Bifunctional electrode materials: Enhancing microbial fuel cell efficiency with 3D hierarchical porous Fe3O4/Fe-N-C structures.

The rational development of high-performance anode and cathode electrodes for microbial fuel cells (MFCs) is crucial for enhancing MFC performance. However, complex synthesis methods and single-performance electrode materials hinder their large-scale implementation. Here, three-dimensional hierarchical porous (3DHP) Fe3O4/Fe-N-C composites were prepared via the hard template method. Notably, Fe3O4/Fe-N-C-0.04-600 demonstrated uniformly dispersed Fe3O4 nanoparticles and abundant Fe-Nx and pyridinic nitrogen, showing excellent catalytic performance for oxygen reduction reaction (ORR) with a half-wave potential (E1/2) of 0.74 V (vs. RHE), surpassing Pt/C (0.66 V vs. RHE). Moreover, Fe3O4/Fe-N-C-0.04-600 demonstrated favorable biocompatibility as an anode material, enhancing anode biomass and extracellular electron transfer efficiency. Sequencing results confirmed its promotion of electrophilic microorganisms in the anode biofilm. MFCs employing Fe3O4/Fe-N-C-0.04-600 as both anode and cathode materials achieved a maximum power density of 831.8 ± 27.7 mW m-2, enduring operation for 38 days. This study presents a novel approach for rational MFC design, emphasizing bifunctional materials capable of serving as anode materials for microorganism growth and as cathode catalysts for ORR catalysis.

Urban agglomerations as an environmental dimension of antibiotics transmission through the "One Health" lens.

The spatiotemporal distributions of antibiotics in different media have been widely reported; however, their occurrence in the environmental dimension of the Chinese urban agglomerations has received less attention, especially in bioaccumulation and health risks of antibiotics through the "One Health" lens. The review presents the current knowledge on the environmental occurrence, bioaccumulation, as well as health exposure risks in urban agglomerations through the "One Health" lens, and identifies current information gaps. The reviewed studies suggested antibiotic concentrations in water and soil were more sensitive to social indicators of urban agglomerations than those in sediment. The ecological risk and resistance risk of antibiotics in water were much higher than those of sediments, and the high-risk phenomenon occurred at a higher frequency in urban agglomerations. Erythromycin-H2O (ETM-H2O), amoxicillin (AMOX) and norfloxacin (NFC) were priority-controlled antibiotics in urban waters. Tetracyclines (TCs) posed medium to high risks to soil organisms in the soil of urban agglomerations. Health risk evaluation based on dietary intake showed that children had the highest dietary intake of antibiotics in urban agglomerations. The health risk of antibiotics was higher in children than in other age groups. Our results also demonstrated that dietary structure might impact health risks associated with target antibiotics in urban agglomerations to some extent.

Biogenic silica in intertidal marsh plants and associated sediments of the Yangtze Estuary.

Biogenic silica (BSi) contents in the marsh plants (Phragmites australis, Scirpus mariqueter and Spartina alterniflora) and associated sediments in Chongming Island eastern intertidal flat of the Yangtze Estuary were determined. The BSi contents in P. australis, S. mariqueter and S. alterniflora varied from 25.78-42.74 mg/g, 5.71-19.53 mg/g and 6.71-8.92 mg/g, respectively. Over the entire growth season, P australis and S. mariqueter were characterized by linear accumulation patterns of BSi. The aboveground biomass (leaves and culms) of the marsh plants generally contained more BSi than underground biomass (roots). BSi contents were relatively higher in dead plant tissues than in live tissues which was probably due to the decomposition and the leaching of labile components of plant tissues such as organic carbon and nitrogen. Comparing with the habitats of S. mariqueter and S. alterniflora, the highest BSi content was recorded in sediments inhabited by P. australis, with an annual average of 15.69 mg/g. Overall, the intertidal marshes in the Yangtze Estuary may act as a net sink of BSi via plant uptake and sedimentary burial.

[Distribution and ecological risk assessment of polycyclic aromatic hydrocarbons in overlying waters and surface sediments from the Yangtze estuarine and coastal areas].

Polluted levels, temporal and spatial distributions of polycyclic aromatic hydrocarbons (PAHs) were studied in overlying water and surface sediments from nine typical sampling sites in the Yangtze estuarine and coastal areas. The results showed that PAHs concentrations in overlying waters and surface sediments in dry season (1988 ng/L and 1154 ng/g) were both higher than those in flood season (1727 ng/L and 605 ng/g). And phenanthrene (Phe) was dominant among PAH compounds. Temperature was the most important factor that controlled PAHs seasonal variation in overlying waters, while organic carbon and soot carbon influenced PAHs accumulation in surface sediments. Complicated hydrodynamic conditions and pollutant inputs caused by various anthropogenic activities not only affected on PAHs spatial distribution, but also led to complicated sources in the Yangtze estuarine and coastal areas. Ecological risk assessment indicated that PAHs in water-sediment system from the Yangtze estuarine and coastal areas might potentially damage the Yangtze estuary ecosystem to some extent. Some of PAH compounds in overlying waters had exceeded the ecotoxicological assessment standard or EPA National Recommended Water Quality Criteria, and BaP also exceeded the normal concentration of Chinese Environmental Quality Standards for surface water. Some of PAH compounds in surface sediments had exceeded the effects range low (ER-L) levels and ISQV-L values.

