A Comparative Study on Removal Efficiency of Cr(VI) in Aqueous Solution by <Emphasis Type="Italic">Fusarium</Emphasis> sp. and <Emphasis Type="Italic">Myrothecium</Emphasis> sp.

Environmental pollution with chromium is due to residues of several industrial processes. Bioremediation is an alternative actually considered to remove Cr (VI) from the environment, using adapted organisms that grow in contaminated places. Have been conducted studies with fungi mechanisms of interaction with chromium, most of which have focused on processes biosorption, characterized it by passive binding of metal components of the cell surface, and bioaccumulation, wherein the metal entry to cells occurs with energy expenditure. The paper presents the results of studies carried out on sorption of chromium (VI) ions from aqueous solutions by Fusarium sp. and Myrothecium sp. Both biomasses have the ability to take up hexavalent chromium during the stationary phase of growth and as well inactive conditions. Fusarium sp. showed 26% of biosorption with active biomass and 64% in inactive biomass; meanwhile, Myrothecium sp. obtained 97 and 82%, respectively. Both fungi showed adjust to pseudo-second-order model in active (Fusarium sp. R ² = 0.99; Myrothecium sp. R ² = 0.96) and inactive biomass assay (Fusarium sp. R ² = 0.99; Myrothecium sp. R ² = 0.99). The data of the active biomass test also confirmed to the intraparticle diffusion model (Fusarium sp. R ² = 0.98; Myrothecium sp. R ² = 0.93). The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Fusarium sp. and Myrothecium sp.     

Biosorption of Toxic Metals by Water Lettuce (<Emphasis Type="Italic">Pistia stratiotes</Emphasis>) Biomass

Adsorption isotherms were constructed to evaluate the potential use of water lettuce (Pistia stratiotes) dry biomass for the biosorption of zinc and cadmium. One gram of dry biomass of this plant was treated with five increasing doses of zinc (1.8, 18, 50, 79, and 105 mg L^?1) and four doses of cadmium (0.01, 0.1, 1, and 10 mg L^?1), for nine collection times (1, 3, 6, 12, 24, 36, 48, 60, and 72 h). The levels of these metals were determined by atomic absorption spectrophotometry. To evaluate changes in the surface morphology of the dry biomass, scanning electron microscopy (SEM) images were taken of the samples subjected to the greatest contamination, and these were compared with the images of the samples without zinc and cadmium (control). The ISOFIT software was used to select the isotherm model that best fit the biosorption of metals by water lettuce dry biomass. The linear model was determined to be the best-fitting isotherm model, because it had the lowest corrected Akaike information criterion (AICc) value and a Akaike weight (AICw) value closest to one, which indicates the high affinity of the biosorbent for the adsorbates evaluated. The results for both metals demonstrated greater than 70% reductions in the concentrations of the metals in the contaminated solutions. The SEM images indicated changes in the morphology of the contaminated biomass, thus demonstrating the biosorption mechanisms and confirming the potential of the dry biomass of this plant for use in the remediation of solutions contaminated with zinc and cadmium.     

Concentrations and Exports of Fecal Indicator Bacteria in Watersheds with Varying Densities of Onsite Wastewater Systems

The research goal was to determine if onsite wastewater system (OWS) density had an influence on the concentrations and watershed exports of Escherichia coli and enterococci in urbanizing watersheds. Eight watersheds with OWS densities ranging from <?0.1 to 1.88 systems ha^?1 plus a watershed served by sewer (Sewer) and a mostly forested, natural watershed (Natural) in the Piedmont of North Carolina served as the study locations. Stream samples were collected approximately monthly during baseflow conditions between January 2015 and December 2016 (n?=?21). Median concentrations of E. coli (2014 most probable number (MPN) 100 mL^?1) and enterococci (168 MPN 100 mL^?1) were elevated in streams draining watersheds with a high density of OWS (>?0.77 system ha^?1) relative to watersheds with a low (<?0.77 system ha^?1) density (E. coli: 204 MPN 100 mL^?1 and enterococci: 88 MPN 100 mL^?1) and control watersheds (Natural: E. coli: 355 MPN 100 mL^?1 and enterococci: 62 MPN 100 mL^?1; Sewer: 177 MPN 100 mL^?1 and 130 MPN 100 mL^?1). Samples collected from watersheds with a high density of OWS had E. coli and enterococci concentrations that exceeded recommended thresholds 88 and 57% of times sampled, respectively. Results show that stream E. coli and enterococci concentrations and exports are influenced by the density of OWS in urbanizing watersheds. Cost share programs to help finance OWS repairs and maintenance are suggested to help improve water quality in watersheds with OWS.     

