First, photolysis Herbicides applied to plants and soil surfaces undergo photochemical decomposition under sunlight. This photolysis is caused by ultraviolet light. The rate of photolysis depends on the type, variety and molecular structure of the herbicide. The intensity of ultraviolet light, the ability of herbicide molecules to absorb light, and temperature are all factors that affect photolysis. Most herbicide solutions can perform photolysis, which absorbs spectra from 220 to 400 nm. The photolysis rates of different types of herbicides vary widely. Dinitroaniline herbicides, especially trifluralin, are most easily photolyzed. Other types of herbicides have a slightly slower photolysis rate. To prevent photolysis, the agent should be mixed in the soil after spraying. Second, volatilization Volatilization is one of the important ways for herbicides, especially soil treatment herbicides, to disappear. The volatility is closely related to the physical properties of the compound and the saturated vapor pressure. It is also restricted by environmental factors. The herbicide with high saturated vapor pressure is volatile. Strong; dinitroaniline herbicides belong to the class of higher saturated vapor pressure, followed by thiourethane herbicides. These herbicides will quickly evaporate and lose their activity when sprayed on the soil surface. Volatile gases are more likely to damage sensitive crops. Among the environmental factors, temperature and soil moisture have the greatest influence on the volatilization of herbicides: the temperature rises, the saturated vapor pressure increases, and the volatility is stronger; the soil moisture is large, which is beneficial to desorption and makes the herbicide easy to release in the soil solution. It is in a free state, so it is easy to vaporize and volatilize. Third, soil adsorption Adsorption is closely related to the biological activity of the herbicide and its residual and persistence period in the soil. Herbicides are mainly adsorbed by soil colloids in the soil, including physical adsorption and chemical adsorption. The adsorption of herbicides on soil depends on the molecular structure of the herbicide on the one hand, and on the organic matter and clay content of the soil on the other hand, and many types of herbicides such as urea, tricus triphenylbenzene and thioamino acid esters in the soil. It is easy to be adsorbed, while sulfonylureas and imidazolinone herbicides are not easily adsorbed; soil organic matter and soil with high clay content have strong adsorption to herbicides. In the use of soil treatment herbicides, the adsorption capacity of the soil colloid to the herbicide should be considered to be saturated. Therefore, the dosage per unit area should be appropriately increased or decreased with the soil organic matter and clay content, and irrigation can also be carried out to promote the herbicide. Desorption to enhance the herbicide effect. Four, leaching Leaching is the distribution of herbicides in the soil along the soil in the soil profile. The leaching of herbicides in the soil is determined by its characteristics and water solubility, soil structure, organic matter content, pH value, permeability and water flow. The water-soluble varieties are easy to be leached, and the salts of the compounds are more leaching than the esters; the soils are different, resulting in a large difference in surface area, and the soils with high clay and organic matter have strong adsorption to herbicides, making them difficult. Leaching; on the contrary, sandy soil and sandy loam have strong soil permeability and poor adsorption, so it is beneficial for leaching. The pH value of soil mainly affects the leaching of herbicides by affecting the chemical reaction between adsorption and herbicide and soil components. The leaching of sulfonylurea herbicides in soil increases with the increase of PH value, so it is in alkaline soil. Medium is easier to leaching than acidic soil. The leaching herbicide easily penetrates into the lower layer of the soil profile, which not only reduces the herbicide effect, but also easily accumulates or pollutes the groundwater in the lower layer of the soil. When using the difference in selectivity, the herbicide enters the soil layer where the crop seed is located due to leaching, which is easy to cause phytotoxicity. Therefore, it should be based on the water solubility and mobility of the herbicide variety, soil characteristics and other factors affecting water movement. The best way to determine the method is to buy the method and the amount of medication per unit area to improve the herbicidal effect and prevent soil and groundwater contamination. 