China Education Equipment Purchasing Network News: Recently, media reports "Yunnan Qujing Luliang Chemical Industry Co., Ltd. more than 5000 tons of industrial waste chromium slag illegal dumping caused pollution" caused concern. Yesterday, an expert group composed of the Pearl River Water Conservancy Commission of the Ministry of Water Resources came to the illegal dumping site of Qujing chromium waste for sampling and investigation.
This time, about 40,000 cubic meters of water were contaminated with highly toxic water, and 77 animals died without casualties. At present, the relevant departments have reduced and detoxified the approximately 40,000 cubic meters of water that was accumulated at that time and the nearly 3,000 cubic meters of water that had been stored by the Chuchong Reservoir. The water quality reached the safe discharge standard and was discharged. According to Qujing Municipal Party Committee Propaganda Minister He Hua, the local villagers ’drinking water is tap water, and the source of tap water is very far from their villages, so it has no effect on drinking water.
So what kind of substance is chromium and what harm will it do to the human body and the environment?
Chromium is widely present in nature, and its natural source is mainly rock weathering, which is mostly trivalent; the source of man-made pollution is mainly industrial chromium-containing waste gas and wastewater discharge. Industrial wastewater is mainly hexavalent chromium compounds, often in the presence of chromate ion (CrO42-). The exhaust gas from coal and petroleum combustion contains particulate chromium.
Chromium is a trace element necessary for humans and animals. Chromium deficiency can cause atherosclerosis. Chromium has a stimulating effect on plant growth and can increase harvest. But if it contains too much chromium, it is harmful to people, animals and plants.
Both trivalent chromium and hexavalent chromium are harmful to human health and are suspected of having carcinogenic effects. Hexavalent chromium is 100 times more toxic than trivalent chromium and is a strong mutagenic substance that can induce lung cancer and nasopharyngeal cancer. Trivalent chromium has teratogenic effects.
Both trivalent chromium and hexavalent chromium have lethal effects on aquatic organisms. Chromium can accumulate in fish. Trivalent chromium is more toxic to fish than hexavalent chromium. When there is too much chromium in the soil, it will inhibit the nitrification of organic substances and allow chromium to accumulate in plants. According to experiments, chromium in water can stimulate crop growth at 1 ppm, slowing crop growth at 1-10 ppm, and stopping crop growth almost completely at 100 ppm, dying. The wastewater contains chromium compounds, which can reduce the efficiency of wastewater biochemical treatment.
A training chair is a seat designed specifically for activities such as training and meetings. It has the characteristics of comfort, durability, and ease of movement, which can meet the needs of different groups of people. Training chairs can be classified into various categories based on material, structure, function, and other aspects. Below will be a brief introduction to the classification of training chairs.
1. Material classification
The materials of the training chair mainly include metal, plastic, and fabric. Metal training chairs typically have strong stability and durability, making them suitable for long-term meetings or training activities. The training chair made of plastic material has the characteristics of lightweight and easy to clean, making it easy to arrange the meeting site at any time and suitable for use in multifunctional halls and other places. The training chair made of fabric has a comfortable sitting experience and good breathability, making it suitable for long-term meetings or training activities.
2. Structural classification
The structure of training chairs mainly includes single chairs, linked chairs, and foldable chairs. Single chairs are the most common training chairs, with each seat being independent and adjustable as needed. Chainage refers to the connection of multiple seats together, usually in the form of one or more rows, suitable for use in large training venues. Stackable chairs are training chairs that can be folded and stacked, saving space and facilitating storage and handling.
3. Functional classification
The main functions of the training chair are adjustable, rotatable, foldable, and storable. The adjustable training chair can adjust the height and angle according to personal needs, providing a more comfortable sitting posture. The rotatable training chair can rotate 360 degrees, facilitating communication and interaction with people around it. The foldable training chair can be conveniently stored and transported, making it suitable for use in multifunctional halls and other places. The training chair that can store items is designed with storage space below or behind the chair, making it convenient to store items such as stationery and documents.
In summary, the classification of training chairs mainly includes material classification, structural classification, functional classification, etc. Choosing a suitable training chair can provide a better user experience and improve the effectiveness of training and meetings.
Meeting Chair,,Foldable Chair,Customized Chair
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