Jun 2022, Volume 16 Issue 3

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    Xiaoqiang Gong, Jinbiao Li, Scott X. Chang, Qian Wu, Zhengfeng An, Chengpeng Huang, Xiangyang Sun, Suyan Li, Hui Wang

    • Earthworms increase CO2 and N2O emissions in agricultural and forest soil.

    • 10% biochar suppresses CO2 and N2O emissions in forest soil.

    • Biochar interacted with earthworm to significant affect CO2 and N2O emissions.

    The application of manure-derived biochar offers an alternative to avoid the direct application of manure to soil causing greenhouse gas emission. Soil fauna, especially earthworms, can markedly stimulate carbon dioxide (CO2) and nitrous oxide (N2O) emissions from soil. This study therefore investigated the effect of cattle manure biochar (added at rates of 0, 2%, or 10%, coded as BC0, BC2 and BC10, respectively) application, with or without earthworm Aporrectodea turgida, on emissions of CO2 and N2O and changes of physic-chemical properties of agricultural and forest soils in a laboratory incubation experiment. The BC10 treatment significantly enhanced cumulative CO2 emissions by 27.9% relative to the untreated control in the agricultural soil. On the contrary, the BC2 and BC10 treatments significantly reduced cumulative CO2 emissions by 16.3%–61.1% and N2O emissions by 92.9%–95.1% compared to the untreated control in the forest soil. The addition of earthworm alone significantly enhanced the cumulative CO2 and N2O fluxes in agricultural and forest soils. Cumulative CO2 and N2O fluxes were significantly increased when BC2 and BC10 were applied with earthworm in the agricultural soil, but were significantly reduced when BC10 was applied with earthworm in the forest soil. Our study demonstrated that biochar application interacted with earthworm to affect CO2 and N2O emissions, which were also dependent on the soil type involved. Our study suggests that manure biochar application rate and use of earthworm need to be carefully studied for specific soil types to maximize the climate change mitigation potential of such management practices.

    Yicai Huang, Jiayuan Chen, Qiannan Duan, Yunjin Feng, Run Luo, Wenjing Wang, Fenli Liu, Sifan Bi, Jianchao Lee

    • A spectral machine learning approach is proposed for predicting mixed antibiotic.

    • Pretreatment is far simpler than traditional detection methods.

    • Performance of the model is compared in different influencing factors.

    • Spectral machine learning is promising in the detection of complex substances.

    Antibiotics are widely used in medicine and animal husbandry. However, due to the resistance of antibiotics to degradation, large amounts of antibiotics enter the environment, posing a potential risk to the ecosystem and public health. Therefore, the detection of antibiotics in the environment is necessary. Nevertheless, conventional detection methods usually involve complex pretreatment techniques and expensive instrumentation, which impose considerable time and economic costs. In this paper, we proposed a method for the fast detection of mixed antibiotics based on simplified pretreatment using spectral machine learning. With the help of a modified spectrometer, a large number of characteristic images were generated to map antibiotic information. The relationship between characteristic images and antibiotic concentrations was established by machine learning model. The coefficient of determination and root mean squared error were used to evaluate the prediction performance of the machine learning model. The results show that a well-trained machine learning model can accurately predict multiple antibiotic concentrations simultaneously with almost no pretreatment. The results from this study have some referential value for promoting the development of environmental detection technologies and digital environmental management strategies.

    Zhike Li, Jie Chi, Zhenyu Wu, Yiyan Zhang, Yiran Liu, Lanlan Huang, Yiren Lu, Minhaz Uddin, Wei Zhang, Xuejun Wang, Yan Lin, Yindong Tong

    • Hg bioaccumulation by phytoplankton varies among aquatic ecosystems.

    • Active Hg uptake may exist for the phytoplankton in aquatic ecosystems.

    • Impacts of nutrient imbalance on food chain Hg transfer should be addressed.

