Ratio Of Humic Acid Research Articles

Increases in soil and woody biomass carbon stocks as a result of rangeland riparian restoration

BackgroundGlobally, vegetation in riparian zones is frequently the target of restoration efforts because of its importance in reducing the input of eroded sediment and agricultural nutrient runoff to surface waters. Here we examine the potential of riparian zone restoration to enhance carbon sequestration. We measured soil and woody biomass carbon stocks, as well as soil carbon properties, in a long-term chronosequence of 42 streambank revegetation projects in northern California rangelands, varying in restoration age from 1 to 45 years old.ResultsWhere revegetation was successful, we found that soil carbon measured to 50 cm depth increased at a rate of 0.87 Mg C ha−1 year−1 on the floodplain and 1.12 Mg C ha−1 year−1 on the upper bank landform. Restored sites also exhibited trends toward increased soil carbon permanence, including an increased C:N ratio and lower fulvic acid: humic acid ratio. Tree and shrub carbon in restored sites was modeled to achieve a 50-year maximum of 187.5 Mg C ha−1 in the channel, 279.3 Mg ha−1 in the floodplain, and 238.66 Mg ha−1 on the upper bank. After 20 years of restoration, the value of this carbon at current per-ton C prices would amount to $US 15,000 per km of restored stream.ConclusionWe conclude that revegetating rangeland streambanks for erosion control has a substantial additional benefit of mitigating global climate change, and should be considered in carbon accounting and any associated financial compensation mechanisms.

Spatial and temporal comparisons of dissolved organic matter in river systems of the Three Gorges Reservoir region using fluorescence and UV–Visible spectroscopy

Understanding optical characteristics, composition and source of dissolved organic matter (DOM) in rivers of the Three Gorges Reservoir (TGR) region is important for region and global carbon cycle. However, chemical compositions and source of DOM from the tributary to mainstream in the TGR region are not well studied. Consequently, 126 water samples were collected from rivers in different land use region, and these rivers covered the main tributaries of the Yangtze River in the TGR region. The temporal and spatial variations of DOM structure and source identification in different land use region were investigated using UV–visible absorbance and fluorescence spectroscopy. Overall, there were higher ratio of humic acid to fulvic, aromaticity, molecular weight and proportion of colored humic substances in DOM in the wet season than in the dry season. The weaker biologic/microbial and stronger terrestrial sources in DOM were observed in the wet season than in the dry season. DOM comparison in variable land use demonstrated the higher terrestrial sources and weaker biologic/microbial sources in DOM in the forest-affected rivers irrespective of hydrological seasonality, as well as in the wet season irrespective of land use types. DOM in the farmland-affected rivers showed more protein-like signal. We found that monsoonal precipitation, anthropogenic activities and land use were important drivers for the DOM quality variations. These findings will be beneficial to unravel riverine DOM structure and sources in relation to anthropogenic activities and also improve our understanding of DOM biogeochemical cycle in the rivers.

Resolving humic and fulvic acids in binary systems influenced by adsorptive fractionation to Fe-(hydr)oxide with focus on UV–Vis analysis

Humic acid (HA) and fulvic acid (FA) are two operationally defined classes of natural organic matter. In the environment, both materials are present simultaneously and bind in a competitive manner to Fe-(hydr)oxides and other minerals, but their quantification in mixtures is a challenge. In this study, an UV–Vis method was developed to quantify concentrations of HA and FA without and after adsorptive fractionation by an iron oxide (goethite, α-FeOOH). In addition, the performance of the UV–Vis method was compared to that of acid precipitation and size exclusion chromatography (SEC). Among the three methodologies (UV–Vis, acid precipitation, SEC), the UV–Vis method is the most successful in quantifying the ratio of HA to FA subject to fractionation. The UV–Vis method is based on distinct differences in the UV–Vis spectra of HA and FA, including fingerprints in both the spectra shape and intensity. Adsorption to goethite decreased the specific light absorbance of HA and FA, but the changes in spectral shape were not significant enough to cover their differences. The acid precipitation method can also quantify the HA to FA ratio. But to minimize the influence of incomplete HA precipitation or co-precipitation of FA, the concentration of both HA and FA needs to be at least ~20 mgC L−1. The SEC method is not suitable to measure HA and FA after adsorption, because preferential adsorption significantly affects the shape of SEC chromatograms.

