The effect of Phanerochaete chrysosporium inoculation during drum composting of agricultural waste was performed at different composting stages. Three trials were carried out with (5:4:1) combination of vegetable waste, cattle manure, and sawdust along with 10 kg of dried leaves with a total mass of 100 kg in a 550 L rotary drum composter. Trial 1 was a control without inoculation of fungus, while trial 2 was inoculated during the initial day (0th day of composting), and trial 3 was inoculated after the thermophilic phase, i.e., on the 8th day of composting period. The inoculation of fungus increased the volatile solids reduction by 1.45-fold in trial 2 and 1.7-fold in trial 3 as compared to trial 1 without any fungal inoculation. Total Kjeldahl Nitrogen (TKN) was observed with 2.31, 2.62, and 2.59 % in trials 1, 2, and 3, respectively, at the end of 20 days of composting period. Hence, it can be concluded that inoculation of white-rot fungus increased the decomposition rate of agricultural waste within shorter time in drum composting. However, inoculation after the thermophilic phase was found more effective than inoculation during initial days of composting for producing more stabilized and nutrient-rich compost.

Despite literature evidence suggesting the importance of sampling methods on the properties of sediment pore waters, their effects on the dissolved organic matter (PW-DOM) have been unexplored to date. Here, we compared the effects of two commonly used sampling methods (i.e., centrifuge and Rhizon sampler) on the characteristics of PW-DOM for the first time. The bulk dissolved organic carbon (DOC), ultraviolet-visible (UV-Vis) absorption, and excitation-emission matrixes coupled with parallel factor analysis (EEM-PARAFAC) of the PW-DOM samples were compared for the two sampling methods with the sediments from minimal to severely contaminated sites. The centrifuged samples were found to have higher average values of DOC, UV absorption, and protein-like EEM-PARAFAC components. The samples collected with the Rhizon sampler, however, exhibited generally more humified characteristics than the centrifuged ones, implying a preferential collection of PW-DOM with respect to the sampling methods. Furthermore, the differences between the two sampling methods seem more pronounced in relatively more polluted sites. Our observations were possibly explained by either the filtration effect resulting from the smaller pore size of the Rhizon sampler or the desorption of DOM molecules loosely bound to minerals during centrifugation, or both. Our study suggests that consistent use of one sampling method is crucial for PW-DOM studies and also that caution should be taken in the comparison of data collected with different sampling methods.

To study the potential effects of climate change on water quality in a shallow reservoir in China, the field data analysis method is applied to data collected over a given monitoring period. Nine water quality parameters (water temperature, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, total phosphorus, chemical oxygen demand, biochemical oxygen demand and dissolved oxygen) and three climate indicators for 20 years (1992–2011) are considered. The annual trends exhibit significant trends with respect to certain water quality and climate parameters. Five parameters exhibit significant seasonality differences in the monthly means between the two decades (1992–2001 and 2002–2011) of the monitoring period. Non-parametric regression of the statistical analyses is performed to explore potential key climate drivers of water quality in the reservoir. The results indicate that seasonal changes in temperature and rainfall may have positive impacts on water quality. However, an extremely cold spring and high wind speed are likely to affect the self-stabilising equilibrium states of the reservoir, which requires attention in the future. The results suggest that land use changes have important impact on nitrogen load. This study provides useful information regarding the potential effects of climate change on water quality in developing countries.

As children represent one of the most vulnerable groups in society, more information concerning their exposure to health hazardous air pollutants in school environments is necessary. Polycyclic aromatic hydrocarbons (PAHs) have been identified as priority air pollutants due to their mutagenic and carcinogenic properties that strongly affect human health. Thus, this work aims to characterize levels of 18 selected PAHs in preschool environment, and to estimate exposure and assess the respective risks for 3–5-year-old children (in comparison with adults). Gaseous PAHs (mean of 44.5 ± 12.3 ng m⁻³) accounted for 87 % of the total concentration (ΣPAHₛ) with 3–ringed compounds being the most abundant (66 % of gaseous ΣPAHₛ). PAHs with 5 rings were the most abundant ones in the particulate phase (PM; mean of 6.89 ± 2.85 ng m⁻³) being predominantly found in PM₁ (78 % particulate ΣPAHₛ). Overall child exposures to PAHs were not significantly different between older children (4–5 years old) and younger ones (3 years old). Total carcinogenic risks due to particulate-bound PAHs indoors were higher than outdoor ones. The estimated cancer risks of both preschool children and the staff were lower than the United States Environmental Protection Agency (USEPA) threshold of 10⁻⁶ but slightly higher than WHO-based guideline.