    The bioaccumulation of mercury (Hg) in aquatic ecosystem poses a potential health risk to human being and aquatic organism. Bioaccumulations by plankton represent a crucial process of Hg transfer from water to aquatic food chain. However, the current understanding of major factors affecting Hg accumulation by plankton is inadequate. In this study, a data set of 89 aquatic ecosystems worldwide, including inland water, nearshore water and open sea, was established. Key factors influencing plankton Hg bioaccumulation (i.e., plankton species, cell sizes and biomasses) were discussed. The results indicated that total Hg (THg) and methylmercury (MeHg) concentrations in plankton in inland waters were significantly higher than those in nearshore waters and open seas. Bioaccumulation factors for the logarithm of THg and MeHg of phytoplankton were 2.4–6.0 and 2.6–6.7 L/kg, respectively, in all aquatic ecosystems. They could be further biomagnified by a factor of 2.1–15.1 and 5.3–28.2 from phytoplankton to zooplankton. Higher MeHg concentrations were observed with the increases of cell size for both phyto- and zooplankton. A contrasting trend was observed between the plankton biomasses and BAFMeHg, with a positive relationship for zooplankton and a negative relationship for phytoplankton. Plankton physiologic traits impose constraints on the rates of nutrients and contaminants obtaining process from water. Nowadays, many aquatic ecosystems are facing rapid shifts in nutrient compositions. We suggested that these potential influences on the growth and composition of plankton should be incorporated in future aquatic Hg modeling and ecological risk assessments.

    Shuangyang Zhao, Chengxin Chen, Jie Ding, Shanshan Yang, Yani Zang, Nanqi Ren

    • BiVO4/Fe3O4/rGO has excellent photocatalytic activity under solar light radiation.

    • It can be easily separated and collected from water in an external magnetic field.

    • BiVO4/Fe3O4/0.5% rGO exhibited the highest RhB removal efficiency of over 99%.

    • Hole (h+) and superoxide radical (O2) dominate RhB photo-decomposition process.

    • The reusability of this composite was confirmed by five successive recycling runs.

    Fabrication of easily recyclable photocatalyst with excellent photocatalytic activity for degradation of organic pollutants in wastewater is highly desirable for practical application. In this study, a novel ternary magnetic photocatalyst BiVO4/Fe3O4/reduced graphene oxide (BiVO4/Fe3O4/rGO) was synthesized via a facile hydrothermal strategy. The BiVO4/Fe3O4 with 0.5 wt% of rGO (BiVO4/Fe3O4/0.5% rGO) exhibited superior activity, degrading greater than 99% Rhodamine B (RhB) after 120 min solar light radiation. The surface morphology and chemical composition of BiVO4/Fe3O4/rGO were studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The free radicals scavenging experiments demonstrated that hole (h+) and superoxide radical (O2) were the dominant species for RhB degradation over BiVO4/Fe3O4/rGO under solar light. The reusability of this composite catalyst was also investigated after five successive runs under an external magnetic field. The BiVO4/Fe3O4/rGO composite was easily separated, and the recycled catalyst retained high photocatalytic activity. This study demonstrates that catalyst BiVO4/Fe3O4/rGO possessed high dye removal efficiency in water treatment with excellent recyclability from water after use. The current study provides a possibility for more practical and sustainable photocatalytic process.

    Jiaheng Zhao, Bing Li, Pin Lv, Jiahui Hou, Yong Qiu, Xia Huang

    • Distribution of ARGs in decentralized sewage facilities were investigated.

    • Bacitracin-ARGs were most predominant ARGs in rural wastewater.

    • ARGs were identified in bacterial and viral community.

    • ARGs of rpoB, drfE, gyrA and parC were both correlated with bacteria and phages.

    • More attention should be paid to the risk of spreading ARG by phages.

    The distribution of antibiotic resistance genes (ARGs) has been intensively studied in large-scale wastewater treatment plants and livestock sources. However, small-scale decentralized sewage treatment facilities must also be explored due to their possible direct exposure to residents. In this study, six wastewater treatment facilities in developed rural areas in eastern China were investigated to understand their risks of spreading ARGs. Using metagenomics and network analysis tools, ARGs and bacterial and viral communities were identified in the influent (INF) and effluent (EFF) samples. The dominant ARGs belonged to the bacitracin class, which are different from most of municipal wastewater treatment plants (WWTPs). The dominant hosts of ARGs are Acidovorax in bacterial communities and Prymnesiovirus in viral communities. Furthermore, a positive relationship was found between ARGs and phages. The ARGs significantly correlated with phages were all hosted by specific genera of bacteria, indicating that phages had contributed to the ARG’s proliferation in sewage treatment facilities. Paying significant concern on the possible enhanced risks caused by bacteria, viruses and their related ARGs in decentralized sewage treatment facilities is necessary.

