Limited effects of different real groundwaters from three coastal cities in China on the transport of low-concentration nanoplastics in quartz sand.

Nanoplastics (NPs) have been widely detected in soil-groundwater systems. However, to date, the effect of real groundwater on the fate and transport of NPs has been poorly understood. In this study, the transport and retention behaviors of both polystyrene and poly(lactic-co-glycolic acid) NPs (PS NPs and PLGA NPs) in different real groundwaters from three coastal cities in China were explored using column experiments. PS (0.51 and 1.1 µm) and PLGA (1 µm) NPs with a low concentration of 2 mg L-1 were employed. Close observation showed that the transport of PS NPs was much higher than PLGA NPs in different groundwaters, with an average breakthrough curve plateau (C/Co) of ∼0.81 for PS NPs and ∼0.19 for PLGA NPs, respectively. As observed for PLGA, the plastic shape- and size-induced straining may be the reason for the minimal transport. Interestingly, we found that although the physicochemical characteristics of different real groundwaters varied significantly, the transport of certain NPs in real groundwater was similar with negligible differences. Closer inspection indicated that similar pHs of different groundwaters may be the reason contributing to these findings. Further investigation revealed that the transport behaviors of PS and PLGA NPs in real groundwater did not follow the classical DLVO theory. These findings suggest that the fate and transport of NPs in real soil-groundwater systems are much more comprehensive than the prediction based on DLVO theory and need intensive investigation.

Proceeding the categorization of microplastics through deep learning-based image segmentation.

Microplastics (MPs) have been recognized as prominent anthropogenic pollutants that inflict significant harm to marine ecosystems. Various approaches have been proposed to mitigate the risks posed by MPs. Gaining an understanding of the morphology of plastic particles can provide valuable insights into the source and their interaction with marine organisms, which can assist the development of response measures. In this study, we present an automated technique for identifying MPs through segmentation of MPs in microscopic images using a deep convolutional neural network (DCNN) based on a shape classification nomenclature framework. We used MP images from diverse samples to train a Mask Region Convolutional Neural Network (Mask R-CNN) based model for classification. Erosion and dilation operations were added to the model to improve segmentation results. On the testing dataset, the mean F1-score (F1) of segmentation and shape classification was 0.7601 and 0.617, respectively. These results demonstrate the potential of proposed method for the automatic segmentation and shape classification of MPs. Furthermore, by adopting a specific nomenclature, our approach represents a practical step towards the global standardization of MPs categorization criteria. This work also identifies future research directions to improve accuracy and further explore the possibilities of using DCNN for MPs identification.

Ozone micro-nano bubble water preserves the quality of postharvest parsley.

The production and use of ozone micro-nano bubble water (O3-MNBW) is an innovative technology that prolongs the reactivity of aqueous-phase ozone and maintains the freshness and quality of fruits and vegetables by removing pesticides, mycotoxins, and other contaminants. The quality of parsley treated with different concentrations of O3-MNBW was investigated during storage at 20 ℃ for 5 d, and found that a ten-minute exposure of parsley to 2.5 mg·L-1 O3-MNBW effectively preserved the sensory quality of parsley, and resulted in lower weight loss, respiration rate, ethylene production, MDA levels, and a higher level of firmness, vitamin C, and chlorophyll content, relative to untreated parsley. The O3-MNBW treatment also increased the level of total phenolics and flavonoids, enhanced peroxidase and ascorbate peroxidase activity, and inhibited polyphenol oxidase activity in stored parsley. Five volatile signatures identified using an electronic nose (W1W, sulfur-compounds; W2S, ethanol; W2W, aromatic- and organic- sulfur compounds; W5S, oxynitride; W1S, methane) exhibited a significant decrease in response to the O3-MNBW treatment. A total of 24 major volatiles were identified. A metabolomic analysis identified 365 differentially abundant metabolites (DMs). Among them, 30 and 19 DMs were associated with characteristic volatile flavor substance metabolism in O3-MNBW and control groups, respectively. The O3-MNBW treatment increased the abundance of most DMs related to flavor metabolism and reduced the level of naringin and apigenin. Our results provide insight into the mechanisms that are regulated in response to the exposure of parsley to O3-MNBW, and confirmed the potential use of O3-MNBW as a preservation technology.

