The diffusive gradients in thin films (DGT) technique has been used routinely for monitoring the dissolved, bioavailable fraction of trace metals in freshwater during field campaigns. Nevertheless, for long deployment times, the biofilm formed on the filter of the DGT devices restricts trace metal uptake and hence interferes with the DGT measurements. In this work, we design different experiments to evaluate the potential of silver nanoparticles (AgNPs) in preventing the formation of biofilms on in-house manufactured mercury-specific DGTs. Laboratory tests were carried out by a microcosm system in independent glass containers, where biofilms obtained from field inocula were grown for weeks. Afterward, several experiments were performed with Hg-spiked river water, biofilms and DGTs treated and untreated with AgNPs to better understand biofilm colonization, inhibition and Hg uptake. The results showed that the treatment is very useful, since the mass of the biofilm accumulated at the surface of the treated DGT is significantly (p < 0.05) lower than in control (untreated) devices. Tests in colonized environments and Hg-spiked river water showed that the Hg uptake by the treated DGT matched the theoretical values and prevented biofilm formation up to 24 days post-deployment. Conversely, in deployments longer than two weeks using the untreated DGT, measurements could be underestimated by 35%. The results in the field reveal that in sampling stations with high levels of suspended matter, the filter becomes clogged despite there being no biofilm, thereby explaining its low efficiency for the uptake of Hg. In summary, the use of AgNPs inhibits biofilm formation and their use is especially recommended in eutrophic freshwaters with low amounts of suspended particulate matter.

薄膜中的扩散梯度（DGT）技术已被常规用于在野战期间监测淡水中痕量金属的溶解，生物利用度。然而，对于较长的部署时间，在DGT装置的过滤器上形成的生物膜会限制痕量金属的吸收，因此会干扰DGT的测量。在这项工作中，我们设计了不同的实验来评估银纳米颗粒（AgNP）防止在内部制造的汞特异性DGT上形成生物膜的潜力。实验室测试是通过缩影系统在独立的玻璃容器中进行的，从田间接种物中获得的生物膜在其中生长了数周。之后，用掺汞的河水进行了几次实验，AgNPs处理和未处理的生物膜和DGT，以更好地了解生物膜的定殖，抑制和汞吸收。结果表明该处理是非常有用的，因为在处理过的DGT表面积聚的生物膜的质量比对照（未处理）设备显着（p <0.05）低。在殖民地环境和掺汞的河水中进行的测试表明，处理后的DGT吸收的汞与理论值相符，并且在部署后的24天内阻止了生物膜的形成。相反，在使用未经处理的DGT进行的部署超过两周的情况下，测量可能会被低估35％。现场结果表明，在悬浮物含量高的采样站中，尽管没有生物膜，但过滤器仍被堵塞，从而解释了其吸收汞的效率很低。