The nitrogen (N) and phosphorus (P) loadings in coastal waters have greatly increased due to anthropogenic input. However, the silicate levels have remained stable in the past decades, leading to nutrient status alternating from N limitation to Si limitation. Few studies have examined the effects of such nutrient imbalance on Cd accumulation in marine diatoms. In the present study, we provide multiple lines of evidence that Si limitation reduced the Cd binding capability in the marine diatom Nitzschia closterium. Diatom cells adapted to lower Si exposure had weaker mechanical strength and less negatively charged surfaces. Close examination of the cell surface revealed that Si shortage changed the biochemical composition of the cell surface and decreased the diatom’s silicification ability. The lower density of the silanol groups in the cell wall is the most likely reason for the weaker Cd adsorption ability observed in the Si limited diatom cells. This study demonstrates the significance of Si in controlling the metal accumulation in marine diatoms.

由于人为输入，沿海水域的氮（N）和磷（P）含量大大增加。然而，在过去的几十年中，硅酸盐的含量一直保持稳定，导致营养状况从氮限量到硅限量交替变化。很少有研究检查这种营养失衡对海洋硅藻中Cd积累的影响。在本研究中，我们提供了多条证据，表明Si限制会降低海洋硅藻Nitzschia closterium中Cd的结合能力。。适于降低Si暴露的硅藻电池的机械强度较弱，带负电的表面较少。对细胞表面的仔细检查表明，硅的缺乏改变了细胞表面的生化成分，并降低了硅藻的硅化能力。细胞壁中硅烷醇基团的较低密度是在硅有限的硅藻细胞中观察到的Cd吸附能力较弱的最可能原因。这项研究证明了硅在控制海洋硅藻中金属积累中的重要性。