Enhanced <Emphasis Type="Italic">Scirpus triqueter</Emphasis> phytoremediation of pyrene and lead co-contaminated soil with alkyl polyglucoside and nitrilotriacetic acid combined application

Purpose

This study aimed to evaluate the effect of combination of alkyl polyglucoside (APG) and nitrilotriacetic acid (NTA) on improving the efficiency of phytoremediation for pyrene and lead (Pb) co-contaminated soil by Scirpus triqueter.

Materials and methods

Seedlings of S. triqueter with a similar size and biomass (3 g/pot) were grown on 2-month aged soil contaminated with 184.5 mg kg^?1of pyrene and 454.3 mg kg^?1 of Pb at pH?=?8.3. After growth for 10 days, different doses of APG and NTA were added into the soil. After 60 days, the height of plants, Pb concentrations in plants, and pyrene amounts in soil were determined.

Results and discussion

Combined application of NTA and APG with lower dosage (1 + 1 g kg^?1 soil and 1 + 2 g kg^?1 soil) had no notable negative influence on the growth of S. triqueter. Moreover, significant synergy on Pb accumulation in S. triqueter was achieved with APG and NTA combined application. Besides, the dissipation of pyrene from soil after 60-day planting was increased in APG and NTA treatments when compared with the control treatments. Application of APG alone or combined with NTA had greater effect on enhancing dissipation of pyrene from soil than NTA alone.

Conclusions

This study demonstrated that the remediation of Pb and pyrene co-contaminated soil by S. triqueter can be enhanced by combined application of APG and NTA. Long-term evaluation of this strategy is needed in co-contaminated field sites.

     

<Emphasis Type="Italic">Trichoderma</Emphasis> improves the growth of <Emphasis Type="Italic">Leymus chinensis</Emphasis>

Bio-fertilizer application has been proposed as a strategy for enhancing soil fertility, regulating soil microflora composition, and improving crop yields, and it has been widely applied in the agricultural yields. However, the application of bio-fertilizer in grassland has been poorly studied. We conducted in situ and pot experiments to investigate the practical effects of different fertilization regimes on Leymus chinensis growth, with a focus on the potential microecological mechanisms underlying the responses of soil microbial composition. L. chinensis biomass was significantly (P?<?0.05) increased by treatment with 6000 kg ha^?1 of Trichoderma bio-fertilizer compared with other treatments. We found a positive (R² =?0.6274, P <?0.001) correlation between bacterial alpha diversity and L. chinensis biomass. Hierarchical cluster analysis and nonmetric multidimensional scaling (NMDS) revealed that soil bacterial and fungal community compositions were all separated according to the fertilization regime used. The relative abundance of the most beneficial genera in bio-fertilizer (BOF) (6000 kg ha^?1Trichoderma bio-fertilizer) was significantly higher than in organic fertilizer (OF) (6000 kg ha^?1 organic fertilizer) or in CK (non-amend fertilizer), there the potential pathogenic genera were reduced. There were significant negative (P?<?0.05) correlations between L. chinensis biomass and the relative abundance of several potential pathogenic genera. However, the relative abundance of most beneficial genera were significantly (P?<?0.05) positively correlated with L. chinensis biomass. Soil properties had different effects on these beneficial and on these pathogenic genera, further influencing L. chinensis biomass.     