Development and verification of a risk prediction model for bronchopulmonary dysplasia in very low birth weight infants.

BACKGROUND: To analyze the risk factors of bronchopulmonary dysplasia (BPD) of very low birth weight infants (VLBWIs), and to develop and verify a risk prediction model of BPD. METHODS: The data of 611 VLBWIs from the neonatal intensive care unit (NICU) of a tertiary grade A hospital in Suzhou from January 2017 to September 2019 were collected. The data was randomly divided into the modeling set (451 cases) and the validation set (160 cases). Binary logistic regression was used to analyze the data, and the model was examined by a receiver operating characteristic (ROC) curve. The grouped data was used to verify the sensitivity and specificity of the model. RESULTS: The study found that neonatal asphyxia, the positive rate of sputum culture, neonatal sepsis, neonatal respiratory distress syndrome (NRDS), blood transfusions (≥3), patent ductus arteriosus (PDA), the time of invasive mechanical ventilation, the duration of oxygen therapy, and the time of parenteral nutrition were the independent risk factors of BPD, while 1 min Apgar score was a protective factor. The model formula was Z=neonatal asphyxia * 1.229 + the positive rate of sputum culture * 1.265 + neonatal sepsis * 1.677 + NRDS * 1.848 + blood transfusions (≥3) * 1.455 + PDA * 1.835 - 1 min Apgar score * 0.25 + the time of invasive mechanical ventilation * 0.123 + the duration of oxygen therapy * 0.09 + the time of parenteral nutrition * 0.057 - 8.077. The area under the ROC curve of this model was 0.965 (95% CI: 0.946-0.983), with a sensitivity of 93.7% and a specificity of 91.3%. Verification of this prediction model showed a sensitivity of 92.9% and a specificity of 76%, demonstrating that the effects of this model were satisfactory. CONCLUSIONS: The risk prediction model had a good predictive effect for the risk of BPD in VLBWIs, and can provide a reference for preventive treatment and nursing intervention.

Separation and enrichment of nanoplastics in environmental water samples via ultracentrifugation.

Nanoplastics are an emerging contaminant in aquatic environments. However, analytical methods for the separation, concentration, and identification of nanoplastics, which are essential to assess nanoplastic presence in the environment, are lacking. Here, we developed a new and easy-to-use method to separate and enrich nanoplastics in field water samples with ultracentrifugation. River water was spiked with polystyrene fragments (< 1000 nm) at an environmentally relevant concentration (108-109 particles/L). The polystyrene fragments were successfully separated and enriched by a factor of nearly 50 times with a high recovery rate (87.1%) after undergoing our process. Particles were then characterized using UV-vis spectroscopy, scanning electron microscopy (SEM), and enhanced darkfield microscopy with a hyperspectral imaging (HSI) spectrometer. These techniques are non-destructive and allow the assessment of plastic concentration, morphology, and polymer type. Our method can potentially be applied to other water samples to supply clean, enriched nanoplastic samples that can facilitate their identification in environmental samples.

Microplastic quantification affected by structure and pore size of filters.

