The topic of this work was based on the assessment of aquatic systems quality related to the persistent metal pollution. The use of aquatic organisms as bioindicators of metal pollution allowed the obtaining of valuable information about the acute and chronic toxicity on common Romanian aquatic species and the estimation of the environment quality. Laboratory toxicity results showed that Cd, "s, Cu, Zn, Pb, Ni, Zr, and Ti have toxic to very toxic efects on Cyprinus carpio, and this observation could raise concerns because of its importance as a ishery resource. The benthic invertebrates' analysis showed that bioaccumulation level depends on species, type of metals, and sampling sites. The metal analysis from the shells of three mollusk species showed that the metals involved in the metabolic processes (Fe, Mn, Zn, Cu, and Mg) were more accumulated than the toxic ones (Pb, Cd). The bioaccumulation factors of metals in benthic invertebrates were subunitary, which indicated a slow bioaccumulation process in the studied aquatic ecosystems. The preliminary aquatic risk assessment of Ni, Cd, Cr, Cu, Pb, "s, and Zn on C. carpio revealed insigniicant to moderate risk considering the measured environmental concentrations, acute and long-term efects and environmental compartment.Keywords: metals, ish, crustaceans, benthic invertebrates, toxicity, LC 0, M"TC, bioaccumulation, risk © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. . IntroductionMetals are constantly released in aquatic systems from natural and anthropic sources such as industrial and domestic sewage discharges, mining, farming, electronic waste, anthropic accidents, navigation traic as well as climate change events like loods (Figure ) [1, 2]. Moreover, metals are easily dissolved in water and are subsequently absorbed by aquatic organisms such as ish and invertebrates inducing a wide range of biological efects, from being essential for living organisms to being lethal, respectively. In spite of the fact that some metals are essential at low concentrations for living organisms, such as (i) micronutrients (Cu, Zn, Fe, Mn, Co, Mo, Cr, and Se) and (ii) macronutrients (Ca, Mg, Na, P, and S) at higher concentrations, they could induce toxic efects disturbing organisms' growth, metabolism, or reproduction with consequences to the entire trophic chain, including on humans [3]. In addition, the nonessential metals such as Pb, Cd, Ni, "s, and Hg enhance the overall toxic efect on organisms even at very low concentrations. ...

The aquatic environment is under increased pressure by pharmaceutically active compounds (PhACs) due to anthropogenic activities. In spite of being found at very low concentrations (ng/L to μg/L) in the environment, PhACs represent a real danger to aquatic ecosystems due to their bioaccumulation and long-term effects. In this study, the presence in the aquatic environment of six non-steroidal anti-inflammatory drugs (ibuprofen, diclofenac, acetaminophen, naproxen, indomethacin, and ketoprofen), caffeine, and carbamazepine were monitored. Moreover, their aquatic risk and ecotoxicity by three biological models were evaluated. The monitoring studies performed in Romania showed that all studied PhACs were naturally present at concentrations >0.01 μg/L, pointing out the necessity to perform further toxicity tests for environmental risk assessment. The toxicity studies were carried out on aquatic organisms or bacteria and they indicated, for most of the tested PhACs, an insignificant or low toxicity effects: lethal concentrations (LC50) on fish Cyprinus carpio ranged from 42.60 mg/L to more than 100 mg/L; effective concentrations (EC50) on planktonic crustacean Daphnia magna ranged from 11.02 mg/L to more than 100 mg/L; inhibitory concentrations (IC50)/microbial toxic concentrations (MTC) on Vibrio fischeri and other bacterial strains ranged from 7.02 mg/L to more than 100 mg/L. The PhAC aquatic risk was assessed by using the ratio between measured environmental concentration (MEC) and predicted no effect concentration (PNEC) calculated for each type of organism. The average of quotient risks (RQs) revealed that the presence of these compounds in Romania's aquatic environment induced a lower or moderate aquatic risk.

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This study, analyzes the benthic macroinvertebrates community structure and composition in order to assess the ecological status as required by the Water Framework Directive (WFD). Macroinvertebrates are the appropriate indicators to describe habitat heterogenity and the water bodies ecological status by turning the allochtone material into biomass, which is then transferred to the upper trophic levels. Moreover, the macroinvertebrates have the capacity to integrate in their structure the effects of environmental pressure at a temporal and spatial scale. In this particular case, the spatial scale is represented by the Danube Delta, Saint (St) Gheorghe Branch with a length of 112 km, carrying 22% of the Danube flow. The samples include all the organisms life cycle and were collected each month from July to October 2012. The structure and composition of macroinvertebrates were the main target of this study. Furthermore, the structural response of macroinvertebrates to environmental pressure was characterized by quantitative and qualitative analysis. Also, the ecological status was assessed by a surface water bodies methodology in accordance with WFD. This present study brings new information of the benthic community structure and dynamics, reflects the long-term effect of environmental pressure, and it is an effective tool for evaluating integrative ecological status of lotic aquatic systems.

The present paper aims to evaluate the toxic effects generated by conventional treated mine water as well as freshwater samples (Macris river) on primary producers (green algae, Selenastrum capricornutum) and primary consumers (planktonic crustaceans, Daphnia magna). Those organisms could be very realiable biological models to assess the toxic effect of mine waters on the environment. The green algae growth inhibition test (performed according to OECD201) and the acute immobilization test of freshwater crustaceans (Daphnia magna) (performed according to OECD 202) showed no growth inhibition or Daphnia magna immobilization / mortality during 72h and 48h incubation in presence of surface water samples from Macris river. The aqueous system with 1.89 g/L sulphate ion (SO4 2-) concentration, containing treated mine water mixed with freshwater sample (ratio 2.4:1), generated 100% toxic effect on crustaceans (Daphnia magna) after 48h incubation.