This study examines the renewable energy production of crops used for phytoremediation. Our analysis is based on a case study in the Campine region (Belgium and The Netherlands), where agricultural ...soils are diffusely contaminated with cadmium, lead, and zinc, with an enhanced risk for uptake of these metals in crops and leaching to the groundwater. However, the area has such a large extent (700 km2) that conventional remediation is not applicable. Cultivation of crops for energy purposes on such land offers the opportunity to come up with an approach that efficiently uses contaminated agricultural land and that can be beneficial for both farmer and society. Performing a Life Cycle Analysis (LCA), we examined the energy and CO2 abatement potential of willow (Salix spp.), silage maize (Zea mays L.), and rapeseed (Brassica napus L.) originating from contaminated land. Taking into account the marginal impact of the metals in the biomass on the energy conversion efficiency and on the potential use of the biomass and its rest products after conversion, digestion of silage maize with combustion of the contaminated digestate shows the best energetic and CO2 abating perspectives. The replacement of cokes based electricity by willow is more efficient in CO2 abatement than willow used in a Combined Heat and Power (CHP) unit, despite lower net energy production in the former option. Willow reaches the same energy production and same CO2 abatement per hectare per year as silage maize when its biomass yield is respectively 13 and 8.7 Mg dm ha−1 y−1.
► We study the energy potential of Salix, Zea mays and Brassica after phytoremediation. ► The case study contains agricultural soils that are contaminated with cadmium. ► We include the impact of metals on energy conversion efficiency and rest product use. ► Higher biomass yields for Salix would make it energetically competitive with Z. mays.
Remediation of soil pollution is one of the many current environmental challenges. Anthropogenic activity has resulted in the contamination of extended areas of land, the remediation of which is both ...invasive and expensive by conventional means. Phytoextraction of heavy metals from contaminated soils has the prospect of being a more economic in situ alternative. In addition, phytoextraction targets ecotoxicologically the most relevant soil fraction of these metals, i.e. the bioavailable fraction. Greenhouse experiments were carried out to evaluate the potential of four high biomass crop species in their potential for phytoextraction of heavy metals, with or without with the use of soil amendments (EDTA or EDDS). A calcareous dredged sediment derived surface soil, with high organic matter and clay content and moderate levels of heavy metal pollution, was used in the experiments. No growth depression was observed in EDTA or EDDS treated pots in comparison to untreated controls. Metal accumulation was considered to be low for phytoextraction purposes, despite the use of chelating agents. The low observed shoot concentrations of heavy metals were attributed to the low phytoavailability of heavy metals in this particular soil substrate. The mobilising effects induced by EDTA in the soil were found to be too long-lived for application as a soil amendment in phytoextraction. Although EDDS was found to be more biodegradable, higher effect half lives were observed than reported in literature or observed in previous experiments. These findings caution against the use of any amendment, biodegradable or otherwise, without proper investigation of its effects and the longevity thereof.
Worldwide there are numerous regions where conventional agriculture is affected by the presence of elevated amounts of plant-available trace elements, causing economic losses and food and feed ...quality and safety. The Belgian and Dutch Campine regions are a first-class example, with approximately 700
km
2 diffusely contaminated by historic atmospheric deposition of Cd, Zn and Pb. Primary land use in this region is agriculture, which is frequently confronted with crops exceeding the European standards for heavy metal contents in food and feed-stuffs. Phytoremediation as a soil remediation technology only appears feasible if the produced biomass might be valorised in some manner. In the current case, we propose the use of energy maize aiming at risk-reduction and generation of an alternative income for agriculture, yet in the long run also a gradual reduction of the pollution levels. Since the remediation aspect is demoted to a secondary objective with sustainable risk-based land use as first objective, we introduce the term ‘phytoattenuation’: this is in analogy with ‘natural attenuation’ of organic pollutants in soils where also no direct intended remediation measures but a risk-based management approach is implemented. In the current field experiment, cultivation of energy maize could result in 33,000–46,000
kW
h of renewable energy (electrical and thermal) per hectare per year which by substitution of fossil energy would imply a reduction of up to 21
×
10
3
kg
ha
−1
y
−1 CO
2 if used to substitute a coal fed power plant. Metal removal is very low for Cd and Pb but more significant for Zn with an annual reduction of 0.4–0.7
mg
kg
−1 in the top soil layer.