SOIL FERTILITY AND POTATO PRODUCTIVITY UNDER DIFFERENT COMPOSTING TECHNOLOGIES

The article presents the results of studies, describing the effect of various methods of peat-and-manure compost embedding on the fertility of sod-podzolic light loamy soil. When peat-and- manure compost is smothered with a longline plow PYa-3-35 at a depth of 25-27 cm compared to embedding with an ordi-nary plow by 20-22 cm and a heavy disc harrow by 15-17 cm, soil factors for growth and development of plants, edaphobiotics vital activity: acidity of soil solution, content of exchangeable potassium, mobile phosphorus and nitrate nitrogen, sum of the absorbed bases, base absorption capacity, humus content, ratio of humic acids to fulvic acids and carbon to nitrogen in humus. At the plot of a deep compost em-bedding in the 0-30-cm layer, the decomposition of linen cloth was more intense due to the participation of aerobic and anaerobic bacteria in this process. In the profile of 0-20 cm, under aerobic conditions, mineralization of linen cloth occurred more quickly under usual and disk embedding, but in the layer of 20-30 cm under deep processing with a lack of oxygen, a slowdown in decomposition of organic matter was established. In this layer, the disintegration of linen cloth was 1.5-2 times slower than in the rest of the compost, which contributed to a longer preservation of embedded organic matter. The presence of a sufficient amount of organic matter in the lower soil layer promoted the intensive reproduction of a larg-er macrofauna of soil - earthworms. On this plot, the number of earthworms in the lower layer was great-er compared not only with the control variant, but with other fertilized plots. Owing to the more active formation of humic substance in the soil with the sealing of the peat compost at 25-27 cm with a two-tier plow, the content of waterproof aggregates was much higher, thereby significantly reducing the density of its build-up during vegetation. The most optimal soil factors, provided by long-combined processing, al-lowed obtaining a higher productivity of potato tubers and with better indicators of their quality.

Land–Use Changes Influencing C Sequestration and Quality in Topsoil and Subsoil

Soil capacity as a major carbon (C) sink is influenced by land use. Estimates of soil organic carbon (SOC) sequestration have mostly focused on topsoils [0–30 cm official Intergovernmental Panel on Climate Change (IPCC) soil depth]. We investigated SOC stocks and their quality as influenced by land-use changes. Soil samples were collected from five soil depths down to 100 cm of three adjacent fields each representing a different land use—forest, cassava, and rice paddy—in Northeast Thailand. Sequestration of SOC in topsoils under all land uses was higher, as indicated by SOC stocks (59.0–82.0 Mg ha−1) than subsoils (30–100 cm) (27.0–33.0 Mg ha−1). The soil profile (0–100 cm) of the forest had higher stocks of SOC and humic acid (115.0 and 6.8 Mg ha−1, respectively) than those of cultivated land uses [paddy (100.0 and 4.8 Mg ha−1, respectively) and cassava (87.0 and 2.3 Mg ha−1, respectively)], which accounted for an average 30% increase in SOC sequestration over those with only topsoil. Topsoils of the forest had higher humic acid content but narrower E4:E6 ratio [the ratio of absorbances at 465 nm (E4) and at 665 nm (E6)] of humic acids (2.8), indicating a higher degree of humification and stabilization than the cultivated soils (3.2–3.6). Subsoil C was higher quality, as indicated by the lower E4:E6 ratio of humic acids than topsoils in all land uses.

