Effects of acid rain on forest ecosystem in Southwestern China

The study of effects of acid rain in Southwestern China on forest ecosystems .has been inrestigated since 1984. The results have shown that the ecosystem of Pinus massoniana forest has been damaged severely by acid rain. Comparing the areas where the annual mean pH value is lower than 4.5 with that higher than 4.5, the productivity of the ecosystems decreased 50 percent. Both the percentages of the green leaves and the content of chlorophyll cut down; the acidity of soil increased a bit and the fertility showed the tendency to lower. The microbial population components in surface soil were changed and the total number of soil microbes reduced from 63.5 to 92.6 percent. Besides the direct effects of acid rain, the insect pest, especially, Blastophagus piniperdoz and Monochamus galloprovincialis, seized the opportunity to enter and reproduce in it so as to aggravate the forest dieback of P.massoniana in the areas where the annual average pH value is lower than 4.5.Additionally, the simulation study on the     

Study on the proposed environmental guidelines for Cd, Hg, Pb and As in soil of China

This paper deals with the soil-environmental standard. According to the current situation of researching on the soil-environmental quality guideline at home and abroad, and on the basis of the foundations and principles of enacting the soil-environmental standard, the soil environment quality guideline values of Hg, Cd, Pb and As were suggested.     

有机酸与表面活性剂联合作用对土壤重金属的浸提效果研究

重金属污染土壤的原位淋洗修复既要实现对重金属的高效去除,还要尽量减少对土壤性质的破坏,这一点在农业污染土壤修复中尤为重要。以张士污灌区农田土壤为研究对象,利用振荡浸提技术筛选有机酸和表面活性剂组合,并确定了两者联合淋洗修复污染土壤的最佳配比。结果表明:有机酸(酒石酸、乙酸、柠檬酸和苹果酸)中的酒石酸浓度为0.5 mol.L-1和表面活性剂(SDBS、鼠李糖和皂素)中的皂素质量分数为0.7%时对土壤Cd、Pb、Zn的浸提效果较好;在酒石酸与皂素体积配比为1∶1时,对重金属Cd、Pb、Zn浸提效果最好,浸提率分别为87.62%、36.30%、20.67%;单一有机酸、表面活性剂或者有机酸与表面活性剂的混合溶液,对土壤重金属的浸提效果均为Cd>Pb>Zn。虽然有机酸与表面活性剂联合浸提效果略低于酒石酸浸提,但其弱酸性对土壤性质影响较小,在原位淋洗修复工程中有较好的应用前景。     

H_2O_2在石油污染土壤微生物治理过程中的作用

为探讨缩短石油污染土壤微生物治理过程的有效途径，采用生物泥浆法，系统地研究了Ｈ２Ｏ２对土壤中烃类污染物微生物降解速度的影响。结果表明，Ｈ２Ｏ２既可直接氧化一部分烃类污染物，又可为微生物的氧化过程提供充足的电子受体，强化它们对烃类污染物的氧化降解作用，通过添加适量的Ｈ２Ｏ２，使土样中石油污染物的去除率增加了近３倍     

长春市供暖季办公建筑室内PM2.5中金属元素的污染特征及风险评估

对长春市供暖季某办公建筑室内PM_(2.5)进行采样,用电感耦合等离子发射光谱法(ICP-OES)对其中金属元素进行检测。采用富集因子法与主成分分析法对PM_(2.5)中的金属元素进行源解析,并对其潜在生态风险和人体健康风险进行评估。结果显示,室内PM_(2.5)中金属元素来源主要有燃煤排放尘、工业过程排放尘、机动车排放尘、室内污染源排放尘及土壤扬尘,5种来源的贡献率分别为27.35%、17.57%、12.44%、8.93%、8.05%。PM_(2.5)中金属元素的综合潜在生态风险指数为1 729.63,存在极强生态危害;金属元素对成人的非致癌暴露量以呼吸摄入为主,对儿童的非致癌暴露量以手口摄入为主,对成人和儿童均具有非致癌风险,但不具有致癌风险。     

振动与冲击试验中单自由度线性系统损坏可能性的比较

比较了单自由度线性机械系统在稳态振动，随机振，运输试验以及冲击试验中响应的大小。     

大港海滨盐土的腐蚀性研究

含可溶性盐量多、含水量高、电阻率极低等土壤性质决定了大港海滨盐土具有很强的腐蚀性。本次试验主要研究了碳钢、ＬＹ１１铝合金、Ｈ６２黄铜、１Ｃｒ１３不锈钢、１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢几种金属材料经过１、３、５年三个试验周期的腐蚀行为及特征     

摆动辗压高颈法兰工艺研究

此文阐述了高颈法兰的摆辗工艺,对其变形和力能参数进行了分析,并对其模具的设计进行了探讨.实践证明,高颈法兰的锻造——扩辗——摆辗复合成形工艺是合理的,完全达到了质量指标和技术要求,现已批量生产.