Spatiotemporal variation in microplastics derived from polymer-coated fertilizer in an agricultural small river in Ishikawa Prefecture, Japan.

Marine plastic pollution has highlighted the need to address the disposal of plastic materials used in agricultural fields and prevent their runoff. To assess the status of microplastics derived from polymer-coated fertilizers (microcapsules), we investigated their seasonal and daily variations in a small agricultural river in Ishikawa Prefecture, Japan, throughout the irrigation period of April to October 2021 and 2022. We also investigated the relationship between microcapsule concentration and water quality. The mean microcapsule concentration over the study period ranged from 0.0 to 783.2 mg/m3 (median 18.8 mg/m3) and was positively correlated with total litter weight, but it was not correlated with common water quality parameters such as total nitrogen or suspended solids. Concentrations of microcapsules in river water showed distinct seasonal variations, being particularly high in late April and late May (median 55.5 mg/m3 in 2021, 62.6 mg/m3 in 2022) and almost undetectable thereafter. The timing of the increase in concentration coincided with the timing of the outflow from paddy fields, suggesting that microcapsules that flowed out of the paddy fields would reach the sea relatively quickly. The results of a tracer experiment supported this conclusion. Intensive observations revealed that microcapsule concentrations varied widely over time, with differences reaching a maximum of 110-fold (range 7.3-783.2 mg/m3) over a 3-day period. Daytime concentrations were higher than those at night, reflecting the fact that microcapsules are discharged from paddies by daytime operations such as puddling and surface drainage. Microcapsule concentrations in the river were not correlated with river discharge, making estimating their loading a future research challenge.

Addition of polyvinyl pyrrolidone during density separation with sodium iodide solution improves recovery rate of small microplastics (20-150 µm) from soils and sediments.

The purpose of this study was to identify a method to accurately separate small microplastics (<100 µm) from soil and sediment. We initially conducted spike-and-recovery tests using polyethylene microbeads and density separation and found that the recovery rate of microplastic particles smaller than 100 µm was less than 60%. This result suggested that previous reports have underestimated the concentrations of microplastics smaller than 100 µm in soil. When polyvinyl pyrrolidone was added and dispersed in a heavy liquid, the recovery rate exceeded 90%, regardless of the microplastic particle size. This improved recovery rate was independent of the type of polymer (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, or nylon 6) and the physicochemical properties of the soil (Andisols, Entisols, or Ultisols), and the method was also effective for marine and lake sediments. Using this method, we measured microplastic concentrations in paddy soil. The results showed that the most common particle size, 20-100 µm, accounted for 64% of all microplastics. Accurate separation from the soil of fractions smaller than 100 µm, which account for the majority of microplastics in soil, will enable an accurate assessment of the impact of microplastics on the soil ecosystem. The method identified in this study can serve as the basic technique for achieving that goal.

Effects of changes in polycyclic aromatic hydrocarbons (PAHs) emissions and degradation on their concentrations in Tokyo from 2007 and 2016.

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in aerosol were measured in Shinjuku, which is central Tokyo, Japan, for 10 years from 2007 to 2016. The effects of changes in emission sources and their degradation by reaction with ozone were assessed in this study. There was no significant increasing or decreasing trend of the PAH concentrations during 10 years (P > 0.05). The average selected seven the PAH concentrations (0.88 ng m-3) during 10 years was lower than those in New York and Paris. However, the trend of ozone concentrations is increasing in central Tokyo. This inconsistency raises a question. Did the fact that the ozone concentration was higher than the PAH concentrations promote PAH degradation? To apportion the PAH sources, we used PAH concentration profiles and positive matrix factorization analysis. The contribution of vehicle emissions to the PAHs ranged from 40 to 80%. Ozone concentrations increased by 3.70%/year during 10 years. The theoretical degradation rates of PAHs by ozone, which were calculated using a pseudo-first-order rate equation, suggested that the lifetimes of benzo[a]pyrene (BaP) decreased by 1 min from 2007 to 2016. We investigated the aging of BaP using the profile of the isomer ratios. We found that the aging of BaP at the urban and roadside sites were nearly identical indicating aging regardless of the season. Although the decomposition of BaP is promoted by the photochemical oxidation reaction, this result suggests that a certain threshold value exists as the degree of the decomposition. This degradation of PAH can improve chemical loss processes in air quality model.