Contamination levels and spatial and temporal distributions of six typical synthetic musks (SMs) in water and sediment of the Songhua River in Northeastern China were investigated. Experimental data for 72 water and 52 sediment samples collected at 29 sampling sites over 12 months spanning 2011–2012 showed that the Songhua River had been contaminated to different degrees at various sites separately from the river’s source. The polycyclic musks 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB) (Galaxolide) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) (Tonalide) were found most frequently and at the highest levels. Concentrations of HHCB were <2–37 ng/L in water and <0.5–17.5 ng/g dry weight (dw) in sediment. AHTN was <1–8 ng/L in water and <0.5–5.7 ng/g dw in sediment. Statistical relationships between SM concentrations and four environmental variables (temperature, illumination, runoff, and population density) in the Songhua River Basin were formulated. Concentration levels varied proportionately with the size of the city along the river, while the distribution patterns showed clear seasonal variations. HHCB/AHTN ratios mirrored the transfer and transmitting process of SMs. Concentrations of target compounds were correlated with each other, suggesting similar exposure sources. Environmental risk assessment of SMs presented seasonal variations and provided baseline information on SM exposure in the Songhua River Basin.

This study models the biodegradation kinetics of two toxic xenobiotic compounds in enriched mixed cultures: a commonly applied herbicide (3,4-dichloropropionanilide or propanil) and its metabolite (3,4-dichloroaniline or DCA). The dependence of the metabolite degradation kinetics on the presence of the parent compound was investigated, as well as the influence of the feeding operation strategy. Model equations were proposed incorporating substrate inhibition of the parent compound and the metabolite during dump feed operation of a sequencing batch reactor (SBR). The kinetic parameters of the biomass were compared to step feed degradation of the SBR. The relationship between propanil and DCA degradation rates with the concentration of each compound was studied. A statistical comparison was carried out between the model predictions and experimental results. Substrate inhibition by both propanil and DCA was prominent during dump feed operation but insignificant during step feed. With both feeding strategies, the metabolite degradation was found to be dependent on the concentration of both the parent compound and the metabolite, suggesting that the DCA degrading enzymatic activity was independent of the detachment of the propionate moiety from the propanil molecule. After incorporating this finding into the model equations, the model was able to describe well the propanil and DCA degradation profiles, with an r²correlation >0.95 for each case. A kinetic model was developed for the degradation of the herbicide propanil and its metabolite DCA. An exponential inhibition term was incorporated to describe the substrate inhibition during dump feeding. The kinetics of metabolite degradation was dependent of the sum of the concentrations of metabolite and parent compound, which could also be of relevance to future xenobiotic modelling applications from wastewater.

The role of chemical interactions in shaping microbial communities has raised increasing interest over the last decade. Many benthic microorganisms are known to develop chemical strategies to overcome competitors, but the real importance of chemical interactions within freshwater biofilm remains unknown. This study focused on the biological and chemical mechanisms of an interaction involving two benthic microorganisms, an allelopathic filamentous green alga, Uronema confervicolum, and a common diatom, Fistulifera saprophila. Our results showed that functions critical for benthic phototrophic microorganisms were inhibited by U. confervicolum extracts. Growth, cell motility, adhesion, and photosynthetic activity were impaired at extract concentrations ranging between 5 and 20 μg ml⁻¹. The adhesion inhibition was mediated by intracellular nitric oxide (NO) induction. A bioassay-guided fractionation of the extract with HPLC helped to identify two C18 fatty acids present in the growth-inhibiting fractions: linoleic (LA) and α-linolenic (LNA) acids. These compounds represented 77 % of the total free fatty acids of U. confervicolum and were present in the culture medium (1.45 μg l⁻¹ in total). Both could inhibit the diatom growth at concentrations higher than 0.25 μg ml⁻¹, but had no effect on cell adhesion. The discrepancy between the effective concentrations of fatty acids and the concentration found in culture medium may be explained by the presence of high-concentration microenvironments. The compounds involved in adhesion inhibition remain to be identified. Though further experiments with complex biofilms are needed, our results suggest that U. confervicolum may participate to the control of biofilm composition by inhibiting diatom adhesion.

