土壤中重金属的污染严重影响了农业和食品安全，因此，对重金属污染的高效、准确的检测是目前亟需解决的问题。采用激光诱导击穿光谱技术（Laser induced breakdown spectroscopy，LIBS）对土壤中Ni元素进行定量分析时发现，土壤中波长为373.68 nm的Ni元素的特征峰会受到Al元素在373.39 nm处谱线的影响，因此，将纯铝基底土壤光谱与压片土壤光谱进行了对比测量。提出了以纯Al作为基底，采用纯Al基底谱线扣除土壤背景中Al元素谱线的方法，来消除土壤背景中Al元素对Ni元素干扰，该方法被称为背景扣除法。实验确定了两种土壤样品的最佳延迟时间均为1.0 μs，透镜到样品的距离（Lens to sample distance，LTSD）分别为97 mm和96 mm。采用内标法对两种土壤样品中的Ni进行了定量分析，得到纯Al基底土壤样品中Ni元素的定标曲线拟合效果较好，相关系数R²为0.997，最大标准偏差（Relative standard deviation，RSD）为4.34%，采用基底背景扣除法后的纯铝基底土壤样品中Ni元素检测的相对误差降低到4%。实验结果表明：采用LIBS技术对土壤中重金属元素含量测量时，在元素特征谱线有限的情况下，为避免谱线干扰，提高检测精度，采用背景扣除的方法能够有效消除元素间的谱线的干扰。

The pollution of heavy metals in the soil has seriously affected agriculture and food safety. Therefore, efficient and accurate detection of heavy metal pollution is a problem that needs to be solved urgently. When using laser induced breakdown spectroscopy (LIBS) to quantitatively analyze the Ni element in the soil, it was found that the characteristic peak of the Ni element with a wavelength of 373.68 nm in the soil would be affected by the spectral line of the Al element at 373.39 nm. Therefore, the spectra of pure aluminum-based soil and tableted soil were compared and measured. A method of using pure aluminum as the substrate and subtracting the spectral line of the Al element in the soil background to eliminate the interference of the Al element in the soil background to the Ni element was proposed. This method was called the background subtraction method. The experiment determined that the optimal delay time for both soil samples was 1.0 μs, and the lens-to-sample distance (LTSD) was 97 mm and 96 mm, respectively. The internal standard method was used to quantitatively analyze Ni in the two soil samples. The calibration curve fitting effect of the Ni element in the pure aluminum-based soil samples was good, the correlation coefficient R² was 0.997, and the maximum standard deviation (RSD) was 4.34%. The relative error of the Ni element in the soil sample after the base background subtraction method was reduced to 4%. The experimental results show that: when using LIBS technology to measure the content of heavy metal elements in the soil, under the condition that the characteristic line of the element is limited, in order to avoid the interference of the line and improve the detection accuracy, the background subtraction method can effectively eliminate the line between the elements Interference.