    Yanan Bai, Xiuning Wang, Fang Zhang, Raymond Jianxiong Zeng

    • AO7 degradation was coupled with anaerobic methane oxidation.

    • Higher concentration of AO7 inhibited the degradation.

    • The maximum removal rate of AO7 reached 280 mg/(L·d) in HfMBR.

    • ANME-2d dominated the microbial community in both batch reactor and HfMBR.

    • ANME-2d alone or synergistic with the partner bacteria played a significant role.

    Azo dyes are widely applied in the textile industry but are not entirely consumed during the dyeing process and can thus be discharged to the environment in wastewater. However, azo dyes can be degraded using various electron donors, and in this paper, Acid Orange 7 (AO7) degradation performance is investigated using methane (CH4) as the sole electron donor. Methane has multiple sources and is readily available and inexpensive. Experiments using 13C-labeled isotopes showed that AO7 degradation was coupled with anaerobic oxidation of methane (AOM) and, subsequently, affected by the initial concentrations of AO7. Higher concentrations of AO7 could inhibit the activity of microorganisms, which was confirmed by the long-term performance of AO7 degradation, with maximum removal rates of 8.94 mg/(L·d) in a batch reactor and 280 mg/(L·d) in a hollow fiber membrane bioreactor (HfMBR). High-throughput sequencing using 16S rRNA genes showed that Candidatus Methanoperedens, affiliated to ANME-2d, dominated the microbial community in the batch reactor and HfMBR. Additionally, the relative abundance of Proteobacteria bacteria (Phenylobacterium, Pseudomonas, and Geothermobacter) improved after AO7 degradation. This outcome suggested that ANME-2d alone, or acting synergistically with partner bacteria, played a key role in the process of AO7 degradation coupled with AOM.

    Feng Hou, Ting Zhang, Yongzhen Peng, Xiaoxin Cao, Hongtao Pang, Yanqing Shao, Xianchun Lu, Ju Yuan, Xi Chen, Jin Zhang

    • A full scale biofilm process was developed for typical domestic wastewater treatment.

    • The HRT was 8 h and secondary sedimentation tank was omitted.

    Candidatus Brocadia were enriched in the HBR with an abundance of 2.89%.

    • Anammox enabled a stable ammonium removal of ~15% in the anoxic zone.

    The slow initiation of anammox for treating typical domestic wastewater and the relatively high footprint of wastewater treatment infrastructures are major concerns for practical wastewater treatment systems. Herein, a 300 m3/d hybrid biofilm reactor (HBR) process was developed and operated with a short hydraulic retention time (HRT) of 8 h. The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process. The percentage abundance of Candidatus Brocadia in the total bacterial community of the anoxic zone increased from 0 at Day 1 to 0.33% at Day 130 and then to 2.89% at Day 213. Based upon the activity of anammox bacteria, the removal of ammonia nitrogen (NH4+-N) in the anoxic zone was approximately 15%. This showed that the nitrogen transformation pathway was enhanced in the HBR system through partial anammox process in the anoxic zone. The final effluent contained 12 mg/L chemical oxygen demand (COD), 0.662 mg/L NH4+-N, 7.2 mg/L total nitrogen (TN), and 6 mg/L SS, indicating the effectiveness of the HBR process for treating real domestic wastewater.

    Ziyan Qin, Qun Gao, Qiang Dong, Joy D. Van Nostrand, Qi Qi, Yifan Su, Suo Liu, Tianjiao Dai, Jingmin Cheng, Jizhong Zhou, Yunfeng Yang

    • The α-diversities of resistome were lower in manure and compost than in soils.

    • There were significant correlations between the resistome and bacterial taxonomy.

    • Bacterial taxonomy was the highest in explaining resistome variances.

