In the present study, 885 surface soil samples were collected to study the spatial variations and correlations between total contents of organic carbon (C), nitrogen (N) and sulfur (S) in surface soil across the Pearl River Delta (PRD) area. The results showed that soil C and N had similar spatial patterns, and the soil C:N ratio had a relative stable value of 9.63, suggesting that soil biological processes were the primary factor determining the soil C:N ratio. The spatial distribution of soil S was different from that of soil C and N, and there was no correlation between soil S and C. Soil samples with relatively high S content were mainly distributed along the regional rivers. The mean of soil C:S ratios was 42.6, and a constant C:S ratio did not exist. This finding revealed that the geochemical processes of soil S cycling and exogenous S inputs had more important effects on the spatial distribution of soil S, and soil C:S ratio than plant/microbe-related nutrient cycling. The present results revealed that soils with higher C and N content were more likely to accumulate C and N, while soils with lower C and N content could lose these nutrients more easily. Furthermore, the fertile farmland with high C and N content had excessive N input, while the poor farmland with low C content had an obvious N loss. The results demonstrated that the soil C:N ratio remained constant across the study area that is attributed to soil biological processes, whereas higher fluctuations were detected for the soil C:S ratio, which was primarily driven by geochemical processes and exogenous S inputs.

在本研究中，收集了885个表层土壤样本，以研究珠江三角洲（PRD）区域表层土壤中有机碳（C），氮（N）和硫（S）的总含量之间的空间变化和相关性。结果表明，土壤碳和氮具有相似的空间格局，土壤碳氮比的相对稳定值为9.63，表明土壤生物过程是决定土壤碳氮比的主要因素。土壤S的空间分布不同于土壤C和N，并且土壤S和C之间没有相关性。土壤中S含量较高的土壤样品主要分布在区域河流中。土壤C：S比的平均值为42.6，并且不存在恒定的C：S比。这一发现表明，土壤S循环和外源S投入的地球化学过程对土壤S的空间分布和土壤C：S比率的影响比与植物/微生物相关的养分循环更重要。目前的结果表明，碳和氮含量较高的土壤更容易积累碳和氮，而碳和氮含量较低的土壤则更容易失去这些养分。此外，高碳，高氮的肥沃农田氮素输入过多，而低碳低劣的农田氮素流失明显。结果表明，由于土壤生物过程，整个研究区域的土壤碳氮比保持恒定，而土壤碳氮比的波动较大，这主要是由地球化学过程和外源硫输入引起的。