An aptasensor for the detection of ochratoxin A (OTA) in environmental samples was developed. It displayed high sensitivity and good selectivity. Factors such as specific binding between a FAM (5-carboxyfluorescein)-labeled aptamer (f-RP) and OTA, and a magnetic property of a streptavidin magbeads-modified capture probe (bm-CP) resulted in aptasensor’s linear relationship between fluorescence intensity and the concentration of OTA. This characteristic is present at the OTA concentration ranges from 0.100 μM to 25.00 μM with a LOD (limit of detection) of 0.0690 μM. The bm-CP can be reused through melting, washing and magnetic separation, which contributes to cost reduction. In addition, the proposed method is simple and detection process is fast. The aptasensor can be used in real samples.

Cold atomic absorption spectrophotometry and atomic fluorescence methods were employed to ascertain the total mercury concentration in soil samples. A systematic comparison and analysis were conducted on the operational procedures, precision and detection limits of these methodologies. The standard curve for total mercury determination in soil using the atomic fluorescence method is y = 851.98 x +16.771 ( R ² = 0.9996, 0–2.5 µg l ⁻¹ ), with a detection limit of 0.0006 mg kg ⁻¹ . This method demonstrates superior precision and accuracy not only for samples with high and medium concentrations but also for those with low concentrations. For the cold atomic absorption spectrophotometry method, the standard curve for total mercury determination is y = 0.0547 x + 0.0047 ( R ² = 0.9998, 0–15 µg l ⁻¹ ). For high-concentration samples, the curve is y = 0.0007 x − 0.0003 ( R ² = 0.9998, 0–600 µg l ⁻¹ ). The detection limit for this method is 0.06 μg kg ⁻¹ , indicating better sensitivity and accuracy compared with the atomic fluorescence method. While the precision for low-concentration (0.017 ± 0.003 mg kg ⁻¹ ) samples is moderate, it is higher for medium (0.030 ± 0.003 mg kg ⁻¹ ) and high-concentration (0.590 ± 0.05 mg kg ⁻¹ ) samples. Overall, there is no significant difference between the two detection methods. However, the cold atomic absorption spectrophotometry method has the advantage of not requiring pre-treatment, making it more convenient and environment friendly.

A derivative of tetraiodofluorescein (i.e., allyltetraiodofluorescein) was synthesized as a fluorescence dye in the fabrication of a sensor for 2,4,6-trinitrophenol determination. It was photo-copolymerized on the silanized glass surface to prevent the leakage of dye. The fluorescence intensity of the sensing membrane decreased with the increase of 2,4,6-trinitrophenol when it was excited at 531 nm. The linear response range covers the concentration of 2,4,6-trinitrophenol from 1 × 10^–7 ∼ 0.5 × 10^–1M. The sensor was characteristic of satisfactory reproducibility, reversibility and the response time (t ₉₉) was of the order of 45 s. A good stability with a lifetime of at least one month was obtained. In addition, the sensor was workable in real water samples and has been applied to detect the concentration of quinine indirectly.

Green manure (GM)-rice rotation is an effective practice for yield-increasing and soil-fertilizing in southern China, while the effects of GM, and the co-utilization with rice straw return on secondary and micronutrients in rice grain remains unclear. This study systematically investigated the regulatory effects of the co-utilization of GM and rice straw combined with reduced nitrogen (N) fertilizer application on grain secondary and micronutrients based on a field experiment in the southern Jiangsu rice-growing area. Results showed that the five-year average rice yield under GM increased by 5.65% relative to that under winter fallow (WF). The co-utilization of GM and rice straw with 40% reduction of N fertilizer (GMS_N60) was identified as the optimal mode. It achieved a rice yield increased by 16.87% compared with the WF with straw return and conventional N fertilization (WFS_N100), and the accumulation of N, phosphorus (P), and potassium (K) improved simultaneously. Green manuring promoted the uptake of secondary and micronutrients in rice grain and silicon (Si) in straw. The average contents of calcium (Ca), iron (Fe), copper (Cu), molybdenum (Mo), and selenium (Se) in rice grain increased by 8.08%, 17.75%, 3.99%, 13.56%, and 20.25%, respectively, and the rice straw Si content increased by 5.24% under GM relative to that under WF. The contents of zinc (Zn) and Mo under GMS_N60 increased by 8.38% and 19.12%, respectively, relative to those under WFS_N100. Correlation analysis indicated that GM facilitated the synergistic absorption of magnesium (Mg), manganese (Mn), and Zn. This study elucidates the roles of GM in stabilizing and increasing rice yields and enhancing the nutritional quality of rice, providing important support for high-yield and high-quality rice production in southern China.