Characteristics of Dissolved Organic Matter
Content in Urban Rivers under Different
Environmental Impact Zones:
A case study of China’s Tuo River

<p>The biogeochemical interfaces are hotspots for organic matter (OM) transformation. However, direct and continuouxiacis tracing of OM transformations and N and P degradation processes are lacking due to the heterogeneous and opaque nature of soil microenvironment. To investigate these processes, a new soil microarray technology (SoilChips) was developed and used. Homogeneous 2-mm-diameter SoilChips were constructed by depositing a dispersed paddy soils with high and low soil organic carbon (SOC) content. A horizon suspension on a patterned glass. Dissolved organic matter from the original soil was added on the SoilChips to mimic biogeochemical processes on interfaces. The chemical composition of biogeochemical interfaces were evaluated via X-ray photoelectron spectroscopy (XPS) and the two-dimensional distribution of enzyme activities in SoilChips were evaluated by zymography. Over 30 days, soil with high SOC content increases microbial nutrition (N and P) requirements than soil with low SOC evidenced by higher hotspots of &#946;-1,4-N-acetaminophen glucosidase, and acid phosphomonoesterases and higher 16S rRNA gene copies. The degree of humification in dissolved organic matter (DOM) was higher and the bioavailability of DOM was poorer in soil with high SOC than soil with low SOC. The poorest bioavailability of DOM was detected at the end of incubation in soil with high SOC. Molecular modeling of OM composition showed that low SOC mainly facilitated the microbial production of glucans but high SOC mainly facilitated the microbial production of proteins. We demonstrated that SOC content or DOM availability for microorganisms modifies the specific OM molecular processing and N and P degradation processes, thereby providing a direct insight into biogeochemical transformation of OM at micro-scale.</p>

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Potential of Wastewater Valorization after Wet Extraction of Proteins from Faba Bean and Pea Flours

Recent Progress in Materials ◽

10.21926/rpm.2102013 ◽

2020 ◽

Vol 03 (02) ◽

pp. 1-1

Author(s):

Sofía Albolafio ◽

◽

María I. Gil ◽

Ana Allende ◽

Epameinondas Xanthakis ◽

...

Keyword(s):

Antioxidant Activity ◽

Organic Matter ◽

Environmental Impact ◽

Faba Bean ◽

Phenolic Content ◽

Organic Matter Content ◽

Oxygen Demand ◽

Value Added ◽

Matter Content ◽

Two Stages

The present study aimed to characterize wastewater fractions obtained after the wet extraction of proteins from legumes. In addition, the suitability of wastewater fractions for the potential recovery of high value-added compounds was also examined, and consequently, the prevention of the environmental impact of these wastes was explored. Similar to the industrial production of proteins, wet alkaline and acidic extractions of proteins from faba bean and pea flours were performed in two stages of extraction. The different wastewater fractions were characterized by measuring their organic matter content, total solids (TS), total dissolved solids (TDS), electrical conductivity (EC), pH, and turbidity. The value-added compounds from these wastewater fractions were quantified, which included the protein content, carbohydrate content, phenolic content, and antioxidant activity. In addition, the phenolic compounds in these factions were identified and quantified. It was observed that the fractions obtained in the first extraction stage had 60%–90% higher organic matter content, measured as the chemical oxygen demand (COD), compared to the second fractions, indicating a higher environmental impact of the former in case of disposal. The results obtained for COD, TS, TDS, EC, pH, and turbidity demonstrated that microfiltration reduced only the turbidity (85%), and consequently, a decrease was observed in the particulate matter, while there was a practically negligible reduction in the soluble matter. Wastewater from faba exhibited the highest polyphenol content and antioxidant activity, and was, therefore, considered the most valuable fraction for potential valorization.

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Predicting soil-water partition coefficients for Hg(II) from soil properties

Water Science & Technology ◽

10.2166/wst.2001.0089 ◽

2001 ◽

Vol 43 (2) ◽

pp. 187-196 ◽

Cited By ~ 10

Author(s):

S.-Z. Lee ◽

L. Chang ◽

C.-M. Chen ◽

Y. I. Tsai ◽

M.-C. Liu

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Partition Coefficient ◽

Metal Oxides ◽

Partition Coefficients ◽

Organic Matter Content ◽

Matter Content ◽

Natural Soil ◽

Solution Ph ◽

Adsorption Sites

The metal adsorption characteristics for fifteen Taiwan soils by Hg(II), were evaluated using pH as the major variable. The soil samples were thoroughly characterized for their physical chemical properties and composition, particularly organic matter and metal oxides. The adsorption of Hg(II) increased with increasing pH between pH 2.5 and 5.5, whereas the adsorption significantly decreased above around pH 5.5. Below pH 5.5, greater adsorption was found for soils with a higher organic matter content at constant pH and metal concentration. To better understand the mechanism of adsorption, the experimental results for Hg (II) were tested in a partition coefficient model to relate the adsorption of the Hg(II) by the different soils with soil components: organic matter, iron oxide, aluminium oxide and manganese oxide. This model was not successful when applied to measurements at the differing natural soil pHs because of the importance of pH. At pH greater than 5.5 the model fails because of the complexation of Hg by the dissolved organic matter. However, partition coefficients obtained from experimental data were highly correlated with those calculated for a partition coefficient between mercury and organic matter alone at lower pH. Normalization of the partition coefficients, Kd, for the organic matter content of the soils, Kom, greatly improved the correlation between the partition coefficient and pH under pH 5.5 (R2 increased from 0.484 to 0.716). This suggests that the surficial adsorption sites are principally due to organic matter for pH less than 5.5. For the 24-hour equilibration period employed, diffusion of Hg through this superficial organic matter coating to underlying sorptive materials, including metal oxides, is not important in the partitioning of Hg. At pH above 5, a decrease of mercury adsorption with increasing solution pH was also found. This result may be explained in part by the complexation of mercury by soil dissolved organic matter whose concentration increased with increasing pH.

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