5. Chemical decomposition Chemical decomposition is one of the important ways for herbicides to disappear in the soil, including oxidation, reduction, hydrolysis and formation of insoluble salts and complexes. Sulfonylurea herbicides are gradually disappeared by hydrolysis in acidic soils. When the content of high-valent metal ions such as Ca2+, Mg2+, Fe2+ in the soil is high, some herbicides can react with these ions to form insoluble salts; some herbicides form cobalt, copper, iron, magnesium and nickel in the soil. A stable complex remains in the soil. 6. Biodegradation Biodegradation of herbicides includes soil microbial degradation and degradation in plants after absorption by plants. Microbial degradation is the most important route for most herbicides to disappear in the soil. Fungi, bacteria and actinomycetes are involved in degradation. Under the action of microorganisms, the molecular structure of the herbicide is subjected to dehalogenation, dealkylation, hydrolysis, oxidation, cyclohydroxylation and cleavage, nitro reduction, condensation and formation of a conjugate, and the herbicide activity is lost by these reactions. Soil moisture, temperature, pH and organic matter content significantly affect the microbial degradation of herbicides, and suitable high temperature and soil moisture promote degradation. In different regions, it is necessary to go deeper to explain the speed and half-life of the herbicide in order to rationally use and properly arrange the crops. Herbicides absorbed by crops and weeds disappear through a series of biological metabolisms including oxidation, reduction, hydrolysis, dehalogenation, displacement, deuteration, cyclization, isomerization, ring cleavage and binding, among which The main reflections are oxidation, reduction, hydrolysis and combination. More pesticide knowledge , please pay attention to China Pesticide Network With the continuous development of drilling production, the use conditions of drilling rigs have become more and more diversified, and various types of drilling rigs have appeared accordingly. Factors affecting the type and composition of drilling rigs include drilling method, drilling depth, borehole size and drilling tool size, and drilling area conditions (such as electricity or fuel, transportation, and meteorological conditions). Oil Drilling Rigs,Mine Drilling Rigs,Water Well Drilling Rigs,Exploration Drilling Rigs Rugao Yaou Import & Export Trade Co., Ltd , https://www.ntyaous.com
1. According to drilling method
(1) Impact drilling rigs, such as wire rope impact drilling rigs (drilling rigs), vibration drilling rigs, etc.
(2) Rotary drilling rigs, such as those used in rotary drilling.
(3) Downhole power drilling tools, such as rotary drilling tools, turbo drilling tools, screw drilling tools, electric drilling tools, etc.
2. Divided by drilling depth
(1) Ultra-deep well drilling rig. It adopts a drilling rig with a diameter of 114 mm drill pipe, a nominal drilling depth range of more than 7000 meters, and a maximum hook load of more than 4,500 kN.
(2) Deep well drilling rig. The drill rod is 114 mm in diameter, the nominal drilling depth is 4000-7000 meters or more, and the maximum hook load is 2250-4500 kN or more.
(3) Drilling rigs for medium and deep wells. It adopts a drilling rig with a diameter of 114 mm drill pipe, a nominal drilling depth range of 1500-4000 meters or more, and a maximum hook load of 900-2250 kN or more.
Three, according to power equipment
(1) Diesel Engine-driven drilling rigs, which use diesel engines as power through mechanical transmission or hydraulic transmission.
(2) AC driven drilling rig, suitable for use in oil fields with industrial power grids.
(3) The drilling rig is driven by direct current, and the working unit is driven by a direct current motor.
Fourth, according to the driving mode
(1) Drive alone. Each working machine is driven by generators of different sizes, which are mostly used for electric drive. The transmission is simple and easy to install, but the power utilization rate is low and the total equipment mass is large.
(2) Unified drive. The three working units of drawworks, drilling Pump and turntable are driven by the same power unit. Most drilling rigs use this scheme. The unified drive can also include only one drilling pump, and the other drilling pump is driven separately. The unified drive drilling rig has high power utilization and can be adjusted mutually when the engine fails, but the transmission is complicated, installation and adjustment are troublesome, and the transmission efficiency is low.
(3) Group drive. The combination of power is between individual drive and unified drive. There are two options for three working machines. The power utilization rate of this kind of drilling rig is higher than that of a single drive, and the transmission ratio is simple to drive in a unified manner. Two sets of working machines can also be installed on different heights and scattered sites.
Six ways of herbicide degradation