Laser-induced breakdown spectroscopy (LIBS) is a new analytical method in the field of spectroscopic analysis. The principle is to generate high-intensity plasma on the surface of the sample by high-energy laser. The light generated by sample excitation is analyzed by the spectrum detection system. . Therefore, LIBS technology is convenient, requires no pre-processing, and can analyze multiple elements at the same time.
As industrialization continues to advance, heavy metals in water sediments have become an important factor influencing environmental quality. Heavy metals in water can combine with sediments, which can migrate or release heavy metals after changes in environmental conditions. Therefore, the detection and analysis of heavy metal pollutants in water sediments is not only the main basis for inversion and traceability of metal pollution history in the region, but also the key to identifying the heavy metal pollution in the water system. With the development of the economy, more and more pollutants containing heavy metals are discharged into rivers, causing serious damage to the ecological environment. At present, China's heavy metals listed in the blacklist of environmental priority pollutants include Cd, As, Be, Cr, Cu, Pb, Hg, Ni and Ti [10]. Among them, the harm of chromium to human health has attracted people's attention. The pollution of chrome metal mainly comes from industrial production such as chemical, refractory, electroplating, tanning, pigment and chrome ore smelting, as well as chromium-containing waste gas, waste water and waste residue from fuel combustion. Relevant research shows that hexavalent chromium can cause anemia and nerves. Inflammation, nephritis, circulatory failure and other diseases, long-term intake can lead to lung cancer, adenocarcinoma. Therefore, the detection and monitoring of chromium in water sediments is of great significance.
In addition to quantitative analysis of water sediments, LIBS technology can also classify heavy metals according to their distribution characteristics. For geological studies in shallow coverage areas, only water sediments or soil data are often used. Therefore, the classification of water sediments by LIBS technology and principal component analysis can be further applied to the lithology and structure of rocks in shallow coverage areas. Identification studies, and currently there are few studies in this area.
Wang Yangen et al. based on laser-induced breakdown spectroscopy for the rapid quantitative detection of chromium in water sediments, using the RT100-HP laser induced breakdown spectrometer (model is now updated to J200) produced by American Applied Spectrometry The sample was analyzed and a calibration curve between the concentration of chromium in the standard and the intensity of the laser-induced breakdown spectrum was established. The linear correlation coefficient reached 0.992, and the chromium content in the sample was obtained. At the same time, the samples were analyzed by principal component analysis. The results show that LIBS technology can be used for the classification and identification of water sediments.
Standard sample and sample spectrum
Calibration curve
The content of chromium in the sample can be calculated from the calibration curve:
The content of chromium in the sample (samples 1 to 5 were taken from the canal sediments in the residential area of ​​the city, the small river sediments next to the paint plant, the sediments of the moat, the mud of the Yangtze River, and the sandstone of the Yangtze River)
Based on the above results, it can be inferred that the chromium content in the sample is related to the degree of pollution of the river. Due to the good effect of environmental protection in the waters near the villages in the villages and the moats in recent years, the chromium content of samples 1 and 3 is lower than that of other samples. The small river next to the paint factory is contaminated by anti-corrosion coatings produced by the paint factory, so the chromium contained in sample 2 is high. As the pollution of the Yangtze River is gradually increased, the chromium content of sample 2 is higher. The chromium content in sample 5 is similar to the chromium content in the crust.
Principal component two-dimensional scatter plot of the sample to be tested
It can be seen from the figure that the two-component scatter distribution of the principal components of the five samples is significantly different, indicating that the main reason for determining the position of the two-dimensional scatter is the nature of the sample on the two-dimensional scatter plot of the principal component. This result provides a new approach to the classification of water-based sediments and will demonstrate its potential for application in the quantitative analysis of further water-based sediments.
Conclusion <br>The analysis of water sediments by LIBS technology, using the characteristic line of chromium at 302.156nm and calibration of the standard, the quantitative analysis of chromium content in the sample is completed, and the results show that the water pollution is in the sediment. The content of chromium has a large effect. At the same time, the principal component analysis of the sample shows that LIBS technology can be used for classification and identification of water sediments.
Note: The above excerpt mainly "Laser-induced breakdown spectroscopy for classification and chromium stream sediments measured" in 2014 Wang Yang, fine and published in the "Laser Medicine" article from
American ASI's J200 laser mass spectrometer elemental analyzer is the result of more than 30 years of research on the basic theory of laser chemical analysis by Lawrence Berkeley National Laboratory. It has created a new era of laser plasma spectrochemical analysis technology. Combine LIBS technology with LA-ICP-MS. It realizes the measurement of almost all elements from hydrogen to antimony, including light elements such as H, N, O, and other elements that cannot be measured by other traditional methods such as halogen (including ICP-MS). The measurement speed is fast, and the result can be obtained in a few seconds. . In addition, J200 laser mass spectrometry elemental analyzer can also directly send the ablated nano-scale solid sample particles to ICP-MS for more accurate analysis, effectively avoiding secondary pollution caused by complex sample pretreatment such as acid dissolution and digestion. And the introduction of possible errors, while greatly improving the element detection limit, achieving a wide range of measurements from below ppb to 100%.
At present, the J200 laser mass spectrometer elemental analyzer has been widely used in international high-end and national laboratories, such as Lawrence Berkeley National Laboratory, US Clarmando Crime Lab, University of Sao Paulo, Brazil , Pacific Northwest National Laboratory, etc. Many well-known institutions. 
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China Telecom's Global Eye and the former China Netcom have developed remote video monitoring in conditional households. For example, the wide view video monitoring business has been launched in China Netcom's Shanxi, Shandong, Jilin, Zhejiang, Henan and other provincial companies in the early stage, and has been widely welcomed by customers. The wide view business has developed rapidly. In the first half of this year, only Hubei Netcom's "wide view - God's Eye" business has developed more than 500 households. With the rapid development of family information technology, users' demand for family security is becoming stronger and stronger, and the broad horizon will maintain rapid development. China Mobile is also developing mobile MMS monitoring represented by "Handyantong", and 3G video monitoring is also being tested and commercially tested. It is difficult to develop and promote home video surveillance because of the huge data and signal flow relying on the network and the need to deploy home gateways and cameras.
Video monitoring is mainly used in the communities closely connected with families in the industry field, but it is still less used for home monitoring. Under the guidance of the policy of safe cities and safe families, the domestic family monitoring will begin to rise with the continuous improvement of family network environment, the improvement of users' consumption ability, the growth of security awareness, and the increase of independent living families. The integrated video monitoring that integrates limited, wireless access and linkage alarm will become a development trend. Full service operation has arrived. Operators will certainly provide users with wired and wireless diversified technical monitoring means. Through business integration, they will bring users endless monitoring services. Monitoring realizes the discovery and prevention of family safety, and also reflects family care. In addition, efforts should be made to solve the problem of security. Therefore, family monitoring needs to gradually increase some new functions and applications such as linkage alarm and security services, such as emergency help, interaction with public security, medical care, housekeeping, and calling.
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