One, pesticide pollution
Pesticide is a kind of special chemicals, which can not only control agricultural pests, will be harmful to humans and animals. Therefore, the use of pesticides, mankind the benefit on the one hand, on the other hand also to the human survival environment harm Raij, according to reports in the literature, the utilization of pesticides is generally 10% approximately 90% of the residues in the environment, pollution to the environment. Substantial loss of pesticide volatilized to the air, into the water, sedimentation accumulation in soil, pollution of livestock and Fisheries fruit products, and through the food chain bioaccumulation transferred to the human body, cause harm to the human body. Pesticides can be indirectly harm on human body. The indirect pathway is pesticide pollution to the environment, through the food chain of the progressive enrichment, finally entering the human body, causing chronic poisoning. Highly toxic pesticides, toxicity, and in the environment of the residues in a long time, when people and animals edible contain residues of pesticides in food, it will cause the accumulation of poisoning. This kind of harm are often have to go through a long time accumulation of only showing symptoms, is not known; it is through the food chain bioaccumulation, before finally entering the human body, is not easy to find, therefore, generally do not take seriously for people place, and this kind of pollution range is wide, harm people is numerous, in many case, was man himself in harm to oneself, say so, this kind of harm more dangerous. The extensive use of pesticides, in to kill pests at the same time, it will also kill the other insects the birds beast, benefit, make the birds, insects beneficial animal is greatly reduced, thereby destroying the ecological balance. In addition to regular use of pesticides, the pest resistant, lead to medication frequency and dosage increases, increased environmental pollution and the ecological destruction, resulting in pesticide abuse the vicious spiral. With the drainage or rain water entering pesticide, poisoning water biology of reproduction and growth, so that fresh water fishery waters and coastal waters water damage, affecting fish embryo, so that after hatching fry slow growth or death in adults, accumulation, so that it can't eat and leads to propagation of recession. Along with the quantity increases ceaselessly, fishery water quality worsens ceaselessly, fishery pollution accidents have occurred, the fishery production is threatened seriously, often resulting in fishery substantially reduction of output, direct economic loss caused by the compounds toxicity is the human ( or animal ) of damage caused by the inherent characteristics, harmfulness and compounds ( hazard ) their toxicity is the function, namely under specific environmental conditions and the compound degree of contact ( exposure ), is to cause injury to the conditions of possibility.
Harm = toxicity x contact degree
On the production, processing and application of pesticide workers, and pesticide exposure are mostly high concentration, have long-term and also had a short contact. For the majority of people, mainly through the edible with pesticide residue in food and pesticide exposure, this contact every day, is a long-term. The last residue in foods is the main problem of heavy metals and persistent organochlorine pesticide. But in our country, toxic organic phosphorus and ammonia in the carbamate pesticide unreasonable use, resulting in many edible fruits and vegetables from the acute and subacute poisoning.
Analysis method of pesticide residue in two, for example
1, rapid screening test method
1.1 choline ester or esterase inhibition method
Domestic and foreign has developed a variety of types and methods of determination of organophosphorus and carbamate pesticide residues in.
1.2 immunoassay
The antibody antigen reaction and modern testing means the combination of trace analysis. With high sensitivity and high efficiency advantages, with only a little equipment and professional training, is the primary screening and determination of carcinogen and a number of highly toxic pesticide good method. But the method of development of high cost, long development time of about 1 years, and only suitable for the analysis of a pesticide or pesticide.
1.3 sensor technology
The above two methods can be used in sensor technology, the use of enzymes or antibodies as obtain high sensitivity of basic substances, in particular film or the like on the surface reaction, through the determination of pH, conductance or conduction changes can be output information. If it is used in field test, it can enlarge the use. But its shelf life, the interference of other substances, induction of repeatability, are needed to solve the problem.
2, sample pretreatment technology
The 2.1 gel chromatography ( Gel Permeation Chromatography )
With different pore diameter of the porous gel column packing, according to porous gel on different size molecules help effect separation line. Large molecules ( lipid, pigment chlorophyll, xanthophyll ), alkaloid, polymer to leaching out, pesticides and industrial pollutants such as smaller molecular weight, after the leaching out. There is more used in XAD series gel, different ratio of cyclohexane and ethyl acetate as leaching agent, method can be automated, reproducible, solvent and GLC matching. Common defect is small molecular disruptor and pesticides from flowing out, larger molecules pesticides may first outflow, sometimes to add column chromatography purification.
2.2 phase extraction and adsorption column chromatography?
