Fate and abundance of antibiotic resistance genes on microplastics in facility vegetable soil.

Microplastics (MPs) and antibiotic resistance genes (ARGs) coexist widely in farmland soils, but the fate and abundance of ARGs on MPs is rarely explored. In this study, high-throughput fluorescent quantitative polymerase chain reaction was used to determine ARGs on MPs in facility vegetable soil. The results indicated that when the particle size of the MPs was larger, the weathering was more serious, or the MPs came from soils with a long vegetable cultivation period, the levels of antibiotics and heavy metals on the MPs were higher. The distribution of the detected ARGs types on distinct MPs showed changes. Compared with weakly weathered MPs, the detected beta lactamase and aminoglycoside resistance genes on strongly weathered MPs were decreased by 2.6% and 1.7%, while the detected sul-ARGs and Macrolide-Lincosamide-Streptogramin B (MLSB) resistance genes were increased by 1.5% and 2.8%. Compared with smaller MPs, the detected MLSB and vancomycin resistance genes on larger MPs were decreased by 2.0% and 1.4%, while the detected fluoroquinolone, quinolone, florfenicol, chloramphenicol, and amphenicol (FCA) resistance genes and sul-ARGs were increased by 1.2% and 1.0%. Compared with MPs in soil after three years of vegetable cultivation, the detected FCA resistance genes and sul-ARGs on MPs in soil after ten years of vegetable cultivation were decreased by 1.3% and 1.6%, while the detected beta lactamase and aminoglycoside resistance genes were increased by 1.0% and 1.7%. This study suggests that MPs with larger size, stronger weathering or from soil after long-term vegetable cultivation adsorb more antibiotics and heavy metals and cause more mobile genetic elements, which can contribute to antibiotic resistance on the MPs.

Effects of planting densities on water quality improvements and Pontederia cordata's physiology.

Various planting densities (5, 10, or 20 plants per tank) of Pontederia cordata were water-cultivated in purifying tanks to treat polluted water. Seasonal effects of the planting densities on the water quality improvement and the morphology and physiology of the plant were analyzed. Results indicated that planting densities affected the nitrogen and phosphorus removal of water, and the morphology and physiology of plants, including activity of peroxidise and catalase, content of chlorophyll and soluble protein (SP), the length of root, stem and leaf, tiller number and root density. When planting density increased from 10 to 20 plants per tank, the morphology and physiology of plants, and the nitrogen and phosphorus removal by plants improved slowly, but caused a tiller number decline in individual plants. This variation was significant in autumn, and associated with seasonal variations of plant physiology. During autumn, there were 26 tillers in each plant with 10 plants per tank, compared to 14 tillers per plant with 20 plants per tank. Increase in the nitrogen and phosphorus contents of the plants for 5-10 plants per tank was 5.41 and 0.79 g kg(-1), compared to 1.17 and 0.12 g kg(-1) for 10-20 plants per tank, respectively.

Seasonal variations and aeration effects on water quality improvements and physiological responses of Nymphaea tetragona Georgi.

Seasonal variations and aeration effects on water quality improvements and the physiological responses of Nymphaea tetragona Georgi were investigated with mesocosm experiments. Plants were hydroponically cultivated in six purifying tanks (aerated, non-aerated) and the characteristics of the plants were measured. Water quality improvements in purifying tanks were evaluated by comparing to the control tanks. The results showed that continuous aeration affected the plant morphology and physiology. The lengths of the roots, petioles and leaf limbs in aeration conditions were shorter than in non-aeration conditions. Chlorophyll and soluble protein contents of the leaf limbs in aerated tanks decreased, while peroxidase and catalase activities of roots tissues increased. In spring and summer, effects of aeration on the plants were less than in autumn. Total nitrogen (TN) and ammonia nitrogen (NH4(+)-N) in aerated tanks were lower than in non-aerated tanks, while total phosphorus (TP) and dissolved phosphorus (DP) increased in spring and summer. In autumn, effects of aeration on the plants became more significant. TN, NH4(+)-N, TP and DP became higher in aerated tanks than in non-aerated tanks in autumn. This work provided evidences for regulating aeration techniques based on seasonal variations of the plant physiology in restoring polluted stagnant water.

GPR12 selections of the metabolites from an endophytic Streptomyces sp. associated with Cistanches deserticola.

An endophytic Streptomyces sp. (AC-2) was isolated from the root of Cistanches deserticola Y.C.Ma.. Chemical investigations of the culture broth of AC-2 afforded fifteen compounds including K1115 A (1), tyrosol (2), phenylethylamine derivatives (3, 4), cyclic dipeptides (5-8), nucleosides and their aglycones (9-13), N-acetyltryptamine (14), and pyrrole-2-carboxylic acid (15). Only tyrosol can promote an increase of intracellular cAMP special on GPR12 transfected cells, such as CHO and HEK293, which means it may be a possible ligand for GPR12.

[Experimental study on characteristics of biodiesel exhausted particle].

A particle emission experiment of a direct-injection turbocharged diesel engine with biodiesel and diesel was carried out. A pump of 80 L/min and fiber glass filters with diameter of 90 mm was used to sample engine particles in exhaust pipe. The size distribution, soluble organic fraction (SOF) and 16 polycyclic aromatic hydrocarbons (PAHs) of particles were analyzed by a laser diffraction particle size analyzer and GC-MS. The results indicate that the volume weighted size distribution of biodiesel particle is single-peak and its median diameter d(0.5) and mean diameter d32 are decreased with the increasing speed. At the high speed the d32 and d(0.5) of biodiesel are larger than those of diesel, and quite the contrary at the low speed. SOF mass concentration and mass percentage of biodiesel are 12.3 - 31.5 mg/m3 and 38.2% - 58.0% respectively, which are much higher than those of diesel. The total PAHs emission concentration of biodiesel is 2.9 - 4.7 microg/m3 lower than that of diesel as much as 29.1% - 92.4%.

[Preparation of biodiesel from waste edible oils and performance and exhaust emissions of engines fueled with blends of the biodiesel].

The purpose of this study is to evaluate the effect of biodiesel on environment and to investigate the effect of the biodiesel made of waste edible oils on the performance and emissions of engines. Life cycle assessment (LCA) of biodiesel and diesel was introduced and the results of the LCA of both the fuels were given. The technological process of biodiesel production from waste edible oils, which is called transesterification of waste oils and methanol catalyzed with NaOH, was presented. Two turbocharged DI engines fueled with different proportions of biodiesel and diesel, namely, B50 (50% biodiesel + 50% diesel) and B20 (20% biodiesel + 80% diesel), were chosen to conduct performance and emission tests on a dynamometer. The results of the study indicate that there was a slight increase in fuel consumption by 8% and a drop in power by 3% with the blends of biodiesel, compared with diesel, and that the best improvements in emissions of smoke, HC, CO and PM were 65%, 11%, 33% and 13% respectively, but NOx emission was increased. The study also shows that it is satisfied to fuel engines with the low proportion blends of the biodiesel, without modifying engines, in performance and emissions.