Modelling metal accumulation using humic acid as a surrogate for plant roots

Metal accumulation in roots was modelled with WHAM VII using humic acid (HA) as a surrogate for root surface. Metal accumulation was simulated as a function of computed metal binding to HA, with a correction term (EHA) to account for the differences in binding site density between HA and root surface. The approach was able to model metal accumulation in roots to within one order of magnitude for 95% of the data points. Total concentrations of Mn in roots of Vigna unguiculata, total concentrations of Ni, Zn, Cu and Cd in roots of Pisum sativum, as well as internalized concentrations of Cd, Ni, Pb and Zn in roots of Lolium perenne, were significantly correlated to the computed metal binding to HA. The method was less successful at modelling metal accumulation at low concentrations and in soil experiments. Measured concentrations of Cu internalized in L. perenne roots were not related to Cu binding to HA modelled and deviated from the predictions by over one order of magnitude. The results indicate that metal uptake by roots may under certain conditions be influenced by conditional physiological processes that cannot simulated by geochemical equilibrium. Processes occurring in chronic exposure of plants grown in soil to metals at low concentrations complicate the relationship between computed metal binding to HA and measured metal accumulation in roots

Long-Term Outcome of Immediate Versus Postponed" Intervention in Patients With Infected Necrotizing Pancreatitis" (POINTER)" Multicenter Randomized Trial

Objective: To compare the long-term outcomes of immediate drainage versus the postponed-drainage approach in patients with infected necrotizing pancreatitis. Background: In the randomized POINTER trial, patients assigned to the postponed-drainage approach using antibiotic treatment required fewer interventions, as compared with immediate drainage, and over a third were treated without any intervention. Methods: Clinical data of those patients alive after the initial 6-month follow-up were re-evaluated. The primary outcome was a composite of death and major complications. Results: Out of 104 patients, 88 were re-evaluated with a median followup of 51 months. After the initial 6-month follow-up, the primary outcome occurred in 7 of 47 patients (15%) in the immediate-drainage group and 7 of 41 patients (17%) in the postponed-drainage group (RR 0.87, 95% CI 0.33-2.28; P=0.78). Additional drainage procedures were performed in 7 patients (15%) versus 3 patients (7%) (RR 2.03; 95% CI 0.56-7.37; P=0.34). The median number of additional interventions was 0 (IQR 0-0) in both groups (P=0.028). In the total follow-up, the median number of interventions was higher in the immediate-drainage group than in the postponed-drainage group (4 vs. 1, P=0.001). Eventually, 14 of 15 patients (93%) in the postponed-drainage group who were successfully treated in the initial 6-month follow-up with antibiotics and without any intervention remained without intervention. At the end of follow-up, pancreatic function and quality of life were similar. Conclusions: Also, during long-term follow-up, a postponed-drainage approach using antibiotics in patients with infected necrotizing pancreatitis results in fewer interventions as compared with immediate drainage and should therefore be the preferred approach.</p

Effects of land use changes on organic matter dynamics and trace metal solibity in soils

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Protocols for Applying Phytotechnologies in Metal-Contaminated Soils

Contamination with heavy metals continues to pose a serious challenge for the remediation of polluted soil, as they are not degradable and must be physically removed. At present, most technologies used for removing heavy metals from the soil greatly affect the biogeochemical characteristics of the soil. In many cases, the soil can no longer be considered a useful and productive soil resource, and the treated soil has to be disposed of in landfills. Phytoremediation is the only solution that approaches the problem from an eco-sustainable point of view—it is environmentally friendly and relatively cheap. In this chapter, two phytotechnology approaches for remediating heavy metal-contaminated soil will be discussed, along with protocols for their implementation: phytoextraction and phytostabilization. Phytoremediation as a technique for rehabilitating heavy metal-polluted land therefore requires protocols and decision-support tools to assess the most appropriate approach, based on site-specific characteristics and requirements for soil status during and after remediation. Decisions have to be made on whether to use phytoextraction or phytostabilization, or even reject phytoremediation as a whole. Protocols and decision tools, from modeling and laboratory tests to full-blown feasibility studies, will be discussed

Ashes from fluidized bed combustion of residual forest biomass : recycling to soil as a viable management option

Although bottom ash (BA) [or mixtures of bottom and fly ash (FA)] from clean biomass fuels is currently used as liming agent, additive for compost, and fertilizer on agricultural and forest soils in certain European countries, in several other countries most of the ashes are currently disposed in landfills. This is due to both a lack of a proper classification of the materials and of regulatory barriers. Chemical characterization including analysis of an array of potentially toxic elements (PTEs) proved that over 100,000 tons of BA currently landfilled every year in Portugal actually complied with legal limits for PTEs for soil fertilizers applied in other countries. Pot experiments were conducted, testing three dosages of BA and FA (1, 2.5, and 5%, in weight) in three mining soils with different properties. Additions of ash materials to soils led to an increase in the pore water pH relative to control pots (0% of ash added) and had a clear impact on DOC and on the solubilization of both macro- and micronutrients (notably Cu). The results from the case study using BA and FA from a Portuguese biomass thermal power plant demonstrate that it is imperative to further develop a regulatory framework to alleviate technological and environmental barriers for biomass ash utilization as raw material for fertilizers and/or soil liming agent, in accordance with the goals of the circular economy. A more harmonized view on how to assess the merits and risks of the re-use of these materials is also needed