The input-output balance of microplastics derived from coated fertilizer in paddy fields and the timing of their discharge during the irrigation season.

Polymer-based microcapsules derived from coated fertilizers are not recovered after use. Therefore, they are a source of microplastics to the agricultural lands and coastal areas of Japan. In this study, we investigated the input-output balance of microcapsules in three paddy fields and the timing of microcapsule discharge from the fields with the aim of developing effective techniques to reduce microcapsule discharge. Microcapsules were discharged from the paddy fields primarily during puddling, when the weir plate was overflowed, and when surface drainage was implemented. About 50% of the total discharge during the irrigation period occurred during puddling, which is a process for leveling paddy fields. Therefore, contamination of the surrounding environment by microcapsules from paddy fields can be effectively reduced by preventing the release of microplastics from paddy fields during puddling. We also showed that the total microcapsule discharge cannot be controlled solely by irrigation water management, such as by adjusting the height of the weir plate. We found that about 0.067-0.076% of the total number of microcapsules accumulated in the soil of the paddy fields was discharged during the irrigation season in 2020. Furthermore, 70% of the microcapsules discharged from one field in 2020 had resided in the soil for at least two years. The use as fertilizer coatings of biodegradable polymers that would degrade completely in the soil within a few years could therefore substantially reduce the amount of microplastics released into the ocean from agricultural fields, and their development is thus urgently needed.

Accumulation of microcapsules derived from coated fertilizer in paddy fields.

Japanese agriculture uses large amounts of plastics. Fertilizer-containing plastic microcapsules with a diameter of 2-5 mm ("coated fertilizer") are not recovered after use, and after diffusion of the fertilizer components these microcapsules are found in large quantities, not only on agricultural land but also along the coast of Japan. Here, we investigated the accumulation of microcapsules derived from coated fertilizer in 19 paddy fields. Microcapsules were detected in all of the paddy fields surveyed, at concentrations in the range of 6-369 mg/kg (mean 144 mg/kg)-much higher than the concentrations of microplastics in farmlands in other countries. There was no difference in mean microcapsule concentration between sampling sites with continuous rice cultivation and those with crop rotation, but that of a paddy field that had never received coated fertilizer was significantly lower. Examination of the spatial distribution of microcapsules in one paddy field showed that there was a hot spot with a high concentration near the drainage outlet. This was likely due to the strong influence of irrigation water flowing from the water inlet to the drainage outlet. The amount of microcapsules accumulated in Japanese paddy fields, as estimated from our results, and the amount applied to the fields, as estimated from the statistics, were almost equivalent. Therefore, most of the microcapsules that have already been applied to paddy fields may continue to accumulate. The impact of these high concentrations of microcapsules on the soil environment needs to be assessed.

Prevention of the rise in plasma cholesterol and glucose levels by kaki-tannin and characterization of its bile acid binding capacity.

BACKGROUND: Bile acid-binding agents, such as cholestyramine and colesevelam, improve both cholesterol and glucose metabolism. Kaki-tannin, a polymerized condensed tannin derived from persimmon (Diospyros kaki), has been shown to have bile acid-binding capacity and a hypocholesterolemic effect. However, its effects on glucose metabolism have not been well studied, and the binding selectivity of kaki-tannin to bile acid molecules has not been reported. RESULTS: In vivo experiments using mice with high-fat diet-induced obesity showed that kaki-tannin intake (20 g kg-1 of the diet) increased fecal bile acid excretion by 2.3-fold and prevented a rise in plasma cholesterol levels and fasting plasma glucose levels. Kaki-tannin also suppressed the development of impaired glucose tolerance. To characterize the bile acid-binding capacity of kaki-tannin, we investigated its capacity to bind to eight types of bile acid and cholesterol in vitro. Kaki-tannin showed strong capacity to bind to lithocholic acid (85.5%), which has one hydroxy group. It also showed moderate capacity to bind to bile acids with two hydroxy groups (53.3%), followed by those with three hydroxy groups (39.0%), but kaki-tannin did not show binding capacity to cholesterol. These results suggest that the binding capacity of kaki-tannin to bile acids tends to decrease as the number of hydroxy groups increases. Interestingly, the binding capacity of kaki-tannin correlated with that of cholestyramine (correlation coefficient: r = 0.900). CONCLUSION: Our findings indicate that kaki-tannin binds preferentially to bile acids with fewer hydroxy groups and has beneficial effects on glucose metabolism as well as cholesterol metabolism. © 2020 Society of Chemical Industry.