Filters of various structures (filter by pore depth or pore width) and pore sizes are used to extract microplastics (<5 mm) in researches. In present study, we demonstrate that filters with different structures and pore sizes can lead to different outcomes in microplastic filtering. Our results showed that when filtering large-sized microplastics, nylon filter (double-layer-hole type) retained nearly 100% of fibers, while polycarbonate filter (single-layer-hole type) only retained 61.7%. Polycarbonate filter retained the most fragments (80.8%), while cotton fiber filter (multilayer-hole type) retained the least (54.4%). Pellets were retained on different layers of nylon and cotton fiber filters, and could not be quantified accurately. Additionally, the sizes of some fibers and fragments captured were not within the expected ranges by lattice-knitting filters. Large fiber (3568.0 µm) was not filtered out after 1000 µm pore-size filtration. Small fragment (37.2 µm) was found on 50 µm pore-size filters. To validate laboratory results, filed waters containing microplastics (∼90% in form of fibers) were filtered through different pore-size filters. As expected, the relationship between abundance and pore size followed a same trend as that in laboratory fiber samples. Thereby, our results indicated that filter structure and pore size could affect the abundances of microplastics with different shapes. To obtain more accurate abundance of microplastics in a wide size range, and to consider filtration duration, size limitation of observation, and spatial resolution of identification instrument, we recommend that water samples should be filtered using 20 µm pore-size filters with a double-layer-hole type of structure.

Microplastics in take-out food containers.

Microplastics have been detected in various media including water, sediment, and seafood, whereas there are few studies focusing on microplastics in take-out containers. In this study, we collected take-out containers made of common polymer materials (polypropylene, PP; polystyrene, PS; polyethylene, PE; polyethylene terephthalate, PET) from five cities in China. Microplastics in the containers were analyzed after different treatments (direct flushing and flushing after immersing with hot water). Our results showed that microplastics were found in all take-out containers and abundance ranged from 3 to 29 items/container. The highest abundance occurred in PS containers with rough surface. The polymer types of some detected particles were the same as those of original containers, accounting for 30% of the total microplastics; other types included polyester, rayon, acrylic, and nylon. Treating the containers with hot water did not influence microplastic abundance. Our study indicates that microplastics in take-out containers come from atmospheric fallout and flakes from container's inner surfaces. Under slight mechanical force, loose structure and rough surface of PS containers can flake off microplastics, entering water more easily. Based on the microplastic abundance in take-out containers, people who order take-out food 4-7 times weekly may ingest 12-203 pieces of microplastics through containers.

Offshore multi-purpose platforms for a Blue Growth: A technological, environmental and socio-economic review.

"Blue Growth" and "Blue Economy" is defined by the World Bank as: "the sustainable use of ocean resources for economic growth, improved livelihoods and jobs, while preserving the health of ocean ecosystem". Multi-purpose platforms (MPPs) can be defined as offshore platforms serving the needs of multiple offshore industries (energy and aquaculture), aim at exploiting the synergies and managing the tensions arising when closely co-locating systems from these industries. Despite a number of previous projects aimed at assessing, from a multidisciplinary point of view, the feasibility of multipurpose platforms, it is here shown that the state-of-the-art has focused mainly on single-purpose devices, and adopting a single discipline (either economic, or social, or technological, or environmental) approach. Therefore, the aim of the present study is to provide a multidisciplinary state of the art review on, whenever possible, multi-purpose platforms, complementing it with single-purpose and/or single discipline literature reviews when not possible. Synoptic tables are provided, giving an overview of the multi-purpose platform concepts investigated, the numerical approaches adopted, and a comprehensive snapshot classifying the references discussed by industry (offshore renewables, aquaculture, both) and by aspect (technological, environmental, socio-economic). The majority of the multi-purpose platform concepts proposed are integrating only multiple offshore renewable energy devices (e.g. hybrid wind-wave), with only few integrating also aquaculture systems. MPPs have significant potential in economizing CAPEX and operational costs for the offshore energy and aquaculture industry by means of concerted spatial planning and sharing of infrastructure.

Microplastic Fallout in Different Indoor Environments.

