The effect of nitrogen form on rhizosphere soil pH and zinc phytoextraction by Thlaspi caerulescens

The aims of this study are to investigate whether and how the nitrogen form (nitrate (NO 3 -) versus ammonium (NH 4 + )) influences cadmium (Cd) uptake and translocation and subsequent Cd phytoextraction by the hyperaccumulator species Sedum plumbizincicola. Plants were grown hydroponically with N supplied as either NO 3 -or NH 4 + . Short-term (36 h) Cd uptake and translocation were determined innovatively and quantitatively using a positron-emitting 107 Cd tracer and positron-emitting tracer imaging system. The results show that the rates of Cd uptake by roots and transport to the shoots in the NO 3 -treatment were more rapid than in the -promoted the major steps in the transport route followed by Cd from solution to shoots in S. plumbizincicola, namely its uptake by roots, xylem loading, root-to-shoot translocation in the xylem and uploading to the leaves. S. plumbizincicola prefers NO 3 -nutrition to NH 4 + for Cd phytoextraction.

Section: Plant Biomass and CD Accumulationsupporting

confidence: 82%

mentioning

confidence: 99%

Nitrate facilitates cadmium uptake, transport and accumulation in the hyperaccumulator Sedum plumbizincicola

Yin

Ishikawa

et al. 2013

“…Similar results were found for Sedum plumbizincicola in solution culture; NO 3 − stimulated Cd uptake by roots, xylem loading, shoot-to-root translocation, and uploading to the leaves and thus enhanced Cd phytoextraction (Hu et al 2013). Monsant et al (2008) showed that NO 3 − nutrition improved Zn phytoextraction in solution culture by increasing the biomass and Zn concentration of shoots of N. caerulescens. This soil-based pot experiment compared the effects of manure-N and different forms of chemical N supply (NO 3 − -N, NH 4 + -N, and urea-N) on Cd uptake by Carpobrotus rossii, a newly found Australian Cd hyperaccumulator .…”

Section: Introductionsupporting

confidence: 70%

“…This application rate of DCD had no significant effect on plant growth and was effective in minimizing nitrification (Monsant et al 2008 Pre-culture of stem cuttings of C. rossii (family Aizoaceae) were grown in plastic nursery cells for 3 weeks , and then three uniform rooted stem cuttings were transplanted into each pot. The plants were harvested on day 78.…”

Section: Cd-contaminated Soilmentioning

confidence: 99%

Influence of nitrogen form on the phytoextraction of cadmium by a newly discovered hyperaccumulator Carpobrotus rossii

Liu

Zhang

et al. 2015

Using hyperaccumulator plants is an important method to remove heavy metals from contaminated land. Carpobrotus rossii, a newly found Cd hyperaccumulator, has shown potential to remediate Cd-contaminated soils. This study examined the effect of nitrogen forms on Cd phytoextraction by C. rossii. The plants were grown for 78 days in an acid soil spiked with 20 mg Cd kg −1 and supplied with (NH 4 ) 2 SO 4 , Ca(NO 3 ) 2 , urea, and chicken manure as nitrogen (N) fertilizers. Nitrification inhibitor dicyandiamide (DCD) was applied to maintain the ammonium (NH 4 + ) form. Nitrogen fertilization increased shoot biomass but decreased root biomass with the highest shoot biomass occurring in the manure treatment. Compared to the no-N control, urea application did not affect shoot Cd concentration, but increased Cd content by 17 % due to shoot biomass increase. Chicken manure significantly decreased CaCl 2 -extractable Cd in soil, and the Cd concentration and total Cd uptake in the plant. Rhizosphere pH was the highest in the manure treatment and the lowest in the NH 4 + treatments. The manure and nitrate (NO 3 − ) treatments tended to have higher rhizosphere pH than their respective bulk soil pH, whereas the opposite was observed for urea and NH 4 + treatments. Furthermore, the concentrations of extractable Cd in soil and Cd in the plant correlated negatively with rhizosphere pH. The study concludes that urea significantly enhanced the Cd phytoaccumulation by C. rossii while chicken manure decreased Cd availability in soil and thus the phytoextraction efficiency.

“…Concerning the use of synthetic fertilizers, previous pot studies showed that nitrogen fertilization enhances N. caerulescens biomass production (+30%) , while its effects on phytoextraction efficiency can either be neutral or positive with a stronger effect with NO 3 − compared to NH 4 + (Monsant et al 2008;Schwartz et al 2003). In the case of Ni phytomining, Álvarez-López et al (2016) showed that compost addition enhances biomass production and extraction by Ni hyperaccumulators, despite lowering metal bioavailability.…”

Section: Responsible Editor: Elena Maestrimentioning

confidence: 99%

Phytoremediation of urban soils contaminated with trace metals using Noccaea caerulescens: comparing non-metallicolous populations to the metallicolous ‘Ganges’ in field trials

Jacobs

Drouet

Sterckeman

et al. 2017

Urban soil contamination with trace metals is a major obstacle to the development of urban agriculture as crops grown in urban gardens are prone to accumulate trace metals up to toxic levels for human consumption. Phytoextraction is considered as a potentially cost-effective alternative to conventional methods such as excavation. Field trials of phytoextraction with Noccaea caerulescens were conducted on urban soils contaminated with Cd, Cu, Pb, and Zn (respectively around 2, 150-200, 400-500, and 400-700 μg g −1 of dry soil). Metallicolous (Ganges population) and non-metallicolous (NMET) populations were compared for biomass production and trace metal uptake. Moreover, we tested the effect of compost and fertilizer addition. Maximal biomass of 5 t ha −1 was obtained with NMET populations on some plots. Compared to Ganges-the high Cd-accumulating ecotype from South of France often used in phytoextraction trials-NMET populations have an advantage for biomass production and for Zn accumulation, with an average Zn uptake of 2.5 times higher. The addition of compost seems detrimental due to metal immobilization in the soil with little or no effect on plant growth.In addition to differences between populations, variations of growth and metal accumulation were mostly explained by soil Cd and Zn concentrations and texture. Our field trials confirm the potential of using N. caerulescens for both Cd and Zn remediation of moderately contaminated soils-with uptake values of up to 200 g Cd ha −1 and 47 kg Zn ha −1 -and show the interest of selecting the adequate population according to the targeted metal.