模拟酸雨对羟基磷灰石稳定化土壤镉的分布、可浸出性及生物可给性的影响

通过室内土柱淋溶实验,以0.5%的质量比向镉污染土壤中添加羟基磷灰石（HAP）,以不施HAP土壤为对照,考察p H 3.5、4.5和5.6的模拟酸雨对土壤镉的分布、可浸出性、生物可给性及其健康风险的影响。结果表明：酸雨淋溶显著降低了对照处理表层土壤p H,添加HAP增加了土壤对酸雨淋洗的缓冲能力,土壤p H较对照高约1个单位。对照处理酸雨p H的降低加剧了Cd在土柱内的下移,但HAP处理各土层全Cd分别较对照0～5 cm和5～10 cm土壤高出8.54～10.0、3.13～3.29 mg·kg^-1。对照处理土壤在酸雨作用下可浸出性Cd含量从0～5 cm的0.17～0.23 mg·L^-1增加到10～20 cm的0.61～0.68 mg·L^-1,但HAP处理各土层可浸出性Cd维持在0.45～0.50 mg·L^-1。总体上,对照和HAP处理土壤胃液和肠液阶段溶解态Cd含量及胃液阶段Cd的生物可给性均随酸雨pH的降低而降低。与对照相比,HAP处理土壤增加了胃液和肠液阶段溶解态Cd含量及胃液阶段Cd的生物可给性,但显著降低了肠液阶段Cd的生物可给性。对照和HAP处理土壤胃液和肠液阶段无意摄入土壤中Cd对儿童的每月允许摄入量PTMI（Provisional tolerable monthly intake）贡献率均随酸雨p H的降低而降低,且HAP处理显著高于对照。以上结果表明高强度酸雨淋溶下,HAP能够有效提高土壤对酸雨的缓冲能力,降低土壤Cd的淋失,但增加了表层土壤Cd的生物可给性及人体健康风险,需要引起特别关注。

热休克、PMA对体外培养人角朊细胞表达ENA的影响

ENA在角朊细胞膜表达被认为与 LE的发病有关。为了探讨热休克和 PMA对 ENA表达的影响 ,我们用加热和 PMA刺激体外培养角朊细胞 ,用间接免疫荧光法观察了角朊细胞 ENA的表达。结果 ,4 2℃、4 5℃热休克 90 min后 ,分别可使 9.1± 1.2 %、2 0 .0± 4 .7%的细胞出现 ENA膜表达 ;5μg/ L、10 μg/ L PMA刺激 2 h后 ,2 2 .6± 7.6%、2 3.1± 4 .9%的角朊细胞膜出现 ENA表达。提示 ENA在角朊细胞膜的表达与热刺激和蛋白激酶 C传导路径有关。

Leaching kinetics of acid-soluble Cr(Ⅵ) from chromite ore processing residue with hydrofluoric acid

Leaching kinetics of acid-soluble Cr（VI） in chromite ore processing residue （COPR） using hydrofluoric （HF） acid solution as a leaching agent was investigated for potential remediation of COPR with industrial waste water containing HF. The results show that HF can effectively destabilize the Cr（VI）-bearing minerals, resulting in the mobilization of Cr（VI） from COPR into the leachate. Particle size significantly influences the leaching of acid-soluble Cr（VI） from COPR, followed by leaching time, whereas the effects of HF concentration and leaching temperature are slight and the influence of stirring rate is negligible. The leaching process of acid-soluble Cr（VI） from COPR is controlled by the diffusion through the product layer. The apparent activation energy is 8.696 kJ/mol and the reaction orders with respect to HF concentration and particle size is 0.493 8 and -2.013 3, respectively.

Bioleaching of soluble phosphorus from rock phosphate containing pyrite with DES-induced Acidithiobacillus ferrooxidans

The effects of Acidithiobacillus ferrooxidans(At. f) mutated with diethyl sulfate(DES) as a mutagen on the bioleaching of soluble phosphorus(P) from rock phosphate(RP) were investigated. The results show that the oxidative activity of At. f is greatly improved by 1.0%(volume fraction) of DES. Correspondingly,the highest leaching rate of soluble P is also obtained to be 14.9% by the At. f mutated,which is 85.8% higher than that of the adapted At. f without mutation. In addition,the SEM images are significantly performed that the corrosion of RP residue surfaces leached by 1.0% DES-induced At.f is much worse than that of leached by the adapted At. f. All the above indicate that the leaching efficiency of soluble P from RP with pyrite can be greatly improved by using DES-induced At. f to a certain extent.