Assessment of Group Composition of Peat Organic Matter for Industrial Processing

The results of studies of the group composition of peat organic matter of low-lying deposits of the Northern Trans-Urals sub-taiga zone are presented. It is established that the number of bitumen in the sedge-reed peat of the Ernyakul swamp most often amounts to 6.2-6.8%. In the Usalskoe swamp, their number is in the range of 3.9 to 4.7 percent. The most mobile part of the hydrolysis compounds in the peat from the Ernyakul swamp is 3.4 to 5.5%. In the sedge-reed peat of the Usalskoe swamp, their maximum number (4.1-5.3%) is concentrated in the layer of 0.4 m, the minimum (1.9%) – at a depth of 1.0 m in the hypnum type of peat. 27.0-31.8% of substances, hydrolyzed by 2% HCL, is in the peat of Ernyakul swamp. In the Usalskoe swamp in the meter layer of peat, the average content of this group of substances is by 3.6% more than in the Ernyakul swamp. The minimum amount of humic acids (HA) (30.3%) in peat from the Ernyakul swamp is contained in the sedge type of peat with a decomposition degree of 25%. The number of HA increases to 34.5-35.8 percent with an increasing decomposition degree up to 35-45%. The ratio of HA and FA is 1.6-1.7 with the decomposition degree of peat of 15-25%; with an increase to 35-45%, it increases to 1.9-2.0. The maximum number (32.7 per cent) of the humic acids contained in the hypnum type of peat of Usalskoe swamp is 4.7% more than in the sedge-reed peat. The content of substances, which are difficult to hydrolyze with acids, in the peat of Ernyakul swamp, does not exceed 2.4% and 2.7%. The lowest (1.9%) amount of this group of substances in peat from the Usalskoe swamp is determined in a layer of 0.6 m of sedge-reed peat, the maximum – at a depth of 0.8-1.0 m of the hypnum peat type (3.6%). The amount of lignin in peat from the Ernyakul swamp fits into the interval of 4.5-5.0%, which is 1.5 times more than the cellulose content. The content of lignin in the Usalskoe swamp in the meter layer is 4.2%, which is 3.5 times more than cellulose.

Effects of organic wastes on structural characterizations of humic acid in semiarid soil under plastic mulched drip irrigation

The objective of this work was to evaluate the variation in the amount and structure of humic acid (HA) after the application of organic wastes (OWs) in semiarid soil under plastic mulched drip irrigation, measured by elemental composition, excitation-emission matrix (EEM) fluorescence, and carbon 13 nuclear magnetic resonance (13C CPMAS NMR). The experiment involved chemical fertilizer combined with chicken manure (CM), sheep manure (SM), maize straw (MS), fodder grass (FG), and tree leaves (TL), while chemical fertilizer only was used as control (CK). The highest cation exchange capacity (CEC), soil organic carbon (SOC), and HA contents (P < 0.05) were achieved for TL compared to other OWs. The E4/E6 ratio, ΔlogK value, and the aliphatic C/aromatic C ratio of HA were the lowest for TL treatment than for other OW treatments, whereas the highest C/H ratio was obtained. The specific fluorescence intensities (SFI) of peak A (330–370/460-490 nm), peak B (450–465/515-525 nm), and peak C (255–270/465-490 nm) mainly referred to humic acid component from EEM fluorescence spectrum of HA were lower for TL compared to other OWs. In conclusion, the application of TL was the most effective for improving the accumulation of SOC and HA, and making the structure of HA complex and stability. Thus, TL is the recommended OW for use in semiarid soil under plastic mulched drip irrigation conditions.

Differences of C sequestration in functional groups of soil humic acid under long term application of manure and chemical fertilizers in North China

The differences of molecular characteristic of humic acid (HA) under long-term application of chemical fertilizer and manure for 34 years were determined by 13C cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy in order to investigate the carbon (C) sequestration in soils. The results showed that the relative content of alkyl C increased in manure treatments, compared to control and chemical fertilizer treatments. There were positive correlations between alkyl C and hydrogen to carbon (H/C) ratio (R2=0.84, P<0.01), alkyl C and amounts of HA (R2=0.57, P<0.01) as well as alkyl C and E4/E6 ratio (R2=0.55, P<0.01). Conversely, negative correlations were found between aromatic C and alkyl C (R2=0.76, P=0.01), H/C ratio and aromaticity (R2=0.37, P=0.04), aromaticity and amounts of HA (R2=0.71, P<0.01) as well as aromaticity and E4/E6 ratio (R2=0.65, P<0.01). Compared to control treatment, the amorphous C/crystalline C ratio increased for 0.02–0.14 and 0.30–0.78 in chemical fertilizer treatments and manure treatments, separately. Moreover, the short-chain (CH2)n/Long-chain (CH2)n ratio increased for 0.03–0.37 and 0.03–0.18 in chemical fertilizer treatments and manure treatments, separately.These findings suggest that application of manure favours alkyl C sequestration in HA and tends to be more closely linked to amorphous C than crystalline C, while incorporates less short-chain (CH2)n, compared to chemical fertilizer treatments. Moreover, the E4/E6 ratio of HA increased with more alkyl C.