    Antibiotic resistance genes comprising antibiotic resistome are of great concern due to their increase in the environment. Recent evidence of shared resistomes between soils and animal husbandry has imposed potential risks to human health. However, the correlation between a given community’s resistome and bacterial taxonomic composition is controversial. Here, a transmission chain of resistomes from swine manure to compost and compost-amended soil were analyzed in five suburban areas of Beijing, China, with unamended agricultural soils as control soils. Antibiotic resistomes and bacterial taxonomic compositions were distinct between (I) manure and compost; and (II) compost-amended and control soils. In manure, compost, and compost-amended soils, the β-diversity of the resistome and bacterial taxonomic composition was significantly correlated, while no correlation was detected in control soils. Bacterial taxonomic composition explained 36.0% of total variations of the resistome composition, much higher than environmental factors. Together, those results demonstrated that antibiotic resistome was closely related to bacterial taxonomic composition along the suburban transmission chain.

    Allan Gomez-Flores, Gukhwa Hwang, Sadia Ilyas, Hyunjung Kim

    • Coulomb and Lennard−Jones forces were considered for droplet interactions.

    • The net droplet interactions were repulsive.

    • Repulsive droplet interactions increased the transport of droplets.

    • Repulsive droplet interactions significantly modified the fate of droplets.

    Previous studies reported that specially designed ventilation systems provide good air quality and safe environment by removing airborne droplets that contain viruses expelled by infected people. These water droplets can be stable in the environment and remain suspended in air for prolonged periods. Encounters between droplets may occur and droplet interactions should be considered. However, the previous studies focused on other physical phenomena (air flow, drag force, evaporation) for droplet transport and neglected droplet interactions. In this work, we used computational fluid dynamics (CFD) to simulate the transport and fate of airborne droplets expelled by an asymptomatic person and considered droplet interactions. Droplet drag with turbulence for prediction of transport and fate of droplets indicated that the turbulence increased the transport of 1 μm droplets, whereas it decreased the transport of 50 μm droplets. In contrast to only considering drag and turbulence, consideration of droplet interactions tended to increase both the transport and fate. Although the length scale of the office is much larger than the droplet sizes, the droplet interactions, which occurred at the initial stages of release when droplet separation distances were shorter, had a significant effect in droplet fate by considerably manipulating the final locations on surfaces where droplets adhered. Therefore, it is proposed that when an exact prediction of transport and fate is required, especially for high droplet concentrations, the effects of droplet interactions should not be ignored.

    Wenping Zhang, Changsheng Guo, Jiapei Lv, Xu Li, Jian Xu

    • Eleven OPEs were detected in river sediment and lake sediment in Taihu Lake.

    • TnBP dominated in river sediment, while TBEP dominated in lake sediment.

    • A strong correlation existed between logKoc and logKow of OPEs.

    • Vertical profiles of OPEs in sediment cores varied according to sampling location.

    Surface sediment samples from Taihu Lake in China and its inflow rivers, along with two lake sediment core samples, were collected and analyzed for organophosphate esters (OPEs). The concentrations of total OPEs varied from 28.60 ng/g to 158.72 ng/g (median: 54.25 ng/g) in river surface sediment and from 62.57 ng/g to 326.84 ng/g (median: 86.37 ng/g) in lake sediment. Tributyl phosphate (TnBP) was the predominant compound in river surface sediment, and tris(2-butoxyethyl) phosphate was predominant in lake sediment. High contamination occurred in the north-west region, which was related to the high level of urbanization and high usage of OPEs. The sediment–water partition coefficients of OPEs (logKoc) were calculated, showing a significant correlation with logKow (p<0.05). The concentration and composition of OPEs in two sediment cores varied due to the different sampling locations, with more OPE species found in the northern region than in the southern one. Principal component analysis and positive matrix factorization indicated that sewage discharges, vehicle emissions, and atmospheric deposition were the possible sources of OPEs in Taihu Lake sediments. Tris(1-chloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, and TnBP were the main OPEs causing ecological risks.

    Zhenming Zhou, Canyang Lin, Shuwen Li, Shupo Liu, Fei Li, Baoling Yuan

    • Lanthanum modified bentonite (LMB) can effectively absorb phosphorus (P).

    • Water treatment plant sludge (WTPS) capping is effective for controlling P release.

    •Aluminum-based P-inactivation agent (Al-PIA) is an efficient P control material.

    •The P adsorbed by WTPS and Al-PIA is mainly in the form of NAIP.

