Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11 A Datun Road, Beijing, 100101, People's Republic of China.
Biol Trace Elem Res. 2013 Dec;156(1-3):367-75. doi: 10.1007/s12011-013-9822-5. Epub 2013 Sep 27.
To clarify the relationship between the soil selenium distribution and its bioavailability with the distribution of Kashin-Beck disease (KBD) endemic areas on the eastern edge of the Tibetan Plateau, samples of natural soil (0-20 cm), cultivated topsoil, and main crops of the region (highland barley) were collected at different altitudes according to topographical and geomorphological features in both KBD and non-KBD areas of Songpan County. These samples were used for determination and analysis of total selenium content in soil and highland barley and available selenium that can be absorbed and utilized by plants. The results showed that the average total selenium content of natural and cultivated topsoil in KBD areas was lower than that in non-KBD areas (natural soil, P = 0.061; cultivated soil, P = 0.002), which is in agreement with the geographical distributions of selenium in other KBD-affected areas. However, the total soil selenium content exhibits certain micro-spatial distribution features, namely, the total selenium content in some endemic areas was significantly higher than that of non-KBD areas. This result was contrary to the general distribution that total selenium content in a KBD-affected area is lower than that in a non-KBD area. We further studied the extraction rate and content of soil selenium in six different fractions. The results indicated that the content and extraction rate of available selenium in KBD-affected areas were significantly lower than those in non-KBD areas. There is a distinct positive correlation between plant-available selenium and highland barley selenium (r = 0.875, P = 0.001) and a distinct negative correlation with altitude (r = -0.801, P = 0.010). Therefore, in KBD endemic areas, the selenium content in crops decreases as the available selenium content in soil decreases and is closely related to the geographical environment features (such as altitude and precipitation). These results suggest that the soil available selenium and ecological features are important factors that restrict the dietary selenium flux for residents in KBD endemic areas of the Tibetan Plateau, providing a theoretical and experimental basis for implementing agricultural measures to regulate the ecological cycle of the selenium flux in the KBD endemic area.
为了阐明青藏高原东缘土壤硒分布及其生物有效性与大骨节病（KBD）流行区分布之间的关系，根据松潘县 KBD 和非 KBD 地区的地形和地貌特征，在不同海拔高度采集了天然土壤（0-20 厘米）、耕作表土和该地区的主要作物（青稞）样本，用于测定和分析土壤和青稞中的总硒含量以及植物可吸收和利用的有效硒。结果表明，KBD 区天然和耕作表土的平均总硒含量均低于非 KBD 区（天然土壤，P=0.061；耕作土壤，P=0.002），这与其他 KBD 病区的硒地理分布一致。然而，土壤总硒含量表现出一定的微空间分布特征，即在一些流行区的总硒含量明显高于非 KBD 区。这一结果与 KBD 病区总硒含量低于非 KBD 区的一般分布情况相反。我们进一步研究了 6 种不同分数的土壤硒的提取率和含量。结果表明，KBD 病区土壤有效硒的含量和提取率明显低于非 KBD 区。KBD 病区植物可利用硒与青稞硒含量呈显著正相关（r=0.875，P=0.001），与海拔呈显著负相关（r=-0.801，P=0.010）。因此，在 KBD 流行区，随着土壤有效硒含量的降低，作物中的硒含量也随之降低，且与地理环境特征（如海拔和降水）密切相关。这些结果表明，土壤有效硒和生态特征是限制青藏高原 KBD 流行区居民膳食硒通量的重要因素，为实施农业措施调节 KBD 流行区硒通量的生态循环提供了理论和实验依据。
