The Effect Of Acid Rain On The Anatomy,Physiology Of Needle Leaf And Elements Of Different Organs Of Pinus Massoniana

Acid rain is widely distributed and seriously endangers land and aquatic ecosystem. Acid rain has become one of the top-ten environmental questions in the world. This paper combined the on-spot inspection and contrasted research to investigate the chemical characteristic of rainfall?anatomy and physiology of needle leaf?the content of chemical elements of different organs through the contrasted plots in seriously polluted area (Changtang) and lightly polluted area (Sanmenjiang) in Liuzhou . The effects of liming were also experimental researched. The results of study showed:(1)SO2 is ejected to the atmosphere because of burning a lot of coal with high sulphur content and Liouzhou is a basin with a high frequency of adverse thermal layer. All these prevent the diffusion of SO2. High temperature and moisture accelerate the transform of SO2. Soil acidification and low content of alkalescence substance in atmosphere make Liouzhou a high acidity rainfall area.(2)In the course of observing the anatomy of needle leaf, I found that the cuticle thickness obviously got thinner in the experimental area especially in Changtang. Compared with the cuticle thickness of normal needle leaf (2-2.5μm), the average cuticle thickness of Changtang (G+B) and Sanmenjiang were separately 1.43 μm and 1.73μm and they were lessened about 28.50%-42.80% and 13.50%-38.80% respectively. Changtang's (the stub axle 527.9μm and the major axis 807.8μm) were 53.9μm and 92.2μm shorter than Sanmenjiang's (the stub axle 581.8μm and the major axis 900.1μm). The stub axle and the major axis length of need leaf were obviously shorter than normal needle leaf (the stub axle 800μm and the major axis 1200μm) and needleleaf got shorter by acid rain. The stomatal density of Changtang and Sanmenjiang were 123.5 num/mm2 and 143.1 num/mm2. The stomatal density in seriously polluted area was lessened about 13.70% compared with that in the lightly polluted area. The stomatal density was shorter in two experimental areas than that in clear area (180 num/mm2). Hence, acid rain could reduce the stomatal density of needle leaf. The observation still showed that there was seasonal variation in stomatal apertura. It turned out to be that summer >autumn >spring> winter, which was consistent with the seasonal pH variation of acid rain. It showed that high acidity in winter and spring could restrain stomatal apertura.(3)Acid rain had obvious impact on the physiology of needle leaf. First, Cell membrane permeability was added by acid rain. The cell membrane permeability in Changtang was 25.3%-149.19% higher than that in Sanmenjiang. We could also see the cell membrane permeability of seriously damaged leaf were 2.66%-9.77% (Changtang) and 0.67%-5.77%(Sanmenjiang) higher than that of lightly damaged leaf. Second, the content of chlorophyll of needle leaf in seriously damaged area was 50.70%-64.62% lower than that of lightly damaged area. In the same experimental area, heavily damaged needle leaf were 7.67%-16.30%(Changtang) and 6.25%-9.35%(Sanmenjiang) lower than lightly damaged needle leaf. Acid rain still influenced the structural ratio of chlorophyll a and b. Third, acid rain made total sugar content reduced, the activity of peroxidase increased and the activity of PPO reduced.(4)The effect of acid rain on content of chemical elements of different organs was different with different organs and different elements. Except some exceptional organs and elements, the nutrient element content of different organs of Pinus massioniana in Sanmenjiang were higher than that in Changtang, especially for N, the content of N in over-bark pole in Sanmenjiang was almost twice as much as that in Changtang. Except Ca, Mg which had biggest content in branch least content in timber, other elements appeared the regularity: the needle leaf>over-bark pole, branch > the bark.(5)The effects of liming on needle leaf were as follows: First was on the anatomy of needle leaf. Liming could increase the cuticle thickness (average increase was 0.07um) and accelerated the growth of needle...