Variations of Escherichia coli O157:H7 Survival in Purple Soils.

Escherichia coli O157:H7 is a well-recognized cause of human illness. Survival of Escherichia coli O157:H7 in five purple soils from Sichuan Province was investigated. The dynamics of E. coli O157:H7 survival in purple soils were described by the Weibull model. Results showed that this model is suitable to fit survival curves of E. coli O157:H7 in purple soils, with the calculated td value (survival time needed to reach the detection limit of 100 CFU·g−1) ranging from 2.99 days to 26.36 days. The longest survival time of E. coli O157:H7 was observed in neutral purple soils (24.49 days), followed by alkalescent purple soil (18.62 days) and acid purple soil (3.48 days). The redundancy analysis (RDA) revealed that td values were significantly enhanced by soil nutrition (total organic carbon (OC), total nitrogen (TN), available potassium (AK) and the ratio of humic acid to fulvic acid (Ha/Fa)), but were significantly suppressed by iron and aluminum oxide.

Humic Acid Coated Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Nanoparticle for Phenol Sorption

The coating Fe3O4 using humic acid (HA) to form HA-coated Fe3O4 (Fe3O4/HA) was conducted and applied for phenol sorption. Fe3O4/HA was prepared using co-precipitation method in an alkaline condition using ammonium hydroxide and the addition of HA with mass ratios of Fe3O4 and HA=20:1, 10:1, 10:2, 10:3. The HA from peat soil in Sambutan village, East Kalimantan, Indonesia and was extracted in NaOH 0.1 M solution. The FT-IR characterization indicated that the coating of HA on the surface of Fe3O4 was successfully synthesized by forming a bond between the carboxylate group of HA and iron of Fe3O4. The coating of HA on the surface of Fe3O4 did not change the crystal structure of Fe3O4, but had lower peak intensities than Fe3O4 if added with HA with mass ratios 20:1, 10:1, 10:2, 10:3. The saturation magnetization of Fe3O4 decreased with the increased content of HA. SEM image indicated the magnetic particle size was almost homogenous by 10-18 nm. Iron and HA in Fe3O4/HA materials synthesized using different mass ratios were stable in pH range of 3.0-11.0 and 1.0–11.0, respectively. The phenol sorption on Fe3O4 was optimum at pH 5.0 and on Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3 were optimum at pH 5.0-6.0. The kinetics model for phenol adsorption on Fe3O4 and Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3 could be described using pseudo second-order equation and was in accordance with the Langmuir isotherm model with maximum adsorption capacity of 0.45 mmol/g for Fe3O4 and 0.55, 0.56, 0.58, 0.56 mmol/g respectively for Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3. The adsorption capacity increased with the increased content of HA, but the adsorption energy decreased except Fe3O4/HA with a mass ratio of 10:3. Generally, the performance of Fe3O4/HA materials was much higher than of bare Fe3O4.

Evident variations of fungal and actinobacterial cellulolytic communities associated with different humified particle-size fractions in a long-term fertilizer experiment

Cellulose is the dominant form of carbon (C) existing in arable soils, however the ecology of its degradation in soil is still relatively poorly understood. Here, community abundance and composition of fungal and actinobacterial cellulolytic genes (cbhI and GH48) from glycoside hydrolase family 7 and 48 together with characterization of fulvic acid (FA) and humic acid (HA) determined by cross polarization magic angle spinning (CPMAS) 13C nuclear magnetic resonance (NMR) spectroscopy were explored in five soil particle-size fractions (large macroaggregate, coarse sand, fine sand, silt and clay), collected from a 33-yr mineral and organic fertilizer experiment. The results revealed the significant effects of particle-size fraction and fertilization on the distribution of soil humus and cellulolytic microbial community abundance. Strong correlations were detected between C content and structure of soil humus with cellulolytic microbial abundance. Generally, larger fractions (>63 μm) especially fine sand, which showed a lower degree of humification with higher aromaticity, lower HA/FA ratio, aliphaticity and alkyl/O-alkyl ratio of HA, were associated with greater abundance of cellulolytic microbes. However, smaller fractions (<63 μm), especially the clay fraction, showed lower cbhI and GH48 gene abundances with a greater degree of humification indicated by 13C NMR spectra. Phylogenetic analysis of the obtained nucleotide sequences revealed undiscovered sequences of both fungal and actinobacterial cellulolytic microbes. However, no clear clustering of sequences from particular particle-size fraction or fertilizer treatment was observed, even though combined application of chemical fertilizer and manure significantly increased cellulolytic gene abundances.

