Single injection by LC-ESI-MS/MS for simultaneous determination of organophosphate tri- and di-esters in plant tissue based on ultrasonic-assisted sequential extraction and single-step purification.

A novel methodology based on ultrasonic-assisted sequential extraction, dispersive-SPE purification, and single-injection on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is proposed, for the first time, to simultaneously measure 14 tri-OPEs and 9 di-OPEs in plant tissues. The samples were successively ultrasonicated with a mixture of hexane:dichloromethane (1:1, v/v) and 8% acetic acid in acetonitrile for extracting tri- and di-OPEs purified with graphitized carbon black and quantitated on LC-MS/MS at the same time. The recoveries of targeted tri- and di-OPEs in the matrix spike ranged from 66% to 120% and 71% to 110% respectively. The proposed method was validated by processing eight types of common vegetables including spinach (Spinacia oleracea L.), lettuce (Lactuca sativa), carrot (Daucus carota var. sativa Hoffm.), sweet potato (Solanum tuberosum L.), cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), green beans (Phaseolus vulgaris), and cowpeas (Vigna unguiculata), with the recoveries of surrogates ranging from 84% to 98%.

Microplastics in take-out food: Are we over taking it?

Take-out food has become increasingly prevalent due to the fast pace of people's life. However, few study has been done on microplastics in take-out food. Contacting with disposable plastic containers, take-out food may be contaminated with microplastics. In the present study, abundance and characteristics of microplastics in total of 146 take-out food samples including solid food samples and beverage samples (bubble tea and coffee) were determined and identified. The mean abundance of microplastics in take-out food was 639 items kg-1, with the highest value in rice and the lowest value in coffee. Fragments shape, transparent color and sizes ≤ 500 µm were the main characteristics of microplastics in those food, and polyethylene was the main polymer type. Our results indicated that microplastics in take-out food was influenced by food categories and cooking methods, as well as food packaging materials. Approximately 170-638 items of microplastics may be consumed by people who order take-out food 1-2 times weekly.

Soil C-N-P pools and stoichiometry as affected by intensive management of camellia oleifera plantations.

Intensive management of C. oleifera has produced many pure C. oleifera plantations. The transmission of C. oleifera plantation will potentially affect soil C, N, and P pools as well as their stoichiometric characteristics both in top soil layer and vertical soil profile due to the intensive management. To understand changes in vertical pools and stoichiometric characteristics of soil C, N, and P as affected by intensive management of C. oleifera plantations, both mixed and pure C. oleifera plantations were studied. We conducted studies in five locations in Jiangxi, China with both pure and mixed C. oleifera plantations, to compare changes in vertical pools and stoichiometry of C, N, and P. Both C and N pools were significantly different between mixed and pure plantation types of C. oleifera. However, the ratio of C:N, C:P, and N:P was consistently higher in mixed plantations with C:P and N:P altered but C:N ratio did not change with soil depth. The intensive management significantly impact both C and N pools and the stoichiometry of C, N, and P. Intensive management of C. oleifera plantations decreased both C and N pools, especially at the depth of 30-50 cm soil layer. C. oleifera plantation alteration from mixed to pure should be considered in future forest management practice considering the substantial effects on soil element cycling and distribution along vertical soil profile.

Polycyclic aromatic hydrocarbons affiliated with microplastics in surface waters of Bohai and Huanghai Seas, China.

Microplastics (MPs) sized between 0.33 and 5 mm were collected using Manta trawls from ten surface seawater sites in Bohai and Huanghai Seas, China. A total of 1024 (Bohai Sea) and 132 (Huanghai Sea) microplastic pieces were classified, including polystyrene foams, polyethylene films and lines, and other plastic pellets, with concentrations of MPs ranging from 3 to 162 particles per 100 m3 (0.012-2.96 mg m-3). A pretreatment of MPs with 30% H2O2 in water did not significantly lower polycyclic aromatic hydrocarbon (PAH) concentrations on MPs compared to no H2O2 pretreatment. Measurements of PAHs carried on the collected MPs indicated that the concentrations of the sum of 16 PAHs were in the range of 3400-119,000 ng g-1. The sources of PAHs in Bohai and Huanghai Seas were highly similar, with petroleum and gasoline probably as the dominant sources. The present study shows the relative importance of MPs in regards to chemical transport in the marine environment. The combination of high concentrations of PAHs affiliated with MPs and the increasing magnitude of plastic pollution in the world's oceans demonstrates the considerable importance of MPs to the fate of PAHs in marine environments.

[Fine-root character and its action mechanism of forest at its initial reestablished stage on degraded red soil].

This paper studied the fine-root character and its action mechanism of forest reestablished by different models for 10 years on a seriously degraded red soil, and analyzed their correlation with soil property. The results showed that fine-roots mostly distributed in 0-20 cm soil layer, accounted for 73.39% -87.41% of those in 0-40 cm soil layer. There were notable differences in nutrient storage of fine-roots under different reestablishment models. The fine- roots of medium density pure Pinus serotina forest had a much higher storage of total nitrogen, phosphorus and potassium, with the content of total nitrogen, phosphorus, potassium, calcium and magnesium being 84.47, 5.55, 38.42, 17.00 and 10.76 kg hm(-2), respectively. Soil organic matter, total nitrogen, available nitrogen, available potassium and pH had significant correlations with fine-root biomass (P < 0.05). The effects of fine-roots on soil physical properties mainly reflected on soil capillary porosity and total porosity. Fine-roots obviously increased the contents of > 0.25 mm and > 5 mm soil waterstable aggregates, and improved soil structure-stability. The correlations between fine-roots and soil bacteria and microbial quantities were significant.