Short-term uptake of <Superscript>15</Superscript>NH<Subscript>4</Subscript><Superscript>+</Superscript> into soil microbes and seedlings of pine,spruce and birch in potted soils

Short-term competition between soil microbes and seedlings of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) for N was assessed in a pot study using (¹⁵NH₄)₂SO₄ as a tracer. Seedlings were grown in organic and mineral soil, collected from a podsol soil; 3.18 mg (¹⁵NH₄)₂SO₄ per pot were injected into the soil, corresponding to 4 µg ¹⁵N g^-1 d.m. (dry matter) mineral soil and 17 µg ¹⁵N g^-1 d.m. organic soil. The amounts of N and ¹⁵N in the seedlings and in microbial biomass derived from fumigation-extraction were measured 48 h after addition of ¹⁵N. In the mineral soil, 19–30% of the added ¹⁵N was found in the plants and 14–20% in the microbial biomass. There were no statistically significant differences between the tree species. In the organic soil, 74% of the added ¹⁵N was recovered in the microbial biomass in birch soil, compared to 26% and 17% in pine and spruce soils, respectively. Correspondingly, about 70% of the ¹⁵N was recovered in pine and spruce seedlings, and only 23% in birch seedlings. In conclusion, plants generally competed more successfully for added ¹⁵NH₄ ⁺ than soil microbes did. An exception was birch growing in organic soil, where the greater amount of available C from birch root exudates perhaps enabled micro-organisms to utilise more N.     

Effects of Residual Mulch Film on the Growth and Fruit Quality of Tomato (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.)

The quantities of residual mulch film in the soil will further increase with the wide application of agricultural plastic mulch film, and the pollution of residual mulch film, which is a continuous pollutant and the one that is difficult to degrade, is a major limiting factor for the sustainable development of agriculture in China. Residual mulch film in the soil inevitably affects soil hydrodynamic parameters, destroys the homogeneity of the soil texture, seriously impedes the movement of soil water and solutes, and thus greatly influences crop growth and fruit quality. To unravel the effects of residual mulch film on tomato growth and fruit quality, pot experiments in the greenhouse were carried out in 2015 and 2016 in Northwest China. Six levels of residual mulch film were applied: 0 kg ha^?1 (CK), 80 kg ha^?1 (T1), 160 kg ha^?1 (T2), 320 kg ha^?1 (T3), 640 kg ha^?1 (T4), and 1280 kg ha^?1 (T5). Plant height, stem diameter, dry biomass, yield, root length, root surface area, fruit shape index (FSI), soluble sugar content (SSC), organic acid (OA), vitamin C (VC), lycopene, and nitrate content (NC) were measured. Plant height, stem diameter, dry biomass, and yield of tomato had a downward trend as the residual mulch film amount increased. Root length and root surface area were significantly decreased with an increasing amount of residual mulch film, but root volume and root diameter showed an inconspicuous decrease. When the amount of residual mulch film was more than 80 kg ha^?1, growth indexes, dry biomass, and yield of tomato showed a sharp decline. FSI, OA, and lycopene decreased as the residual mulch film amount increased, whereas SSC, VC, and NC showed an increase trend. With the increase in residual mulch film amount, the F and membership function values (X _μ ) all showed a declining trend in comparison to the CK. Therefore, residual mulch film can aggravate the negative effects on the comprehensive fruit quality of tomato.     

