乙醇汽油对国六直喷汽油车排放特性的影响

选择5台国六直喷汽油车采用3种不同组分的E10乙醇汽油和1种不含含氧化合物的国VI汽油,按照国六排放标准开展了WLTC循环测试,研究乙醇和基础油组分对污染物排放的影响规律.结果表明,多数国六直喷汽油车的CO、THC和PM排放有所降低,NO_x排放无明显差异,PN排放微增,所有样车的CO、THC和PM平均排放降低为6%、7%和14%.E10乙醇汽油中的重质芳香烃含量增高时,PN排放明显增加,PN排放与PMI指数呈现较强的正相关关系.     

Population structure and sex-change in the coral-inhabiting snailCoralliophila violacea at Hsiao-Liuchiu,Taiwan

Surveys of the coral-inhabiting snailCoralliophila violacea (Lamarck) (=C. neritoidea Kiener) were made on shallow fringing reefs (<8 m deep) around Hsiao-Liuchiu, Taiwan, between July and October 1990. The snails were aggregated into patches on the surface of massive poritid coral colonies. Coral colonies >40 cm in diameter were more likely to bear patches of snails than smaller colonies, and also to have more snails. The coralliophilids ranged from 5 to 30 mm in aperture length. The sex ratio of the population was biased toward males (539:279), with only a few small individuals of indistinguishable sex. Snails between 6 and 10 mm were all males, while most snails with aperture lengths 20 mm were females. Judging from the distinct size ranges of males and females within patches and from the observed degeneration of the penis, the snails may have changed sex from male to female with increasing size. Sex-change may occur across a wide size range (10 to 20 mm). The correlation of smallest female size and largest male size among patches indicates that snail size at sex-change is peculiar to each individual patch. Those females in patches with a single female (but many males) were significantly smaller than females in multiple-female patches. It is likely that in the absence of females males change sex at a smaller size, whereas in the presence of large females males delay sexchange until they have reached a larger size. The plasticity of size at sex-change may be adaptive and a result of natural selection at the individual level.     

Dry aerial fallout of organochlorine insecticide residues in Delhi, India

Monitoring of airborne dust in Delhi during May to July 1985 revealed residues of DDT varying from 1.3 to 7.14 ng mg(-1) (4.06-22.31 ng m(-2) day(-1)) with an average of 3.32 ng mg(-1) (10.38 ng m(-2) day(-1)), and HCH which ranged from 0.46 to 2.35 ng mg(-1) (1.44-7.34 ng m(-2) day(-1)) with a mean of 1.16 ng mg(-1) (3.63 ng m(-2) day(-1)). The concentration of total DDT was almost 3 times greater than that of HCH.     

Reversibility of stemflow-induced soil acidification in Swedish beech forest

Stemwater running down the trunks of beech (Fagus sylvatica L.) has an acidifying effect on soil near the stem. The deposition of acidifying substances may be two to four times higher close to the stem compared to in the stand in general. To study reversibility of soil acidification, 72 stumps of beech trees were chosen from five different year classes of felling (3, 6, 9, 14-15, 25-30), representing the years when stemflow ceased to affect the soil. The H(+) concentration (pH KCl) in the topsoil (0-5 cm) differed between the distances 10-30 cm and 230-250 cm from the stumps, the soil close to the stem being more acid. The longer the time since felling the smaller the differences in H(+) concentration became. This reduction in soil acidity amounted to ca. 50% after 15 years, and only small further changes occurred over the next ten years. This indicates that soil may not recover fully from acidification, or does so at a rather slow rate after the initial 15 years of recovery.     

Impact of repeated application on the binding and persistence of [14C]-DDT and [14C]-HCH in a tropical soil

An Indian sandy loam soil was initially treated with 1 kg a.i. ha(-1) of either [(14)C]-p,p'-DDT or [(14)C]-gamma-HCH during winter. DDT concentration after 30 days declined to 75.3%, which included 2.1% soil-bound residues. After 150 days, DDT levels further decreased to 42.4% with a concomitant increase in bound residues amounting to 5.9%. Identical treatment with HCH caused the residue levels to be reduced to 67.4 and 23.6%, after 30 and 150 days, respectively. During this period, the soil-bound residues of HCH increased from 5.2 to 12.8%. Repeat application to pre-treated soils in summer and subsequent field exposure for 30 days reduced the concentration of DDT to 52.1% and that of HCH to 42.4% of the total concentration following the second treatment. In parallel control experiments, which received only a single treatment, DDT levels declined to 61.3%, while HCH slumped to 45.3%, indicating a slower dissipation rate than in the corresponding repeated treatments. In repeat experiments, the soil-bound residues of DDT and HCH showed only a 1.07 to 1.08-fold increase in 30 days, as compared to three to ten-times increase in the control experiments. The results amply demonstrate that pre-treatment of tropical soils with DDT or HCH enhances their rate of dissipation and significantly reduce the formation of their soil-bound residues.     

Effect of methyl mercuric chloride treatment on haematological characteristics and erythrocyte morphology of Swiss mice

Effects of methyl mercuric chloride (MMC) on the blood parameters of Swiss mice (Mus musculus) were studied. The mice received an initial dose of MMC (24 mg kg(-1) body wt) as intraperitoneal injection followed by a second similar dose on the 14th day of the first dose administration. Significant (p < or = 0.001) decreases in haemoglobin content, red blood cell (RBC) count and haematocrit value were observed in the MMC injected mice when compared to the control mice. The effect of the second dose was severe, after which no significant recovery in the values of these parameters was observed. The result also showed a high degree of mercury accumulation in the blood of the MMC exposed mice. Interesting features were marked in the erythrocyte morphology of the exposed mice. An initial shrinkage followed by swelling of the cells was observed after each injection. The outline of the exposed cells was irregular with beak like or small finger like projections. Rupturing and disintegration of the erythrocyte membrane, leading to erythrolysis, were also noticed.     

Effect of shore position and environmental metal levels on body metal burdens in the barnacle, Elminius modestus

Body (thorax and prosoma) weight, shell growth, and Zn, Cu, Fe, Mn and Ca levels were measured in artificially settled Elminius modestus over a 14-month period following transfer to high, mid and low tide positions in the uncontaminated Menai Strait and two mid tide sites within a Zn and Cu polluted bay on the North West coast of Anglesey. Barnacles showed higher mortality and slower growth at the upper shore position than at any other site. There was no evidence of Zn and Cu regulation by the bodies or shells, and both seemed to reflect environmental levels. Body metal levels were lowest in early winter and the highest second year values were found in January (Zn), March (Cu, Fe) or May (Ca). Higher shore barnacles contained larger concentrations of Zn than mid or low tide animals. Differences in feeding activity and the amount of testes may account for these variations. Reciprocal transplants between polluted and 'clean' sites indicate that body Cu and Zn accumulation and loss was very rapid. Spatial and temporal changes in shell metal levels closely mirror that of the body.