Early using Florisil and alumina loaded column adsorption to purify the moderately polar and nonpolar pesticides, but many polar pesticides and metabolites are easily lost, or need to use polar solvent for leaching. The laboratory in Florisil adding small amounts of activated carbon for leaf vegetables, especially suitable for the purification, can also be used for other vegetables and fruit purification. Solid phase extraction techniques typically use a solid phase binding phase ( Solid bond phase ), namely in the silicone unreacted silicon alcohol base is connected with the various functional groups, usually with nonpolar ( C8-C18 ) ( RPLC), polarity (positive ion exchange chromatography), three. As of C18 pillar, can adsorb high-molecular-mass nonpolar interfering substances, particularly applicable to low-fat fruit vegetables purification. Can : 1 selective leaching, pesticide leaching down first, strong retention of debris. The selective elution, solvent strength can make weak impurities retained first eluted, make pesticide retention.
2.3 supercritical fluid extraction ( Supercritical Fluid Extraction )
Supercritical fluid extraction is the use of certain materials ( or solvent ) at more than the critical point has the characteristics to extract mixtures of soluble fractions of a kind of new separation technology. The supercritical fluid is the material at the critical temperature and pressure above the critical state, between gas between gas and liquid, both gas and liquid with certain of its physical properties, such as similar to the liquid has a greater density and solubility, similar to the gas has a strong penetration ability. Is called a supercritical fluid or high density gas ( densegases ).
Usually the gas has a critical temperature ( Critical temperature, Tc ), refers to the highest temperature can be liquefied gas, if the temperature is higher than the critical temperature, no matter how much pressure can make the liquefied, just as the pressure increases and the density increase, in the supercritical state, therefore, also known as the high density gas. Gas is a critical pressure ( Pc ), refers to the critical temperature of the gas is liquefied the minimum pressure, such as carbon dioxide Pc 73 atmospheric pressure, namely 1073psi, if pressure is less than Pc, regardless of the temperature is reduced, material cannot be liquefied. On the critical temperature and critical condition of pressure, pressure and small changes in temperature, can cause gas density very big change, the solubility of 100-1000 times change. Supercritical fluid density is about 0.2-0.9g/cm.s, close to the liquid, several hundred times more than gas. The fluidity and viscosity is very low, close to the gas. Diffusion coefficient than the small gas, about gas one percent, and a liquid in a hundred times. Thus the analyte such as pesticide movement and distribution, in supercritical fluid than in the liquid solvent for fast. In general, the supercritical fluid density is bigger, its ability to dissolve the greater, and vice versa. That is to say in supercritical fluids solubility of pesticides, at constant temperature with the pressure P ( P > Pc ) increases. The temperature and pressure changes can be suitable, pesticides and other substances solubility in 100-1000 times in the range of variation, and in liquid extraction is obviously different, this property is beneficial from material in deep extraction of some easy solution composition. Because can pass the temperature and pressure changes to adjust its dissolution, the dissolution of the controllable also is increasing extraction selectivity. Although the supercritical fluid density and solubility and many organic solvents, but compared with the liquid viscosity is low, about 1-2 orders of magnitude, the diffusion coefficient is high, about 1-2 orders of magnitude. It is precisely because of its high mobility and diffusion capacity, can penetrate into the sample matrix and gap, increase and pesticide exposure probability and speed, accelerating dissolution equilibrium so that the pesticide from the matrix transfer, can improve the extraction efficiency, also contribute to the dissolved between the components separation. The supercritical fluid extraction is achieved by temperature and pressure is adjustable to control the dissolution ability. Its advantages are Huan take time is short, cost saving, extraction can be carried out thoroughly, heat sensitive samples and trace sample extraction. The basic solution of solvent effects on the environment.
3, measurement technology
Current pesticide active ingredients are typical of small molecular compounds, analysis using gas chromatography ( GLC ), liquid chromatography ( HPLC ). This paper mainly introduced the technique of two-dimensional gas chromatography.
Two dimensional chromatography applied the earliest paper chromatography and thin layer chromatography, using different solvents were launched two-way, separation efficiency is greatly improved. Two dimensional chromatography in gas chromatography is the use of two different selective chromatographic column, the sample simultaneously determination, since the advent of capillary chromatographic column, development is very rapid. Usually can use two different instruments or the use of a double column ( different polarity ), dual channel, dual detector apparatus, a sample can be obtained at the same time the two group information. The United States of America FDA, the EC is the first to use this method for qualitative. Selection of aldrin, parathion, chlorpyrifos or atrazine and other standard pesticide different detector as internal standard, determination of multiple pesticide in different polar column and internal standard pesticide relative retention time, as a preliminary qualitative basis. This method is more suitable for China's actual.
