[Soil heavy metal cadmium standard limit and range of background value research].

With the rapid development of industrial and agricultural production in China, problems such as excessive soil pollutants worsen year by year, and soil cadmium pollution resulting from the emergence of "cadmium rice" and other food security incidents occur frequently. It causes the extensive concern of society on soil cadmium environmental standards. A soil environmental standard is the foundation for the evaluation of soil environmental quality. The maximum allowable value of cadmium that affects plant and animal and human health is regarded as the basis value all over the world; however, the certification methods and the goals of standard application are different, thus the standard limit has a great difference. Through the research on domestic and foreign soil cadmium standard limits and the soil cadmium background values in China, the soil cadmium background content range values of the provinces and of some types of soil are given. We report the outstanding problems existing in China's current environmental quality standard of soil cadmium. It is proposed that the soil environmental quality standard should allow the coexistence of gradient of soil cadmium standard limit, effective state and total standard limit, and anthropogenic pollution and background values exceeding the standard should be strictly distinguished.

Investigations on boron levels in drinking water sources in China.

To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results showed that boron existed in public drinking water sources mainly in dissolved status with total concentrations ranging from 0.003 to 0.337 mg/L (mean = 0.046 mg/L). The mean boron concentrations in mineral and pure bottled water were 0.052 and 0.028 mg/L, respectively. The results obtained in this work showed that there was no health risk on view of boron in public drinking water sources and bottled water. In boron industrial area, boron concentrations in surface water and ground water were 1.28 mg/L (range = 0.007-3.8 mg/L) and 18.3 mg/L (range = 0.015-140 mg/L), respectively, which indicated that boron industry caused boron pollution in local water system.