Biological polymers related to catechol: electron paramagnetic resonance and infrared studies of melanin, tannin, lignin, humic acid and hydroxyquinones.
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Animals↗
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Effect of soil humic and fulvic acids, pH and ionic strength on Th(IV) sorption to TiO2 nanoparticles.
Thorium is considered as a chemical analog of other tetravalent actinides. Herein, the sorption of Th(IV) on TiO(2) in the presence or absence of soil fulvic acid (FA)/humic acid (HA) as a function of pH, ionic strength and FA/HA concentration has been studied by a batch method. The morphology was characterized by scanning electron microscopy (SEM). The results indicate that sorption of Th(IV) on TiO(2) increases from 0% to approximately 94% at pH 1 approximately 4, and then maintains level with increasing pH values. Both FA and HA have a positive effect on Th(IV) sorption at low pH values and the contribution of FA on Th(IV) sorption is rather higher than that of HA at pH<4. The sorption is weakly dependent on the concentration of KNO(3) in solution, but the cations K(+), Na(+) and Li(+) influence Th(IV) sorption more obviously. The batch results indicate that the inner sphere complex formation is formed at bare surfaces or FA/HA-bound TiO(2) particle surfaces. Results of SEM analysis show that the particle sizes of TiO(2), Th-TiO(2) and Th-HA-TiO(2) colloids are quite different. Surface complexation may be considered as the main sorption mechanism.
Adsorption↗
Influence of dissolved organic matter on nickel bioavailability and toxicity to Hyalella azteca in water-only exposures.
Dissolved organic matter (DOM) is known to reduce the bioavailability of metals in aquatic systems. This study evaluated the effects of DOM from various sources (e.g., Little Bear Lake sediment, Suwannee River, peat moss) and various DOM fractions (humic acids, HA; fulvic acids, FA) on the bioavailability of nickel (Ni) to Hyalella azteca, a common freshwater benthic invertebrate. In particular, this study was conducted to evaluate the effect of surficial sediment DOM on Ni bioavailability. Short-term (48 h) acute toxicity tests with H. azteca conducted in synthetic water demonstrated that the aqueous Ni concentrations required for lethality were greater than what could be significantly complexed by environmentally relevant concentrations of dissolved organic carbon (DOC: 0.6-30.4 mg/L). At Ni concentrations sublethal to H. azteca (500 microg/L), the bioavailability of Ni was significantly reduced in the presence of representative surface water DOC concentrations regardless of DOC source or fraction. DOC fraction (i.e., FA and HA) differentially affected Ni speciation, but had little or no effect on Ni accumulation by H. azteca. Tissue Ni was found to be strongly dependent upon the Ni(2+) concentration in the exposure solutions and the Ni:DOC ratio. Overall, the concentration of DOC played a greater role than either DOC source or fraction in determining Ni speciation and hence bioavailability and toxicity to H. azteca.
Amphipoda↗
Humic acid reduces gonadotropin activity and hormonal sensitivity of frog oocytes.
The specific stimulatory effect of sturgeon Acipenser güldenstädti Br. gonadotropic hormone (GTH) on frog Rana temporaria L. oocyte maturation in vitro was investigated in relation to humic acid (HA) concentrations from 12.5 to 50 mg/l. HA was observed to bind to both the follicular membrane of the oocytes and the GTH molecule, reducing the oocytes' hormone sensitivity and maturation ability. It was also shown that HA inactivated GTH, lowering its specific ability to stimulate oocyte maturation.
Animals↗
Cadmium accumulation in zebrafish (Danio rerio) eggs is modulated by dissolved organic matter (DOM).