[Polycyclic aromatic hydrocarbons partition in particle-water interface in the Yangtze Estuarine and nearby coastal areas].

Based on polycyclic aromatic hydrocarbons (PAHs) field data of particle phase and dissolved phase, partition coefficients Kp in particle-water interface from the Yangtze Estuarine and nearby coastal areas were obtained. The results show partition coefficients of PAHs in dry season were higher than those in flood season, and all of them ranged from 507 L/kg to 10,179 L/kg, increasing with the rise of PAH compounds. The linear free-energy relationship coefficients between Koc value and octanol-water partition coefficients Ko, in dry season and flood season were 0.82 and 0.68, respectively. These relationships inferred that suspended particle matters in the Yangtze Estuarine and coastal areas had weakly lipophilic characteristics and adsorption ability. lgKoc values of PAH compounds in the different sampling sites were higher than the upper limit value predicted by the classic equilibrium partition model. The partition processes of PAHs were not controlled by concentrations of suspended particle matters, particle grain sizes, overlying water salinity and dissolved organic carbon ( R2 < 0.1), but influenced by particle organic carbon and heterogeneous mixtures of particle soot carbon. The expanded partition model which included soot partitioning could well predict in situ partition processes of PAH compounds whose octanol-water partition coefficients lgKow was lower than 6.

[Distribution and origin of polycyclic aromatic hydrocarbons in suspended particulate matters from the Yangtze estuarine and nearby coastal areas].

Parent PAHs have been quantified in suspended particulate matters from the Yangtze Estuarine and Coastal Areas. The results show that the concentrations of total PAHs ranged from 2278.79-14293.98 ng/g, and were characterized by greatest content near sewage discharge point with trend to decrease by increasing distance. As for PAHs composition, 4-6 rings PAHs were dominant while 2-3 rings PAHs were relative low. Cluster analysis found that except urban sewage discharge, the hydrodynamic force was influencing PAHs distribution patterns. Moreover, the content of suspended particulate matters, organic carbon and soot carbon of suspended particulate matters also play the important roles in PAHs distribution from the Yangtze estuarine and nearby coastal areas. Principal component analysis and PAH ratios demonstrated that uncompleted combustion of fossil fuels was the main source of PAHs in coastal areas, as well as a few anthropogenic releases of oil and oil products. Ecological risk assessment indicated that most of PAH compounds exceeded the effects range ER-L values and ISQV-L values, which might certain potential damage to the Yangtze Estuary ecosystem.

[Accumulation characteristics of PAHs in multimedia from various urban functional areas].

Taking Shanghai city as an example, the study analyzed the difference of concentration levels in road dust, soil and leaves besides roads. The reasons and mechanisms of the accumulation characteristics were also been discussed. The result shows that, in a same functional area, road dusts and soils accumulated more PAHs while leaves did less, and the concentrations of PAHs in P. orientalis L. leaves were higher than those in Buxus sinica leaves. Total PAHs concentrations in road dust and soil ranged from 8992 ng x g(-1) to 141723 ng x g(-1), averaged in 54964 ng x g(-1), and from 9306 ng x g(-1) to 146689 ng x g(-1), averaged in 56883 ng x g(-1), respectively. Total PAHs concentrations in P. orientalis L. leaves and Buxus sinica leaves varied from 2423 ng x g(-1) to 32883 ng x g(-1), with a mean value of 12983 ng x g(-1), from 1498 ng x g(-1) to 19418 ng x g(-1), with a mean value of 7612 ng x g(-1). Among various functional areas, there were significant differences in PAHs concentrations in road dusts and soils while those in leaves were similarly. PAH homologue concentrations in road dusts and soils had significant difference in various functional areas with the priority of high molecular homologues. However, PAH homologue concentrations in leaves were similarly dominated by low molecular homologues. The accumulation characteristics were closely corresponding with the physicochemical property of PAHs and the main accumulation ways of PAHs in multimedia.

Distribution and accumulation of biogenic silica in the intertidal sediments of the Yangtze Estuary.