Copper/Zinc Bioaccumulation and the Effect of Phytotoxicity on the Growth of Lettuce (<Emphasis Type="Italic">Lactuca sativa</Emphasis> L.) in Non-contaminated,Metal-Contaminated and Swine Manure-Enriched Soils

Copper/zinc bioaccumulation and the effect of phytotoxicity on the growth of lettuce (Lactuca sativa L.) were studied in plastic vessels containing (i) non-contaminated soil, (ii) copper-contaminated soils at concentrations of 75.0 and 125.0 mg kg^?1, (iii) zinc-contaminated soils at concentrations of 1200 and 2400 mg kg^?1, and (iv) soil enriched with swine manure. Copper and zinc concentrations in lettuce leaves were determined by flame atomic absorption spectrometry during 42 days of growth. Copper concentrations from 0.92 to 13.06 mg kg^?1 were found in lettuce leaves grown in copper-contaminated soils and zinc concentrations from 58.13 to 177.85 mg kg^?1 were found in lettuce leaves grown in zinc-contaminated soils. Copper and zinc concentrations in lettuce leaves grown in swine manure-enriched soils ranged from 0.82 to 8.33 and 0.68 to 13.27 mg kg^?1, respectively. Copper and zinc bioaccumulation caused a decrease in lettuce growth in metal-contaminated soils and an increase in phytotoxicity effects when compared to growth in non-contaminated and manure-enriched soils. These findings were confirmed by measuring leaf areas and biomasses. Copper was less toxic to lettuce than zinc due to the different concentrations in the soil. Lettuce growth and development was better in the swine manure-enriched soil than non-contaminated soil, which indicates that swine manure is a safe agricultural biofertilizer when used in appropriate amounts to avoid metal bioaccumulation in soil and plants.     

Kinetics of Lead Bioaccumulation from a Hydroponic Medium by Aquatic Macrophytes Pistia stratiotes

The goal of this work was to study quantitatively lead bioaccumulation from a lead-doped nutrient medium by using a living aquatic macrophytes Pistia stratiotes. Several sets of aquatic plants with approximately 30 g weight were grown in greenhouse conditions and in hydroponic solutions supplied with a non-toxic Pb²⁺ concentration. The synchrotron radiation total X-ray fluorescence spectrometry was used to determine the metal concentrations in dry plants and hydroponic media as a function of time. Four different non-structural bioaccumulation models were applied to describe the process dynamics and to estimate the accumulated lead maximum capacity and rate constants. According to the experimental data, both biosorption and bioaccumulation mechanisms can be considered. Due to the low desorption rate constant, the experimental data were well described by the irreversible kinetic model. The results concerning modeling of living macrophytes’ metal bioaccumulation kinetics can be used to predict the heavy metal removal dynamics from wastewaters in artificial wetlands.     

Phytoremediation Potential of <Emphasis Type="Italic">Helianthus annuus</Emphasis> and <Emphasis Type="Italic">Hydrangea paniculata</Emphasis> in Copper and Lead-Contaminated Soil

This study was conducted to assess the hyperaccumulation and phytoremediation potential of copper (Cu) and lead (Pb) in Hardy ‘Limelight’ Hydrangea (Hydrangea paniculata) and the common sunflower (Helianthus annuus). The study also investigated the capacity of these two plants to transpire the metals in a temperature-controlled greenhouse. Plants were grown for 4 weeks and periodically watered with known elemental concentrations of copper oxide nanoparticles, copper sulfate, and lead nitrate. Both H. annuus and H. paniculata accumulated significant amounts of Cu and Pb to be classified as hyperaccumulator species. H. annuus took up significant amounts of Cu in the shoots, specifically the leaves (Cu max.?=?1368 ppm), and easily translocated it from stem to leaf (translocation factor (TF) ranged from 2.7 to 81.0). Pb was not as easily taken up and translocated (TF?=?0.6) as Cu was by this species. H. paniculata took up Cu and Pb in high concentrations but preferentially stored more metals in the stems (Cu max.?=?1757 ppm; Pb max.?=?780 ppm) than in the leaves (Cu max.?=?126 ppm; Pb max.?=?35 ppm). The translocation ability of H. paniculata was much lower for both metals compared to H. annuus. Both Cu and Pb transpired from H. annuus at concentrations of 0.04 and 0.005 ppm, respectively.     

