Biochar applications enhance the phytoextraction potential of Salix smithiana [Willd.] (willow) in heavily contaminated soil: potential for a sustainable remediation method?

Journal of Soils and Sediments - The combination of chemostabilization and phytoextraction provide an affordable and environmentally effective remediation technology for the heavy metals in...     

Antifouling Activity of Synthetic Alkylpyridinium Polymers Using the Barnacle Model

Polymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC₅₀) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC₅₀: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC₅₀ of 4.83 and 1.86 mg/L.     

Comparison of thermal and chemical stability of Cu–humic complexes

Purpose

The purpose of this study was to investigate relationships between chemical and thermal stabilities of Cu–humic complexes. The study of the chemical stability was based on pedological methods used for the determination of the bond strength of metal ions in soils by chemical leaching agents. The samples with various contents of the Cu(II) ions and their bond strength were put to the thermal analysis in order to correlate their thermo-oxidative behavior with their stability determined by leaching.

Materials and methods

The humic acid was extracted from the South-Moravian lignite by standard alkaline extraction. The humic sample was used in two different forms: as the solid powder and as the hydrogel prepared by the acidic precipitation of humate. Six various concentrations of copper(II) solutions were used for the complexation of the humic powder and the hydrogel, in order to study the influence of their initial concentration on both the determined stabilities of the prepared complexes. Their chemical stability was assessed in terms of the Cu(II) ions release from the humic acid structure into two different extraction agents (MgCl₂ and HCl solutions). Their thermo-oxidative behavior was investigated employing the thermogravimetry.

Results and discussion

The complexation capacity of the humic hydrogel was higher in comparison with the humic powder. The amounts extractable from the Cu–humic complexes by the used leaching agents are higher for the humic powder, which shows on the lower chemical stability. The thermal degradation of the prepared complexes proceeds in several steps and this character remains also after the removal of the mobile and the ion-exchangeable fractions by the MgCl₂. The elimination of these fractions as well as the extraction of the strongly bound Cu(II) ions shift the thermal degradation to higher temperatures. The incombustible residue increases with the Cu(II) content in the complexes except for the samples extracted by the HCl.

Conclusions

The form of humic sample used for the preparation of the Cu–humic complexes influences both the chemical stability and the thermal one. The main reason is probably a better accessibility of the functional groups in the humic gel, which enables forming stronger binding copper(II) ions. The results showed that the thermal and chemical stabilities are closely related, which corresponds with the shift of the thermal degradation to higher temperatures after removing the less stable fractions from the humic complexes.     

Heavy Metal Content of Soils and Plum Orchards in an Uncontaminated Area

There are multiple stressors derived from urbanizations that result in frequent disturbances on streams and rivers reducing water quality and threatens aquatic biota. P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) is a defence mechanism analogous to multidrug resistance (MDR), which has been demonstrated in several aquatic organisms. This system protects cells against the entry and the accumulation of xenobiotics and has been proposed as a biomarker for pollution assessment. We conducted a study in a post-urban reach of Esquel stream (Chubut Province) downstream a wastewater treatment plant, in order to assess the presence and activity of MXR in five freshwater macroinvertebrate species (Helobdella michaelseni, Helobdella simplex, Patagoniobdella variabilis, Hyalella curvispina and Chironomus riparius). We measured the accumulation of the model P-gp substrate rhodamine B (RB) in organisms previously exposed to pollution. Our results described the activity of the MXR system in the three species of leeches suggesting their suitability as the in vivo biomonitoring. We also identified a dependence of the transporter activity with the development stage in H. simplex, highlighting the importance of using organisms of similar size classes since it may affect observed results. Finally, we concluded that benthic freshwater macroinvertebrates possess different species-specific levels of MXR activity possibly influencing their natural distribution as well as their survival.     

Changing parameters of Czechoslovak obsolete and modern bread wheat cultivars (Triticum aestivum L.) over 90 years

Differences achieved in 18 selected morphological, phenological and grain parameters attributable to the wheat breeding process were evaluated on the basis of 262 original Czech and Slovak winter bread wheat cultivars (Triticum aestivum L.) developed during 1911–2008 and cultivated in the field and climatic conditions of Crop Research Institute Prague-Ruzyně for 3 years (2010–2012). The wheat breeding process unambiguously has improved grain production parameters, lodging and mildew resistance compared to wheat landraces and obsolete cultivars. Only wheat landrace ‘Visnovska Hustoklasa’ showed a higher resistance to lodging (8 points), no old cultivars registered till 1930 were resistant to mildew. Nevertheless, these economically positive properties of modern wheat cultivars are negatively reflected in lower crude protein content, protein content’s lower stability year to year, and decreased stability of Zeleny sedimentation. The breeding of wheat cultivars during 1961–1990 points to a key period responsible for these parameter changes. At the same time, within this somewhat older wheat group (from 1961–1990), several perspective wheat cultivars with acceptable spike productivity (e.g., ‘Regina’) and high crude protein stability (e.g., ‘Diana II’) were also identified.     