Ovariectomized rodents model human menopause in that they rapidly gain weight, reduce spontaneous physical activity (SPA), and develop metabolic dysfunction, including insulin resistance. How ...contrasting aerobic fitness levels impacts ovariectomy (OVX)-associated metabolic dysfunction is not known. Female rats selectively bred for high and low intrinsic aerobic fitness high-capacity runners (HCR) and low-capacity runners (LCR), respectively were maintained under sedentary conditions for 39 wk. Midway through the observation period, OVX or sham (SHM) operations were performed providing HCR-SHM, HCR-OVX, LCR-SHM, and LCR-OVX groups. Glucose tolerance, energy expenditure, and SPA were measured before and 4 wk after surgery, while body composition via dual-energy X-ray absorptiometry and adipose tissue distribution, brown adipose tissue (BAT), and skeletal muscle phenotype, hepatic lipid content, insulin resistance via homeostatic assessment model of insulin resistance and AdipoIR, and blood lipids were assessed at death. Remarkably, HCR were protected from OVX-associated increases in adiposity and insulin resistance, observed only in LCR. HCR rats were ∼30% smaller, had ∼70% greater spontaneous physical activity (SPA), consumed ∼10% more relative energy, had greater skeletal muscle proliferator-activated receptor coactivator 1-alpha, and ∼40% more BAT. OVX did not increase energy intake and reduced SPA to the same extent in both HCR and LCR. LCR were particularly affected by an OVX-associated reduction in resting energy expenditure and experienced a reduction in relative BAT; resting energy expenditure correlated positively with BAT across all animals (r = 0.6; P < 0.001). In conclusion, despite reduced SPA following OVX, high intrinsic aerobic fitness protects against OVX-associated increases in adiposity and insulin resistance. The mechanism may involve preservation of resting energy expenditure.
Pb is one of the most widespread and metal pollutants in soil. It is generally concentrated in surface layers with only a minor portion of the total metal found in soil solution. Phytoextraction has ...been proposed as an inexpensive, sustainable, in situ plant-based technology that makes use of natural hyperaccumulators as well as high biomass producing crops to help rehabilitate soils contaminated with heavy metals without destructive effects on soil properties. The success of phytoextraction is determined by the amount of biomass, concentration of heavy metals in plant, and bioavailable fraction of heavy metals in the rooting medium. In general, metal hyperaccumulators are low biomass, slow growing plant species that are highly metal specific. For some metals such as Pb, there are no hyperaccumulator plant species known to date. Although high biomass-yielding non-hyperaccumulator plants lack an inherent ability to accumulate unusual concentrations of Pb, soil application of chelating agents such as EDTA has been proposed to enhance the metal concentration in above-ground harvestable plant parts through enhancing the metal solubility and translocation from roots to shoots. Leaching of metals due to enhanced mobility during EDTA-assisted phytoextraction has been demonstrated as one of the potential hazards associated with this technology. Due to environmental persistence of EDTA in combination with its strong chelating abilities, the scientific community is moving away from the use of EDTA in phytoextraction and is turning to less aggressive alternative strategies such as the use of organic acids or more degradable APCAs (aminopolycarboxylic acids). We have therefore arrived at a point in phytoremediation research history in which we need to distance ourselves from EDTA as a proposed soil amendment within the context of phytoextraction. However, valuable lessons are to be learned from over a decade of EDTA-assisted phytoremediation research when considering the implementation of more degradable alternatives in assisted phytoextraction practices.
Objective
Aerobic capacity is the most powerful predictor of all‐cause mortality in humans; however, its role in the development of obesity and susceptibility for high‐fat diet (HFD)‐induced weight ...gain is not completely understood.
Methods
Herein, a rodent model system of divergent intrinsic aerobic capacity high capacity running (HCR) and low capacity running (LCR) was utilized to evaluate the role of aerobic fitness on 1‐week HFD‐induced (45% and 60% kcal) weight gain. Food/energy intake, body composition analysis, and brown adipose tissue gene expression were assessed as important potential factors involved in modulating HFD‐induced weight gain.
Results
HCR rats had reduced 1‐week weight gain on both HFDs compared with LCR. Reduced HFD‐induced weight gain was associated with greater adaptability to decrease food intake following initiation of the HFDs. Further, the HCR rats were observed to have reduced feeding efficiency and greater brown adipose mass and expression of genes involved in thermogenesis.
Conclusions
Rats with high intrinsic aerobic capacity have reduced susceptibility to 1‐week HFD‐induced weight gain, which is associated with greater food intake adaptability to control intake of energy‐dense HFDs, reduced weight gain per kcal consumed, and greater brown adipose tissue mass and thermogenic gene expression.