The role of coated fertilizer used in paddy fields as a source of microplastics in the marine environment.

Fixed-point and multi-point field survey was conducted to determine the actual contamination of the Japanese coast by microcapsules derived from coated fertilizers. The results indicated that the amount of microcapsules increased during the irrigation season (9423-74,869 pieces/m2) and decreased in the non-irrigation season (77-1471 pieces/m2). Microcapsules accounted for 90% of all microplastics sampled during the irrigation season. The lack of correlation between the area of agricultural land in the watershed and the microcapsule density on the coast suggested that the density of microcapsules on the coast was not only dependent on the total load to the ocean, but also on topographic and meteorological conditions. More than 90% of the microcapsules collected from the shoreline were made of polyethylene. Scanning electron microscopic observation of the surface of the microcapsules revealed that portions of the microcapsules were removed as secondary microplastics in the process of migration to the ocean.

Characterization of physicochemical and digestive properties of starches from various "dainagon" adzuki beans (Vigna angularis) cultivated in Japan.

We investigated the physicochemical properties of starches extracted from Vigna angularis variants Noto-dainagon, Kyoto-dainagon, dainagon, and erimo-type adzuki beans. The particle size was larger in the Noto-dainagon starch than in the other starches, but all starches displayed a C-type crystal structure in the X-ray diffraction analysis. The onset and peak temperatures of gelatinization were approximately 7 °C lower in the Noto-dainagon and Kyoto-dainagon starches than in the dainagon and adzuki bean starches. The dainagon and adzuki bean starches also demonstrated lower swelling power at 60 °C than the other starches. The rapid visco-analyser curves of all starches showed no breakdown during the heating process, and the final viscosities of the starches increased with decreasing temperature. The apparent amylose and phosphorus contents were highest in the Noto-dainagon starch (36.6% and 95.6 ppm, respectively). The branched- chain length degree of polymerization 6-12 was lowest in the adzuki bean starch. In vitro and in vivo analyses of the digestive properties indicated that dainagon starch was more indigestible than the other starches. We considered that dainagon starch was a potentially viable health-promoting ingredient.

Physicochemical Properties of Starches from Lotus Rhizomes Harvested in Different Months.

We investigated the physicochemical properties of starches extracted from 8 lotus (Nelumbo nucifera Gaertn.) rhizomes harvested in different months (September 2012 to May 2013). The physicochemical properties of the lotus starches depended on the harvest date. The peak viscosity (PV) in the Rapid Visco-Analyser analysis, and the viscosity at 65 °C (V65) in the rotational viscometer analysis were significantly lower in SEP starch (extracted from the September-harvested sample) than in the other lotus starches. The Spearman's rank correlation coefficients of potassium ion (K) content vs. V65 and of K content vs. PV were 0.905 and 0.714, respectively, indicating that potassium ions are important for expressing the pasting properties of lotus starch. Principal component analysis suggested that the potassium, magnesium, calcium, and phosphorus contents are important for displaying both the pasting and gelatinization properties of the lotus starches. Meanwhile, the cluster analysis revealed that physicochemical properties of the SEP starch were different from those of the starches harvested in other months.

Characterization of soil organic matter with different degrees of humification using evolved gas analysis-mass spectrometry.