Comparison of the <Emphasis Type="Italic">Rhodotorula mucilaginosa</Emphasis> Biofilm and Planktonic Culture on Heavy Metal Susceptibility and Removal Potential

This study compares the effect of heavy metals (Hg²⁺, Cu²⁺, and Pb²⁺) on the Rhodotorula mucilaginosa and Saccharomyces boulardii biofilm and planktonic cells. A MBEC^TM-HTP assay was used to test the levels of tolerance to heavy metals. The minimum inhibitory concentration (MICp) and minimum lethal concentration (MLCp) of the R. mucilaginosa and S. boulardii planktonic cells were determined, as well as minimum biofilm eradication concentration (MBEC). Metal removal efficiency was determined by batch biosorption assay. Previous studies had focused on heavy metal tolerance and removal efficiency of planktonic cells from Rhodotorula species only. Hence, our study presents and compares results for metal tolerance and removal efficiency of the R. mucilaginosa planktonic cells and biofilm. Biofilm tolerance was higher than the planktonic cells. The R. mucilaginosa planktonic cells showed the tolerance in the presence of Hg²⁺ (MICp 0.08 mM), Cu²⁺ (MICp 6.40 mM), and Pb²⁺ (MICp 3.51 mM), while the S. boulardii planktonic cells only tolerated Pb²⁺ (MICp 0.43 mM). The R. mucilaginosa biofilm showed the highest tolerance in the presence of Hg²⁺ (MBEC >0.31 mM), Cu²⁺(MBEC >12.81 mM), Pb²⁺ (MBEC >7.12 mM), and obtained results were confirmed by fluorescence microscopy. S. boulardii did not show potential in biofilm formation. The R. mucilaginosa biofilm exhibited better efficiency in removal of all tested metals than the planktonic cells. Metal removal efficiency was in the range from 4.79–10.25% for planktonic cells and 91.71–95.39% for biofilm.     

Tolerance and Bioaccumulation of Arsenate by <Emphasis Type="Italic">Aspergillus Oryzae</Emphasis> TLWK-09 Isolated from Arsenic-Contaminated Soils

Eleven indigenous arsenic-tolerant fungi were isolated from arsenic-contaminated mine tailing and identified by molecular biology methods. Among them, Aspergillus oryzae (denoted as A. oryzae TLWK-09) had high tolerance and bioaccumulation of As(V). The maximum tolerance to As(V) concentration of A. oryzae TLWK-09 reached 5000 mg/L. As(V) bioaccumulation on A. oryzae TLWK-09 in the aqueous system was investigated under different environmental conditions such as mycelia dosage, contact time, pH, and ionic strength. Bioaccumulation data of As(V) were fitted to Langmuir model, and the maximum uptake capacity of A. oryzae TLWK-09 for As(V) was 54.12 mg/g at 301 K. The morphological structures of mycelia changed obviously under As(V) stress by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The analysis of Fourier transform infrared spectroscopy (FTIR) indicated the presence of carboxyl, hydroxyl, and amino groups on the fungal mycelia, which showed that these groups accounted for As(V) bioaccumulation. These results suggested that A. oryzae TLWK-09 could be an efficient and promising bioremediation material for As(V) pollution.     

Assessment of <Emphasis Type="Italic">Koelreuteria paniculata</Emphasis> Seedling for Phytroremediation of Pyrene-Contaminated Soils

