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Pollution of Cd has seriously threatened environmental safety and human health. The field experiment was conducted to investigate the effects of calcium-magnesium phosphate fertilizer and water management on bioavailability of Cd in soils and its accumulation in rice. The results revealed that continuous flooding has enhanced soil pH from 5.10 to 5.72 and reduced soil redox potential (Eh) from 164 to − 60 mV. Application of calcium-magnesium phosphate fertilizer has significantly raised soil pH from 5.10 to 6.45 (P

A colloidal gold immunochromatographic strip (ICS) for simultaneous detection of multiple transgenic proteins, including CP4 EPSPS, BT-Cry1Ab and BT-Cry1Ac, was developed in this study. The sensitivity of the strip to the target protein was 5 ng/mL for CP4 EPSPS, 100 ng/mL for BT-Cry1Ab and Cry1Ac, respectively. Parallel analysis for maize, soybean, sugar beet and cotton showed the strip could detect 1% of transgenic content in crops containing BT-Cry1Ab and Cry1Ac, and, at least, 0.1% of content in crops containing CP4 EPSPS. The detection results for seed samples indicated the multicomponent analysis ICS had good accuracy. The analysis could be completed within 10 min and had the advantages of being high-throughput, easy to operate and visual detection. This is the first report of semi-quantitative ICS for detecting three transgenic proteins simultaneously. The developed approach may provide insights into the development of ICS for analyzing simultaneously multiple components in genetically modified crops.

The intensive human activities are the major cause of heavy metals pollution in suburban farmland, which poses threats to soil environment and safety of agricultural products. The combination of spatial analysis (SA), principal component analysis (PCA), input fluxes analysis (IFA) and UNMIX model have precisely analyzed the sources and relative contribution of heavy metals from each source. The results revealed that average contents of Cr, Ni, Cu, Zn, Pb and Cd were 37.82, 13.65, 17.93, 93.78, 48.84 and 0.24 mg kg−1, respectively. The spatial distribution indicated that parent materials, industrial activities and traffic emissions had significant effects on contents of heavy metals in topsoil. According to UNMIX model, the contribution rates of soil parent material, industrial/ traffic emissions, and agricultural activities to heavy metals in soil were 49.15%, 35.00% and 15.85% respectively. Which indicated largest contribution of natural sources, but input of human activities including industry, transportation and agriculture could not be ignored. The input fluxes analysis (IFA) reveals that atmospheric deposition was main source of heavy metals in soil, followed by fertilizer and irrigation. This study has presented reliable methods for analysis of sources of heavy metals in suburban farmland soil. The combination of UNMIX and IFA can accurately identify and quantify pollution sources.

Recombinase polymerase amplification (RPA) was first reported in 2006 and has recently been shown to improve the detection of genetically modified organisms (GMOs). This study developed a more efficient RPA-based and lateral flow test strip (LFD)-based platform for the detection of P–35S and T-nos for GMOs, circumventing the need for expensive instruments and technicians. Other methods were compared to our assay. The RPA forward and reverse primers were labeled with the fluorophore biotin, digoxin, and FITC at the 5′ end and quickly determined whether the sample contains P–35S and T-nos of GMOs using the RPA-LFD method at room temperature. Nine events of GMOs were collected to determine the specificity of the RPA-LFD method, including KMD1, MON531, Rf1, Kefeng6, RRS, Bt11, MON863, Bt176, and Ms1. The results showed that the limit of detection of RPA-LFD was 50 copies and 100 copies, which was consistent with the limit of detection of RPA-AGE. The specificity and stability among the nine events were consistent, respectively. Finally, the perfect fitness for the detection of the nine double-blind samples indicated that the detection method is practical. In conclusion, we developed a more sensitive, specific, and stable field screening method for determining the GMO content with large-scale field applications.

Tunable diode laser absorption spectroscopy(TDLAS) is a high sensitive and high resolution gas absorption spectrum detection technology, with fast response, high precision, excellent single mode characteristics and strong versatility. The temperature and concentration of the detected gas were calculated by measuring the absolute absorption intensity in the direct absorption method of TDLAS, but was easily affected by particle concentration and fluctuation of laser intensity. The laser was modulated through high frequency sinusoidal signal in the wavelength modulation method of TDLAS, making the laser output frequency and intensity modulated simultaneously, with the characteristics of high signal-to-noise ratio and sensitivity, but the gas parameters were determined by calibration experiments or complex algorithms. Therefore, the expression of harmonic terms containing molecular absorption information was deduced through the theory of absorption spectrum and wavelength modulation, and the relationship between harmonic signal and absolute absorption intensity of detected gas was analysed, establishing the measurement algorithm of absolute absorption intensity based on harmonic signal. The absorption spectral line of NH3 molecule near 1 531 nm was taken as an example for numerical analysis, and the relative errors between theoretical calculation (a=0) and simulation values were no more than 2% when the modulation amplitude reached up to a=0.032 cm-1(m=2), which further proved the reliability of on-line measurement algorithm.

Genetically modified carnation (Dianthus caryophyllus L.) Moonshade was approved for planting and commercialization in several countries from 2004. Developing methods for analyzing Moonshade is necessary for implementing genetically modified organism labeling regulations. In this study, the 5'-transgene integration sequence was isolated using thermal asymmetric interlaced (TAIL)-PCR. Based upon the 5'-transgene integration sequence, conventional and TaqMan real-time PCR assays were established. The relative limit of detection for the conventional PCR assay was 0.05 % for Moonshade using 100 ng total carnation genomic DNA, corresponding to approximately 79 copies of the carnation haploid genome, and the limits of detection and quantification of the TaqMan real-time PCR assay were estimated to be 51 and 254 copies of haploid carnation genomic DNA, respectively. These results are useful for identifying and quantifying Moonshade and its derivatives.