Evolved gas analysis-mass spectrometry (EGA-MS) provides a direct connection between the pyrolyzer and mass spectrometer through a deactivated capillary tube, and provides both a thermal profile relating to the differential thermogravimetric curve of the sample and a mass spectrum of evolved gas from the sample. In this study, EGA-MS was performed to obtain thermal profiles and identify the pyrolysis products of 12 humic acids (HAs) with different degrees of humification extracted from 5 Andisols, 3 Entisols, and 3 Inceptisols, as well as soil samples. All HAs were thermally decomposed gradually over a wide temperature range (100-700°C), and the EGA curves showed four peaks and shoulders at around 250, 350, 450, and 550°C. The peaks at around 550°C were observed for the Andisol HAs only. Carboxyl groups, carbohydrates, and short chain alkanes and alkenes of the HAs and bulk soil samples evolved at a relatively low-temperature region (200-300°C). On the other hand, aromatics including benzenes and lignin derivatives evolved at a relatively high-temperature region (300-600°C). While the shapes of the EGA curves were different between the soils and extracted HAs, the major components of the evolved gas and the pyrolysis behavior of the constituents in the HAs and soil samples were similar. The amount of evolved gas from the Andisol HAs, which mainly consisted of CO2, was very low in comparison to that from the Entisol and Inceptisol HAs. The amount of evolved gas and the molecular weight of the pyrolysis products decreased as humification progressed, but the proportion of CO2 in the total area of the EGA curves increased. The results demonstrated that humification reduces the proportion of volatile components and increases the amount of carboxyl groups. As a result, the molecular structure of HAs is found to be mainly composed of non-volatile components and carboxyl groups. Since EGA-MS can provide information about the chemical structure and pyrolysis characteristics of a small sample without pretreatment, it is a useful tool for soil organic matter research.

Effects of heating on composition, degree of darkness, and stacking nanostructure of soil humic acids.

Wildfires and prescribed burning can affect both the quality and the quantity of organic matter in soils. In this study, we investigated qualitative and quantitative changes of soil humic substances in two different soils (an Entisol from a paddy field and an Inceptisol from a cedar forest) under several controlled heating conditions. Soil samples were heated in a muffle furnace at 200, 250, or 300 °C for 1, 3, 5, or 12h. The humic acid and fulvic acid contents of the soil samples prior to and after heating were determined. The degree of darkness, elemental composition, carbon and nitrogen stable isotope ratios, (13)C nuclear magnetic resonance spectra, and X-ray diffraction patterns of humic acids extracted from the soils before and after heating were measured. The proportion of humic acids in total carbon decreased with increasing heating time at high temperature (300 °C), but increased with increasing heating time at ≤ 250 °C. The degree of darkness of the humic acids increased with increasing heating time and temperature. During darkening, the H/C atomic ratios, the proportion of aromatic C, and the carbon and nitrogen stable isotope ratios increased, whereas the proportions of alkyl C and O-alkyl C decreased. X-ray diffraction analysis verified that a stacking nanostructure developed by heating. Changes in the chemical structure of the humic acids from the heated soils depended on the type of soil. The major structural components of the humic acids from the heated Entisol were aromatic C and carboxylic C, whereas aliphatic C, aromatic C, and carboxylic C structural components were found in the humic acids from the heated Inceptisol. These results suggest that the heat-induced changes in the chemical structure of the humic acids depended on the source plant.

Physicochemical Properties of Starches from Different Lotus Cultivars in Japan: Shinashirobana cultivar and Kanasumi-line No. 20.

We investigated the physicochemical properties of starches from rhizomes of two lotus (Nelumbo nucifera Gaertn.) cultivars, Shinashirobana cultivar and Kanasumi-line No. 20, harvested at the same farm in Japan. A rapid visco analyser analysis indicated that pasting temperatures of the starches from Shinashirobana cultivar and Kanasumi-line No. 20 were 62.1 and 66.5 °C, respectively, and the peak viscosities of the starch of both lotuses were similar 244 and 240 RVU, respectively. The starch from the Kanasumi-line No. 20 at 60 °C had low viscosity, 16.2 mPa∙s, but the starch from Shinashirobana cultivar had higher viscosity, 2,720 mPa∙s, at 60 °C. The onset and peak temperatures of the differential scanning calorimetry (DSC) curve of the starch from Shinashirobana cultivar were 4-5 °C lower than those of the starch from Kanasumi-line No. 20, although both exhibited similar ΔH values (13.4 and 11.6 J/g). The distribution patterns of the branched chain lengths of amylopectin in the two starches indicated that the rate of low-degree of polymerization (DP 5-12) of all branched chains was higher for the starch from Shinashirobana cultivar than that for the starch from Kanasumi-line No. 20. These results suggest that the increased rate of DP 5-12 in the starch from Shinashirobana cultivar is related to the higher viscosity of the starch.