Phytoremediation is a cost-effective and environmentally friendly technology using plants for the cleanup of both inorganic and organic contaminated sites. In this study, a pot culture experiment has been conducted for 180 days in a greenhouse to examine the capability of Koelreuteria paniculata on pyrene (Pyr) dissipation in contaminated soil. Three treatments were employed and they were: (1) polluted soil with K. paniculata fine roots addition (T1), (2) polluted soil with planted seedlings (T2), and (3) polluted soil (C). Results showed Pyr concentration in soils was reduced by 21.4, 36.2, and 86.4% by natural losses, fine roots addition, and planted K. paniculata treatments, respectively, meaning plants substantially enhanced the dissipation of Pyr from soil. Cultivated K. paniculata seedlings significantly increased soil total nitrogen (TN), total organic carbon, dissolved organic carbon (DOC), and microbial biomass carbon, but not total phosphorus, when compared to the control. The removal efficiency of Pyr was lower in the adding of fine roots treatment than in the planted K. paniculata treatment. The principal component analysis indicated the promotional dissipation of Pyr in soil by planted K. paniculata was likely attributed to increased microbial quantity and activity, DOC, and TN content in the rhizosphere. Our results suggest that K. paniculata is a suitable plant species used in phytoremediation for Pyr-contaminated soils and the efficiency on the dissipation of Pyr is considerably enhanced using living plants than adding dead organic matters. The study provided a reference for the application of K. paniculata in the remediation of Pyr-contaminated soil.     

High Zn concentration does not impair biomass,cutting radial growth,and photosynthetic activity traits in <Emphasis Type="Italic">Populus alba</Emphasis> L.

Purpose

Evaluate the efficiency of Populus alba clone Villafranca in the uptake and translocation of Zn from contaminated soils.

Materials and methods

The effects of 48 days of zinc treatment (Zn _t ) on the growth and the photosynthetic activities of P. alba L. clone Villafranca were studied using ZnSO₄ (375 ppm per unit of soil dry weight) added in sand and peat moss substrate at the beginning of the treatment (T ₀) and again after 30 days (T ₁) in order to reach a target Zn concentration of 375 ppm at T ₀ and 750 ppm at T ₁ per unit of soil dry weight.

Results and discussion

Zn uptake in the different organs was analyzed after 30 (T ₁) and 48 days (T ₂) from the beginning of treatment, showing the following order: root ? leaves ≥ woody cutting = stem. The leaf area increased by 12 % in comparison to control plants at the end of second treatment (48 days). Cutting radial growth showed a high synchronicity in the growth rate fluctuation among control and Zn _t plants, but a higher increase in radial diameter of Zn _t cutting was observed starting from day 38 (after 8 days of second Zn _t ) reaching after 48 days 38 % higher than control plants.

Conclusions

Although our data of leaf Zn concentration were in the range usually reported as toxic for plants, Villafranca clone in Zn _t substrate were unaffected in terms of net CO₂ assimilation and stomatal conductance to water vapor.

     

Intracellular chromium accumulation by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. MC1

Streptomyces sp. MC1, previously isolated from sugar cane, has shown ability to reduce Cr(VI) in liquid minimal medium and soil samples. The objective of this work was to demonstrate the intracellular chromium accumulation by Streptomyces sp. MC1 under different culture conditions. This strain was able to accumulate up to 3.54 mg of Cr(III) per gram of wet biomass, reducing the 98% of Cr(VI) and removing 13.9% of chromium from the culture medium supernatants. Streptomyces sp. MC1 chromium bioaccumulation ability was corroborated by using Timm’s reagent technique, a low-cost method, which has been used by first time to detect chromium deposits in bacteria. The results of atomic absorption spectrometry, scanning electron microscopy, and energy dispersive X-ray analysis suggest that the mechanism of Cr(VI) resistance observed in Streptomyces sp. MC1 includes adsorption coupled with reduction to Cr(III), and finally, Cr(III) bioaccumulation. This mechanism have special relevance to remediation of Cr(VI) contaminated environments by Streptomyces sp. MC1.     