Experiments were conducted to investigate factors influencing the accumulation of cadmium (Cd(2+)) into zebrafish (Danio rerio) eggs. The accumulation of (109)Cd was affected by: (1) concentration, (2) time, (3) presence of dissolved organic material (DOM), (4) different origin of DOM and (5) different parts of fish eggs. Over a 5-h exposure, zebrafish eggs showed a steady increase in Cd-accumulation. DOM-concentrations over 15ppm carbon (C) decreased Cd-uptake significantly. Both samples of DOM, brown water marsh (LM) and a eutrophic pond (SP), at 16.9ppmC, reduced the Cd-accumulation in the chorion, perivitelline liquid and the embryo. Cd was mainly accumulated in the egg's outer shell chorion (61%) and only small amounts passed through the chorion into the perivitelline liquid (38%) and embryo (1%). In the presence of LM-DOM, the accumulation of Cd into the egg components was decreased by 43% (chorion), 52% (perivitelline liquid) and 52% (embryo), respectively, compared with the control group. Similarly, the presence of SP-DOM reduced the Cd-accumulation by 29% (chorion), 61% (perivitelline liquid) and 60% (embryo), respectively, compared with the controls. DOM-concentration should be taken into consideration when determining ecotoxicological effects of Cd on fish populations.
Animals↗
Ash in composting of source-separated catering waste.
Our earlier experiments in small composters (220 l) indicated the favourable effect of ash from co-incineration of sorted dry waste on the composting of catering waste. The aim of this new study was to clarify further, at a scale of 10 m3, the feasibility of using similar ash as an additive in composting. Source-separated catering waste was mixed with bulking agent (peat and wood chips) and fuel ash from a small (4 MW) district heating power plant. Three compost mixes (CM) were obtained: CM I with 0%, CM II with 10% and CM III with 20 wt.% of fuel ash. These three different mixes were composted in a 10-m3 drum composter as three parallel experiments for 2 weeks each, from January to April 2000. After drum composting, masses were placed according to mixing proportions in separate curing piles. The catering waste fed to the drum was cold, sometimes icy. Even then the temperature rapidly increased to over 50 degrees C. In CM III, the temperature rose as high as 80 degrees C, and after the first week of composting the temperature was about 20 degrees C higher in the CMs II and III than in the CM I. It also improved the oxygen concentrations at the feeding end of the drum and obviously prevented the formation of H2S. No odour problems arose during the composting. Addition of ash increased the heavy metal contents of the composting masses, but the compost was suitable for cultivation or green area construction. Ash clearly decreased the loss of total nitrogen in a time span of 2 years. The lower amounts of nitrogen mean that the amounts applied per hectare can be greater than for normal composts. Measured by mineralization, the breaking down of the organic matter was more rapid in the CM III than in the CM I. Humic acid increased steadily during first 12 months composting, from the initial 39 mg/g organic matter to 115 and 137 mg/g in CMs II and III. Measured by temperature, mineralization and humification the addition of ash appeared to boost the composting. Ash had also other beneficial effects on composting it improved the availability of oxygen in compost mass during the drum composting phase and reduced the formation of odorous gases, especially H2S.
Finland↗
Aerobic composting of chips from clear-cut trees with various co-materials.
Swollen chips made from trees felled during clear-cutting were composted with various organic and inorganic materials in an aerobic composting reactor for 5 months and then piled for 5 months. The organic materials included chicken feces, urea, nitrogenous lime (calcium cyanamide, manure), and material rapidly composted from food garbage in 24-h bacterial fermentation, while the inorganic materials were coal ash and volcanic ash. In this paper, we first attempt to estimate the quality and degree of maturity of each compost from its chemical properties. Furthermore, we try to calculate the maturity of the fermented wood chip composts from their mixture ratio of the initial materials by multiple linear regression analysis. We measured changes in the C/N ratio, nitrate nitrogen (NO3-N) content, percentage of humic acid in the alkali soluble fraction (PQ), cation exchange capacity, pH, and EC during the composting period. The degrees of maturity of the composts were estimated via a plant growth test using Chinese cabbage. We found that the CN ratio, NO3-N concentration, and PQ were suitable for estimating the degree of maturity of wood chip composts. For maturity, the CN ratio should be less than 14, the PQ more than 66.2, and the NO3-N concentration more than 853 mgkg-1. We devised an equation to estimate the degree of maturity after 10 months by a multiple linear regression analysis from the mixing ratio of wood chips and the co-composted materials. From the multiple linear regression analysis, the above three indices of compost maturity could be estimated from the mixing ratio of the initial materials. This equation should enable us to determine the degree of compost maturity after 10 months based on the initial mixing ratio.
Brassica↗
Characterisation of the organic matter pool in manures.
