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The characteristics of organic acids in plant organs (roots, stems and leaves) , and root exudates of seedlings of Orychophragmus violaceus and Brassica napus were investigated under the stress of Zn deficiency and excessive bicarbonate by ion chromatography, the two plant species were hydroponically grown and cultured in four different treatments: + Zn0 (the treatment of adequate Zn and none HCO3-), + Zn10 (the treatment of adequate Zn and HCO3- addition), —Zn10 (the treatment of Zn deficiency and none HCO3-) , and —Zn10 (the treatment of Zn deficiency and HCO3- addition) , respectively. The results were as follows: (1) The total content of organic acids in plant organs and root exudations of the two plant species were significantly increased under excessive bicarbonate treatment, particularly under the dual treatment of Zn deficiency and excessive bicarbonate conditions (—Zn10 treatment) ,the organic acids in organs and root exudates of O. violaceus were more sensitive than that of B. napus , oxalic, citric and malic acids were the dominant organic acids in organs and root exudates of 0. violaceus , the content of these three organic acids took account for more than seventy five percent of the total content of organic acids in organs and root exudates of O. violaceus; (2) The leave was the main region of organic acids production of the two plant species, the content and the allocated proportion of organic acids decreased from aboveground parts (leaves and stems) to belowground parts; (3) The variation trends of organic acids contents of organs were identical with that of root exudates in O. violaceus and B. napus , and the source of organic acids in leaves of the two plant species was derived from the processes of dark respiration and photorespiration, while the source of organic acids in other organs such as stems and roots, as well as the source of organic acids in root exudates were come from the process of dark respiration; (4) The adaptability to the environment of low Zn and excessive HCO3- of O. violaceus was higher than that of B. napus ,which provided evidences for the adaptability to karst environment of 0. violaceus , and ecological restoration in environments with low Zn and excessive HCO3-, such as a karst area. [ABSTRACT FROM AUTHOR]

In order to understand the pollution level and ecological risk of heavy metals in topsoil of Chuzhou City, a total of 4360 soil samples in Chuzhou City were collected, and the concentrations of eight heavy metals including Cr, Zn, Pb, Cu, Ni, Cd, As, and Hg were measured. Correlation analysis, cluster analysis, and principal component analysis were used to analyze the sources of the heavy metals, and the enrichment factor index, single-factor pollution index, pollution load index, geo-accumulation index method, and potential ecological risk index were selected to assess the environmental risk of the eight heavy metals in the topsoil. The results showed that the average values of Cr, Zn, Pb, Cu, Ni, Cd, As, and Hg contents in the surface soil of Chuzhou City were higher than the background value of that in the soil of Yangtze-Huaihe River Basin of Anhui, and Cd, Ni, As, and Hg were significantly different in space and influenced by external disturbance. The eight types of heavy metals could be divided into four categories based on correlation analysis, cluster analysis, and principal component analysis. Cr, Zn, Cu, and Ni were from natural background sources; As and Hg mainly came from sources of industrial and agricultural pollution; Pb mainly came from the sources of transportation pollution and industrial and agricultural pollution; and Cd came from the sources of transportation pollution, natural background, and industrial and agricultural pollution. The overall pollution degree of Chuzhou City was low, and the ecological risk level was at a slight level based on the pollution load index and the potential ecological risk index; however, the ecological risk of Cd and Hg was generally serious, and these two heavy metals should be taken as the objects of priority control. The results provided a scientific basis for soil safety utilization and classification control in Chuzhou City.

To investigate the dry deposition pattern of particulate matter and lead in urban Beijing, dry deposited particles were collected based on a surrogate surface between December 2013 and November 2014 and subjected to elemental analysis by using microwave digestion and inductively coupled plasma mass spectrometry. The results showed that dry deposition fluxes of particle mass and total lead were 0.84 t·(hm 2 ·a) -1 and 7.56 mg·(m 2 ·a) -1 , respectively, with a seasonal trend of spring > winter > autumn~summer, exhibiting a similar temporal pattern to that of coarse particles. In addition, dry deposition flux of water-soluble lead was 3.14 mg·(m 2 ·a) -1 . It was found that the ratio of soluble fraction to total lead in dry deposited particles reached up to 43%, coinciding with a seasonal variation of ambient sulfur dioxide. The findings highlighted the anthropogenic imprints on the dry deposition flux of particles and heavy metals as well as the solubility of lead. This study also provides a first-hand dataset that can be used to assess ecological and environmental impacts of dry deposited lead, and an up-to-date scientific basis for the crafting abatement strategies to further reduce emission of heavy metals in China.