The impact of Sodium Chloride Snow Melting Agent on the environment has multi-dimensional characteristics and needs to be analyzed from all links of the ecological chain: Water pollution level: As the snow melts, sodium chloride enters the surface water and groundwater in large quantities, increasing the salinity of the water. Taking the urban drainage system as an example, high concentrations of chloride ions will inhibit the activity of water microorganisms, resulting in a 15%-30% decrease in BOD/COD degradation efficiency; for aquatic ecology, salinity exceeding 1000 mg/L can cause an imbalance in the osmotic pressure of fish gill cells and reduce reproductive capacity. For example, the spawning volume of crucian carp is reduced by 20%-40% in a high-salt environment. It may also change the structure of algae communities and cause the risk of algal blooms. Soil ecological damage: Sodium chloride that penetrates into the soil will replace calcium and magnesium ions in clay minerals, destroy the soil aggregate structure, and cause soil compaction. Experimental data show that the soil porosity of road green belts that have used sodium chloride deicing agent for three consecutive years has decreased by 8%-12%, resulting in obstruction of plant root respiration; high-salt environment will also dehydrate plant cells. For example, the salt damage index of the leaves of the street tree Sophora japonica increases with the increase of soil salt content (>0.3%), and the wilting rate of branches born in the same year can reach 30%, which has a long-term impact on the succession of vegetation communities. Corrosion of municipal facilities: Chloride ions are highly corrosive and have significant damage to reinforced concrete roads and bridges. In a dry-wet alternating environment, sodium chloride will accelerate the electrochemical corrosion of steel bars, increase the carbonization depth of concrete by 0.5-1.2mm per year, and the corrosion rate of bridge support steel structures is 2-3 times faster than in normal environments; for urban underground pipes (such as cast iron drainage pipes), the penetration of salt solutions can cause the annual corrosion thickness of the pipe wall to reach 0.1-0.3mm, shortening the service life of the facilities by 30%-50%. Ecological chain reaction: Soil contaminated by salt will affect terrestrial organisms through the food chain. For example, the survival rate of soil invertebrates (earthworms) decreases with the increase of soil salt content, resulting in a decrease in the decomposition efficiency of soil organic matter. After birds eat salty snow water, the excretion burden of the kidneys increases, the electrolyte balance is disturbed, and the mortality rate of urban birds in winter can increase by 10%-15%. Although sodium chloride deicing agent has low cost and high snow melting efficiency, its environmental cost involves multiple systems such as water, soil, and organisms. It is necessary to reduce ecological impact through precise spreading (such as controlling the spreading amount ≤30g/m²) and the coordinated application of alternative deicing agents (such as potassium acetate).

The working principle of Sodium Chloride Snow Melting Agent is based on the dual effects of freezing point depression effect and salt water characteristics. When sodium chloride particles are spread on the surface of ice and snow, they will quickly absorb snow water and dissolve to form sodium chloride aqueous solution (brine). According to the colligative properties of dilute solutions, the dissolution of salt destroys the crystalline network structure of water, causing the freezing point of ice and snow to drop from 0℃ to -10℃ to -15℃ (the lowest eutectic point is -21.2℃ when the concentration is 23.3%). Under natural ambient temperature (such as -5℃ to 0℃), the solid-liquid equilibrium of the original ice and snow is broken, and the solid ice and snow continue to transform into liquid. At the same time, the density of salt water is greater than that of ice and snow, and it will form a continuously penetrating solution layer on the surface of ice and snow, accelerating heat transfer - on the one hand, it absorbs weak heat in the environment (such as sunlight radiation, sensible heat of air), and on the other hand, it uses the heat release characteristics of salt water solidification (latest heat released during crystallization) to further promote the melting of ice and snow. In addition, the fluidity of the sodium chloride solution gradually expands the melting area, achieving a "point-to-surface" snow melting effect, and the freezing point of the salt water is continuously lower than the ambient temperature, which can inhibit the formation of new ice and ensure that the road will not freeze again within a certain period of time. However, this process relies on sufficient snow water to dissolve the sodium chloride. Under extremely low temperatures (<-15℃), the snow melting efficiency will be significantly reduced because the salt water is difficult to form, and other processes need to be used to enhance the effect.