Activation of Nitrogen-Fixing Endophytes Is Associated with the Tuber Growth of Sweet Potato.

Endophytic nitrogen-fixing organisms have been isolated from the aerial parts of field-grown sweet potato (Ipomoea batatas). The (15)N dilution method, which is based on the differences in stable nitrogen isotope ratios, is useful for measuring nitrogen fixation in the field. In this study, seedlings of two sweet potato cultivars, 'Beniazuma' and 'Benikomachi,' were transplanted into an alluvial soil that had been treated with organic improving material in advance. Whole plants were sampled every 2 or 3 weeks. After separating plants into tuberous roots and leaves, the fresh weights of the samples were measured, and the nitrogen content and natural (15)N content of leaves were determined with an elemental analyzer and an isotope ratio mass spectrometer linked to an elemental analyzer, respectively. The contribution of nitrogen fixation derived from atmospheric N2 in sweet potato was calculated by assuming that leaves at 2 weeks after transplanting were in a non-nitrogen-fixing state. The contribution ratios of nitrogen fixation by nitrogen-fixing endophytes in leaves of both sweet potato cultivars increased rapidly from 35 to 61 days after transplanting and then increased gradually to 55-57% at 90 days after transplanting. Over the course of the sweet potato growing season, the activity of nitrogen-fixing endophytes in leaves began to increase at about 47 days after transplanting, the weight of leaves increased rapidly, and then growth of tuberous roots began a few weeks later. Our findings indicate that nitrogen-fixing endophytes will be activated under inorganic nitrogen-free sweet potato cultivation, allowing for growth of the tuberous roots.

[NSAID and its effect on prostaglandin].

Recently, the use of non-steroidal anti-inflammatory drug(NSAID) as an anti-inflammatory analgesic and antithrombotic has increased with the general aging of our society. Although it is understood that gastric mucosal injury is most-frequent side-effect of NSAID, there are actually a variety of mechanisms that NSAID has, some which are due to the depressed production of prostaglandin (PG). The main action of PG in the gastric mucosa is the regulation of gastric mucosa protecting mechanism and if PG is insufficient, the gastric mucosa is weakened. As endogenous PG decreases, there is a decrease in mucus production accompanied by a decrease in bicarbonate secretion, problems with, an increase of stomach motility, tissue restoration suppression and so on. As a result, it is considered that the defense mechanisms decrease and gastric mucosal injury occurs.

Effect of oral branched chain amino acid-rich nutrient administered during endoscopic injection sclerotherapy of cirrhotic patients.

Endoscopic injection sclerotherapy (EIS) is conducted to treat esophageal varices associated with liver cirrhosis. Cirrhotic patients have protein energy malnutrition (PEM), and their malnutrition is aggravated during EIS due to dietary restrictions. The aim of this study was to evaluate the dietetic benefits of oral branched chain amino acid-rich nutrient (BCAA-rich nutrient) administered during EIS. Cirrhotic patients admitted for prophylactic EIS were divided into three groups: Group A given a general liquid nutrient in two divided doses, Group B given a BCAA-rich nutrient in two divided doses, and Group C given the BCAA-rich nutrient in four divided doses. The nutritional state was evaluated based on physical examinations, biochemical parameters, and indirect calorimetry. A total of 29 patients were enrolled. Blood biochemical examinations showed a significant increase in the Fischer's ratio in Groups B and C. Group B showed significant decreases in resting energy expenditure/basal metabolic rate, while Group C showed a significant rise in non-protein respiratory quotient. The oxidation rate of carbohydrate significantly increased and that of fat significantly decreased in Group C. Administration of the BCAA-rich nutrient is considered to be useful in improving abnormalities of energy metabolism during EIS.

New guide wire technique for stent placement through an occluded self-expandable metal stent: The hairpin technique.

