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The impact of acid rain on mango trees
Author: Deng Xuexian Posted from: sjhx Number of hits: 1243
Topic Materials: There are many mango trees planted around the sports ground of our school. They have started to bear fruit since 1999, and they mature around June every year. They bear a lot of fruit, sour and sweet, and delicious. Every year, the school picks mangoes and distributes them to each class for students to try. However, starting from 2003, although the mango trees are still blooming and bearing fruit, around March, when the mangoes are still very young, they turn yellow, rot, and fall off. , and most of the leaves have turned yellow and fallen off, making the mangoes inedible.
Discover the problem: Why is this happening? Why do leaves and mangoes turn yellow? And what about the browning that occurs on the leaf tips and the part of the mango facing underground? Are there bugs? Or is it because of something else?
Putting forward a hypothesis: Let the students observe the current situation of the mango tree, the surrounding environment, and the weather conditions around February and March. It was found that there were no traces of insect bites on the leaves, and the school also regularly sent people to spray Pesticides are not a pest problem. The weather in February, March, and April is often cloudy and rainy. There are many ceramic factories outside the school. Could it be a pollution problem? What causes pollution? After observing and thinking, and combining the knowledge they have learned, the students proposed that the hazards of acid rain may be SO2.
Project title: The impact of acid rain on mango trees
Research purpose:
1. Through experimental research, prove the impact of acid rain on mango trees
2. Understand the harm of acid rain to the environment and cultivate students' environmental awareness
3. Cultivate students' hands-on ability, learn basic research methods, and improve analysis and problem-solving abilities
Research content:
1. Standards for good air quality
2. Composition of acid rain
3. Effects of acid rain on leaves and mangoes
4. Propose a solution to the problem
Research methods: survey method, information check, comparison method, experimental verification method
Experimental steps:
1 .Preparation stage
Collect information about the components and harmful consequences of acid rain through books, newspapers, magazines, and the Internet (a week)
2. Experimental stage
(1) Collect leaves and mangoes from similar mango trees that are not contaminated elsewhere and clean them
(2) Collect some rainwater around the mango tree in the school and measure its pH value
p>(3) Prepare H2SO4 aqueous solution with the same pH value in the laboratory
(4) Soak the unpolluted mangoes and leaves in the collected acid rainwater and the prepared H2SO4 aqueous solution respectively ,
Contrast in normal rain.
(5) Record the phenomenon
3. Summary stage
Organize, analyze and summarize the experimental results, draw conclusions, and complete the written materials of the topic
p>
Group members: He Jiawen, Zeng Jinbin, Liang Keling, Shum Hongji, He Shunhuang and other ***12 students
Expected results: investigation reports or papers, written materials
Material preparation: relevant books, newspapers, magazines, cameras, computers, experimental instruments, reagents, etc.
Investigation results:
1. The components of acid rain: SO42-, H+, NO3 -Wait, pH? 5.6
2. Good air quality standard is
3. The pH value of rainwater in the school sports field is between 3 and 4
4 .The PH value of normal rainwater is about 5
5. Experiment:
6. Experimental results:
Time
Rainwater in the sports field
Sulfuric acid solution with the same pH value
Normal rainwater
On the first day
No change
No change
No change
The next day
No change
No change
No change
On the third day
Brown spots began to appear
Brown spots began to appear
No change
On the fourth day
The spots become larger and more numerous
The spots become larger and more numerous
No change
On the fifth day
A large area changed Yellow
A large area turned yellow
No change
Result analysis: The mangoes and mango leaves in the school turned yellow and fell off due to the impact of acid rain for a long time.
Experimental conclusion: Since there are many ceramic factories around the school, the ceramic factories use heavy oil as fuel and emit streams of white smoke, which contains a large amount of dust and SO2 gas. In addition, in February and March It rained continuously and there was enough rain. As a result, the mango trees were harmed by acid rain. And because the rain stays for a long time on the leaf tips and the downward-facing parts of the mango, the yellowing occurs first in that place.
Countermeasures to solve the problem:
1. Factory
1. Install flue gas desulfurization device
2. Improve coal combustion utilization
3. Choose low-sulfur coal
4. Use natural gas
5. Increase the proportion of green energy used
II. Society and citizens
1. Use coal gas or natural gas instead of burning coal. The former does not produce acid gas after burning
2. Use energy-saving appliances, because most of China’s electricity is still self-fired Coal-based power generation
3. Taking the bus and reducing the number of vehicles can reduce car exhaust
4. Choose products with simple packaging, because excessive production and packaging will consume more electricity
< p>5. Participating in waste recycling and using recycled resources to manufacture products can save electricity[NextPage]
[Note] In 2003, the air quality of all cities in Guangdong Province was only Foshan. There is no national second-level standard, and other cities have reached the second-level standard, and some have reached the first-level standard.
Appendix:
Classification and standard classification of ambient air quality functional areas
1. Ambient air quality functional area classification Class I areas include nature reserves, scenic spots and other areas that require special protection.
The second-category areas are residential areas, commercial, traffic and residential mixed areas, cultural areas, general industrial areas and rural areas determined in urban planning.
The third category area is a specific industrial area.
2. Classification of ambient air quality standards. Ambient air quality standards are divided into three levels.
The first-class area implements the first-level standard
The second-level area implements the second-level standard
The third-level area implements the third-level standard
3 .Concentration limits
This standard stipulates the concentration limits that are not allowed to be exceeded for various pollutants, see table
Pollutant names
Value time< /p>
Concentration limits
First-class standards
Second-level standards
Third-level standards
Concentration units
p>Sulfur dioxide SO2
Annual average
Daily average
1 hour average
0.02
0.05
0.15
0.06
0.15
0.50
0.10
0.25< /p>
0.70
Total suspended particulate matter TSP
Annual average
Daily average
0.08
0.12
0.20
0.30
0.30
0.50
Inhalable particulate matter PM10
< p>Annual averageDaily average
0.04
0.05
0.10
0.15
< p>0.150.25
Nitrogen oxides
NOx
Annual average
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 state)
Nitrogen dioxide
NO2
Annual average
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
CO
Daily average
1 hour average
4.00
10.00
4.00
10.00
6.00
20.00
Ozone
O3
1 hour average
0.12
0.16
0.20
Lead Pb
Quarterly average
Annual average
1.50
1.00
Benzo[a]pyrene
B[a]P
Daily average
0.01
μg/m3
(Standard state)
Fluoride
Daily average
1 hour average
7①
20①
F
Monthly average
Plant growing season average
1.8②
1.2②
3.0③
2.0③
μg/(dm2·d)
Note:
1) Applicable to cities Region;
2) Applicable to pastoral areas, semi-agricultural and semi-pastoral areas dominated by animal husbandry, and sericulture areas;
3) Applicable to agricultural and forestry areas.
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