Abstract Sedimentary biogenic silica is known to be an important parameter to understand biogeochemical processes and paleoenviromental records in estuarine and coastal ecosystems. Consequently, it is of great significance to investigate accumulation and distribution of biogenic silica in sediments. The two-step mild acid-mild alkaline extraction procedure was used to leach biogenic silica and its early diagenetic products in intertidal sediments of the Yangtze Estuary. The results showed that total biogenic silica (t-BSi) in the intertidal sediments varied from 237.7-419.4 micromol Si/g, while the mild acid leachable silica (Si-HCl) and the mild alkaline leachable silica (Si-Alk) were in the range of 25.1-72.9 micromol Si/g and 208.1-350.4 micromol Si/g, respectively. Significant correlations were observed for the grain size distributions of sediments and different biogenic silica pools in intertidal sediments. This confirms that grain size distribution can significantly affect biogenic silica contents in sediments. Close relationships of biogenic silica with organic carbon and nitrogen were also found, reflecting that there is a strong coupling between biogenic silica and organic matter biogeochemical cycles in the intertidal system of the Yangtze Estuary. Additionally, the early diagenetic changes of biogenic silica in sediments are discussed in the present study.

[Effective factors on accumulation and transportation of PAHs in road dust from Shanghai].

The influencing factors on the accumulation and transportation of PAHs (polycyclic aromatic hydrocarbons) in road dust from Shanghai city were systematically discussed. The results showed that grain size was only a minor factor affecting the adsorption of PAHs by urban road dust, and there was no obvious correlation between grain size and PAHs concentrations. TOC (total organic carbons) was significantly correlated with PAHs concentration (r = 0.62, p < 0.0001; r = 0.55, p = 0.002 for winter and summer, respectively), which suggested that for urban road dust, the higher the organic matters were, the stronger the adsorption capacity was. The result was consistent with the hydrophobic characteristic of PAHs theoretically. Wind direction significantly influenced the accumulation and transportation of PAHs in urban road dust. Wind direction could directly affect the spatial distribution of PAHs, which led the leeward was ready to accumulate less PAHs while the windward was likely to accumulate more. In summer, the highest concentration existed in northwest of Shanghai, with a value of 27,766 ng x g(-1), and in winter, the south and east of Shanghai were the most polluted areas, with values of 30,741 ng x g(-1), 32,573 ng x g(-1), respectively. And the "Hollow Effect" was found at urban centre area. Temperature was an important factor affecting the accumulation and transportation of PAHs in urban road dust.

Organochlorine pesticides in surface sediments and suspended particulate matters from the Yangtze estuary, China.

Total HCHs' and total DDTs' levels in surface sediments (SS) ranged from 0.5 to 17.5 ng g(-1) and from 0.9 to 33.1 ng g(-1), averaged 6.0 and 8.2 ng g(-1), respectively. Total HCHs' and total DDTs' levels in suspended particulate matters (SPM) varied from 6.2 to 14.8 ng g(-1) with a mean value of 12.3 ng g(-1) and were from 3.4 to 25.7 ng g(-1) with an average of 16.4 ng g(-1), respectively. Lindane is the main HCHs' source and continuing use in the Yangtze Delta areas of 'pure' gamma-HCH (lindane) rather than technical HCH (a mix of largely alpha- and some gamma-HCH). DDTs in SS are mainly accumulated in history. However, high DDT fractions in SPM are indicators of new input of typical dicofol type DDT from 2002 to 2004. It can be seen that most samples from the Yangtze estuary were in ranges where adverse biological effects are expected, either occasionally or frequently.

[Seasonal variation and function-area difference of PAHs in road dust from Shanghai urban area].

Seasonal variation and function-area difference of polycyclic aromatic hydrocarbons (PAHs) in road dust from Shanghai centre area were studied, and the probable reasons were also discussed. The result showed that the accumulation level of PAHs varied significantly from winter to summer, namely, and the concentrations of total PAHs and the homologues in winter were higher than that in summer. Total PAH concentrations (t-PAH) in winter samples ranged from 9176 to 32,573 ng x g(-1), with a mean value of 20,648 ng x g(-1), whereas they varied from 6875 to 27,766 ng x g(-1) in summer, with an average of 14098 ng x g(-1). The individual PAHs composition ranged from 50 (acenaphthylene) to 3162 (indeno (1,2,3,-cd) pyrene) ng x g(-1) in winter, and 3 (acenaphthene) to 1485 (indeno(1,2,3,-cd) pyrene) ng x g(-1) in summer. The results exhibited that the levels showed a great rise from summer to winter. The difference of PAHs concentrations in road dust from functional areas were also obvious, that is, in winter, PAHs concentrations in road dust at industrial area (ID), commercial area (CO) and traffic area (TR) were much higher than those in other areas, with t-PAH mean concentration of 31 163, 24 932 and 18 815 ng x g(-1) resepectively, while city park (CP) and public lawn (PL) had the lowest level (7885, 8036 ng x g(-1)). In summer, the lowest concentration (7942 ng x g(-1)) appeared in CP, however, TR, ID and CO were the most polluted areas, with t-PAH mean concentration of 14,528, 14,247 and 11,523 ng x g(-1), respectively. The concentration of PAH homologues raised gradually with the ring number or molecular weight. Seasonal variation and function-area difference of PAHs in road dust from urban area correlated with both their sources and their physical and chemical characteristics.