生态环境与氧气含量.doc

Worksheet Data Analysis Module 11. Fill in Table DA 1.1 by following Steps 1-6 in Module 1. A.TimeB.Temp.oCC.Dissolved oxygen(mg/L)D.Dissolved oxygen at saturation(mg/L)E.Departure from saturation(C-D)F.Change in oxygen(mg/L/hr)(C2-C1)G.Respiration(mg/L/hr)H.Gas exchange rate(mg/L/hr)I.Gas exchange rate * departure(E*H)J.Gross primary production (mg/L/hr)(F+G+I)16:0030.87.527.45 0.0717:0030.66.547.48-0.94-0.986.550.71-0.674.918:0029.95.417.57-2.16-1.136.140.70-1.503.519:0028.84.307.72-3.42-1.125.650.68-2.322.220:0027.62.697.89-5.21-1.615.240.66-3.450.221:0026.61.798.02-6.23-0.904.910.65-4.040.022:0025.81.438.13-6.71-0.364.670.64-4.280.023:0025.21.348.25-6.92-0.094.480.63-4.350.00:0024.61.308.32-7.02-0.034.340.62-4.36-0.11:0024.21.338.39-7.060.034.210.61-4.34-0.12:0023.81.378.45-7.090.034.110.61-4.32-0.23:0023.51.408.50-7.100.044.030.61-4.29-0.24:0023.31.418.50-7.100.003.980.60-4.28-0.35:0023.11.428.55-7.130.013.940.60-4.28-0.36:0022.91.458.59-7.140.033.880.60-4.26-0.37:0022.81.768.60-6.840.313.860.60-4.070.18:0022.82.378.62-6.250.613.860.60-3.720.79:0022.93.268.58-5.320.903.920.60-3.191.610:0023.65.558.48-2.932.294.190.61-1.804.711:0025.18.238.24-0.012.684.790.64-0.017.512:0027.0 10.037.972.061.805.390.671.388.613:0028.5 10.557.752.790.525.940.691.938.414:0029.69.857.612.24-0.706.180.701.567.015:0029.98.437.570.85-1.436.370.710.605.516:0029.97.497.58-0.09-0.946.270.70-0.065.3_ 2. Which direction is oxygen diffusing (into or out of the water) when the values are negative or positive? 当环境中氧气含量（Change in oxygen）为负的时候氧气向水中扩散。反之，即为正的时候氧气扩散方向为向水外向。3. At what time of day are changes in oxygen concentration (column F) most positive? Why?约为10：00至12:00之间。如上表所示此刻氧气含量（Change in oxygen）数值最大，也就是说随着光照强度增强光合作用的作用达到最大。4. From 1:00 am to sunrise, dissolved oxygen concentrations in table DA1-1 are very low, why is this? At what time do you think sunrise occurred? 是因为在黑暗中只发生呼吸作用以至于氧气被大量消耗。所以在7:00之后日光增强光合作用变强，氧气量开始恢复。5. During the period of 1:00 am to sunrise, dissolved oxygen changes little, yet respiration is still occurring (column G). Considering the physical and biological processes at play, how is this possible? 即使呼吸作用在夜间持续消耗氧气，大气中的氧气也会渗透进水中使氧气量平衡。午夜时分的低氧环境足以扼杀大多数的对低氧环境敏感的水生生物。当呼吸作用降到最低的时候环境趋向于成为一个完全缺氧环境。6. Based on these values, at what times of the day is oxygen diffusing into or out of the water at the highest rates, and why?当光合速率最大时系统中氧气含量会过饱和。此时是氧气扩散出水体的最高峰时刻。反之在午夜时分光合最低的时候氧气从外界进入水体。7. Based on your answer, would you classify this stream as primarily autotrophic or heterotrophic, in other words, is P/R greater than or less than 1?因为呼吸作用终大于光合作用的产物，所以此生态系统还是归类于异养一类。8. What are the major energy sources to food webs in this stream? 在此溪流中向食物网路提供能量的主要提供者可能是水草等的植物组织。9. Why might it be more useful to talk about these values in terms of carbon rather than oxygen. 氧气的流动量与碳的流动量是成正比的，这样的话我们就可以利用它来估计呼吸作用的强度了。因为碳的流量可以代表能量的流动。所以碳是个完美的“货币”。10. Based on relationships between dissolved oxygen, primary production, and respiration explored above, is any primary production occurring in the stream without Hydrilla? 这个水体环境中并不存在初级生产者。11. How would overall carbon fluxes in this stream differ from the one with Hydrilla? 在光合作用过程中并没有足够的碳提供。因为此溪流中没有足够的生物量，碳的含量很低。12. What are the likely energy sources for food webs in this stream?为了维持这个水体环境的生物活动必须依赖外来的碳源或者溶解进水体的碳带来的能量。13. What do you think would have happened to patterns of productivity in the Hydrilla stream if the forest had been cleared but Hydrilla had not been introduced? Would production still increase?3窗体顶端砍伐森林的增