Transformation and synthesis of humic substances during bioremediation of petroleum hydrocarbons

The aim of this paper was to investigate whether changes in the quantity and structure of humic acids (HA) occur during bioremediation of waste mazute (heavy residual fuel oil). The effects of humification on the structure of HA were evaluated by Fourier Transform Infrared Spectroscopy (FT-IR), potentiometric titrations, the ratio of absorbances at 465 and 665 nm (E4/E6 ratio) and the C/H ratio. Also, the quality of humification was monitored by determining parameters which are important for measuring the evolution of humic substances (HS), such as CHA/CFA (the humic acid/fulvic acidratio), the rate of extraction (TE) and the index of polymerization (IP). An increase of the content of HA from 0.23% to 0.70% was observed during the bioremediation process. The FT-IR spectra and C/H ratio of HA extracted at the beginning and the end of the process indicate structural changes during the bioremediation process. The groups containing aromatic and carboxylic carbon increased, resulting in HA structures of higher aromaticity. An increase of the E4/E6 ratio during bioremediation treatment implied the enrichment of HA with functional oxygen groups. Potentiometric titrations of HA solution showed increases in the buffering and the redox capacities of HA during the bioremediation process. The results of parameters of humification showed an increase of the compositional carbon in HA at the end, compared to at the start, of bioremediation, while the carbon that belonged to fulvic acids (FA) reduced by 44%. Transformation into HA is the likely cause of this observed reduction. The TE and the IP demonstrated that humification occured during the bioremediation process. According to the available data, this is the first report on synthesis of HS during bioremediation of petroleum hydrocarbons.

EVOLUTION OF HUMIC SUBSTANCES DURING ANAEROBIC SLUDGE DIGESTION

A comparative study of humic substances (HS) extracted from raw sludge and its digested product was carried out in order to analyze HS evolution during sludge anaerobic digestion. HS content, elemental composition, functional groups, infrared spectra and ultraviolet absorbances were analyzed by means of chemical and spectrographic methods. The extracted HS were also fractionated by ultrafiltration in order to obtain their molecular weight (MW) distribution. The results showed that humic acids (HAs) were the major constituent of sludge HS. During anaerobic digestion of sludge, 16.3% of HAs and 27.0% of fulvic acids (FAs) were degraded, and simultaneously, limited humification processes occurred. After anaerobic digestion, the O/C ratio of HAs increased from 0.32 to 0.39 and the C/N ratio decreased from 9.06 to 6.41. The total acidity of HAs increased from 2.32 mmol/g to 3.29 mmol/g, and the ratio of carboxyl hydroxyl to phenolic hydroxyl increased from 0.15 to 0.25. The proportion of FAs with MWs higher than 50 kDa increased from 14.65% to 38.51%, and the proportion of the HAs with MWs higher than 100 kDa increased from 65.31% to 85.49%. Although HS in digested sludge on average contained more oxygen functional groups and had more aromatic structures and larger molecular size, the humification degree was relatively low compared with sludge compost. Mineralization was still the main process observed during sludge anaerobic digestion.

