On October 28th, the Ministry of Ecology and Environment announced to the media the national surface water environmental quality in the third quarter of 2023 (July-September) and January-September.

Overall situation

In the third quarter, among the 3,641 national surface water assessment sections, the proportion of sections with excellent water quality (Class I-III) was 77.3%, down 1.7 percentage points year-on-year; The proportion of inferior V section was 0.9%, down 0.2 percentage points year-on-year. The main pollution indicators are chemical oxygen demand, permanganate index and total phosphorus.

From January to September, among 3,641 national surface water assessment sections, the proportion of sections with excellent water quality (Class I-III) was 87.1%, up 0.8 percentage points year-on-year; The proportion of inferior V section was 0.7%, down 0.2 percentage points year-on-year. The main pollution indicators are chemical oxygen demand, permanganate index and total phosphorus.

Figure 1 Proportion of surface water quality categories in China from January to September

Water quality status of major rivers

In the third quarter, the proportion of sections with excellent water quality (Class I-III) in seven major river basins, such as Yangtze River, Yellow River, Pearl River, Songhua River, Huaihe River, Haihe River and Liaohe River, and rivers in the northwest, southwest and Zhejiang and Fujian provinces was 80.5%, down 1.8 percentage points year-on-year; The proportion of inferior V section was 0.6%, down 0.3 percentage points year-on-year. The main pollution indicators are chemical oxygen demand, permanganate index and total phosphorus. Among them, the water quality of southwest rivers, northwest rivers and Yangtze River basin is excellent; The water quality of the rivers in Zhejiang and Fujian, the Yellow River Basin and the Pearl River Basin is good; Liaohe, Haihe, Huaihe and Songhua river basins are slightly polluted.

From January to September, the proportion of sections with excellent water quality (Grade I-III) in the seven major river basins, such as the Yangtze River, Yellow River, Pearl River, Songhua River, Huaihe River, Haihe River and Liaohe River, and the rivers in the northwest, southwest and Zhejiang and Fujian provinces was 89.2%, up 0.7 percentage points year-on-year; The proportion of inferior V section was 0.5%, down by 0.2 percentage points year-on-year. The main pollution indicators are chemical oxygen demand, permanganate index and five-day biochemical oxygen demand. Among them, the water quality of the Yangtze River basin, Zhejiang and Fujian rivers, southwest rivers, northwest rivers and the Pearl River basin is excellent; The water quality of the Yellow River, Liaohe River, Huaihe River and Haihe River basins is good; Songhua river basin is slightly polluted.

Figure 2 Proportion of water quality categories in seven major river basins, southwest and northwest rivers and rivers in Zhejiang and Fujian from January to September.

Water quality and nutritional status of key lakes (reservoirs)

In the third quarter, among the 209 key lakes (reservoirs) monitored, the number of lakes and reservoirs with excellent water quality (Class I-III) accounted for 72.2%, up 4.1 percentage points year-on-year; The number of lakes and reservoirs with inferior grade V water quality accounted for 3.8%, down 1.0 percentage points year-on-year. The main pollution indicators are total phosphorus, chemical oxygen demand and permanganate index. Among the 204 lakes (reservoirs) monitoring the nutritional status, 18 are moderately eutrophic, accounting for 8.8%; 50 were mildly eutrophic, accounting for 24.5%; The rest of the lakes (reservoirs) are in the state of medium nutrition or poor nutrition. Among them, Taihu Lake is slightly polluted and slightly eutrophic, and the main pollution index is total phosphorus; Chaohu Lake is slightly polluted and moderately eutrophic, and the main pollution index is total phosphorus. Dianchi Lake is moderately polluted and moderately eutrophic, and the main pollution indexes are chemical oxygen demand, total phosphorus and permanganate index. Erhai Lake has good water quality and moderate nutrition; The water quality of Danjiangkou reservoir is excellent and medium nutrition; Baiyangdian Lake is slightly polluted (mainly affected by floods) and moderately nutritious, and the classification index is dissolved oxygen.

From January to September, among the 209 key lakes (reservoirs) monitored, the number of lakes and reservoirs with excellent water quality (Class I-III) accounted for 74.6%, up 0.8 percentage points year-on-year; The number of lakes and reservoirs with inferior grade V water quality accounted for 4.3%, down 0.5 percentage points year-on-year. The main pollution indicators are total phosphorus, chemical oxygen demand and permanganate index. Among the 205 lakes (reservoirs) whose nutritional status was monitored, 7 were moderately eutrophic, accounting for 3.4%; 50 were mildly eutrophic, accounting for 24.4%; The rest of the lakes (reservoirs) are in the state of medium nutrition or poor nutrition. Among them, Taihu Lake and Chaohu Lake are slightly polluted and slightly eutrophic, and the main pollution index is total phosphorus; Dianchi Lake is slightly polluted and moderately eutrophic, and the main pollution indexes are chemical oxygen demand, total phosphorus and permanganate index. The water quality of Erhai Lake and Baiyangdian Lake is good and moderately nutritious. The water quality of Danjiangkou Reservoir is excellent and moderate.