Influence of N-, P- and Si-based Flame Retardant Mixtures on Flammability,Thermal Behavior and Mechanical Properties of PA6 Composite Fibers

This research investigated the influence of two flame retardant (FR) mixtures consisting melamine cyanurate (MeCy) and aluminum diethylphosphinate (AlPi), and MeCy and sodium aluminosilicate (SASi) at different weight ratios, on the flammability, thermal behavior and mechanical properties of polyamide 6 (PA6) composite yarns produced by meltspinning. The morphological and chemical properties of PA6/FR filaments were investigated by scanning electron microscopy and Fourier-transform infrared spectroscopy, flame retardancy by vertical burning test UL-94, thermal behavior by thermogravimetric and differential scanning calorimetric analyses, and mechanical properties by tensile tests. The results indicate that within the UL 94 V2 rating, the composite yarns differed significantly from each other in their burning and dripping behavior. The incorporation of both mixtures, MeCy+AlPi and MeCy+SASi, into the PA6/FR yarns significantly decreased the afterflame time relative to pristine PA6, confirming a lower production of flammable volatiles. This phenomenon was attributed mainly to MeCy, which caused an immediate extinguishment of the flame after the withdrawal of the igniting flame. Compared to one component MeCy, the incorporation of the MeCy+SASi mixture enhanced the thermooxidative stability of the PA6/FR yarns because of their additive effect at higher concentrations. In contrast, an antagonistic effect was obtained for the MeCy+AlPi mixture, irrespective of the concentration. Since the incorporation of MeCy+SASi did not drastically reduce the tensile properties of filaments, this mixture enables the production of the PA6/MeCy+SASi composite yarns with the enhanced flame retardancy and thermo-oxidative stability.     

Biochemical and physiological responses to long‐term Citrus tristeza virus infection in Mexican lime plants

Reactions that occur when a plant is subjected to Citrus tristeza virus (CTV) infection often result in triggering of numerous defence mechanisms to fight the infection. The reactions vary according to virus strain, host genotype, time of exposure to the infection and environmental conditions. To date, no study has examined in detail the consequences of 10‐year exposure to CTV infection on the biochemical and physiological status of susceptible Mexican lime plants (Citrus aurantifolia). To understand the reaction of such plants, changes in nutrient status, total proteins, enzyme activity involved in scavenging of reactive oxygen species, photosynthetic and transpiration rates, chlorophyll content, membrane permeability and water content were analysed in plants infected with different CTV isolates and in healthy plants. The activity of superoxide dismutase and polyphenol oxidase significantly decreased in the infected leaves, and membrane permeability was lower in the infected plants. Macro‐ and micronutrient elements were significantly changed: concentrations of leaf nitrogen, zinc, magnesium and iron were elevated but potassium concentration depressed in comparison to noninfected control leaves. Levels of other analysed nutrient elements, enzymes, photosynthesis and stomatal conductance, chlorophyll content and relative water content were unchanged. Clear physiological changes were found among infected and noninfected control plants but none between plants infected with different CTV isolates. The data suggest that some of the defence mechanisms investigated here were suppressed due to the continuous and long‐term pressure of biotic stress.     

The isoflavone daidzein directly affects porcine ovarian cell functions and modifies the effect of follicle‐stimulating hormone

