[Dynamic response and variance of vegetation in China from 1982 to 2015 under the asymmetric rate of temperature fluctuation.] / 1982­2015年昼夜不对称增温下中国自然植被动态响应及差异.

The impact of global warming on the growth and development of natural vegetation is an important concern worldwide. Based on the data from the vegetation normalization index, daytime temperature (Tmax), nighttime temperature (Tmin), precipitation, and elevation from 1982 to 2015, we examined the day-night warming response of 42 types of natural vegetation in China. The results showed that both the temperature at day and night was significantly increased in the study area, with obvious asymmetry. The night warming was about 1.6 times as high as that at daytime. The Tmin was more conducive to vegetation growth than the Tmax. The proportion of vegetation types with positive relationship with Tmin was greater than the Tmax, with significant spatial difference. Subtropical vegetation accounted for 85.7% of vegetation with positive correlation with Tmax. The temperate alpine, mountainous, and desert vegetation responded more positively to Tmin. The increase of Tmin was not conducive to the growth and development of vegetation at high altitudes, while that of Tmax was the opposite. The correlations of vegetation growth with Tmax and Tmin were as follows: steppe > meadow > needleleaf forest > desert vegetation > broadleaf forest; meadow > desert vegetation > broadleaf forest > steppe > needleleaf forest.

[Pollution Characteristics and Health Risk Assessment of Heavy Metals in Wheat Grains Cultivated in Kaifeng Irrigation Area of the Yellow River].

In order to monitor heavy metal pollution in agricultural soils and assess the corresponding health risk in the Yellow River irrigation area, this study applied the Nemero index and the health risk index to evaluate heavy metal pollution in wheat grains and the health risks for residents in the lower reaches of the Yellow River. Four towns in Kaifeng, which are within the lower reaches of the Yellow River, were selected as the study area. The examination of wheat samples revealed that the average contents of Cd, Cr, Pb, Cu, Zn, Ni, and Hg in the wheat grains were 0.034, 0.428, 0.279, 5.363, 29.605, 0.305, and 0.003 mg·kg-1, respectively. Among the heavy metals, Pb and Zn exceeded the national food hygiene standards. The pollution indices of Pb and Zn in the wheat grains contributed significantly to the comprehensive pollution index, as each was greater than 1 (1.985), although the pollution indices of the other heavy metals were less than 1. The comprehensive pollution index of wheat in each town ranged from 1.116 to 1.847. The health risk indices of non-carcinogenic heavy metals (Pb, Cu, Zn, and Hg) for adults and children were 1.0558 and 0.5450, respectively. The health risk indices of carcinogenic heavy metals (Cd, Cr, and Ni) for adults and children were higher than the maximum acceptable risk level (1×10-4) recommended by the USEPA, which suggests that residents of the study area have a high risk of developing various forms of cancer.

[Spatial Distribution and Potential Ecological Risk Assessment of Heavy Metals in Sediments of Suya Lake].

In order to study the pollution status of heavy metals in sediments of Suya Lake, the concentrations of heavy metals Cu, Cd, Cr, Zn, Pb and Ni in sediments were measured at three locations in the center, middle and periphery of Suya Lake, the content characteristics and the pollution status of heavy metals in the study area were analyzed by the method of geoaccumulation index and potential ecological risk index, and the distribution and interrelation of heavy metals were evaluated by Kriging method and correlation analysis. The results showed that, on average, Zn was the highest, 112.87 mg·kg-1, followed by Cr, the smallest average of Cd was only 0.41 mg·kg-1. In addition to Cd and Cr, the coefficients of variation of Cu, Zn, Pb and Ni were relatively small, ranging from 24% to 31%, with moderate degree of variation. The coefficients of variation of Cd and Cr were 50.41% and 41.92%, respectively, and the spatial variation was obvious, which indicated that the variation of Cd and Cr was more significant than the others; 2The heavy metals Cu, Cd, Cr, Zn, Pb and Ni had a strong linear relationship, and there was a significant positive correlation, and six kinds of heavy metals had some homologous characteristics, with a common external input; 3The main pollution elements in the study area were Cd, Cr and Zn, the pollution degree was relatively serious, and the scope was extensive. Among them, the pollution degree of Cd was the most serious, the overall pollution level was moderate, and the pollution degree in some sample areas reached up to severe pollution, the pollution status of Cr, Zn and Pb was relatively mild, the pollution status of Cu, Pb and Ni was better, and there was no ecological risk; 4On the whole, the pollution level of the northeastern part of Suya Lake was relatively light, the degree of pollution in the southwest was relatively serious, showing a significant spatial distribution characteristics of decreasing from southwest to northeast, the contents of heavy metals in the samples were higher than those in the southwest of the reservoir, while the northeastern part of the periphery was the area with accumulation of low concentrations of heavy metals., and there was no pollution from Cu, Cr, Zn and Ni.