Previous research has identified ethylenediaminedisuccinate (EDDS) as a promising biodegradable alternative for persistent compounds such as EDTA for application in soil washing or enhanced ...phytoextraction of heavy metals. This study examines heavy metal mobilization in three polluted soils varying in soil composition, with specific attention for competitive behaviour for complexation between the various metals and major elements, such as Al, Fe, Mn, Ca and Mg. In addition, amendment biodegradability was compared between the different soil types. The selected soils included a moderately contaminated calcareous clayey soil, a dredged sediment derived surface soil with similar soil characteristics yet more heavily polluted with Cd, Cr and Zn, and a sandy soil moderately contaminated by historical smelter activity (atmospheric deposition). Biodegradability of EDDS in the three soils varied distinctly. This was mainly expressed in the duration of the lag phase prior to metal complex degradation, and not so much in the half life when degradation effectively did set in. Differences in the lag phase were attributed to differences in soil pollution. However, EDDS was fully degraded within a period of 54
d in all soils regardless of initial delay. Assessment of the cation mobilisation patterns in the three soils under study revealed that mainly Ca, Fe and Al can reduce effectiveness of heavy metal mobilisation by competition for complexation.
The applicability of biodegradable amendments in phytoremediation to increase the uptake of uranium (U), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) by Indian mustard (
Brassica ...juncea) and ryegrass (
Lolium perenne) was tested in a greenhouse experiment. Plants were cultivated during one month on two soils with naturally or industrially increased contaminant levels of U. Treatments with citric acid, NH
4-citrate/citric acid, oxalic acid, S,S-ethylenediamine disuccinic acid (EDDS) or nitrilotriacetic acid (NTA) at a rate of 5 mmol kg
−
1
dry soil caused increases in soil solution concentrations that were up to 18 times higher for U and up to 1570 times higher for other heavy metals, compared to the controls. Shoot concentrations increased to a much smaller extent. With EDDS, 19-, 34-, and 37-fold increases were achieved in shoots of Indian mustard for U, Pb and Cu, respectively. The increases in plant uptake of Cd, Cr and Zn were limited to a factor of four at most. Ryegrass generally extracted less U and metals than Indian mustard. Despite a marked increase of U and metal concentrations in shoots after addition of amendments, the estimated time required to obtain an acceptable reduction in soil contaminant concentrations was impractically long. Only for Cu and Zn in one of the studied soils, could the Flemish standards for clean soil theoretically be attained in less than 100 years.
Three feedstocks, pine wood, grass and cow manure, were pyrolyzed under various conditions and tested on their ability to sorb metals in aquatic systems. The feedstocks were pyrolyzed at 2 different ...temperatures (350 °C and 550 °C) and 2 different residence times (10 and 60 min) and resulting biochars were assessed on their capability to immobilize Pb, Cu, Cd and Zn.
Manure-based chars, and to a lesser extent grass-based chars, featured high concentrations of phosphates and carbonates. These anions play an important role in metal sorption because they form insoluble complexes with the metals. Washing reduced the concentration of these anions, leading to a reduced sorption of metals by the biochar.
The carbonate concentration on the biochars’ surface increased at higher reactor temperature and longer residence times. The opposite trend was observed for the phosphate concentration and the cation exchange capacity. Accordingly, the optimal temperature-residence time combination for sorption was a trade-off between these properties. Biochar produced from cow manure and pyrolyzed at 550 °C for 10 min showed the best sorption for all metals considered.
•Manure-based biochar showed the highest sorption for all metals tested.•Manure-based chars featured the highest concentrations of phosphates and carbonates.•Washing reduced the concentration of these anions and reduced adsorption of metals.•Anions are of practical importance to optimize biochar as a metal adsorbent.
Swine wastewater management is often affected by two main issues: a too high volume for optimal reuse as a fertilizer and a too high strength for an economically sustainable treatment by classical ...solutions. Hence, an innovative scheme has been tested to treat swine wastewater, combining a low cost anaerobic reactor, upflow anaerobic sludge blanket (UASB), with intensified constructed wetlands (aerated CWs) in a pilot scale experimental study. The swine wastewater described in this paper is produced by a swine production facility situated in North Italy. The scheme of the pilot plant consisted of: (i) canvas-based thickener; (ii) UASB; (iii) two intensified aerated vertical subsurface flow CWs in series; (iv) a horizontal flow subsurface CW. The influent wastewater quality has been defined for total suspended solids (TSS 25,025 ± 9,323 mg/l), organic carbon (chemical oxygen demand (COD) 29,350 ± 16,983 mg/l), total reduced nitrogen and ammonium (total Kjeldahl nitrogen (TKN) 1,783 ± 498 mg/l and N-NH
735 ± 251 mg/l) and total phosphorus (1,285 ± 270 mg/l), with nitrates almost absent. The overall system has shown excellent performances in terms of TSS, COD, N-NH
and TKN removal efficiencies (99.9%, 99.6%, 99.5%, and 99.0%, respectively). Denitrification (N-NO
effluent concentration equal to 614 ± 268 mg/l) did not meet the Italian quality standards for discharging in water bodies, mainly because the organic carbon was almost completely removed in the intensified CW beds.
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