Research On Marine Heavy Metals Determination Based On Portable Laser-Induced Breakdown Spectroscopy

The ocean has brought precious resources for human beings.However,in recent days,some human activities have made the marine pollution more and more serious.Heavy metal pollution is harmful to marine life and humans,so it is necessary to detect heavy metals in the ocean.Modern elemental detection techniques require complicated sample pre-treatment and harsh experimental conditions,and often cannot be measured in real-time in an outdoor environment.The Laser-Induced Breakdown Spectroscopy?LIBS?has the advantages of small sample damage,low price,no pretreatment,high detection speed,simultaneous detection of multiple elements,and portability.In this paper,LIBS technology is used to detect and analyze seawater and its related marine substances.By building a hardware system for synchronously acquiring LIBS spectra and writing LIBS control software based on LabVIEW,the detection of heavy metal pollution in seawater and the detection of elements in marine-related samples were accomplished,and the complete system was integrated and portable.The main research contents of this article are as follows:First,using the passive Q Nd:YAG laser,a multi pulse LIBS system is designed,which is triggered by light triggering,and the LIBS system control software based on the LabVIEW platform is written.The software can set the delay of spectral acquisition and the time of integration,and it also has the functions of real-time rendering of spectrogram,automatic identification of elements,storage and reading of spectral data,and wavelength calibration.The standard spectrum library was set up.By the three steps of five point peak finding method,the matching of standard spectrum library and the order of strength priority,the content of the elements in the sample was ordered from high to low,and the real-time automatic identification of the sample composition was realized.Secondly,marine related samples such as seawater,shellfish,reef and sea sand were detected by LIBS system.The heavy metal elements such as Cu and Al were detected in the seawater at the sewage inlet,and the Cu and Al in the solution were measured by Na as the internal standard element.The standard curve of good linearity was obtained.The concentration of Cu²⁺in the seawater at sewage inlet was 0.27 ppm,and the concentration of Al³⁺was 10.98 ppm.Al and Na elements were detected on the surface of shellfish at the sewage inlet,indicating that there were residues of metals and salts in the surface of the shells.The experimental results show that the spectral acquisition and software system designed in this paper has the advantages of high reliability,compact structure and high detection accuracy in the detection of heavy metal pollution in the ocean,realizing real-time detection of samples and automatic identification of elements.