Search

The spatial distribution and depth of precipitation are the main driving factors for the formation of flood disasters. Precipitation nowcasting plays a crucial role in rainstorm warning, flood mitigation and water resources management. However, high spatiotemporal resolution nowcasting is very challenging owing to the uncertain dynamics and chaos, especially at a small-scale region. In recent years, deep learning approaches were applied in precipitation nowcasting and achieved good performance in learning spatiotemporal features. In this paper, ConvLSTM model and sequences of radar reflectivity maps were used to forecast the future sequence of reflectivity maps with up to 2 h lead time in Liulin watershed with a small area of 57.4 km2. Dynamic hierarchical Z–I relationship was employed to calculate the forecasting precipitation and the forecasted spatiotemporal features were compared to the observed. The results indicated that the model can provide a well performance for the reflectivity above 10 dBZ with 0.70 of CSI for 30 min nowcasting and 0.57 for 2 h nowcasting, but was not good at forecasting the reflectivity above 30 dBZ with 0.38 of mean CSI for 30 min nowcasting and 0.12 for 2 h nowcasting, which have a decrease of 45.7% and 78.9%, respectively. The forecasted precipitation could truly show the details of precipitation spatial distribution and provide the accuracy of forecasting area with 49.2% for 30 min nowcasting. The satisfied areal precipitation depth could be offered basically with 26.3% of Bias for 30 min nowcasting in Liulin watershed. [ABSTRACT FROM AUTHOR]

Pesticide residues in kumquat fruits from China, and the quality and chronic/acute intake risks in Chinese consumers, were assessed using the QuEChERS procedure and UHPLC-MS/MS and GC-MS/MS methods. Our 5-year monitoring and survey showed 90% of the 573 samples of kumquat fruits collected from two main production areas contained one or multiple residual pesticides. Overall, 30 pesticides were detected, including 16 insecticides, 7 fungicides, 5 acaricides, and 2 plant growth modulators, of which 2 pesticides were already banned. Two or more residual pesticides were discovered in 81% of the samples, and pesticide residues in 9.4% of the samples surpassed the MRLs, such as profenofos, bifenthrin, triazophos, avermectin, spirodiclofen, difenoconazole, and methidathion. The major risk factors on the safety of kumquat fruits before 2019 were profenofos, bifenthrin, and triazophos, but their over-standard frequencies significantly declined after 2019, which was credited to the stricter supervision and management policies by local governments. Despite the high detection rates and multi-residue occurrence of pesticides in kumquat fruits, about 81% of the samples were assessed as qualified. Moreover, the accumulative chronic diet risk determined from ADI is very low. To better protect the health of customers, we shall formulate stricter organic phosphorus pesticide control measures and stricter use guidelines, especially for methidathion, triazophos, chlorpyrifos, and profenofos. This study provides potential data for the design of kumquat fruit quality and safety control guidelines and for the reduction in health risks to humans. [ABSTRACT FROM AUTHOR]

In the present study, the long-term and short-term cumulative risks of pyrethroids exposured for the Chinese general population and children through fruits consumption were evaluated. A total of 1450 fruit samples and seven pyrethroids were included based on the pesticide residues monitoring programme of China from 2013 to 2015. The exposure was estimated using both deterministic approach and semi-probabilistic model for comparison. The hazard index approach was used to assess cumulative risk. 26% of samples contained pyrethroid residues with concentrations ranged from 0.0050 mg/kg to 1.2 mg/kg, of which 30% simultaneously with 2–4 mixture residues. Results demonstrated that the cumulative health risks were extremely low for both general population and children (1–6 years old) of China in the long term. Acute risk estimations calculated by deterministic method were several or many times overestimated than the results based on semi-probabilistic method. Acute cumulative exposure of children to pyrethroid compounds in 0.76% samples were exceeded 1 in worst case scenario. More detailed assessments with adequate data in the future use probabilistic method is expected to reduce the uncertainties of cumulative dietary exposure. [ABSTRACT FROM AUTHOR]

In this study, residues and potential health risks of 16 commonly used insecticides and acaricides in 1633 citrus samples from nine cultivars in China were systematically analyzed. A quick, easy, cheap, effective, rugged, and safe method combined with gas chromatography tandem mass spectrometry and liquid chromatography tandem mass spectrometry was applied. In total, 77.3% of the samples were with residues, of which 57.7% contained 2–12 multi-residues. Etoxazole and chlorpyrifos were the top two detected pesticides with detection frequencies of 37.1% and 31.1%, respectively. Residues of eight analytes were over their MRLs with exceeding rates of 0.1%− 2.4%. The safety of the nine cultivars ranked as lemon > pummelo > ponkan > satsuma mandarin > orange > citrus hybrids > 'nanfengmiju' mandarin > 'shatangju' mandarin > kumquat according to IqR values and related to the producing areas. Chronic dietary risks of the 16 insecticides and acaricides were negligible low for Chinese consumers. However, %ARfD of triazophos in most citrus cultivars for all population and of bifenthrin in 'nanfengmiju' mandarin for children were beyond the acceptable levels, which indicated potential acute health risks. Application of triazophos, bifenthrin, profenofos and etoxazole in citrus should be controlled. [Display omitted] • 16 insecticides and acaricides were analyzed in 1633 citrus samples. • 77.3% of samples contained residues and 57.7% were multi-residues. • Etoxazole and chlorpyrifos were mostly detected and eight analytes exceeded MRLs. • The safety index followed as LM > PM > PK > SS > OR > CH > NF > ST > KQ. • Acute dietary risks of triazophos and bifenthrin were potential unacceptable. [ABSTRACT FROM AUTHOR]