Table 1 Water quality and nutritional status of six lakes (reservoirs) from January to September.

Fig. 3 Water quality and nutritional status of six lakes (reservoirs) from January to September.

Rank of national surface water assessment sections in prefecture-level and above cities

From January to September, among the cities at the prefecture level and above in China, the water environmental quality of national surface water assessment sections in 30 cities such as Liuzhou, Guilin and Kizilsu Kirgiz Autonomous Prefecture was relatively good (from 1st to 30th), while the water environmental quality of national surface water assessment sections in 30 cities such as wujiaqu city, Shangqiu and Tongliao was relatively poor (from 1st to 30th). See Table 1-2.

The changes of water environmental quality of national surface water assessment sections in 30 cities, such as Shihezi, Baicheng and Xinzhou, are relatively good (from 1st to 30th), while the changes of water environmental quality of national surface water assessment sections in 30 cities, such as Hangzhou, Taizhou and Yancheng, are relatively poor (from 1st to 30th). See attached table 3-4.

Schedule 1

From January to September, 2023, the water environment quality of the national surface water assessment section ranked the top 30 cities and their water bodies.

Schedule 2

From January to September, 2023, the water environment quality of the national surface water assessment section ranked the last 30 cities and their water bodies.

Note: The water quality of the water body marked with * in the table meets Class I or Class II of Environmental Quality Standard for Surface Water (GB3838-2002)Ⅰ); In June and July, the section of Liutuan Bridge in Bailang River in Weifang City was seriously disturbed by human beings, and all the indexes of this section in that month were replaced by the worst value.

Schedule 3

From January to September, 2023, the changes of water environment quality in the national surface water assessment section ranked the top 30 cities and their water bodies.

Note: A negative value indicates that the environmental quality of surface water is getting better year-on-year, while a positive value indicates that it is getting worse year-on-year.

Schedule 4

From January to September, 2023, the changes of water environment quality in the national surface water assessment section ranked the last 30 cities and their water bodies.

Note: The water quality of the water bodies marked with * in the table meets Class I or Class II of Environmental Quality Standard for Surface Water (GB3838-2002)Ⅰ).

Searching for [mini refrigerator], [dormitory refrigerator] and [car refrigerator] on the e-commerce platform is the most common one. Its scientific name is [Semiconductor cooling and heating box] . The principle is very simple. When a special semiconductor is electrified, a temperature difference will occur between its two ends. One end in the refrigerator absorbs heat, and the other end outside the refrigerator emits heat, which will be blown away by a fan, resulting in a refrigeration effect.

The biggest advantage of this small refrigerator is that Cheap and small in size We chose seven 8-L mini-refrigerators on the e-commerce platform, the prices are basically around 100-200, and only delicious and Pepsi ones are more expensive. In addition, we also bought these two small refrigerators with 20L double refrigeration, as a control group, to see how different the small refrigerators are under different specifications.

There are many online complaints about small refrigerators, such as Refrigeration, crotch pulling, loud noise Some people are worried that it is just a sample and lacks practicality. More people are worried that the dormitory power supply or car power supply will not be able to move it. These are the questions to be answered in this program.

Refrigeration test

The first is the most critical refrigeration efficiency. We try our best to find a test environment similar to ordinary university dormitories, with slender apartment, one-sided ventilation, low floors and high floors.

Seven 8L mini-refrigerators to be tested are placed on the ground, and the back end is 20cm away from the corner, leaving enough space for the exhaust port. We use a temperature inspector, put the sensor in the middle of the box and record the temperature every five minutes.

The test starts at 20:00 every day and ends at 16:00 the next day, with a total length of 20 hours. During this period, the power metering socket will record the cumulative power consumption of the small refrigerators.

Test start An hour and a half After that, all refrigerators reached the maximum cooling capacity, and then there was no obvious change. Their refrigeration capacity is divided into four grades:

First gear Delicious and beautiful The temperature in the refrigerator is 17.5℃ lower than the room temperature; The temperature difference between the inside and outside of Oaks is 1℃ less than them, which belongs to the second gear; The third gear is Pepsi, with a refrigeration capacity of about 14℃; Xinfei, SAST, OGE The refrigeration effect is relatively average, which is more than 11℃ and does not exceed 12℃, ranking fourth.

But this is only the case of empty box test. If they are really used to freeze drinks, will there be any difference in refrigeration performance?

So next, we will fill most of the space of these refrigerators with drinks: this small refrigerator with 8L capacity is basically equipped with One bottle plus four cans of drinks is almost full. This load may be smaller than many friends expected.

In this round of test, we have arranged four temperature sensors in each refrigerator, two of which record the air temperature in the box, and the other two probes respectively extend into two cans close to the inner wall of the refrigerator to record the temperature of the liquid. The test still starts at 20:00 every day and ends at 16:00 the next day, with a total length of 20 hours.

The result is really different from the empty box test.