In this research, different types of animal manure were evaluated with respect to organic matter (OM), total organic carbon (C(ot)), total N (N(t)), C(ot)/N(t) ratio, water-soluble organic carbon (C(w)), organic N (N(org)), carbohydrates, C(w)/N(org) ratio, humic acid-like carbon (C(ha)), fulvic acid-like carbon (C(fa)), humification index ((C(ha)/C(ot))x100) (HI) and the C(ha)/C(fa) and NH(4)(+)-N/NO(3)(-)-N ratios. In comparison with the limits set by the Spanish legislation for organic fertilisers, most of the manures had high OM contents, moderate N(org) concentrations (except in the case of the chicken and pig manures where this parameter was high) and C(ot)/N(t) ratios above the value stated in the legislation. The study of the different fractions of organic matter showed that the horse, pig and rabbit manures had the greatest content of C(ot). However, the fraction of easily-biodegradable organic compounds (C(w)) was significantly higher in the horse, goat and chicken manures. The study also showed that, in most cases, the percentage of fulvic acid-like C was greater than that of the humic acid-like C, indicating that the organic matter of these wastes is not completely humified. Values of HI ((C(ha)/C(ot))x100) and C(ha)/C(fa) ratio in the studied manures were not significantly different. Regarding the parameters related to the organic matter stability such as C(w), carbohydrates and the C(ot)/N(t), C(w)/N(org) and NH(4)(+)-N/NO(3)(-)-N ratios, it has been determined that the organic matter of these materials was not completely stabilised. The heterogeneity in OM composition of the studied manures did not allow the formulation of simple equations for evaluation of the composition of these wastes from easily-determined parameters.
Animals↗
Composting of high moisture content swine manure with corncob in a pilot-scale aerated static bin system.
Pilot composting experiments of swine manure with corncob were conducted to evaluate the performance of the aerated static bin composting system. Effects of temperature control (60 and 70 degrees C) and moisture content (70% and 80%) were monitored on the composting by measuring physical and chemical indexes. The results showed that (1) the composting system could destroy pathogens, converted nitrogen from unstable ammonia to stable organic forms, and reduced the volume of waste; (2) significant difference of NH(4)(+)-N (P(12) = 0.074), and (NO(3)(-) + NO(2)(-))-N (P(12) = 0.085) was found between the temperature control treatments; (3) anaerobic reaction in the treatment with 80% moisture content resulted in significant difference of pH (P(23) = 0.006), total organic matter (P(23) = 0.003), and germination index (P(23) = 0.040) between 70% and 80%. Therefore, the optimum initial moisture content was less than 80% with the composting of swine manure and corncob by using the composting system.
Air↗
Transformation of organic matter during co-composting of pig manure with sawdust.
Co-composting of pig manure with sawdust was studied in order to characterize the organic transformation during the process, using both chemical and spectroscopic methods. Humic acids (HA) and fulvic acids (FA) were fractionated from immature and mature pig manure compost, and characterized. After 63 days of composting, the ratio of total organic carbon and soluble organic carbon decreased to a satisfactory low level and the solid and soluble C/N ratios decreased rapidly for the first 35 days before attaining a constant value, indicating compost maturity. Humification could be responsible for the increase in humic acid proportion during composting. The increase in the aromatic bonds after composting, as indicated by the reduction of C/H and C/O ratios of HA and FA, resulted in a more stabilized product. A substantial increase in high molecular weight compounds along with a small increase in low molecular weight compounds was found in mature compost. Moreover the HA also had more complex organic compounds at this stage. Fluorescence spectral analysis showed an increase in the maximum wavelength of HA associated with the contents of aromatic structures in solution. A decrease in relative absorbance of HA at 1160 cm(-1), 2950 cm(-1) and 2850 cm(-1) was seen in the FTIR spectra indicating the decomposition of complex organic constituents, into simpler ones. Increase in the aromatic compounds with higher stability could account for the relative increase in the absorbance of HA at 1650 cm(-1) and 1250 cm(-1) of the mature compost. The composition of FA was not much altered, indicating most of the degradation of organic matter occurred in HA. Data from organic carbon, C/N ratio, elemental analysis, E(4)/E(6) ratio, gel chromatography, fluorescence and FTIR spectra indicated an increase in polycondensed structures and the presence of more stable organic matter in the mature compost.
Animals↗
Organic matter evolution during co-composting of the organic fraction of municipal waste and poultry manure.