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Alpine grassland soils on Qinghai-Tibet Plateau store approximately 33.5 Pg of organic carbon (C) at 0–0.75 m depth and play an important role in the global carbon cycle. We investigated soil organic C (SOC), water-soluble organic C (WSOC), easily oxidizable organic C (EOC), humic C fractions, aggregate-associated C, aggregate stability, and humic acid (HA) composition along an east-west transect across Qinghai-Tibet Plateau, and explored their spatial patterns and controlling factors. The contents of SOC, WSOC, EOC, humic C fractions and aggregate-associated C, the proportions of macro-aggregates (2-0.25) and micro-aggregates (0.25-0.053 mm), and the aggregate stability indices all increased in the order alpine desert < alpine steppe < alpine meadow. The alkyl C, O-alkyl C, and aliphatic C/aromatic C ratio of HA increased as alpine desert < alpine meadow < alpine steppe, and the trends were reverse for the aromatic C and HB/HI ratio. Mean annual precipitation and aboveground biomass were significantly correlated with the contents of SOC and its fractions, the proportions of macro- and micro-aggregates, and the aggregate stability indices along this transect. Among all these C fractions, SOC content and aggregate stability were more closely associated with humic C and silt and clay sized C in comparison with WSOC, EOC, and macro- and micro-aggregate C. The results suggested that alpine meadow soils containing higher SOC exhibited high soil aggregation and aggregate stability. Mean annual precipitation should be the main climate factor controlling the spatial patterns of SOC, soil aggregation, and aggregate stability in this region. The resistant and stable C fractions rather than labile C fractions are the major determinant of SOC stocks and aggregate stability.

Humic Acid Composition and Characteristics of Soil Organic Matter in Relation to the Elevation Gradient of Moso Bamboo Plantations.

Studying the influence of climatic and/or site-specific factors on soil organic matter (SOM) along an elevation gradient is important for understanding the response of SOM to global warming. We evaluated the composition of SOM and structure of humic acids along an altitudinal gradient from 600 to 1400 m in moso bamboo (Phyllostachys edulis) plantations in central Taiwan using NMR spectroscopy and photometric analysis. Total organic C and total nitrogen (N) content increased with increasing elevation. Aromaticity decreased and ΔlogK (the logarithm of the absorbance ratio of humic acids at 400 and 600 nm) increased with increasing elevation, which suggests that SOM humification decreased with increasing elevation. High temperature at low elevations seemed to enhance the decomposition (less accumulation of total organic C and N) and humification (high aromaticity and low ΔlogK). The alkyl-C/O-alkyl-C (A/O-A) ratio of humic acids increased with increasing elevation, which suggests that SOM humification increased with increasing elevation; this finding was contrary to the trend observed for ΔlogK and aromaticity. Such a discrepancy might be due to the relatively greater remaining of SOM derived from high alkyl-C broadleaf litter of previous forest at high elevations. The ratio of recalcitrant C to total organic C was low at low elevations, possibly because of enhanced decomposition of recalcitrant SOM from the previous broadleaf forest during long-term intensive cultivation and high temperature. Overall, the change in SOM pools and in the rate of humification with elevation was primarily affected by changes in climatic conditions along the elevation gradient in these bamboo plantations. However, when the composition of SOM, as assessed by NMR spectroscopy and photometric analysis was considered, site-specific factors such as residual SOM from previous forest and intensive cultivation history could also have an important effect on the humic acid composition and humification of SOM.

Photochemical aqueous mercury removal: effects of DOM and DO

Photochemical reactions between mercury (Hg) and dissolved organic matter were studied to understand what conditions would promote mercury volatilisation from solution. Prepared solutions of mercury (II) nitrate and humic acid (HA) (at different ratios) were exposed to 254-nm ultraviolet irradiation and a continuous purge with nitrogen, air or oxygen gas to create three different dissolved oxygen (DO) concentrations. As HA was introduced into the system with a nitrogen purge, the overall quantity of dissolved gaseous mercury after 60 min, and subsequent mercury removal, decreased. An analysis of variance indicated that there is only a 61% confidence level that the 1:10 and the 1:100 mercury–HA ratios are statistically different, suggesting that the decrease in mercury removal as HA concentration increased cannot be solely attributed to mercury binding with sulfur or other functional groups on the HA. Experiments indicated a positive correlation of HA oxidation as DO increased with an air and oxygen purge.