To determine the amount of Sodium Chloride Snow Melting Agent, it is necessary to consider a variety of factors. Snowfall conditions: The type and thickness of snowfall are key factors. If it is wet snow, due to its high water content, relatively less de-icing agent is needed for the same thickness; while dry snow has a low water content and is more difficult to melt, so more de-icing agent is needed. For example, for wet snow with a thickness of 5 cm, about 20-30 grams of snow melting agent needs to be spread per square meter. If it is replaced with dry snow, the amount per square meter may need to be increased to 30-40 grams. Ambient temperature: The lower the ambient temperature, the worse the snow melting effect of Sodium Chloride Snow Melting Agent, and the greater the amount used. In an environment of about 0℃, the conventional spreading amount can melt ice and snow well; but when the temperature drops to -10℃, in order to achieve the same snow melting effect, the amount of de-icing agent may need to increase by 50% or even more. Road conditions: Different road materials and slopes also affect the amount of snow melting agent used. Rough asphalt pavement is easier to retain snowmelt than smooth cement pavement, so the amount used is relatively small; while on sections with larger slopes, snowmelt is easy to flow away with snow water, so the amount needs to be increased appropriately, generally 10-20% more than on flat roads. Traffic flow: On sections with large traffic flow, the rolling of vehicles will accelerate the mixing of snowmelt and ice and snow, promoting snowmelt, but at the same time it will also cause the snowmelt to be consumed faster, so such sections need to replenish snowmelt in time to ensure the snowmelt effect. In addition, you can also refer to the data on the amount of snowmelt used in the past under similar snowfall weather and similar environmental conditions. On this basis, you can make flexible adjustments based on real-time weather and road conditions to determine the appropriate amount of sodium chloride snowmelt, while ensuring the snowmelt effect, avoiding waste and environmental pollution caused by excessive use.

Compared with other snow melting agents, Sodium Chloride Snow Melting Agent has obvious advantages and disadvantages. Advantages Low cost: Sodium chloride is widely available, mainly extracted from seawater and salt mines, and has a mature production process, so the price is relatively cheap. Compared with some new environmentally friendly de-icing agents, its cost may be only one-third of the latter or even lower, and it can effectively control the cost of road snow removal when used on a large scale. Good snow melting effect: Within a certain temperature range (usually 0℃ to -10℃), sodium chloride can quickly lower the freezing point of ice and snow, causing ice and snow to melt. It dissolves quickly, and can quickly contact and play a role with ice and snow after spreading, and can restore the road to traffic capacity in a short time. Easy to use: Sodium Chloride Snow Melting Agent is mostly crystalline granular, with good fluidity, and can be evenly spread using conventional spreading equipment. It is simple to operate and has low requirements for equipment. Disadvantages Great harm to the environment: Large-scale use will increase soil salinity, affect plant growth, cause plant root dehydration, and even death. At the same time, after flowing into the water body, the salinity of the water quality will increase, which will harm aquatic organisms. Corrosion of infrastructure: The chloride ions in sodium chloride are highly corrosive, which will accelerate the rust and corrosion of metal parts of infrastructure such as bridges, roads, and underground pipelines, shorten the service life of facilities, and increase maintenance costs. Limited applicable temperature range: When the temperature is below -10℃, the snow-melting effect of sodium chloride de-icing agent will be greatly reduced, and even basically lose its effect in extremely cold weather, and it needs to be used in conjunction with other de-icing agents or snow melting aids.

The snow melting effect of Sodium Chloride Snow Melting Agent is significantly affected by temperature, and it shows different performances in different temperature ranges: In the temperature range of 0℃ to -5℃, Sodium Chloride Snow Melting Agent can play a better role. At this time, it can quickly dissolve in the snow water, and by lowering the freezing point of ice and snow, the solid ice and snow can be converted into liquid. Generally speaking, within a short period of time after spreading (about 1-2 hours), you can see obvious snow melting effect, the accumulated snow begins to melt gradually, and the ice and snow cover on the road surface becomes thinner, ensuring the basic traffic capacity of the road. When the temperature is between -5℃ and -10℃, the snow melting efficiency of the de-icing agent decreases. Although it can still lower the freezing point of ice and snow, the speed of dissolution and melting will slow down. It may take 3-4 hours after spreading to see more obvious signs of snow melting. However, as long as the spreading amount is reasonably increased, a certain snow melting effect can still be guaranteed to maintain the passability of the road. However, when the temperature is below -10℃, the snow melting effect of Sodium Chloride Snow Melting Agent will be greatly reduced. On the one hand, the dissolution rate of sodium chloride in low temperature environment becomes extremely slow, and it is difficult to quickly form brine of sufficient concentration to effectively lower the freezing point; on the other hand, even if brine is formed, it is easy to freeze again at extremely low temperatures. This results in that even if a large amount of snow melting agent is spread, the snow melting effect is very limited, and the ice and snow on the road are difficult to melt completely. There may be a lot of snow and ice left, which brings great inconvenience to traffic. Therefore, sodium chloride snow melting agent is more suitable for use in relatively low-temperature environments that are not too cold. When encountering extremely cold weather, it is often necessary to use other snow melting agents that are more resistant to low temperatures, or use other snow removal methods to assist in order to ensure smooth roads.