Controlled Release of TBH Herbicide Encapsulated on Ca-ALG Microparticles: Leaching and Phytointoxication Plants

ABSTRACT: The aim of this work was to demonstrate a detailed study of the controlled release of the herbicide Tebuthiuron (TBH) encapsulated in microparticles of calcium alginate (Ca-ALG), to evaluate the phytotoxicity in different concentrations of herbicide (4, 6 and 8 g L-1), and their correlation with the depth of leaching using bioindicator plants. The Ca-ALG microparticles were prepared from the crosslinking of sodium alginate by Ca++ containing varied amounts of TBH supplied in calcium chloride (CaCl2) aqueous solution. The results showed that TBH herbicide, when encapsulated, leached to shallow depths relative to the conventional, non-encapsulated herbicide (which moved to a depth of 40-50 cm). The concentration of 4 g L-1 was the one that leached most in the PVC columns, but its mobility did not exceed 30 cm of depth. The results of the dry mass corroborated with the phytotoxicity results of the bioindicator plants, evidencing the mobility of the conventional herbicide in the soil at depths around 40 and 50 cm, while the herbicide encapsulated in the Ca-ALG microparticles did not show leaching beyond 20 -30 cm deep. The encapsulation of TBH in Ca-ALG microparticles can thus be considered as a more eco-friendly technology, reducing the leaching process and consequently soil contamination.

摘要：本研究旨在详细探究包埋于海藻酸钙（Ca-ALG）微球中的除草剂特丁噻草隆（Tebuthiuron, TBH）的控释性能，评估该除草剂在4、6和8 g·L⁻¹三种不同浓度下的植物毒性，并结合生物指示植物（bioindicator plants）分析其与除草剂淋溶深度的相关性。本研究通过在氯化钙（CaCl₂）水溶液中加入不同用量的TBH，使海藻酸钠经钙离子交联制备得到Ca-ALG微球。实验结果显示，与可迁移至40~50 cm深度的传统未包埋除草剂相比，包埋后的TBH除草剂淋溶至更浅的土层深度。其中4 g·L⁻¹浓度组在PVC柱中的淋溶量最高，但该组除草剂的迁移深度未超过30 cm。植株干重检测结果与生物指示植物的植物毒性检测结果相互印证：传统除草剂可在40~50 cm深度的土壤中发生迁移，而包埋于Ca-ALG微球中的除草剂淋溶深度未超过20~30 cm。综上，将TBH包埋于Ca-ALG微球可被视为一种更环保的技术，能够降低除草剂的淋溶过程，进而减少土壤污染。