In three, the pesticide pollution prevention suggestions
Pesticide variety, wide range of application, low utilization rate, slow degradation, with the amount increasing, the pollution of the environment is increasing, therefore, to prevent the spread of pesticide pollution has been imminent, in order to maintain a good ecological environment, not only to prevent disease to destroy insects, but also can reduce the pollution to the environment, should emphasize had caught the following the job.
1 control sources of pollution is pollution prevention is the effective way to strengthen the safety, reasonable use pesticide knowledge training, improve the broad masses of the people on the importance of ecological environment protection, prohibition of abuse of chaos make pesticide, strictly limit the scope of pesticide use. For the eradication of pests and diseases and chemical pesticide is necessary, shall strictly abide by the pesticide use, frequency of use and usage method. Not in accordance with the relevant provisions, chaos make pesticide abuse, cause harm to the environment, will be punished according to law.
2 to strengthen environmental protection environmental management, the supervision function
Although pesticides on the environment, harm to human beings, but it is in the control of plant diseases and insect pests are indelible merit, it is impossible to completely cancel. Therefore, the use of pesticide management has be imperative, the relevant departments should pay attention to. As the environmental protection departments, to play a unified supervision and management, establish a complete set of management measures, the control of pesticide pollution in the lowest limit.
( 1) strengthen pesticide on basic research, establish and perfect the environmental standards of pesticide use relevant scientific research departments should carry out pesticides used in the risk assessment of pesticide environmental toxicology, using the basic principles and methods, according to the degradation of pesticide use, transport and environmental effect, some pesticides to ecosystem populations of harmful concentration, on the important biological lethal dose or half lethal dose toxicity effects and so on, to identify these pesticides in various environments in the permissible limit values. On this basis, the establishment of various types of pesticide of national environmental standards. At present, in China's environmental standards, not to allow the value of pesticides clearly defined ( six six six, except DDT, these two kinds of pesticides banned already ), it is necessary to develop a set of suitable for the national conditions of our country to prevent the pesticide pollution of pesticide emissions standards, drinking water, ground water, fishery water allowable limit standard. The pesticide pollution has a legal binding, quantitative management, make environmental protection supervision so the law, to cause the environment harm the punishment done well documented.
( 2) strengthen pesticide monitoring for environmental management oversight role play, must be the pesticide pollution effective monitoring, the monitoring of pesticide into the daily routine monitoring. The toxicity of pesticides, but the concentration in water is very low, common chemical methods cannot satisfy the management requirements, therefore, it is necessary to study the development of more advanced monitoring method, especially the ultra trace analysis and ultra pure analysis technique, and toxicity analysis of technology research, development and production of high performance monitoring apparatus and chemical reagents, improve the monitoring means, obtain the accurate monitoring data, thereby effectively controlling pesticide wastewater.
3 accelerate disease pest control new method research, promote the use of efficient, low toxicity, no pollution new technology
( 1) promote the development of efficient, low toxicity, low residual pesticide new breed as soon as possible, and to promote the use of agricultural production. Biological pesticides and conventional pesticides were compared, not only killing range, high efficiency, and safety to human and livestock, no poison, no pollution to environment, crop residue, not killing insects, make no pest resistance, and helps to improve the quality of crop, promote crop of early maturity and high yield. The Chinese herbal medicine to produce " green pesticide ", harmful organism has high control effect, may be used in treating various diseases of various crops, kill germ and virus, promote plant growth, and no residue, no pollution, to human beings and other beneficial organisms highly secure. To the use of toxic pesticides, promotion application, to carry out ecological and toxicological evaluation, prediction of the impact on the environment, put forward the correct use method and prevention measures of damage to the environment.
( 2) promotion of non-toxic, harmless pest control methods. My province Dingtao County launched the " luring light - " new move, make Cotton Worm moth in the generation of the first generation of septempunctata cotton insect before it was light trapping, reduce pesticide use, reduce the pollution in cotton field. City Forestry Bureau in the city to promote the azure-winged magpie deinsectization method, will foster a magpie in forest pest control to insect, with magpie, raise magpie, form the benign loop of zoology forestry. Ultrasonic pest control, sex attractant, male sterilization technology pest control method, to control plant diseases and insect pests, reduce the environmental pollution caused by pesticide also has an important role in.
( 3) the development of resistance to pests crop research, use of biological engineering technology to produce a variety of diseases and insect pests of crop new breed, can greatly reduce the use of pesticides.
In short, to fully understand the pesticide pollution harm, take various measures, reduce pesticide pollution, both to control plant diseases and insect pests, enhanced the output of agricultural products, but also protect the environment, make us safe from attack.
