Soil testing equipment to achieve waste repair waste repair

The cadmium-related rice storms that appeared earlier in the past caused a public outcry, which not only led to the obstruction of rice sales in Hunan, Jiangxi, and Guangdong, but also caused new public concerns about the threat posed by farmland pollution to people's dining tables. One of the most important tasks to remove the soil pollution behind “Cadmium rice” is the comprehensive consultation of the status of soil heavy metal pollution. Once the soil has been contaminated by heavy metals, it can only be controlled and treated to slowly repair and reduce the "vitality" of heavy metals in the soil.

The status quo of soil heavy metal pollution is shocking

As an important result of the National Land Resources Survey and the investigation of soil pollution throughout the country, the National Multi-Target Regional Geochemical Survey Project has also found serious soil contamination in some areas. For example, cadmium, mercury, lead, arsenic and other abnormalities are common in some regions of the middle and lower reaches of the Yangtze River. Abnormal mercury and lead are common in and around the city, and radioactive anomalies are apparent in some cities. The lake is rich in harmful elements, and the acidification of the soil is serious. Studies have confirmed that there is a close relationship between heavy metals such as cadmium and mercury and human pollution. Heavy metal elements are apparently enriched in the soil surface and closely related to densely populated areas, industrial and mining areas. Compared with the sampling from 1994 to 1995, the distribution area of ​​heavy metal pollution in soil was significantly enlarged and spread to the densely populated areas in the east.

Survey data shows that more than 10% of the country’s cultivated land area has been contaminated by heavy metals, with an area of ​​150 million mu, polluted farmland with 32.5 million mu of irrigated land, solid waste storage and 2 million mu of destroyed fields, most of which are concentrated in the economy. More developed regions. The China International Cooperation Committee for Environment and Development announced that the Ministry of Environmental Protection's sampling of harmful heavy metals in the 300,000 hectares of basic farmland protection areas in China found that 36,000 hectares of soil heavy metals exceeded the standard, exceeding the standard rate by 12.1%.

High-end instruments provide comprehensive inspection solutions

"Soil treatment of soil" must be the focus of environmental remediation in recent years. Inevitably, there is an urgent need for a rapid and highly effective method for soil heavy metal detection. Traditional wet digestion sample pretreatment cannot meet the requirements due to long time consumption, and microwave digestion has The advantages of rapid heating, uniform heating, and time-saving environmental protection are favored by analysts and have been increasingly applied to sample preparation. The determination of heavy metals in soils requires digestion and digestion in most methods. Many companies that produce microwave digestion needles have introduced solutions to detect heavy metals in soil.

High-precision multi-sample and multi-substrate heavy metal analysis instrument can quickly detect and produce linear results with subsequent processing procedures. The detection limit is very low (usually less than ppb), so the detection of trace or trace metals can also achieve high accuracy, high repeatability, and batch processing of samples. At present, in Europe and the United States, this method is being used to replace the traditional atomic absorption method for a large number of environmental emergency monitoring, tap water testing, food, soil heavy metal monitoring.

Another practical instrument is the handheld soil heavy metal analyzer, which can quickly detect heavy metal-contaminated soil and solid waste in situ. It has the characteristics of small size, light weight, and ordinary people can hand-held measurement. It has been widely used in various types of geology. The testing samples include slag, rock, mud, mud, with particular attention to the eight heavy metals in the national standards. Sample morphology can be solids, liquids, powders, and the like. It does not require pretreatment of samples and can detect heavy metals in soil within 5-10S. And its accuracy is close to the laboratory results, and it is the best helper for rapid detection in the field.

"Using waste to cure waste" to achieve integrated repair

“Waste treatment and waste treatment” refers to the preparation of carbon-, silicon-, and phosphorus-based materials that are stabilised and rehabilitated by biomass wastes or mineral tailings, such as crop residues, cyanobacteria, wood chips, rice husks, and cow dung. The integrated remediation technology for soil and groundwater is to add carbon, silicon, and phosphorus materials based on solid wastes to polluted soils. Through a series of reactions such as adsorption, precipitation, complexation, and ion exchange, the heavy metals are transformed into more stable forms. Reducing their mobility and bioavailability can remediate contaminated soil to some extent. At the same time, planting plants that “eat” heavy metals can effectively “eat” cadmium, arsenic, copper, lead, and other heavy metal contaminants in farmland. In addition, the groundwater contaminated by heavy metals is drawn to the surface, sprinkled on the soil to which stabilizers have been added, and the groundwater is returned to the aquifers after the soil is “retained” and the plants “filter”.

After the prepared biochar enters the soil through the agricultural machinery and equipment, it will passivate and block the heavy metals such as lead and cadmium in the soil like a sucker. At the same time, it absorbs herbicides such as atrazine to realize the dual use of heavy metals and organic pollutants. Adsorption to prevent crop absorption. As a green resource, biochar does not destroy the original structure of the soil itself, but also blocks the migration of heavy metals and organic pollutants, increases the amount of water in the soil, increases the exchange capacity of cations in the soil, and enriches nutrients such as nitrogen and phosphorus in the soil. Elements to increase crop yields.

It is reported that the addition of 1% to 2% of phosphorus-based materials to lead-contaminated soil can lead to removal of lead in contaminated groundwater up to 91% after 40 days of remediation. At the same time, the extraction of lead and heavy metals from soil by calcium chloride leaching is tested. Compared with the control group, lead decreased by 60.5% and 62.8%, respectively.