Biodegradation and Detoxification Efficiency of Azo-Dye Reactive Orange 16 by <Emphasis Type="Italic">Pichia kudriavzevii</Emphasis> CR-Y103

In consideration of the hazards associated with the presence of the textile azo-dye and their biotransformation products in the environment, the goal of this work was to study bioremediation process by the yeast strain Pichia kudriavzevii CR-Y103 related to the ability to degrade and detoxify the sulfonated Reactive Orange 16 azo-dye. In experimental conditions, the optimal inoculum/dye concentration ratio required for complete decolorization (100%) of culture medium and biomass within 24 h has been 1 g L^?1 yeast cell (dry weight)/50 mg L^?1 Reactive Orange 16. In the presence of 400 mg L^?1 of Reactive Orange 16 (RO16), 95% of the dye was removed after 72 h of incubation. Also, the yeast strain could decolorize other eight textile dyes (56.48–99.98% decolorization within 24 h). NADH-DCIP reductase and azo reductase activities were significantly increased (ca. 5.4 times and ca. 37 times, respectively) during the decolorization process. UV-VIS spectra, high-performance liquid chromatography (HPLC), and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of new biotransformation products in extracted metabolites, highlighting the partial biodegradation of the dye by the new yeast isolate. The phytotoxicity evaluation strongly supported the decreased toxicity of biodegraded products as minor inhibition on germination (%), root and shoots elongation of T. pratense L. and T. aestivum L. seedlings. Increasing of mitotic index value and decreasing the frequency of chromosomal aberrations in tested plant meristem cells treated with biodegraded products, compared with RO16 treatment (500 ppm), confirmed their slightly toxic nature. A cell viability assay also confirmed the reduced toxicity of biodegraded products on healthy monkey kidney cells (Vero cells).     

Bioaccumulation of Trace and Non-trace Elements in Blood and Fibers of Alpacas (<Emphasis Type="Italic">Vicugna pacos</Emphasis>) that Graze in Italian Pastures

The concentrations of trace and non-trace elements were determined in blood and fibers of alpacas (Vicugna pacos) from a north Italian area, as well as in their pasture forages. This is the first investigation regarding this species in Italy, and the first considering alpaca’s fiber as bioindicator worldwide. Metal contents in blood were in the decreasing order: copper?>?zinc?>?aluminum?>?selenium?>?lead?>?nickel?>?manganese?>?chromium?>?arsenic and cadmium, while in fiber, metal levels were in the following order: aluminum?>?zinc?>?copper?>?manganese?>?chromium?>?nickel?>?selenium?>?lead?>?arsenic and cadmium. Antimony, beryllium, mercury, tin, and thallium were below the limit of quantification (0.010 mg kg^?1). The analysis of the alpacas’ forage confirmed the same trend found in fiber, suggesting that metal bioaccumulation was affected by diet. These preliminary results have shown that all the trace elements studied bioaccumulated to a greater extent in the fibers of the alpaca than in the blood. Accordingly, we may suggest that alpaca fibers could be used for monitoring exposure especially to non-essential metals like aluminum, cadmium, and lead, and could constitute a suitable non-invasive method for measuring trace and non-trace element exposure in camelids.     

Changes in methane emission and methanogenic and methanotrophic communities in restored wetland with introduction of <Emphasis Type="Italic">Alnus trabeculosa</Emphasis>

Purpose

The dynamics and uncertainties in wetland methane budgets affected by the introduction of Alnus trabeculosa H. necessitate research on production of methane by methanogenic archaea and consumption by methane-oxidizing microorganisms simultaneously.

Materials and methods

This study investigated methane emission in situ by the closed chamber method, and methanogenic and methanotrophic communities using denatured gradient gel electrophoresis (DGGE) and quantitative PCR based on mcrA (methyl coenzyme M reductase), pmoA (particulate methane monooxygenase) genes in the rhizosphere and non-rhizosphere soils in the indigenous pure Phragmites australis T., and A. trabeculosa–P. australis mixed communities in Chongxi wetland.