BACKGROUND AND AIMS: Self-expandable metal stents (SEMS) for malignant biliary strictures sometimes occlude, requiring the insertion of another stent. When a guide wire is advanced conventionally through the proximal portion of an occluded SEMS, the guide wire sometimes penetrates the stent mesh. The present study reports a new guide wire insertion technique that prevents this problem from occurring. METHODS: In this new method of advancing a guide wire, the tip is not straight but bent into a curve. Because the advancing end of the guidewire is rounded like a hairpin, it cannot penetrate the stent mesh. Before cannulation, the flexible tip of the guide wire is extended out of the tip of the cannula in the descending duodenum and then cannulation is carried out as the flexible tip makes a hairpin curve. The guide wire with a maintained hairpin curve is advanced through the proximal end of the SEMS. The hairpin curve pops open and the guide wire straightens out when the guide wire has passed through the SEMS. After that, a second stent can be inserted over the guide wire. This technique has been utilized 14 times for occluded SEMS in 10 patients between June 2001 and September 2003. RESULTS: In all patients the technique served to ensure access to the biliary tree and successful placement of a second stent. CONCLUSIONS: This new hairpin guide wire technique was effective in preventing the guide wire from penetrating the stent mesh and, therefore contributed to successful stent placement within occluded SEMS.

Endoscopic hemostasis: safe treatment for peptic ulcer patients aged 80 years or older?

BACKGROUND AND AIM: Recently, the number of peptic ulcer patients aged 80 years or older has been increasing. However, little information is available concerning therapeutic endoscopy for these patients. The objective of this study was to evaluate the efficacy of endoscopic hemostasis for peptic ulcer bleeding in patients aged 80 years or older. METHODS: In this 7-year study, bleeding peptic ulcer patients were divided into group A (>/=80 years old) and group B (<80 years), for which prospective data, endoscopic findings and outcomes of endoscopic treatment were compared. RESULTS: Of the 459 patients who underwent endoscopic hemostasis for peptic ulcer bleeding, the 42 patients (average age 84 +/- 3 years) in group A had a significantly higher incidence of concomitant disease, lower hemoglobin, transfusional requirement over 800 mL and lower serum albumin than the 417 patients (average age 55 +/- 13 years) in group B. Significantly more patients in group A had large gastric ulcers. More patients in group A had ulcers located at the proximal third of the stomach, which is technically difficult to treat endoscopically. Nevertheless, all patients in groups A and B underwent initial hemostasis successfully. The rebleeding rate was not significantly different between group A and B. Neither group had hospital deaths nor complications related to endoscopic procedures. CONCLUSIONS: Endoscopic hemostasis for peptic ulcer bleeding in patients aged 80 years or older is effective and safe. Increasing age may no longer be a risk factor for rebleeding and hospital death after endoscopic hemostasis for peptic ulcer bleeding.

Short-term and long-term benefits of endoscopic hemoclip application for Dieulafoy's lesion in the upper GI tract.

BACKGROUND: Dieulafoy's lesion is an important cause of GI bleeding. The results of hemoclip application as the first treatment of choice for Dieulafoy's lesions have not been reported. This study prospectively examined the short- and long-term outcomes of hemoclip application for Dieulafoy's lesions. METHODS: The study was conducted over a 7-year period beginning in January 1995 during which hemoclip application was used as the first-choice hemostatic treatment for Dieulafoy's lesions. Clinical data, endoscopic findings, and outcome of treatment were evaluated. Long-term outcome for patients was also investigated. RESULTS: A Dieulafoy's lesion was diagnosed in 34 patients (27 men, 7 women; mean age, 54 years, range 21-81 years) after a mean of 1.2 endoscopies; 79.4% of the patients had active bleeding. Initial hemostasis was attained by hemoclip placement in 94.1%. The rate of recurrent bleeding was 9.3%. No patient required additional treatment such as surgery. The 30-day mortality rate was 2.9% (1 death, unrelated). For the remaining 33 patients, median follow-up was 53.8 months (range 19 to 90 months). Another Dieulafoy's lesion developed in one patient during follow-up, but in a different location compared with the index lesion. CONCLUSIONS: Endoscopic hemoclip application for Dieulafoy's lesions was effective and safe with short- and long-term benefits.