Persistence of delltamethrin, endosulfan, and triazophos in egg plant and tomato was studied following application of two ready mix formulations of insecticides viz. deltametrhin and endosulfan (Cobra 5000; 0.75 % deltamethrin + 29.5 % endosulfan) and deltamethrin and triazophos (Annaconda Plus; 1 % deltamethrin + 35 % triazophos) at recommended (1.0 L/ha and double dose 2.0 L/ha). The residues of deltamethrin persisted till 7 and 5 days in tomato and egg plant fruits, respectively, in the ready mix formulation of Cobra 5000 whereas endosulfan persisted till 15 and 10 days in tomato and egg plant fruits, respectively. Dissipation of the insecticides followed first-order kinetics with half-life values of deltamethrin and endosulfan ranged from 2.6 to 4.7 and 1.4 to 1.7 days, respectively, for both the vegetables. In case of combination mix of deltamethrin and triazophos (Annaconda Plus), deltamethrin persisted beyond 5 days in both tomato and egg plant fruits, while triazophos persisted till 10 days in both the vegetables. Residues of deltamethrin and triazophos dissipated with half-life of 2.6–4.2 and 1.7–4.1 days, respectively, on tomato and egg plant fruits. Based on the Codex MRL limits, a safe waiting period of 5 and 3 days is suggested for tomato and egg plant, respectively, for the ready mix formulation of deltamethrin and endosulfan (Cobra 5000), and 5-day waiting period is suggested for tomato and egg plant for the combination mix of deltamethrin and triazophos.

Spatial and temporal distributions of concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment core from Taihu Lake in eastern China were determined. The sum of concentrations of PAHs (sum of total 16 USEPA priority PAH (∑PAHs)) of the entire Taihu Lake ranged from 2.9 × 10²to 8.4 × 10² ng/g dry mass (dm). Concentrations of ∑PAHs in surface sediments near more urbanized regions of the lake shore were greater than those in areas more remote from the urban centers. Temporal trends in concentrations of ∑PAHs ranged from 5.1 × 10²to 1.5 × 10³ ng/g dm, increasing from deeper layers to surface sediments with some fluctuations, especially in the past three decades after the inception of China’s Reform and Opening Up Policy, in which China’s economy and urbanization underwent rapid development. Forensic analysis of surface sediments indicates that PAHs originated primarily from combustion of grass/wood/coal except for the special function water area, which was most likely influenced by petroleum products of traveling vessels. Vertical profiles of relative concentrations of PAHs suggested that the contribution of lesser-molecular-weight PAHs was gradually decreasing, while due to the heavier consumption of petroleum products, the proportion of greater-molecular-weight PAHs was increasing. When assessed by use of the rather conservative, apparent effect threshold method, concentrations of ∑PAHs in sediments from most locations in Taihu Lake are predicted to pose little risk of harm to benthic invertebrates.

To improve the photocatalytic efficiency of chromium-based metal−organic framework (MIL-101) photocatalyst, Pd nanoparticles and reduced graphene oxide were used to modify the MIL-101 via a facile method. The resulting novel photocatalyst was characterized by UV–vis diffuse reflectance spectra (DRS), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was indicated that the photocatalyst afforded high photocatalytic efficiency for degradation of two triphenylmethane dyes, brilliant green and acid fuchsin, under exposure to visible light irradiation. Cyclic experiments demonstrated that the photocatalyst showed good reusability and stability for the dye degradation.