纳米二氧化钛与磷互作对莱茵衣藻砷累积与生物转化的影响

纳米材料因其较大的比表面积以及较强的反应活性，对砷（As）的环境行为具有一定的调控作用，而这可能对微藻As吸收代谢产生潜在的影响。以模式生物莱茵衣藻（Chlamydomonas reinhardtii）为研究对象，探究不同磷酸盐（PO₄ ³⁻）浓度下，纳米二氧化钛（nano-TiO₂）对莱茵衣藻中As(Ⅴ)累积和生物转化的影响。结果表明：暴露初期（第1天）nano-TiO₂作为载体显著促进了0.013、0.100和0.500 mmol/L PO₄ ³⁻处理组藻细胞对As的累积，但随着暴露时间的延长，nano-TiO₂的载体效应呈下降趋势；暴露结束后（第8天），nano-TiO₂添加组中，进入藻细胞的As(Ⅴ)除了还原成As(Ⅲ)及甲基化成二甲基砷外，还能进一步转化为一种可能为砷糖的未知化合物，且随着PO₄ ³⁻浓度的降低，藻细胞内这种砷糖所占比例逐渐增加，这可能会抑制As(Ⅲ)的外排；暴露结束后（第8天），培养基中主要检测到的As形态为As(Ⅴ)和As(Ⅲ)，1.0和0.5 mmol/L处理组还有少量二甲基砷。nano-TiO₂的添加降低了培养基中As(Ⅲ)的浓度，尤其是0.5和1.0 mmol/L PO₄ ³⁻处理组。研究结果表明，纳米材料与PO₄ ³⁻的互作可显著改变微藻As的累积与代谢过程。

The interactive effects of titanium dioxide nanoparticles and phosphate on arsenic accumulation and biotransformation in Chlamydomonas reinhardtii

Nanomaterials can modify the environmental behavior of arsenic (As) due to their large specific surface area and high reaction activity, which may affect the absorption and metabolism of As in microalgae. In this study, Chlamydomonas reinhardtii was used as model organism to investigate the influence of titanium dioxide nanoparticles (nano-TiO2) on As(Ⅴ) accumulation and biotransformation in algal cells at different phosphate concentrations. The results showed that nano-TiO2 significantly promoted As accumulation in algae cells in 0.013, 0.100 and 0.500 mmol/L phosphate groups at the beginning of exposure (1 d), but the carrier effect of nano-TiO2 decreased with the extension of exposure time. After 8 days of exposure, in the nano-TiO2 addition groups, As(Ⅴ) in algal cells was not only reduced to As(Ⅲ) and methylated to dimethyl arsenic, but also further transformed to an unknown As compound, possibly arsenosugars. And the proportion of arsenosugars in algal cells gradually increased with the decrease of phosphate concentration, which might inhibit the efflux of As(Ⅲ). After 8 days of exposure, As(Ⅴ) and As(Ⅲ) were the main As species in the culture medium, and a small amount of dimethyl arsenic was also detected. The addition of nano-TiO2 decreased the proportions of As(Ⅲ) in the culture medium, especially in 0.5 and 1.0 mmol/L phosphate group. This study indicated that the interaction between nanomaterials and phosphate significantly affected the accumulation and metabolism of As in microalgae, which facilitates the application of microalgae in As remediation.