The researchers studied the distribution of available copper in soil in a small watershed in Northern Shaanxi Province. They found that the copper levels were higher than normal in the loess area. Copper was more concentrated in slope areas of gullies compared to mounds. The amount of copper varied depending on the slope aspect, with semi-sunny slopes having the most copper. The strongest link between copper and soil organic matter was found in the 20-30 cm soil layer. This study provides important information about how copper is distributed in the soil in the Loess Plateau region.