Extraction and Composition of Dissolved Organic Matter in Poyang Lake and Its Effects on Morphological Changes of Heavy Metals

Dissolved organic matter (DOM) is generally thought to impact the bioavailability of heavy metals. However, the source of wetland DOM and its interaction with heavy metals remain poorly understood. Fluorescence excitation emission matrices (EEMs)-fluorescence regional integration (FRI) coupling techniques and chromophoric dissolved organic matter (CDOM) was used to explore the source of DOM of Poyang Lake including water body, soil and plants, and the effects on morphological changes of heavy metals. The results showed that the best DOM extraction effect can be obtained with the soil-water mass ratio 1:10, centrifuged at 4 000 rpm for 30 min, and the 0.45 μm glass fiber filter by orthogonal test. There were four types of peaks of DOM in water body of Poyang Lake, which was input mainly by land source, while six types of peaks (ACTDBE) were observed in soil. Soil DOM is highly humified with large molecular weight. More types of fluorescent peaks were observed in plant and the content of DOM in plants was higher than that of water body and soil due to the plant proteins. The content of fulvic acid was less than tryptophan in DOM of Triarrhena lutarioriparia and Phragmites communis in Longkou, while the opposite were in other samples. Furthermore, pot experiment illustrated that DOM had an activation effect on Cd, Cu and Zn and a passivation effect on Cr and Pb with the increase of DOM content. After the addition of exogenous DOM, Cr, Pb and Zn were immobilized by the function together with DOM and plants, while Cd and Cu were activated.

Fluorescence regional integration combined with parallel factor analysis to quantify fluorescencent spectra for dissolved organic matter released from manure biochars

Dissolved Organic Matter (DOM) in biochars is important to carbon dynamics and contaminant transport in soils

Fluorescence Excitation-Emission Spectroscopy: An Analytical Technique to Monitor Drugs of Addiction in Wastewater

Emerging contaminants of concern have become a serious issue for the scientific community and society more broadly in recent years due to their increasingly widespread environmental distribution and largely unknown environmental and human health impacts. This study aimed to explore the use of fluorescence excitation-emission (F-EEM) spectroscopy as an alternative analytical method to evaluate the presence of key drugs of addiction (benzoylecgonine, methamphetamine, MDMA, codeine and morphine) in wastewater treatment plants. The chemicals of interest from wastewater were extracted by mixed-mode solid phase extraction and quantified using liquid chromatography tandem mass spectrometry. The same wastewater samples were also analysed by a fluorescence spectrophotometer for fluorescence spectra at wavelengths 280–600 nm (emission) and 200–600 nm (excitation). The study also investigated the relevance of different methods for interpreting F-EEM matrices data including parallel factor analysis (PARAFAC) modelling and fluorescence regional integration technique. PARAFAC identified four components, and among them, component C2, identified at the λex/λem = 275/340 nm wavelength associated with proteinaceous compounds most likely related to tryptophan amino acid, showed significant correlation with codeine removal. MDMA and morphine were not correlated to any of the fluorescence regions. The fluorescence regions related to aromatic protein-like fluorescence were correlated significantly with drug concentration and so may offer a suitable alternative approach for monitoring drugs including benzoylecgonine, methamphetamine and codeine.

Three-Dimensional Excitation and Emission Fluorescence-Based Method for Evaluation of Maillard Reaction Products in Food Waste Treatment

Hydrothermal treatment (HT) of food waste (FW) can form Maillard reaction products (MRPs), the biorefractory organic matter due to the occurrence of Maillard reaction. However, the integrating qualitative and quantitative approach to assess MRPs is scarce. The goal of this study was to develop a method to characterize and quantify MRPs created by HT of FW. MRPs were identified by molecular weight fractionation, indirect spectrometric indicators, and three-dimensional excitation-emission fluorescence (3DEEM) analysis. The 3DEEM method combined with fluorescence regional integration (FRI) and parallel factor (PARAFAC) analyses was able to differentiate clearly between MRPs and other dissolved organic compounds compared to other approaches. The volume of fluorescence Φ from FRI and maximum fluorescence intensity Fmax from PARAFAC were found to be suitable quantitative parameters for determination of MRPs in the hydrothermal FW system. These two parameters were validated with samples from hydrothermal FW under various operating temperatures and pH.

Characterization of chromophoric dissolved organic matter in lakes on the Tibet Plateau, China, using spectroscopic analysis

Spatiotemporal variations in the characteristics of fluorescent dissolved organic matter (FDOM) components from 63 lakes across the Tibet Plateau, China, are examined using excitation-emission matrix spectra (EEM) and fluorescence regional integration (FRI) from 2014 to 2017. Freshwater (N = 135) and brackish water (N = 109) samples from 63 lakes were grouped according to salinity or electrical conductivity. In order to compare results between the lakes, cumulative volumes beneath the EEM values (φi, i = I, II, III, IV, V) were normalized to a DOC concentration of 1 mg/L. EEM-FRI identified tyrosine-like (φI), tryptophan-like (φII), fulvic-like (φIII), microbial protein-like (φIV), and humic-like (φV) fluorescence regions, as well as their proportions (Pi). Chromophoric dissolved organic matter (CDOM) absorption parameters, fluorescence indices, average fluorescence intensities of the five fluorescent components and total fluorescence intensities (φT) differed under spatial variation among brackish and freshwater lakes (ANOVA, p 0.79, t-test, p 19 ‰ (averaged EC, 23 764 μs cm −1) (t-test, p

Effect of different hydrolytic enzymes pretreatment for improving the hydrolysis and biodegradability of waste activated sludge

In this study, the effects of lysozyme, protease and α-amylase pretreatments for improving the hydrolysis and biodegradability of waste activated sludge (WAS) were investigated. The results showed that lysozyme was more effective in increasing the soluble chemical oxygen demand (SCOD) concentration in the liquid phase of sludge and improving the release of protein and carbohydrate from sludge flocculation to enhance sludge hydrolysis. After 8 h hydrolysis, the net SCOD increase in a reactor with lysozyme was 2.23 times and 2.15 times that of the reactors with protease and α-amylase, respectively. Meanwhile, lysozyme and protease could improve the lysis of microorganism cells and the dissolution of extracellular polymeric substances (EPS) to a certain extent, and lysozyme was more effective. Furthermore, the compositional characteristics of dissolved organic matter (DOM) and EPS were analyzed by EEM fluorescence spectroscopy and fluorescence regional integration (FRI) analysis. Tryptophan-like protein was the main component of sludge, which accounted for 31% and 38% of DOM and EPS, respectively. Lysozyme could decrease the percentage of non-biodegradable materials in sludge, such as humic acid-like substances and fulvic acid-like substances, so it could improve the biodegradability of sludge. This study can provide valuable information for future studies about hydrolytic enzyme pretreatments for WAS disposal.