Microplastics in the air have gradually attracted our attention in recent years; however, temporal and spatial trends of microplastics in indoor air are rarely discussed. In the present study, we tracked microplastic fallout in a dormitory, an office, and a corridor on both workdays and weekends for three months. In addition, an air conditioner was used to understand airflow influence on microplastic resuspension in the dorm. Among the three sampling sites, the highest average microplastic abundance appeared in the dormitory (9.9 × 103 MPs/m2/d), followed by the office (1.8 × 103 MPs/m2/d) and the corridor (1.5 × 103 MPs/m2/d). In the dormitory, the average MP abundance on weekends (1.4 × 104 MPs/m2/d) was approximately three times of that on weekdays (5.8 × 103 MPs/m2/d). In the office; however, the abundance on weekends (1.2 × 103 MPs/m2/d) was 50% of that on weekdays (2.4 × 103 MPs/m2/d). Microplastic fallout existed mostly in the form of fibers and showed similar polymer compositions to the textile products used in indoor environments. The airflow tests using an air conditioner suggested that airflow turbulence increased resuspension of microplastics. Taken together, we conclude that indoor environments are prone to serious microplastic pollution, but microplastic level varies greatly due to different characteristics of indoor setting. Our results also indicate that textile quantity is one of the main factors affecting microplastic abundance in indoor air, whereas air conditioner-induced airflow turbulence can cause microplastic migration in indoor environments.

Fusion of microplastics into the mussel byssus.

Microplastics have been found to adhere to the surface of specific tissues or organs other than being ingested by the organisms. To further test the hypothesis that microplastics might get into specific body parts of organisms, mussel byssus was chosen as a target subject in the present study. In the field investigation, microplastics were found in mussel byssus, and the abundance of microplastics was 0.85-1.02 items/individual mussel and 3.69-9.16 items/g byssus, but the location of microplastics in byssus was not easily determined. Therefore, we simulated environmental conditions in the laboratory for mussels to form fresh byssus in the presence of microplastics. Three types of man-made microplastics (Polystyrene beads, Polyamide fragments, and Polyester fibers) were found in newly formed byssus of mussels after exposure to these test materials. We observed that microplastics not only adhered to the surface but also fused into the byssus of mussels. Since byssus is important for the well-being of mussels, the incorporation of microplastics into the byssus might impair the function of byssus. To the authors' best knowledge, this is the first study to show that microplastics can contact and fuse with the byssus of mussels during their formation, suggesting possible alternations for mussels to grip and interact with microplastics in the aquatic environments.

A practical approach based on FT-IR spectroscopy for identification of semi-synthetic and natural celluloses in microplastic investigation.

In previous studies of marine debris or microplastics (<5 mm), various types of semi-synthetic celluloses (e.g. rayon) are ubiquitous in some field investigations. However, it is hard to distinguish semi-synthetic and natural celluloses clearly even using the spectroscopic method. In this study, 8 semi-synthetic and 4 natural celluloses were employed as the test materials to simulate the environmentally relevant samples. Our results showed that these original commercial products exhibited obvious physical (e.g., color) and chemical (e.g., spectra) changes after UV weathering and agent (H2O2 and KOH) digestion treatments. The changes of 4 characteristic bands (1735, 1425/1419, 1105, 1060-1053/1030-1027 cm-1) were evaluated. We found that the band at 1105 cm-1 which is assigned to the CO antisymmetric in plane stretching band only existed in natural fibers even after the weathering and digestion treatments. The mixture of semi-synthetic and natural fibers from the real field samples was also easily distinguished using the characteristic band at 1105 cm-1. Our results suggest that the characteristic band at 1105 cm-1 could be an ideal reference to distinguish natural and semi-synthetic fibers in field microplastic investigations. We also proposed a practical method to enhance the library of polymer spectra and improve the accuracy of semi-synthetic microplastic identification.

The uptake of microfibers by freshwater Asian clams (Corbicula fluminea) varies based upon physicochemical properties.

Microplastic is an umbrella term that covers particles with various physical and chemical properties. However, microplastics with a consistent shape, polymer type and size are generally used in exposure studies (e.g., spherical polyethylene or polystyrene beads 1-100 µm in size). In the present study, we exposed freshwater Asian clams (Corbicula fluminea) to microfibers with different physicochemical properties at concentrations of 100 and 1000 fibers/L. The first experiment in this study exposed clams to microfibers made from six different polymers, demonstrating that Asian clams uptake more polyester (PET) (4.1 items/g) relevant to other polymers. The next experiment exposed clams to PET fibers of different size classes, demonstrating that uptake in the size range 100-250 µm (1.7 items/g) was greater than other size classes. These results suggest that physicochemical properties such as polymer and size play important roles in the uptake of microfibers by organisms. Thus, we strongly suggest that the properties of microplastics used in future laboratory exposure experiments be considered, with the aim of being "environmentally relevant", i.e., similar to what is found in nature.

