Interactions of metal-based engineered nanoparticles with aquatic higher plants: A review of the state of current knowledge

Abstract

The rising potential for the release of engineered nanoparticles (ENPs) into aquatic environments requires evaluation of risks to protect ecological health. The present review examines knowledge pertaining to the interactions of metal-based ENPs with aquatic higher plants, identifies information gaps, and raises considerations for future research to advance knowledge on the subject. The discussion focuses on ENPs' bioaccessibility; uptake, adsorption, translocation, and bioaccumulation; and toxicity effects on aquatic higher plants. An information deficit surrounds the uptake of ENPs and associated dynamics, because the influence of ENP characteristics and water quality conditions has not been well documented. Dissolution appears to be a key mechanism driving bioaccumulation of ENPs, whereas nanoparticulates often adsorb to plant surfaces with minimal internalization. However, few reports document the internalization of ENPs by plants; thus, the role of nanoparticulates' internalization in bioaccumulation and toxicity remains unclear, requiring further investigation. The toxicities of metal-based ENPs mainly have been associated with dissolution as a predominant mechanism, although nano toxicity has also been reported. To advance knowledge in this domain, future investigations need to integrate the influence of ENP characteristics and water physicochemical parameters, as their interplay determines ENP bioaccessibility and influences their risk to health of aquatic higher plants. Furthermore, harmonization of test protocols is recommended for fast tracking the generation of comparable data.

Engineered nanoparticles interact with nutrients to intensify eutrophication in a wetland ecosystem experiment

“…, Thwala et al. ). In these studies, researchers typically attribute these negative impacts on increases in oxidative stress or membrane damage caused by the NPs but the literature is scarce on the specific toxicity mechanisms of AuNPs in plants and algae.…”

“…We cannot resolve whether the higher tissue concentrations or a higher toxicity of AuNPs led to more severe effects of AuNPs than CuNPs in this experiment. In previous lab based assays, metal NPs have been reported to reduce both algal and macrophyte growth and photosynthesis (Hoecke et al 2013, Thwala et al 2016. In these studies, researchers typically attribute these negative impacts on increases in oxidative stress or membrane damage caused by the NPs but the literature is scarce on the specific toxicity mechanisms of AuNPs in plants and algae.…”

“…We hypothesized that CuNPs would have significant ecological impacts on primary producers due to the welldescribed toxicity and antimicrobial activity of this fungicide, even in the lg/L range in aquatic ecosystems (Wang et al 2011b, Thwala et al 2016, Keller et al 2017). The direction of this effect was difficult to predict a priori, as CuNP fungicides could directly affect algal communities and the photosynthetic potential of macrophytes (Regier et al 2015), or they might indirectly benefit autotrophs because of their toxicity to competing microbes.…”

Nanoparticles in the environment: where do we come from, where do we go to?

“…Those effects indicate implications in population development and suggest the potential for transgenerational effects [ 131 , 132 ]. In addition, algae [ 133 ] and aquatic plants [ 134 ] were altered in their photosynthetic pigment composition and showed effects in photosystem II, while we refer to Thwala et al [ 135 ] for a more detailed review. Similarly, several recent reviews have covered NP accumulation in terrestrial plants which can cause biochemical and physiological changes [ 136 – 138 ]: Cao et al for instance, documented impacts on carbon fixation as well as water use efficiency during photosynthesis in response to CeO 2 NP exposure [ 139 ].…”

INTERACTIONS OF PLANTS WITH NOBLE METAL NANOPARTICLES (review)

“…T h e p e n e t r a t i o n o f n a n o p a r t i c le s i n to p la n t ce l l s a n d t i ss u e s. Recently, several reviews have been published on the interaction of metallic nanoparticles with higher plants [24][25][26][27] and algae [28,29]. It turned out that algae, especially unicellular ones, in particular Dunaliella salina Teod., are a convenient model to investigate the effects of Au NP and Ag NP on living cells [30,31].…”