No matter the temperature in the box or the temperature of the liquid, there is no longer an empty box to test it for an hour and a half and then keep it stable. The cooling speed of the refrigerator has slowed down. And you can always see the downward trend of the temperature curve, although after 14 hours, this trend basically becomes very weak.

There have also been some changes in the ranking of refrigeration capacity of refrigerators.

Let’s look at the temperature in the box first. Oaks’ performance has improved, and it has become the same as delicious and Meiling. Xinfei also caught up with Pepsi, ranking second; By the end of the test, the remaining preclinical and OGE were only about 9℃ lower than the room temperature.

However, the result of liquid temperature is not the same as the air temperature in the box. Delicious, Meiling, Aux Still in the first gear, the performance is closer; The biggest difference is in the second gear, cooling drinks, catching up with Pepsi is Xianke, which is about 1℃ worse than Pepsi; The temperature in the box is ranked second. Xinfei Frozen drinks are the worst, worse than OGE.

Apart from Xinfei and Xianke, the temperature in the other five refrigerators and the temperature of drinks basically change synchronously, but the cooling rate of liquid is faster than that of air, and the final temperature is lower than that of air.

In fact, the temperature measured in all refrigerators is higher than that of empty boxes, and the temperature of drinks is lower than that of empty boxes, and the delicious coke is even lower than 0℃.

However, considering that this round of testing took three days to complete, the room temperature varies by about 1℃ every day. Perhaps due to the influence of room temperature, the cokes of Meiling and Oaks failed to freeze below 0℃? So we made another round of additional tests for the top three to see if they can still freeze out at the current room temperature of 25℃!

As a result, because the room temperature has increased, none of them can freeze the coke below 0℃ this time. However, the three refrigerators are also divided into high and low: Coca-Cola still has the cooling ability of 21.5℃, freezing the liquid temperature of Coke to 3℃; The cooling ability of Meiling and Oaks was obviously affected by the higher room temperature, and their coke liquid temperature stayed at about 6℃.

The above is the refrigeration situation of the 8L small refrigerator. What about the 20L one?

Just say these two models we bought, and the results are a bit confusing: Delicious 20L refrigeration is worse than 8L refrigeration. Pepsi’s 20L has gradually surpassed its own 8L. However, just when we were expecting it to be more than 20L delicious, the monitoring temperature suddenly bounced back. After the retest, it was confirmed that Pepsi was broken!

Power consumption test

Can the power supply in student dormitory support the work of small refrigerator? The e-commerce page is clearly written: The cooling power is about 40W. , the dormitory is available. Note that the 40W here is only when the refrigerator is empty. What will happen if the refrigerator is full?

At the same time of refrigeration test, we also used the power metering socket to test the real-time power of the small refrigerator filled with drinks and the accumulated power consumption after 20 hours of operation.

The test results show that when it is full, The refrigeration power of 8L small refrigerator is generally 50~55W. Continuous operation for 20 hours consumes about 1.1 kwh of electricity. There is no problem in using it in the dormitory. .

Among them, the small refrigerator with the best energy consumption control is Xianke, and the refrigeration power is basically less than half of other products; The second place to save electricity is the delicious 8L refrigerator with excellent refrigeration effect. However, the power consumption of the same 20L refrigerator is "outstanding"; Even more outrageous is Pepsi, whose 8L refrigerator is not efficient, but its 20L refrigerator is surprisingly energy-saving, which is lower than most 8L refrigerators, including Pepsi’s own.

Noise test

Compared with the power consumption of small refrigerators, people may be more concerned about noise.

In a room with a stable noise floor of 48~50 decibels, we tested the noise at the rear fan of each refrigerator, read the data for 20 seconds and recorded the average value.

Test results: the noise champions in the selection are 8L delicious and Oaks. Meiling, a little better. The quietest ones are Xinfei and Xianke. 8L Pepsi ranked third.

Purchase suggestion

After some tossing, we summed up three indicators to evaluate the performance and experience of small refrigerators: Refrigeration effect, power consumption and noise . And give purchase suggestions.

However, for a product like a small refrigerator, which one should you buy Depends on your usage scenario. ：

For the student party who wants to freeze drinks in the dormitory, Meiling is cost-effective, moderately priced, with strong refrigeration performance and good face value, but it is a little noisy. If you or your roommate is sensitive to noise, you have to settle for the second best, and choose Baccalaureate or Pepsi.

The new middle-class car-mounted refrigerator is recommended, with fashionable appearance and eternal refrigeration performance. If there is enough storage space, it can be upgraded to 20L, with limited performance loss, but it can hold many other foods besides drinks, so it is a good companion for camping.

As for OGE, which is the least recommended, it is really an all-round and balanced player. Not only is the refrigeration performance the worst, but the noise is also big. The key point is that the price is not much cheaper.

That’s all the content of this program. With a hard-core attitude, we will make a material evaluation. Here is the evaluation of Huang’s family, and a group of professional, interesting and serious friends are waiting for you.