Results and discussion

Methane flux rate from the pure P. australis community was 2.4 times larger than that of A. trabeculosa–P. australis mixed community in the rhizosphere and 1.7 times larger in the non-rhizosphere, respectively. The abundance of methanogens was lower in the mixed community soils (3.56?×?10³–6.90?×?10³ copies g^?1 dry soil) compared with the P. australis community (1.47?×?10⁴–1.89?×?10⁴ copies g^?1 dry soil), whereas the methanotrophs showed an opposite trend (2.08?×?10⁶–1.39?×?10⁶ copies g^?1 dry soil for P. australis and 6.20?×?10⁶–1.99?×?10⁶ copies g^?1 dry soil for mixed community soil). A liner relationship between methane emission rates against pmoA/mcrA ratios (R ²?=?0.5818, p?<?0.05, n?=?15) was observed. The community structures of the methane-cycling microorganism based on mcrA and pmoA suggested that acetoclastic methanogens belonging to Methanosarcinaceae and a particular type II methanotroph, Methylocystis, were dominant in these two plant communities.

Conclusions

The introduction of A. trabeculosa would promote the proliferation of methanotrophs, especially the dominant Methylocystis, but not methanogens, ultimately diminishing methane emission in the wetland.

     

Bioenergy-derived waste biochar for reducing mobility,bioavailability, and phytotoxicity of chromium in anthropized tannery soil

Purpose

This study was aimed to investigate the potential of biochar (BC), a waste byproduct of a bioenegy industry, Sri Lanka, as a soil amendment to immobilize and reduce the phytotoxicity of Cr in tannery waste-polluted soil (TWS).

Materials and methods

The TWS and bioenergy waste BC were characterized for physio-chemical parameters. A pot experiment was conducted by adding three BC application rates, 1, 2.5, and 5 % (w/w) to investigate the immobilizing capacity and bioaccumulation of chromium (Cr) in tomato plants (Lycopersicon esculentum L.). Soils and plants were digested via microwave digestion and analyzed for total Cr. Further, sequential extraction was conducted to assess the fractionation of Cr before and after the application of bioenergy waste BC on TWS.

Results and discussion

The total Cr concentration in TWS was 12,285 mg/kg. The biomass of tomato plants grown in the 5 % BC amendment doubled compared to the biomass in BC-unamended soil. Bioaccumulation of Cr in plants grown in 5 % BC-amended TWS showed a decrease by 97 % compared to that of the BC-unamended soil. The CaCl₂ extractability of Cr indicated that the bioavailability of Cr in the 5 % BC amendment has decreased by 68 % compared to the control. Sequentially extracted Cr in the exchangeable fraction decreased by 98 % in the 5 % BC amendment.

Conclusions

Pore diffusion, and adsorption via π-π electron donor-acceptor interactions were the primary mechanisms to be involved in the Cr retention in BC. Results suggested that the addition of BC to TWS reduces the mobility, bioavailability, and phytotoxicity of Cr in tomato plants.

     

<Emphasis Type="Italic">Lotus ornithopodioides</Emphasis> L. a potential annual pasture legume species for Mediterranean dryland farming systems

Twenty-three populations of Lotus ornithopodioides L., collected from different regions of the Mediterranean basin, were investigated for their ecological and agronomic traits in Western Australia. Great variability was found between and within populations for flowering time, forage and seed yield. Flowering time ranged between 75 and 120 days, dry matter production from 2.8 to 4.3 t ha^?1 and seed yield from 284 to 684 kg ha^?1. Other important traits such as non-shattering pods and hard seed were taken into account during the selection to assure an easy seed harvesting and legume persistence in the targeted environments. The high level of hard seed recorded in early winter, associated to the low seedling regeneration, indicates that L. ornithopodioides is best suited to ley cropping systems. Elite lines of L. ornithopodioides characterized by early flowering time, high seed yield and non-shattering pods were selected. Two of them, LOR02.1 and LOR03.2, showed dry matter higher than 4.0 t ha^?1 and seed yield around 700 kg ha^?1 resulting the lines with most potential for Mediterranean farming systems. The results encourage the exploitation of L. ornithopodioides germplasm to develop a new annual self-reseeding legume resource for Mediterranean farming systems for both forage production and crop rotation uses.