Citrus is highly consumed in China and considered a major source of pesticide carrier in human diet. In this paper, pesticide residues in mandarins, tangerines and oranges from China were evaluated, as well as the quality and long-term dietary risks for the Chinese consumers. Temporal variations for eight MRL non-compliant pesticides were also investigated. 106 pesticides were analyzed using QuEChERS procedure and UPLC-MS/MS, GC-MS and GC methods. Forty different pesticides were detected in 86% of the 2922 samples from 2013 to 2018. Chlorpyrifos was the most frequently detected pesticide with a detection rate of 40%. Residues of eight pesticides in 3.8% of the total samples exceeded their MRLs. The most severely excessive pesticide was bifenthrin with 283% MRL. The occurrences and exceeding rates of eight pesticides presented clear temporal variations during the six harvesting years. Isocarbophos, carbofuran and triazophos were the main risk factors threatening the citrus safety pre-2015, whereas profenofos and bifenthrin gradually became dominant after 2016, coinciding with government control measures. The index of quality for residues (IqR) levels of 88% of the samples were below 1.0, which indicated a satisfactory quality of citrus fruits in China, although 70% of the samples contained two or more residues. The cumulative chronic dietary risks were acceptable for both the Chinese general population and children and would not pose health risks. However, more strictly enforced control measures for methidathion and isocarbophos, and reduced usage of triazophos, quinalphos, profenofos and bifenthrin should be pursued to further improve the safety of citrus fruits. Image 1 • 40 out of 106 different pesticides were detected in 2922 citrus samples and 3.8% of samples exceeded their MRLs. • Occurrence and MRL exceedance of eight pesticides presented clear temporal variations from 2013 to 2018. • The IqR level for 88% of the samples below 1.0 indicated a satisfactory quality of citrus fruits on the whole. • The cumulative chronic dietary intakes did not pose health risks for Chinese general population and children. [ABSTRACT FROM AUTHOR]

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique using ultrahigh-performance liquid chromatography with tandem mass spectrometry for the analysis of spinosad (spinosyn A + spinosyn D), thiocyclam, and nereistoxin in cucumber was developed with mean recoveries of 93-104%, relative standard deviations of ≤9%, and limits of quantification of 0.01 mg/kg. Field trials of spinosad and thiocyclam were performed in 12 representative cultivating areas in China. Field trial results indicate that spinosyn A and spinosyn D easily dissipated in cucumber with half-lives of 2.48-6.24 and <3 days, respectively. Nereistoxin was produced after thiocyclam application and was more persistent than its parent. The terminal residues of spinosad were all below the maximum residue limits (0.2 mg/kg) in China, whereas the terminal concentration of nereistoxin (calculated as the stoichiometric equivalent of thiocyclam), which was much higher than that of thiocyclam, was far beyond the maximum residue limits of thiocyclam in cucumber (0.01 mg/kg) established by the European Union. The predicted no-effect concentrations of spinosyn A, spinosyn D, thiocyclam, and nereistoxin leaching into groundwater were estimated using China-PEARL (Pesticide Emission Assessment at Regional and Local scales) models after application. However, the dietary (food and water) exposure risk quotient for different populations was below 1 with a preharvest interval set at 5 days after the last application, indicating that the application of spinosad and thiocyclam in cucumber was unlikely to pose unacceptable risk for human health. This study provides data for the safe use of spinosad and thiocyclam in cucumber ecosystem., (© 2023 John Wiley & Sons Ltd.)

Dissipation of imidacloprid (IMI) and its metabolites (urea, olefin, 5-hydroxy, guanidine, 6-chloronicotinic acid) in Chinese prickly ash (CPA) was investigated using QuEChERS combined with UPLC-MS/MS. Good linearity (r 2 ≥0.9963), accuracy (recoveries of 71.8-104.3%), precision (relative standard deviations of 0.9-9.4%), and sensitivity (limit of quantification ≤0.05 mg kg -1 ) were obtained. After application of IMI at dosage of 467 mg a.i. L -1 for three times with interval of 7 d, the dissipation dynamics of IMI in CPA followed first-order kinetics, with half-life of 6.48-7.29 d. IMI was the main compound in CPA, followed by urea and guanidine with small amounts of olefin, 5-hydroxy, and 6-chloronicotinic acid. The terminal residues of total IMI and its metabolites at PHI of 14-21 d were 0.16-7.80 mg kg -1 in fresh CPA and 0.41-10.44 mg kg -1 in dried CPA, with the median processing factor of 3.62. Risk assessment showed the acute (RQa) and chronic dietary risk quotients (RQc) of IMI in CPA were 0.020-0.083% and 0.052-0.334%, respectively. Based on the dietary structures of different genders and ages of Chinese people, the whole dietary risk assessment indicated that RQc was less than 100% for the general population except for 2- to 7-year-old children (RQc of 109.9%), implying the long-term risks of IMI were acceptable to common consumers except for children., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)