Bottino F, Milan J A M, Cunha-Santino M B, Bianchini I
Universidade de São Paulo, Escola de Engenharia de São Carlos, Departamento de Hidráulica e Saneamento, Avenida Trabalhador São-carlense, 400, Pq Arnold Schmidt, São Carlos, SP, CEP 13566-690, Brazil.
Universidade Federal de São Carlos, Departamento de Hidrobiologia, Rodovia Washington Luiz, km 235, São Carlos, SP, CEP 13595-905, Brazil.
Chemosphere. 2017 Nov;186:488-494. doi: 10.1016/j.chemosphere.2017.08.030. Epub 2017 Aug 8.
On November 5th, 2015 the worst environmental disaster in Brazil spilled 60 million m of iron mining residue into Gualaxo do Norte River (Minas Gerais State), an affluent of the highest River Basin of the Brazilian Southeast (Doce River Basin), reaching the Atlantic Ocean. To assess the impact of the iron residue on the aquatic plant metabolism, we performed macrophyte growth experiments under controlled light and temperature conditions using two species (Egeria densa and Chara sp.). The plants' growth data were fitted in a kinetic model to obtain the biomass yields (K) and growth rates (μ). Turbidity and electrical conductivity of the water were measured over time. Both plants showed the highest growth rates in the contaminated condition (0.056 d for E. densa and 0.45 d for Chara sp.) and the biomass increased in the short-term (≈20 days). The control condition (i.e. no impacted water) supported the biomass increasing over time and the development of vegetative buddings with high daily rates (1.75 cm d for E. densa and 0.13 cm d for Chara sp). Turbidity showed a sharp decrease in 48 h and had no effects in the plants growth in the contaminated condition. The contamination affected the plants' yields in the long-term affecting the biomass development. This study provides preliminary information about the ecological consequences of a mining dam rupture aiming to collaborate with monitoring and risk assessments.
2015年11月5日，巴西发生了最严重的环境灾难，6000万立方米的铁矿渣泄漏到北瓜拉肖河（米纳斯吉拉斯州），该河是巴西东南部最高流域（多西河盆地）的一条支流，最终流入大西洋。为了评估铁渣对水生植物代谢的影响，我们在可控的光照和温度条件下，使用两种植物（伊乐藻和轮藻属）进行了大型植物生长实验。将植物的生长数据拟合到一个动力学模型中，以获得生物量产量（K）和生长速率（μ）。同时，对水的浊度和电导率进行了长期测量。两种植物在受污染条件下均表现出最高的生长速率（伊乐藻为0.056天，轮藻属为0.45天），且生物量在短期内（约20天）增加。对照条件（即未受影响的水）支持生物量随时间增加以及营养芽的发育，且日生长速率较高（伊乐藻为1.75厘米/天，轮藻属为0.13厘米/天）。浊度在48小时内急剧下降，且对受污染条件下植物的生长没有影响。从长期来看，污染影响了植物的产量，进而影响了生物量的发展。本研究提供了有关采矿大坝破裂生态后果的初步信息，旨在为监测和风险评估提供参考。
