This study detailed a complete research from Lead (Pb) content level to ecological and health risk to direct- and primary-sources apportionment arising from wheat and rice grains, in the Lihe River Watershed of the Taihu region, East China. Ecological and health risk assessment were based on the pollution index and US Environmental Protection Agency (EPA) health risk assessment model. A three-stage quantitative analysis program based on Pb isotope analysis to determine the relative contributions of primary sources involving (1) direct-source apportionment in grains with a two-end-member model, (2) apportionment of soil and dustfall sources using the IsoSource model, and (3) the integration of results of (1) and (2) was notedly first proposed. The results indicated that mean contents of Pb in wheat and rice grains were 0.54 and 0.45 mg/kg and both the bio-concentration factors (BCF) were <<1; the ecological risk pollution indices were 1.35 for wheat grains and 1.11 for rice grains; hazard quotient (HQ) values for adult and child indicating health risks through ingestion of grains were all <1; Coal-fired industrial sources account for up to 60% of Pb in the grains. This study provides insights into the management of grain Pb pollution and a new method for its source apportionment.

Background: Cation exchange capacity (CEC) is a basic but important soil property of soil fertility or quality, CEC predicting model is often derived from other soil properties measured more easily because the traditional method determining CEC is time-consuming and laborious. It is necessary to establish a new CEC prediction model for a new region because CEC predicting model usually is dependent on the study region. Objective: Chenzhou City is the most important and typical tobacco-planting region with tobacco-rice rotation in Hunan province and China, this study was conducted to establish CEC predicting model for the tobacco-planting fields in Chenzhou because so far no CEC predicting model is available for tobacco-planting fields in Chenzhou and in China. Method: In total 1055 topsoil samples (0∼20 cm) were collected in 2015 from the tobacco-planting fields in Chenzhou, soil properties included the particle size composition, pH, soil organic matter and various nutrients were determined, the status of CEC were assessed, and then CEC predicting models were setup in different regions in Chenzhou. Result: The results showed that CEC in Chenzhou was ranged from 3.50 to 48.50 cmol (+) kg-1 with a mean of 22.05 cmol (+) kg-1, averagely belonged to the very high grade (>20 cmol(+) kg-1). There were significant differences in CECs in different regions in Chenzhou, which was the highest in Jiahe (23.83 cmol(+) kg-1) but the lowest in Anren (15.78 cmol(+) kg-1). CEC was significantly correlated with different soil properties in different regions, which was significantly correlated with coarse sands, fine sands, clays, pH and total P in Chenzhou (R= 0.312**∼0.445**), significantly correlated with coarse sands, silts, fine sands, clays, pH, total P, exchangeable Ca2+, Mg2+ and available Zn in Suxian (R= 0.430**∼0.684**), significantly correlated with coarse sands, fine sands, silts, clays, pH, total P, available B and Cu in Yongxing (R=0.321**∼0.605**), significantly correlated with coarse sands, fine sands and clays and total P in Guiyang (R=0.330**∼0.477**), significantly correlated with coarse sands, silts and total K in Yizhang (R=0.326**∼0.466**), and only significantly correlated with fine sands in Jiahe (R=0.350**). The accuracy of CEC predicting model usually was lower when less properties involved. Based on the comparison of the R2 and RMSE of the established CEC predicting models, it is recommended that the total model for Chenzhou could be used for Guiyang, Jiahe and Yizhang, while the regional models should be selected for Yongxing, Anren and Suxian. Conclusion: This study proves further that different soil properties were most important for CEC predicting models in different regions, new CEC predicting models must be setup for a new study region, and soil organic matter is not a variable in soil CEC predicting models for tobacco-planting fields in Chenzhou, which are different from some previous studies.

Silkworm (Bombyx mori) is a traditional edible insect. Whole silkworm powder contains 1-deoxynojirimycin (DNJ). DNJ is an alpha-glucosidase inhibitor with hypoglycaemic activity. The silkworm cannot synthesise DNJ by itself, most of the DNJ in silkworm is obtained by the consumption of mulberry leaves. In this study, the DNJ content of silkworm in different developmental stages and that of 50 representative resource varieties were measured, its correlation with viability of the variety was analysed. The results showed that silkworms at the peak feeding point of the 3rd instar had the highest DNJ content in seven development stages from the 2nd instar to the pupa stage. There was a large difference in the content of DNJ among varieties. The average DNJ content was 7.528 mg/g and the distribution of DNJ content among varieties conformed to the normal distribution (P>0.05). The varieties could be divided into three clusters according to DNJ content, and the DNJ content in cluster III, which contained 11 varieties was higher than other clusters. There were significant differences among polyvoltine species, Chinese species, and Japanese species, and significant differences between colour-cocoon varieties and white-cocoon ones. DNJ content in silkworm larvae was significantly correlated with larval survival rate and larva-pupa rate. In this study, the cluster III with the highest DNJ content may have the potential to be used as preferred raw material for hyperglycaemia regulation or treatment and candidate parent materials for enriched material. Furthermore, DNJ may have a positive effect on the physical fitness of silkworm.