Temporal and Within-Sporophyte Variations in Triphenyltin Chloride (TPTCL) and Its Degradation Products in Cultivated <i>Undaria pinnatifida</i>

<i>Undaria pinnatifida</i> can effectively deal with organotin pollution through its excellent accumulation and degradation capabilities found under laboratory conditions. However, nothing is known regarding its accumulation, degradation performance, and related impact factors in the wild farming area. In this study, we monitored triphenyltin chloride (TPTCL) contents and degradation products in different algal parts (blades, stipes, sporophylls, and holdfasts) of cultivated <i>U. pinnatifida</i> from December 2018 to May 2019. Our results showed that sporophytes had an accumulation and degradation capacity for TPTCL. The TPTCL contents and degradation products varied with the algal growth stages and algal parts. TPTCL accumulated in the blades at the growth stage and the blades, stipes, sporophylls, and holdfasts at the mature stage. The TPTCL content among algal parts was blades (74.92 ± 2.52 μg kg⁻¹) > holdfasts (62.59 ± 1.42 μg kg⁻¹) > sporophylls (47.24 ± 1.41 μg kg⁻¹) > stipes (35.53 ± 0.55 μg kg⁻¹). The primary degradation product DPTCL accumulated only in the blades at any stage, with a concentration of 69.30 ± 3.89 μg kg⁻¹. The secondary degradation product MPTCL accumulated in the blades at the growth stage and in the blades, stipe, and sporophyll at the mature stage. The MPTCL content among algal parts was blades (52.80 ± 3.48 μg kg⁻¹) > sporophylls (31.08 ± 1.53 μg kg⁻¹) > stipes (20.44 ± 0.85 μg kg⁻¹). The accumulation pattern of TPTCL and its degradation products seems closely related to nutrient allocation in <i>U. pinnatifida</i>. These results provide the basis for applying cultivated <i>U. pinnatifida</i> in the bioremediation of organotin pollution and the food safety evaluation of edible algae.