A straightforward method for measuring the range of apparent density of microplastics.

Density of microplastics has been regarded as the primary property that affect the distribution and bioavailability of microplastics in the water column. For measuring the density of microplastis, we developed a simple and rapid method based on density gradient solutions. In this study, we tested four solvents to make the density gradient solutions, i.e., ethanol (0.8 g/cm3), ultrapure water (1.0 g/cm3), saturated NaI (1.8 g/cm3) and ZnCl2 (1.8 g/cm3). Density of microplastics was measured via observing the float or sink status in the density gradient solutions. We found that density gradient solutions made from ZnCl2 had a larger uncertainty in measuring density than that from NaI, most likely due to a higher surface tension of ZnCl2 solution. Solutions made from ethanol, ultrapure water, and NaI showed consistent density results with listed densities of commercial products, indicating that these density gradient solutions were suitable for measuring microplastics with a density range of 0.8-1.8 g/cm3.

Degradation behavior of triclosan by co-exposure to chlorine dioxide and UV irradiation: influencing factors and toxicity changes.

This study investigated the transformation of triclosan (TCS) following co-exposure to UV irradiation and ClO2. Special attention was given to understand the influencing of water quality parameters and toxicity changes during the co-exposure process. The results show that the co-exposure process prompted TCS elimination quickly and effectively, with more than 99% of TCS degraded under the experimental conditions. The molar yield ratios of 2,4-dichlorophenol/TCS (2,4-DCP/TCS) were calculated to be 35.81-74.49%; however, the by-product of 2,8-dichlorodibenzop-dioxin (2,8-Cl2DD) was not detected. The TCS degradation was sensitive to ClO2 dosage, pH, H2O2, and natural organic matter (NOM), but not to the carbonate (CO32-) concentration. Neutral and slightly alkaline condition were favorable to TCS elimination. The TCS removal rate increased from 85.33 to 99.75% when the ClO2 concentration increased from 0.25 to 1.5 mg L-1. TCS degradation can be promoted at low NOM level (1, 3, and 5 mg L-1), whereas was inhibited at high NOM concentrations of 7 and 9 mg L-1. While adding H2O2, the degradation rate of TCS increased with increasing H2O2 concentration from 1 to 3 mg L-1; however, too low or overdosed H2O2 (0.5 and 5 mg L-1) hindered TCS degradation. Based on the results of a microtox bioassay, the toxicity did not change following the co-exposure process.

Using the Asian clam as an indicator of microplastic pollution in freshwater ecosystems.

Bioindicators play an important role in understanding pollution levels, bioavailability and the ecological risks of contaminants. Several bioindicators have been suggested for understanding microplastic in the marine environment. A bioindicator for microplastics in the freshwater environment does not exist. In our previous studies, we found a high frequency of microplastic pollution in the Asian clam (Corbicula fluminea) in Taihu Lake, China. In the present study, we conducted a large-scale survey of microplastic pollution in Asian clams, water and sediment from 21 sites in the Middle-Lower Yangtze River Basin from August to October of 2016. The Asian clam was available in all sites, which included diverse freshwater systems such as lakes, rivers and estuaries. Microplastics were found at concentrations ranging from 0.3-4.9 items/g (or 0.4-5.0 items/individual) in clams, 0.5-3.1 items/L in water and 15-160 items/kg in sediment. Microfibers were the most dominant types of microplastics found, accounting for 60-100% in clams across all sampling sites. The size of microplastics ranged from 0.021-4.83 mm, and microplastics in the range of 0.25-1 mm were dominant. The abundance, size distribution and color patterns of microplastics in clams more closely resembled those in sediment than in water. Because microplastic pollution in the Asian clam reflected the variability of microplastic pollution in the freshwater environments, we demonstrated the Asian clam as an bioindicator of microplastic pollution in freshwater systems, particularly for sediments.

