[Pollution Characteristics and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Farmland Soil and Crops in the Suburbs of Urumqi].

In order to understand the occurrence of PAHs in soil and crops, the enrichment capacity of different crops for PAHs, and the distribution characteristics of PAHs in different parts of crops, the crops and soil planted in the farmland around Urumqi were studied as examples. Samples were collected in the farmland gathering area in the suburb of Urumqi in July 2021. A total of 100 crop samples were collected, including 21 crop species and 45 surface soil samples. The results showed that 16 types of PAHs were detected in the soil and crops. The total concentration of PAHs in farmland soil ranged from 19.06 to 1870.86 µg·kg-1, and the average concentration was 127.40 µg·kg-1. Seven carcinogenic PAHs accounted for 42.85%-79.20% of the 16 types of PAHs, among which BaP was the main pollutant in the soil. Through the characteristic ratio method, it was found that the main sources of PAHs in the soil were biomass and coal combustion. Total PAHs in crops ranged from 1.86 µg·kg-1 to 974.05 µg·kg-1, with an average of 303.30 µg·kg-1. Different crops had different enrichment capacities for PAHs. Among the 21 crops sampled, the accumulative content of PAHs in pumpkin was the highest (431.75 µg·kg-1). In leaf vegetable crops, the content of PAHs in leaves was higher than that in roots and fruits. In fruit and vegetable crops, the PAH content in fruit was higher than that in the root or leaf. There was a significant correlation between high cyclic PAHs in soil and PAHs in plant leaves. The health risk assessment of PAHs in crops showed that dietary intake had potential carcinogenic risk and even had high carcinogenic risk in adult male and female groups, which requires further attention.

Comparative Analysis of Polyphenols in Lycium barbarum Fruits Using UPLC-IM-QTOF-MS.

Variety, geographical origin, and harvest season are important factors affecting the accumulation of polyphenols in Lycium barbarum. In this study, the effects of these factors on the polyphenolic components of this species were analyzed using ultra-performance liquid chromatography ion mobility quadrupole time-of-flight mass spectrometry. Moreover, the in vitro antioxidant activities of fruit extracts from this species were evaluated. The total polyphenolic contents of L. barbarum fruits from Jinghe County in Xinjiang and Zhongning County in Ningxia were 5.52-11.72 and 7.06-9.37 mg (gallic acid equivalent)/g dry weight, while the total flavonoid contents of L. barbarum fruits from these regions were 12.52-30.29 and 12.67-20.77 mg (rutin equivalent)/g dry weight, respectively. Overall, 39 types of polyphenols were identified in the fruit extracts, including 26 flavonoids, 10 phenolic acids, and three tannins. Of these, 11 polyphenols were quantitatively analyzed, which revealed rutin to be the most dominant polyphenolic component in fruits from Jinghe and Zhongning. There were significant differences (p < 0.05) in the polyphenolic contents and antioxidant activities of L. barbarum fruit extracts, depending on the geographical origin, variety, and harvest season. The antioxidant activity of this species was found to be significantly positively correlated with the polyphenolic contents. This study provided scientific guidance for comprehensive applications of polyphenols from different varieties of L. barbarum from separate geographical origins.

Pesticide Residue Behavior and Risk Assessment in Celery after Se Nanoparticles Application.

This study investigates pesticide levels in celery, and compares their degradation, dissipation, distribution, and dietary risk after spraying with selenium (Se) nanoparticles. Abamectin, imidacloprid, acetamiprid, thiamethoxam, and lambda-cyhalothrin were sprayed at 1.6, 6.8, 2.0, 1.0, and 0.7 g a.i. ha-1 followed by a 2 g·ha-1 Se nanoparticle application during the growing period. Thiamethoxam, abamectin, imidacloprid, lambda-cyhalothrin, and acetamiprid in celery degraded following a first order kinetic model after 2 g·ha-1 Se nanoparticles application. With the exception of acetamiprid, the half-lives of thiamethoxam, abamectin, imidacloprid, and lambda-cyhalothrin were reduced from 2.4, 0.5, 1.2, 4.2 days without Se nanoparticles application to 1.4, 0.2, 0.9, 3.7 days with the addition of Se nanoparticles (2 g·ha-1), respectively. The chronic dietary exposure risk probability (RQc) and the acute dietary exposure risk probability (RQa) of celery after Se nanoparticles application were within acceptable limits for consumption except for abamectin.

Acaricidal Activity and Synergistic Effect of Thyme Oil Constituents against Carmine Spider Mite (Tetranychus Cinnabarinus (Boisduval)).

Studies examining the use of essential oils as replacements for synthetic insecticides require an understanding of the contribution of each constituent present, interactions among these components, and how they relate to overall toxicity. In the present study, the chemical composition of commercial thyme oil was identified by gas chromatography-mass spectrometry. Thyme oil and blends of its major constituents were tested for their acaricidal activitities against carmine spider mites (Tetranychus cinnabarinus (Boisduval)) using a slide-dip bioassay. Natural thyme oil showed greater toxicity than any single constituent or blend of constituents. Thymol was the most abundant component (34.4%), and also possessed the strongest acaricidal activity compared with other single constituents. When tested individually, four constituents (linalool, terpinene, p-cymene and carvacrol) also had activity, while α-pinene, benzoic acid and ethyl gallate had almost no activity. The toxicity of blends of selected constituents indicated a synergistic effect among the putatively active and inactive constituents, with the presence of all constituents necessary to reach the highest toxicity. The results indicated that thyme oil and some of its major constituents have the potential to be developed into botanical acaricides.