 0.81; T. minuta r = 0.75), Cu (T. minuta, r = 0.93), Mn (B. pilosa, r = 0.89) and Zn (B. pilosa, r = 0.91; T. minuta, r = 0.91). Our results indicate that the interaction between rhizospheres increased the phytoextraction of lead, which was accompanied by an increase in the biomass of the phytoextractor species. However, the consumption of lettuce still revealed a toxicological risk from Pb in all treatments.
Asunto(s)
Bidens/metabolismo , Lactuca/metabolismo , Plomo/metabolismo , Contaminantes del Suelo/metabolismo , Tagetes/metabolismo , Agricultura/métodos , ArgentinaRESUMEN
The purpose of this study was to compare the behavior of the root system of one of the most frequently cited species in phytoremediation Indian mustard [Brassica juncea (L.) Czern.] and a representative perennial herb (Bidens pilosa L.) native of Argentina, for different concentrations of lead in soils through chemical and visualization techniques of the rhizosphere. Lead polluted soils from the vicinity of a lead recycling plant in the locality of Bouwer, were used in juxtaposed rhizobox systems planted with seedlings of B. juncea and B. pilosa with homogeneous and heterogeneous soil treatments. Root development, pH changes in the rhizosphere, dry weight biomass, lead content of root and aerial parts and potential extraction of lead by rhizosphere exudates were determined. In both species lead was mainly accumulated in roots. However, although B. juncea accumulated more lead than B. pilosa at elevated concentrations in soils, the latter achieved greater root and aerial development. No changes in the pH of the rhizosphere associated to lead were observed, despite different extractive potentials of lead in the exudates of the species analyzed. Our results indicated that Indian mustard did not behave as a hyperaccumulator in the conditions of the present study.
Asunto(s)
Bidens/metabolismo , Plomo/metabolismo , Planta de la Mostaza/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Contaminantes del Suelo/metabolismo , Bidens/química , Bidens/crecimiento & desarrollo , Biodegradación Ambiental , Biomasa , Planta de la Mostaza/química , Planta de la Mostaza/crecimiento & desarrollo , Raíces de Plantas/química , Raíces de Plantas/metabolismo , Rizosfera , Suelo/químicaRESUMEN
Argentina is one of the major producers of soybean in the world, this generates a high global demand for this crop leading to find it everywhere, even close to human activities involving pollutant emissions. This study evaluated heavy metal content, the transfer of metals and its relation to crop quality, and the toxicological risk of seed consumption, through soil and soybean sampling. The results show that concentrations of Pb and Cd in soils and soybeans at several sites were above the maximum permissible levels. The heavy metal bioaccumulation depending on the rhizosphere soil compartment showed significant and high regression coefficients. In addition, the similar behavior of Cd and Zn accumulation by plants reinforces the theory of other studies indicating that these metals are incorporated into the plant for a common system of transport. On the other hand, the seed quality parameters did not show a clear pattern of response to metal bioacumulation. Taken together, our results show that soybeans grown nearby to anthropic emission sources might represent a toxicological hazard for human consumption in a potential Chinese consumer. Hence, further studies should be carried out taking into account the potential negative health effects from the consumption of soybeans (direct or indirect through consumption of meat from cattle) in these conditions.