Hepp Luiz U, Pratas João A M S, Graça Manuel A S
Departament of Biological Sciences, Universidade Regional Integrada do Alto Uruguai e das Missões, 99709-910 Rio Grande do Sul, Brazil.
MARE - Marine and Environmental Sciences Centre, Department of Earth Sciences, University of Coimbra, 3001-517 Coimbra, Portugal.
Ecotoxicol Environ Saf. 2017 May;139:132-138. doi: 10.1016/j.ecoenv.2017.01.035.
Human activities such as mining have contributed substantially to the increase of metals in aquatic environments worldwide. These metals are bioaccumulated by aquatic organisms and can be biomagnified along trophic webs. The dispersal of contaminants from water to land has been little investigated, even though most aquatic invertebrates in streams have aerial stages. We used field and laboratory approaches to investigate the effects of arsenic pollution on stream invertebrate assemblages, and its bioaccumulation, biomagnification and trophic transfer from aquatic to terrestrial environments by emergent insects. We conducted the study in an arsenic-impacted stream (40μgL As at the most polluted site) and a reference stream (0.3μgL As). Invertebrate abundance and richness were lowest at the most impacted site. Arsenic in biofilm and in invertebrates increased with the arsenic content in the water. The highest arsenic accumulators were bryophytes (1760μgg), followed by the biofilm (449μgg) and shredder invertebrates (313μgg); predators had the lowest arsenic concentration. Insects emerging from water and spiders along streambanks sampled from the reference and the impacted stream did not differ in their body arsenic concentrations. In the laboratory, the shredder Sericostoma vittatum had reduced feeding rates when exposed to water from the impacted stream in comparison with the reference stream (15.6 vs. 19.0mg leaves mg body mass day; p<0.05), but they grew faster in the polluted water (0.16±0.04% dayvs. 0.05±0.01% day, p<0.05). S. vittatum exposed to contaminated stream water accumulated arsenic from food, not through contact with water. We concluded that although arsenic is bioaccumulated, mainly by food ingestion, it is not biomagnified through food webs and is not transported from the aquatic to terrestrial environment when insects leave the stream water.
采矿等人类活动在很大程度上导致了全球水生环境中金属含量的增加。这些金属会被水生生物生物累积，并可能在营养级联中生物放大。尽管溪流中的大多数水生无脊椎动物都有陆生阶段，但污染物从水到陆地的扩散情况却很少被研究。我们采用野外和实验室方法，研究了砷污染对溪流无脊椎动物群落的影响，以及砷通过羽化昆虫从水生环境到陆地环境的生物累积、生物放大和营养转移。我们在一条受砷影响的溪流（污染最严重的地点砷含量为40μg/L）和一条对照溪流（砷含量为0.3μg/L）中进行了这项研究。在受影响最严重的地点，无脊椎动物的丰度和丰富度最低。生物膜和无脊椎动物体内的砷含量随水中砷含量的增加而增加。砷积累量最高的是苔藓植物（1760μg/g），其次是生物膜（449μg/g）和碎食性无脊椎动物（313μg/g）；捕食者体内的砷浓度最低。从对照溪流和受影响溪流采集的羽化出水的昆虫和溪边的蜘蛛，其体内砷浓度没有差异。在实验室中，与对照溪流相比，碎食性的条纹角石蛾（Sericostoma vittatum）暴露于受影响溪流的水中时，摄食率降低（分别为15.6和19.0mg叶片/mg体重/天；p<0.05），但它们在污染水中生长得更快（分别为0.16±0.04%/天和0.05±0.01%/天，p<0.05）。暴露于受污染溪流水体中的条纹角石蛾从食物中积累砷，而不是通过与水接触。我们得出结论，尽管砷主要通过食物摄入进行生物累积，但它不会通过食物网进行生物放大，并且当昆虫离开溪水时，砷不会从水生环境转移到陆地环境。