Modelling the nitrogen loadings from large yellow croaker (Larimichthys crocea) cage aquaculture.

Large yellow croaker (LYC) cage farming is a rapidly developing industry in the coastal areas of the East China Sea. However, little is known about the environmental nutrient loadings resulting from the current aquaculture practices for this species. In this study, a nitrogenous waste model was developed for LYC based on thermal growth and bioenergetic theories. The growth model produced a good fit with the measured data of the growth trajectory of the fish. The total, dissolved and particulate nitrogen outputs were estimated to be 133, 51 and 82 kg N tonne(-1) of fish production, respectively, with daily dissolved and particulate nitrogen outputs varying from 69 to 104 and 106 to 181 mg N fish(-1), respectively, during the 2012 operational cycle. Greater than 80 % of the nitrogen input from feed was predicted to be lost to the environment, resulting in low nitrogen retention (<20 %) in the fish tissues. Ammonia contributed the greatest proportion (>85 %) of the dissolved nitrogen generated from cage farming. This nitrogen loading assessment model is the first to address nitrogenous output from LYC farming and could be a valuable tool to examine the effects of management and feeding practices on waste from cage farming. The application of this model could help improve the scientific understanding of offshore fish farming systems. Furthermore, the model predicts that a 63 % reduction in nitrogenous waste production could be achieved by switching from the use of trash fish for feed to the use of pelleted feed.

Management of marine cage aquaculture. Environmental carrying capacity method based on dry feed conversion rate.

GOAL, SCOPE AND BACKGROUND: Marine cage aquaculture produces a large amount of waste that is released directly into the environment. To effectively manage the mariculture environment, it is important to determine the carrying capacity of an aquaculture area. In many Asian countries trash fish is dominantly used in marine cage aquaculture, which contains more water than pellet feed. The traditional nutrient loading analysis is for pellet feed not for trash fish feed. So, a more critical analysis is necessary in trash fish feed culturing areas. METHODS: Corresponding to FCR (feed conversion rate), dry feed conversion rate (DFCR) was used to analyze the nutrient loadings from marine cage aquaculture where trash fish is used. Based on the hydrodynamic model and the mass transport model in Xiangshan Harbor, the relationship between the water quality and the waste discharged from cage aquaculture has been determined. The environmental carrying capacity of the aquaculture sea area was calculated by applying the models noted above. RESULTS: Nitrogen and phosphorus are the water quality parameters considered in this study. The simulated results show that the maximum nitrogen and phosphorus concentrations were 0.216 mg/L and 0.039 mg/L, respectively. In most of the sea area, the nutrient concentrations were higher than the water quality standard. The calculated environmental carrying capacity of nitrogen and phosphorus in Xiangshan Harbor were 1,107.37 t/yr and 134.35 t/yr, respectively. The waste generated from cage culturing in 2000 has already exceeded the environmental carrying capacity. DISCUSSION: Unconsumed feed has been identified as the most important origin of all pollutants in cage culturing systems. It suggests the importance of increasing the feed utilization and improving the feed composition on the basis of nutrient requirement. For the sustainable development of the aquaculture industry, it is an effective management measure to keep the stocking density and pollution loadings below the environmental carrying capacity. CONCLUSIONS: The DFCR-based nutrient loadings analysis indicates, in trash fish feed culturing areas, that it is more critical and has been proved to be a valuable loading calculation method. The modeling approach for Xiangshan Harbor presented in this paper is a cost-effective method for assessing the environmental impact and determining the capacity. Carrying capacity information can give scientific suggestions for the sustainable management of aquaculture environments. RECOMMENDATIONS AND PERSPECTIVES: It has been proved that numerical models were convenient tools to predict the environmental carrying capacity. The development of models coupled with dynamic and aquaculture ecology is a requirement of further research. Such models can also be useful in monitoring the ecological impacts caused by mariculture activities.