    We determined the effects of quartz sand (QS), water treatment plant sludge (WTPS), aluminum-based P-inactivation agent (Al-PIA), and lanthanum-modified bentonite (LMB) thin-layer capping on controlling phosphorus and nitrogen release from the sediment, using a static simulation experiment. The sediment in the experiment was sampled from Yundang Lagoon (Xiamen, Fujian Province, China), which is a eutrophic waterbody. The total phosphorus (TP), ammonium nitrogen (NH4+-N), and total organic carbon (TOC) levels in the overlying water were measured at regular intervals, and the changes of different P forms in WTPS, Al-PIA, and sediment of each system were analyzed before and after the test. The average TP reduction rates of LMB, Al-PIA, WTPS, and QS were 94.82, 92.14, 86.88, and 10.68%, respectively, when the release strength of sediment TP was 2.26–9.19 mg/(m2·d) and the capping strength of the materials was 2 kg/m2. Thin-layer capping of LMB, WTPS, and Al-PIA could effectively control P release from the sediment (P<0.05). However, thin-layer capping of LMB, Al-PIA, and QS did not significantly reduce the release of ammonium N and organic matter (P > 0.05). Based on our results, LMB, Al-PIA, and WTPS thin-layer capping promoted the migration and transformation of easily released P in sediment. The P adsorbed by WTPS and Al-PIA mainly occurred in the form of NAIP.

    Yali Liu, Jianqing Du, Boyang Ding, Yuexian Liu, Wenjun Liu, Anquan Xia, Ran Huo, Qinwei Ran, Yanbin Hao, Xiaoyong Cui, Yanfen Wang

    •Considering evenness provides a more accurate assessment of sustainable development.

    •Water resource conservation drives industrial transformation.

    •Synergy between economic development and environmental protection is achieved.

    •Regional collaboration over water could promote sustainable development in drylands.

    Water resource availability is the major limiting factor for sustainable development in drylands. Climate change intensifies the conflicting water demands between people and the environment and highlights the importance of effective water resource management for achieving a balance between economic development and environmental protection. In 2008, Inner Mongolia, typical dryland in northern China, proposed strict regulations on water exploitation and utilization aimed at achieving sustainable development. Our study is the first to investigate the effectiveness and performance of these long-standing water conservation regulations. Our analyses found that the regulations drove industrial transformation, evidenced by the decreasing proportion of environmentally harmful industries such as coal and steel, and the increasing proportion of tertiary industries (especially tourism). Following industrial transformation, economic development decoupled from industrial water consumption and subsequently led to reduced negative environmental impacts. Based on these results, adaptive strategies were developed for 12 cities by revealing and integrating their development pathways and relative status in achieving sustainable development. Integration and cooperation between cities were proposed, e.g., a water trade agreement between eastern Inner Mongolia (an economically underdeveloped region with relatively abundant water resources) and central Inner Mongolia (an economically developed region with high water stress). Such an agreement may enable the holistic achievement of sustainable development across regions. By integrating the findings of our research, our study presents a reproducible framework for water-management-based sustainable development strategies in drylands.

    Athiyanam Venkatesan Ramya, Manoj Balachandran

    • Transformation of agro-industrial waste to value-added material via green chemistry.

    • Orange peel is valorized into fluorescent nanodiamond-like carbon (fNDC) sensor.

    • fNDC detects potentially hazardous drug atropine sulfate (AS).

    • fNDC recognizes AS in biological fluids and pharmaceuticals.

    • fNDC assures applications in clinical and forensic toxicology.

    Millions of tonnes of agro-industrial waste are generated each year globally, with the vast majority of it going untreated, underutilized, and disposed of by burning or landfilling, causing severe environmental distress and economic downturn. A practical solution to this global issue is to use green chemistry to convert this waste into value-added products. Accordingly, in the present study, agro-industrial orange peel waste was valorized into fluorescent nanodiamond-like carbon sensor via a green route involving hydrothermal treatment of microwave carbonized orange peel waste. The developed sensor, used for the fluorescence detection of potentially hazardous drug atropine sulfate, exhibits unique dual linearity over concentration ranges of 300 nM to 1 M and from 1 M to 10 M, as well as ultra-low sensitivity of 34.42 nM and 356.46 nM, respectively. Additionally, the sensor demonstrates excellent reproducibility, high stability, and satisfactory recovery when used to identify and quantify atropine sulfate in biological samples and commercially available pharmaceuticals, indicating promising multidisciplinary applications.