The study concerned the evolution of organic matter, and the humification process, during the co-composting of the organic fraction of municipal solid waste (OMSW) and poultry manure (PM); the study was made with two different mixtures (OMSW:PM ratios of 3:2 and 2:3, wet weight:wet weight) and two different particle sizes (1 and 0.2cm). The results suggested that the composting process proceeded unhindered throughout the degradation of easily degradable materials like hemicellulose, and that of the rather less degradable cellulose and lipids, and the concentration of recalcitrant material, i.e. a ligno-humic (LU) fraction. These processes were more evident for mixtures with lower particle size. Throughout the composting, in all mixtures studied, humification proceeded by the formation of a new HA fraction, which was probably the result of the partial degradation and solubilization of more complex insoluble organic molecules, i.e. humin fraction.
Animals↗
Chemolytic and solid-state spectroscopic evaluation of organic matter transformation during vermicomposting of sugar industry wastes.
The molecular structure of humic acid (HA) extracted was investigated by FT-IR and (13)C CP/MAS NMR spectroscopy during the vermicomposting of sugar industry wastes, viz. pressmud, trash and bagasse for 60days. A rapid decrease in C/N and lignocellulosic (lignin, cellulose, hemicellulose) content was observed in vermicompost during early phase of the process. The FT-IR and (13)C CP/MAS NMR spectra of HA indicated a high rate of change in structure with increase in the alkyl C/O-alkyl C ratio during the process. Aromatic structures and carboxyl groups showed an initial increase but decreased after approximately 40days indicating extensive mineralization during final stages of vermicomposting.
Agriculture↗
Changes in the chemical characteristics of water-extractable organic matter during composting and their influence on compost stability and maturity.
Composting is the biochemical transformation of waste organic matter by microorganisms whose metabolism occurs in the water-soluble phase. Therefore, a study of the changes occurring in compost dissolved organic matter can be useful for assessing its stability and maturity. In light of the variety of parameters generally utilized to study composting processes, this work aims at identifying the major chemical processes that occur in solution and their influence on the attainment of stability and maturity with composting time. Compost stability, assessed by means of respirometric analysis which determined oxygen demand as a result of mineralization of the compost's organic matter, and compost maturity evaluated with Lepidium sativum L. seed bioassays, were found to be highly related to the nature and content of water-soluble organic matter. Moreover, fractionation of the water-extractable organic carbon showed that the ratio of hydrophobic to hydrophilic carbon increased to values greater than unity for stabilized compost. These results together with the analysis for non-cellulosic polysaccharides, phenolic compounds and organic nitrogen within the water extracts, confirmed the influence of solubilization, mineralization and organic matter transformation on the quality of the final compost.
Biodegradation, Environmental↗
Transgene and mitochondrial DNA are indicators of efficient composting of transgenic pig carcasses.
Composting is an environmentally sound method for the disposal of on-farm livestock mortalities that generates material suitable for use as fertilizer; however, this method is not generally permitted for disposal of transgenic livestock mortalities during the research and development phase. This study has explored the application of the polymerase chain reaction (PCR) as a method for assessing the persistence of transgene and mitochondrial DNA markers during the composting of euthanized transgenic pig. There was at least a 10(7) fold reduction of genetic material to a level that not either transgene or mitochondrion markers were detectable. At the end of the composting period, only bone fragments that were completely demineralised and chalky were detected. Chemically the compost was similar to that from pig litter and poultry mortalities, except the copper content was lower. Based on these data, composting appears to be an appropriate method for the disposal of transgenic animals.
6-Phytase↗
Evolution of the fulvic acid fractions during co-composting of olive oil mill wastewater sludge and tree cuttings.
