以神府东胜侏罗纪煤田为例，在详细分析煤系的精细地层层序、沉积环境、埋藏和热演化史、主采煤层及上下围岩的展布特点及其差异性的基础上，对煤的组成及有害微量元素的空间变异进行精细的研究，以深刻揭示控制煤中有害微量元素变异的地质成因，并建立煤中有害微量元素变异的精细地质模型。为预测该区煤中有害微量元素的环境危害提供科学依据。.

Dongsheng Coalfield located in the northern part of Ordos basin of China have abundant coal resource. The main coal-bearing measure in Dongsheng Coalfield is Yan'an formation deposited in continental environment of middle-lower Jurassic. The average thickness of Yan'an formation is 206m with 8-12 workable coal seams. The totally workable thickness of coal seams is 12-25m. These coals belong to caking coal or long flame coal with 5%-9% average ash, less than 0.7% average total sulfur. The contents of most of elements in these coals are low. However, some hazardous elements in coal are relatively high in some place or local coal seam, showing variation inside coalfield. The project of "The study on variation of hazardous trace element in Jurassic coal from the north of Ordos basin of China" focused on following contents: ①distribution of hazardous trace elements, REE and minerals in coal; ②mode of occurrence of trace elements in ultraclean Jurassic coal; ④quantitatively organic affinity of tarce elements in low-rank coal; ⑤case study of arsenic occurrence in general coal; ⑥main factors of controlling variation of hazardous trace elements in coal..The main conclusions are as follows: ①The lack of continental debris and sulfides ninerals (pyrite) result in low concentrations of most of hazardous trace element and REE. The variation of pyrite contents in coal is the main cause of variation of concentrations of hazardous trace element. The concentrations of pyrite are relatively high in coal deposited in reduced environment of lake bay. ②Even in ultraclean low-rank coal (low- ash and sulfur low-rank coal), inorganic state of trace elements still exist with the proportion of 30%-50%. Obviuosly, modes of occurrence of trace elements in ultraclean low-rank coal still demostrate diversity. So, hazardous trace elements in Jurassic coal from Dongsheng coalfield can be removed about 30%-50% by washing.