Effect of acid rain on mango trees
Author: Deng Xuexian reposted from: sjhx hits: 1243
Subject matter: There are many mango trees planted around the playground of our school. 1999 begins to bear fruit and matures around June every year. And there are many fruits, which are sweet and sour. Every year, the school picks mangoes and gives them to students in all classes for tasting. However, since 2003, mango trees still blossom and bear fruit, but around March, mangoes turn yellow and rot when they are young, and most leaves turn yellow and fall off, so mangoes can't be eaten.
Found the problem: why? Why do leaves and mangoes turn yellow? And browning occurs in the tip and underground parts of mango? Is there a bug? Or is there something else?
Put forward a hypothesis: let students observe the present situation of mango trees, the surrounding environment and the weather in February and March. The results show that there are no traces of insect bites on the leaves, and the school regularly sends people to spray pesticides, so there is no problem of insect pests. It often rains in February, March and April, and there are many ceramic factories outside the school. Could it be a pollution problem? What causes pollution? After observation and thinking, the students combined their own knowledge and put forward that it may be the harm of SO2, that is, acid rain.
Topic: Effect of Acid Rain on Mango Tree
Research purposes:
1. The influence of acid rain on mango trees was proved through experimental research.
2. Understand the harm of acid rain to the environment and cultivate students' awareness of environmental protection.
3. Cultivate students' practical ability, learn the basic methods of research, and improve their ability to analyze and solve problems.
Research content:
1. Good air quality standard
2. Composition of acid rain
3. Effects of acid rain on leaves and mangoes
4. Propose solutions to problems
Research methods: investigation, data retrieval, comparison and experimental verification.
Experimental steps:
1. Preparation stage
Collect the composition and harmful consequences of acid rain through books, newspapers, magazines and the Internet (within one week).
2. Experimental stage
(1) Collect the leaves and mangoes of similar mango trees that are not polluted in other places and clean them.
(2) Collect some rainwater around the mango tree in school and measure its PH value.
(3) Prepare H2SO4 aqueous solution with the same PH value in the laboratory.
(4) respectively soaking unpolluted mangoes and leaves in the collected acidic rainwater and the prepared H2SO4 aqueous solution,
On a normal rainy day, for comparison.
(5) record the phenomenon
3. Summary stage
Analyze and summarize the experimental results, draw conclusions and complete the written materials of the subject.
Team members: He, Zeng Jinbin, Liang, Cen Hongji, and how students *** 12.
Expected results: investigation reports or papers and written materials.
Material preparation: related books, newspapers, magazines, cameras, computers, experimental instruments, reagents, etc.
Findings:
1. Composition of acid rain: SO42-, H+, NO3-, etc. ，PH？ 5.6
2. Good air quality standards are
3. The PH value of rainwater in the school playground is between 3 and 4.
4. The PH value of normal rain is around 5.
5. Experiment:
6. Experimental results:
time
Rain on the playground
Sulfuric acid solution with the same PH value
Normal rainfall
The Quaker's name for Sunday
uniformity
uniformity
uniformity
the next day
uniformity
uniformity
uniformity
the third day
Brown spots began to appear.
Brown spots began to appear.
uniformity
The fourth day
The spots are getting bigger and bigger.
The spots are getting bigger and bigger.
uniformity
Fifth day
Large areas turn yellow.
Large areas turn yellow.
uniformity
Results Analysis: Mango and mango leaves in school turned yellow and fell off due to the influence of acid rain for a long time.
Experimental conclusion: Because many ceramic factories around the school use heavy oil as fuel, they emit white smoke, which contains a lot of dust and SO2 gas. In addition, it rained continuously in February and March, with abundant rainfall. As a result, mango trees were damaged by acid rain. And because the rain stays at the place where the tip of the leaf and mango face down for a long time, yellowing occurs in that place first.
Countermeasures to solve the problem:
I. Factories
1. Install flue gas desulfurization device.
2. Improve the utilization rate of coal combustion.
3. Choose low sulfur coal
Use natural gas
5. Increase the proportion of using green energy.
Two. Society and citizens
1. Use coal gas or natural gas instead of coal, and the former will not produce acid gas after combustion.
2. Use energy-saving appliances, because most of the electricity in China still comes from coal-fired power generation.
3. By taking the bus, reducing the number of vehicles can reduce automobile exhaust.
4. Choose goods with simple packaging, because excessive packaging will consume more electricity.
5. Participate in waste recycling and use the recycled resources to make products, which can save electricity.
[Next Page]
[Note] In 2003, the air quality of all cities in Guangdong Province reached Grade II standard and Grade I standard except Foshan.
Appendix:
Classification of environmental air quality functional zones and standard classification
1. Classification of functional areas of ambient air quality The first category of areas are nature reserves, scenic spots and other areas that need special protection.
The second-class areas are residential areas, mixed areas of commercial traffic and residents, cultural areas, general industrial areas and rural areas determined by urban planning.
These three types of areas are specific industrial areas.
2. Classification of ambient air quality standards The ambient air quality standards are divided into three levels.
A class area implements a class of standards.
The second class area implements the second class standard.
Class III areas implement Class III standards.
3. Concentration limit
This standard specifies the concentration limits that all pollutants are not allowed to exceed, as shown in the table.
Pollutant name
Time of value acquisition
concentration limit
Reference object
Sub-benchmark
Three-level standard
Concentration unit
sulphur dioxide
Annual average value
daily average
1 hour average
0.02
0.05
0. 15
0.06
0. 15
0.50
0. 10
0.25
0.70
aggregate of suspended particles
Annual average value
daily average
0.08
0. 12
0.20
0.30
0.30
0.50
Inhalable particulate matter PM 10
Annual average value
daily average
0.04
0.05
0. 10
0. 15
0. 15
0.25
oxynitride
compounds of nitrogen and oxygen
Annual average value
daily average
1 hour average
0.05
0. 10
0. 15
0.05
0. 10
0. 15
0. 10
0. 15
0.30
Mg/m3
(standard status)
nitrogen dioxide
NO2
Annual average value
daily average
1 hour average
0.04
0.08
0. 12
0.04
0.08
0. 12
0.08
0. 12
0.24
carbon monoxide
Commander (commanding officer)
daily average
1 hour average
4.00
10.00
4.00
10.00
6.00
20.00
ozone
ozone
1 hour average
0. 12
0. 16
0.20
Lead Pb
Seasonal average
Annual average value
1.50
1.00
Benzo [a] pyrene
BP
daily average
0.0 1
Microgram/m3
(standard status)
fluoride
daily average
1 hour average
7①
20①
F
monthly average
Seasonal average of plant growth
1.8②
1.2②
3.0③
2.0③
Microgram/(dm2 day)
note:
1) is suitable for urban areas;
2) Suitable for animal husbandry areas, semi-agricultural and semi-pastoral areas dominated by animal husbandry, and sericulture areas;
3) Suitable for agricultural and forestry areas.
References:
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