Fulvic acids (FAs) were isolated by a conventional procedure from two mixtures of the sludge residue obtained from olive oil mill wastewater (OMW) evaporated in open-air pond and tree cuttings (TC) at different stages of the co-composting process. The FAs were analyzed for elemental (C, H, N, S, O) and acidic functional group (carboxylic and phenolic) composition, and by ultraviolet/visible, Fourier transform infrared and fluorescence spectroscopies. At the initial stage of composting, FAs from the OMW sludge-TC mixtures were characterized by a prevalent aliphatic character, large contents of C, S-containing groups, proteinaceous materials and polysaccharide components, extended molecular heterogeneity, small O and acidic functional group contents, and small degrees of aromatic ring polycondensation, polymerization and humification. As composting proceeded, C, H and S contents, C/N ratio, and aliphaticity decreased, whereas N, O, COOH and phenolic OH contents, C/H and O/C ratios, and aromaticity increased. These results suggested that, with increasing the composting time, the chemical and structural properties of the FA components of the two OMW sludge-TC mixtures approached the characteristics typical of native soil FAs. Thus, co-composting of OMW sludge mixed with TC may represent a suitable treatment for enhancing the quality of organic matter in these materials when used as soil amendments.
Benzopyrans↗
Optical microsensors for pesticides identification based on porous silicon technology.
A simple and low cost optical sensor, based on porous silicon nanotechnology, has been used to detect and quantify the presence of atrazine pesticide in water and humic acid solutions. In both cases, a well defined optical signal variation can be registered, even at low concentration as 1 ppm. The phenomenon can be ascribed to the capillary infiltration of liquid into the pores, which changes the average refractive index of the structure. Due to the resonant cavity enhanced operation of the proposed sensors, very low detection limits can be reached.
Atrazine↗
Promoting neoplastic transformation of humic acid in mouse epidermal JB6 Cl41 cells.
Humic acid (HA), a group of high-molecular weight polymer, resulting from the decomposition of organic matter has been implicated as a possible etiological factor for Blackfoot disease and cancer. In this study, we evaluate the promotion effect of HA on the transformation in mouse epidermal JB6 clone 41 (JB6 Cl41) cells that have been used to identify the tumor promoting activity of various compounds. Our preliminary assay demonstrated that JB6 Cl41 cells with the treatment of HA at the concentration of 100 microg/ml for 72 and 96 h significantly increased reactive oxygen species (ROS) as compared to the untreated control. In addition, the 48 h cultured cells with HA pretreatment for 48 h also increased ROS as compared to the untreated control. HA-pretreated cells develop highly scattered and spindle-shaped cells with few observable cell-cell contacts, and contain more filopodia. In vitro wound-healing assay showed that JB6 Cl41 cells with HA pretreatment increased the migrating growth. Furthermore, transformed foci of JB6 Cl41 cells following the HA pretreatment were observed after 6 weeks culture. In anchorage-independent growth assay, we found that HA promoted the colony formation and that colonies were inhibited by antioxidant N-acetyl cysteine (NAC). Our results suggest that HA may promote the transformation of epidermal cells and that this process is mediated by the generation of ROS.
Animals↗
Influence of Ca, humic acid and pH on lead accumulation and toxicity in the fathead minnow during prolonged water-borne lead exposure.
The present study examines the influence of Ca2+ as (CaSO4), dissolved organic carbon (DOC) and pH on chronic water-borne lead (Pb) toxicity to the larval fathead minnow (Pimephales promelas) under flow-through conditions. The 30 day LC50 for low hardness basic test water (19 mg CaCO3 L(-1)) was 39 (range: 27-51) microg dissolved Pb L(-1) and was greatly increased by increasing concentrations of CaSO4 and DOC to as much as 1903 (range: 1812-1992) mug dissolved Pb L(-1). Both reduced and increased pH (6.7 and 8.1, respectively) compared to control pH of 7.4 appeared to increase Pb toxicity substantially. Whole body Pb accumulation did not reflect water chemistry and thus exhibited no correlation with Pb induced mortality. One possible explanation for this lack of correlation is that mortality occurred predominantly during the first 4-6 days of exposure, whereas Pb accumulation was determined in surviving fish at the end of 30 days of exposure. Chronic Pb exposure resulted in a general iono-regulatory disturbance affecting K+, Na+ and Ca2+ homeostasis. However, recovery of Na+ and K+ levels and reversal of effects on Ca2+ homeostasis during continued exposure strongly suggest fathead minnow can acclimate to Pb. The gills accumulate the highest Pb concentrations during chronic exposure but the skeleton contains the largest mass of Pb by contributing up to approximately 80% of whole body Pb. In conclusion, water chemistry characteristics like Ca2+ and DOC should be considered for chronic water quality criteria.
Animals↗