Fate of the herbicide metolachlor in aerobic and anaerobic soils

The fate of the herbicide metolachlor in aerobic and anaerobic soils with repeated applications of the metolachlor over a period of 5 years was studied. After 12 weeks incubation, cumulative 14CO2 evolution from the soil accounts for 8.01% in aerobic condition versus 1.5% of 14CO2 in the soil had not been treated with metolachlor. The total 14C recovery in the methanol-water extract and in the non-extractable portion of this aerobic soil accounted for 73.1% and the total metolachlor recovery in the methanol-water extract was 46.7% but 86.9% of 14C was accounted for in the γ-irradiated control soil. There axe no differences in the recovery of 14C between non-sterile and γ-irradiated control soil under anaerobic conditions. The results show that there was some active metolachlor-degrading population in the Virginia soil which had been previously received repeated applications of the metolachlor but only under aerobic condition.     

Analysis of styrene oxide-hemoglobin adducts at different binding sites

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First-trimester maternal serum alpha-fetoprotein as a marker for fetal chromosomal disorders

We evaluated first-trimester maternal serum alpha-fetoprotein (MS-AFP) as a marker for fetal chromosomal disorders. The multicentre study was performed under the auspices of the Dutch Working Party on Prenatal Diagnosis. MS-AFP was measured in 2404 normal pregnancies and 72 chromosomally abnormal pregnancies. The median multiple of the normal median (MOM) in 32 Down's syndrome pregnancies was 0·83 with a 95 per cent confidence interval ranging from 0·60 to 1·04. The difference between the distributions of first-trimester MS-AFP in normal and Down's syndrome pregnancies was statistically significant (t-test: t = 2·34, P<0·05). Thirty-one per cent of the Down's syndrome pregnancies were found below the tenth percentile. We found no difference between normal pregnancies and pregnancies with other chromosomal disorders (eight cases with trisomy 18, MOM = 1·26; seven cases with sex chromosome abnormalities, MOM = 1·07; 22 cases with a chromosomal mosaic pattern in chorionic villi, MOM = 1·08). We conclude that first-trimester MS-AFP can discriminate between normal and Down's syndrome pregnancies, but is not an effective marker. First-trimester MS-AFP has no value as a marker for other fetal chromosomal disorders.     

基因工程的潜在影响及其对有机食品产业的冲击

基因工程的研究发展非常迅速，使其在农业和食品加工领域的应用成为不可避免，但其安全性问题在世界范围内引起了非常广泛的争议。从基因工程内涵和有机农业的要求及目标出发，讨论了基因工程的潜在影响及其对发展有机食品产业的冲击。认为有机农业运动面临的紧迫问题是尽快协调所有的行动方案来保证有机食品永远不涉及基因工程生物体。有机农业正面临基因工程的挑战，其发展的潜力是建立一个完全独立的有机食品市场。     

荔枝、龙眼和香蕉质量与生产环境的关系

对广州市的荔枝、龙眼和香蕉三大类水果产品质量和生产环境进行了质量监测和评价。结果表明,这三类水果的生产环境均遭受一定程度的污染;水果质量广泛受到氟污染,部分受到Pb、Cd污染;荔枝对镉的吸收富集作用较强。     

SO_4~(2-)/TiO_2光催化还原Cr(Ⅵ)的研究

将溶胶-凝胶法制备的SO42-/TiO2在不同温度下焙烧得到了具有不同特性的催化剂,用X射线衍射(XRD)、热重-差热分析(TG-DTA)、氨气程序升温脱附(NH3-TPD)、静态吸附等手段对催化剂进行了表征.研究了不同特性的SO42-/TiO2催化剂光催化还原Cr(Ⅵ)的行为,并对其影响因素进行了分析.结果表明:SO42-/TiO2在300-600℃下焙烧均具有较高的催化效率,而在700℃及800℃下焙烧其催化活性显著降低.SO42-/TiO2的这种催化特性是由其吸附性能、晶相组成及表面酸量决定的.     

土壤污染生物修复的影响因素

从污染物特征、微生物的降解能力和环境因子三个方面对土壤污染生物修复技术中的主要影响因素进行了综合评述,重点分析了修复过程中涉及的物理、化学及生物作用机理,并介绍了消除影响的对策和目前的研究进展。     

混凝絮凝法去除腐质酸的研究

进行了混凝絮凝法去除水中腐殖酸的研究，结果表明，同传统的絮凝剂相比，微生物絮凝剂不仅用量少，去除效果好(去除率可达60％)，而且不产生二次污染，可应用于废水特别是给水中腐殖酸的去除工艺中，对絮凝剂的絮凝机理进行了初步研究，研究表明，微生物絮凝剂去除腐殖酸主要是通过架桥完成的，不同于A12(SO4)3的电中和机理。     

Ti(IV)与铜离子共掺杂的羟基磷灰石薄膜弱紫外光杀菌研究

采用共沉淀水热合成和离子交换的方法,制备了钛与铜离子共掺杂的羟基磷灰石(Ca10(PO4)6(OH)2:HAP)(HAPTiCu),以大肠杆菌为目标物,研究了不同材料负载的多孔镍网薄膜在弱紫外光下的杀菌活性.结果表明,HAPTiCu在弱紫外光下具有高效杀菌效率,并远远高于HAPTi和P25TiO2薄膜.这主要是铜离子的抗菌与光催化分解细菌的协同作用的结果.电子自旋共振(ESR)研究表明杀菌反应的主要活性物种是O-2·.HAPTiCu薄膜释放的铜离子在光催化杀菌反应过程中,被光催化还原沉积在表面,导致了较低的铜离子溶出,从而保证了材料的稳定性.