The key biological active molecule of soya is the isoflavone daidzein, which possesses phytoestrogenic activity. The direct effect of soya and daidzein on ovarian cell functions is not known. This study examined the effect of daidzein on basic porcine ovarian granulosa cell functions and the response to follicle‐stimulating hormone (FSH). We studied the effects of daidzein (0, 1, 10 and 100 μm ), FSH (0, 0.01, 0.1, 1 IU/ml) and combinations of FSH (0, 0.01, 0.1, 1 IU/ml) + daidzein (50 μm ) on proliferation, apoptosis and hormone release from cultured porcine ovarian granulosa cells and ovarian follicles. The expression of a proliferation‐related peptide (PCNA) and an apoptosis‐related peptide (Bax) was analysed using immunocytochemistry. The release of progesterone (P4) and testosterone (T) was detected using EIA. Leptin output was analysed using RIA. Daidzein administration increased granulosa cell proliferation, apoptosis and T and leptin release but inhibited P4 output. Daidzein also increased T release and decreased P4 release from cultured ovarian follicles. Follicle‐stimulating hormone stimulated granulosa cell proliferation, apoptosis and P4, T and leptin release. The addition of daidzein promoted FSH‐stimulated apoptosis (but not proliferation) but suppressed FSH‐stimulated P4, T and leptin release. Our observations of FSH action confirm previous data on the stimulatory effect of FSH on ovarian cell proliferation, apoptosis and steroidogenesis and demonstrate for the first time the involvement of FSH in the upregulation of ovarian leptin release. Our observations of daidzein effects demonstrated for the first time that this soya isoflavone affected basic ovarian cell functions (proliferation, apoptosis and hormones release) and modified the effects of FSH. Daidzein promoted FSH action on ovarian cell proliferation and apoptosis and suppressed, and even inverted, FSH action on hormone release. The direct action of daidzein on basic ovarian cell functions and the ability of these cells to respond to FSH indicate the potential influence of soya‐containing diets on female reproductive processes via direct action on the ovary.     

The onset of puberty in Cameroon Dwarf goats kept as pets in northwestern Croatia

The aim of this study was to determine onset of puberty in Cameroon Dwarf goats (CDGs) kept as pets in northwestern Croatia by determining progesterone (PGS) and insulin‐like growth factor‐I (IGF‐I) levels in the blood by RIA methods. The first cyclic ovarian activity was estimated according to hormone profiles as determined in CDG in a moderate climate environment. Sixteen female CDG kids were kept in stables with access to pasture which provided space for exercise. The goat kids born in winter (December–January–February), spring (March–April–May), summer (June–July–August) and autumn (September–October–November) were assigned into four groups according to the season of the year of birth (n = 4 in each group). At 75 days of age at the initiation of the study, they weighed between 3.2 and 5.1 kg (4.24 ± 0.53 kg). The onset of ovulatory activity was determined by PGS and IGF‐I serum concentrations every 10 days starting from 75 days to 155 days of age. The onset of puberty in CDG kids occurred on average at 141.15 ± 2.66 days of age, but varied depending on the season of birth. All CDG kids born during summer were in heat by 155 days of age. In the other groups (kids born in autumn, winter or spring), one goat in each group was not in heat. Changes in blood serum PGS and IGF‐I concentrations during prepubertal and pubertal periods could aid in the evaluation of reproductive status and determination of the onset of puberty in CDG during all seasons of the year in a moderate climate region.     

Long-term dynamics of causative agents of stem base diseases in winter wheat and reaction of Czech <Emphasis Type="Italic">Oculimacula</Emphasis> spp. and <Emphasis Type="Italic">Microdochium</Emphasis> spp<Emphasis Type="Italic">.</Emphasis> populations to prochloraz

Trichoderma aggressivum is an aggressive contaminant mould in the cultivation of Agaricus bisporus leading to severe reductions in mushroom yields. Production of fully colonised A. bisporus substrate in Europe is commonly carried out in large tunnels (Phase III), after which the substrate undergoes several bulk handling (mixing) operations before ending up on shelves in mushroom growing facilities. The work presented here studied the effect of Trichoderma aggressivum inoculum, substrate mixing and supplementation on Agaricus bisporus yields and evaluated four methods to detect T. aggressivum in bulk handled substrate. Inoculum dilution level was shown to correlate well with mushroom yield (P < 0.0001) with reductions of 2–6 % at the most dilute level (10^?4) and 60–100 % at the most concentrated level (10^?1), depending on the experiment. Supplementation, with or without T. aggressivum, had no significant effect on mushroom yield (P ≥ 0.85) but a high degree of substrate mixing was shown to significantly increase (P < 0.0001) T. aggressivum-associated crop losses. Four T. aggressivum detection methods were evaluated and a quantitative polymerase chain reaction (qPCR) method gave the most consistent and least variable results. Cycle threshold (CT) values ranged from 24 to 40, depending on the experiment and the inoculum dilution level, and false negatives (CT = 40) were reported on one occasion with the most dilute samples. The results indicate that Phase III mushroom substrate is vulnerable to infection by T. aggressivum when the fully colonised substrate is broken up and mixed during bulk handling operations, identifying a previously unidentified risk for Phase III substrate producers.