Actualisering methodiek en protocol om de fosfaattoestand van de bodem vast te stellen

De gebruiksnormen voor stikstof en fosfaat voor landbouwgronden zijn een belangrijke pijler van het Nederlandse mest- en ammoniakbeleid. De fosfaatgebruiksnormen zijn gedifferentieerd naar de fosfaattoestand van de bodem, om op termijn voor alle landbouwgronden een fosfaattoestand te realiseren waarbij (i) fosfaat geen beperkende factor is voor de gewasopbrengst en –kwaliteit, en (ii) de belasting van het oppervlaktewater met fosfaat is teruggedrongen tot een niveau waarbij voldaan kan worden aan de doelstellingen van de Kaderrichtlijn Water. Een goede bepaling en duiding van de fosfaattoestand van de bodem is daarbij van groot belang. Op verzoek van het ministerie van Economische Zaken heeft de Commissie Deskundigen Meststoffenwet (CDM) (i) methoden voor de bepaling van de fosfaattoestand van de bodem beoordeeld, voor de afleiding van fosfaattoestand-afhankelijke fosfaatgebruiksnormen, en (ii) een protocol beschreven voor de bemonstering en analyse van de bodem om de fosfaattoestand te bepalen. De CDM adviseert om een gecombineerde indicator te gebruiken, die de intensiteit (P-CaCl2) en de capaciteit (P-AL-getal) van het fosfaatleverend vermogen van de bodem in beeld brengt. Uit de beschikbare gegevens blijkt dat een gecombineerde indicator een vergelijkbaar voorspellend vermogen heeft van het fosfaatleverend vermogen van de bodem als de nu gebruikte enkelvoudige indicatoren (Pw voor bouwland en P-AL-getal voor grasland). De gecombineerde indicator kan worden toegepast voor zowel bouwland als grasland, en wordt reeds gebruikt op twee derde deel van het landbouwareaal in Nederland voor de bemestingsadvisering. Het protocol voor de bemonstering en analyse van de bodem om de fosfaattoestand te bepalen, is gebaseerd op doelvoorschriften. De vereiste minimale kwaliteit van de bemonstering en analyse is aangegeven; deze kwaliteit moet in de praktijk periodiek worden gecontroleerd door een zogenoemde ‘Toetscommissie’. De CDM adviseert ook om aanvullende studies te verrichten naar het voorspellend vermogen van de gecombineerde indicator voor het risico van fosfaatverliezen naar het oppervlaktewater

Dissolution of Ag nanoparticles in agricultural soils and effects on soil exoenzyme activities

EnvironmentsTo assess environmental risks related to the mobility and toxicity of AgNPs, the chemical availability of AgNPs and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) in three agricultural soils was quantified in a pot experiment. Porewater collection and soil extractions with 0.01 M CaCl2, 0.4 M Glycine (pH 1.5) and 0.05 M NH4-EDTA were performed. The effect on soil exoenzyme activities was also assessed. Porewater concentration was low (<0.4% and <0.04% of dosed Ag, for AgNPs and PVP-AgNPs, respectively) and only detected in acidic soils (pH 4.4 and 4.9). The PVPcoating reduced the downward mobility of AgNPs in soil and possibly also their dissolution rate (and subsequent release of dissolved Ag+ ions into porewater). The effect of variation in organic matter on soil enzymatic activity was larger than that of AgNPs, as no significant additional inhibitory effect from Ag could be observed. Only at low pH and in the presence of complexing ligands that form very stable Ag complexes (0.4 M Glycine extraction at pH 1.5) up to 58% of the Ag added to soil was released (independently of PVP coating). An extraction with glycine is proposed as a useful indicator of potentially available Ag in soilsinfo:eu-repo/semantics/publishedVersio

Testing single extraction methods and in vitro tests to assess the geochemical reactivity and human bioaccessibility of silver in urban soils amended with silver nanoparticles

To assess if the geochemical reactivity and human bioaccessibility of silver nanoparticles (AgNPs) in soils can be determined by routine soil tests commonly applied to other metals in soil, colloidal Ag was introduced to five pots containing urban soils (equivalent to 6.8 mg Ag kg(-1) soil). Following a 45 days stabilization period, the geochemical reactivity was determined by extraction using 0.43 M and 2 M HNO3. The bioaccessibility of AgNPs was evaluated using the Simplified Bioaccessibility Extraction Test (SBET) the \"Unified BARGE Method\" (UBM), and two simulated lung fluids (modified Gamble's solution (MGS) and artificial lysosomal fluid (ALF)). The amount of Ag extracted by 0.43 M and 2 M HNO3 soil tests was <8% and <50%, respectively of the total amount of Ag added to soils suggesting that the reactivity of Ag present in the soil can be relatively low. The bioaccessibility of Ag as determined by the four in vitro tests ranged from 17% (ALF extraction) to 99% (SBET) indicating that almost all Ag can be released from soil due to specific interactions with the organic ligands present in the simulated body fluids. This study shows that to develop sound soil risk evaluations regarding soil contamination with AgNPs, aspects of Ag biochemistry need to be considered, particularly when linking commonly applied soil tests to human risk assessment. (C) 2015 Elsevier Ltd. All rights reserved