Key factors related to drinking water treatment residue selection for adsorptive properties tuning via oxygen-limited heat treatment

The beneficial recycling of drinking water treatment residue (DWTR) for environmental remediation has attracted growing attention, and oxygen-limited heat treatment has a high potential to improve DWTR adsorptive properties for better recycling. In this study, physicochemical property variation induced by oxygen-limited heat treatment was evaluated for six DWTR obtained from different drinking water treatment plants in Australia, China, and Ireland. The results showed that the changes in many properties, typically amorphous Al and Fe contents, mesopores, specific surface area (SSA), and total pore volume (TPV) of DWTR after treatment, showed inconsistent trends. The treatment also led to the varied lability of metals and As in DWTR although the human bioaccessibility and plant bioavailability of most metals decreased. Accordingly, oxygen-limited heat treatment may not be applicable for all DWTR improvement. Based on these findings, pre-screening processes to evaluate adsorptive properties and metal and metalloid lability were determined. Oxygen-limited heat treatment was more applicable to DWTR with neutral and weak alkaline properties (pH 7.0–7.8), low humic acid (HA) content (<2.09mgg−1), and high amorphous Fe and HA ratio (>5.93), as well as with relatively high amorphous Al and HA ratio and high humin content.

The effects of soil sand contents on characteristics of humic acids along soil profiles

It is generally accepted that the compositions and properties of soil organic matter (SOM) are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and its sub-fraction, humic acid (HA), along two soil profiles, a yellow soil profile and a purplish soil profile, under the same climate and vegetation conditions were determined. Results indicate that the decomposition and humification degrees of SOM and HA of the purplish soils are higher than those of the corresponding yellow soils indicated by A/O–A ratios of HAs, TOCs and HA yields of bulk soil samples, nevertheless, the development degree of the purplish soil is lower than that of the yellow soil. The variations of E4/E6 ratios of HAs along the soil profiles indicate the overall molecular sizes of HAs decreased downward along the soil profiles. A/O–A ratios of HAs decreased downward along both the soil profiles indicate that humification processes decrease downward along both the soil profiles. Leaching of SOM shows significant effects on the distribution and characteristics of HAs in the yellow soil profile but the purplish soil profile, which is consistent with the higher hydrophobicity of HAs in purplish soils, shows that the distribution characteristics of SOM along the soil profiles are a complex result of the combination of soil texture and characteristics of SOM itself. The remarkably different sand contents are concluded tentatively as one of reasons to the different distributions and dynamics of HAs along the soil profiles, however, to profoundly understand the evolution and transport of SOM along soil profiles needs more researches.

Isolasi Karakterisasi T Asam Humat dan Penentuan Daya Serapnya Terhadap Ion Logam Pb(II) Cu(II) dan Fe(II)

Coal, which are decomposition resulted of natural biological processes over the years in which the humic acid compound contained. The purposes of this research was tocharacterize and to compare the humic acid of coal from South Borneo. The isolation of humic acid by leaching process uses natrium karbonat 0.1 N and fractionation uses sulfuric acid 6M. The fraction was purified and the deposit was washed by sulfuric acid 1 M, aquadest and ethanol. Moisture content, ash content, cation exchange capacity, C/N ratio and E4/E6ratiowithspectroscopy were characterized. The yields of humic acid areobtained 12.35% of coal. C/N ratio of humic acid 20.72. The infrared spectroscopy results of humic acid from coal figures more of aromatic and -OH group with lower E4/E6 ratio, while from peat soil shows more of aliphatic and carboxylic group supported higher E4/E6 ratio. Kapasitas tukar kation 640,59 mek/100g; dan mempunyai daya serap terhadap ion logam yang cukup baik.

Removal of Humic Acid in Water by Rice Hull Magnetic Activated Carbon and Magnetic Separation

We have newly developed a rice hull magnetic activated carbon (RH-MAC) and studied its adsorption property for humic acid from water and high-gradient magnetic separation (HGMS) characteristics. Rice hull was impregnated with an iron nitrate solution and heat-treated in both nitrogen and carbon dioxide atmosphere. In these processes, the rice hull changed to activated carbon that had a lot of mesopores and nanosize magnetite inside. Magnetization of RH-MAC increased with an increase in iron nitrate concentration during the process and reached 20.8 Am <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /kg at 0.5 T. In the adsorption examination, it was able to adsorb humic acid effectively, and the removal ratio achieved 97.6% from a humic acid solution of 50 mg/L. In HGMS studies, we used the magnetic wire filter rounded on a magnet drum with 0.5-T permanent magnet and the slurry of RH-MAC concentration of 100 mg/L. Consequently, 99.4% of RH-MAC in the slurry of 2 L was captured in the magnetic filter at flow rates of 230 mL/min. These results show that this water purification system has higher removal ratio of humic acid than that for current advanced water treatments.