Assessing the concentrations and risks of toxicity from the antibiotics ciprofloxacin, sulfamethoxazole, trimethoprim and erythromycin in European rivers

This study evaluated the potential concentrations of four antibiotics: ciprofloxacin (CIP), sulfamethoxazole (SUF), trimethoprim (TRI) and erythromycin (ERY) throughout the rivers of Europe. This involved reviewing national consumption rates together with assessing excretion and sewage treatment removal rates. From this information, it was possible to construct best, expected and worst case scenarios for the discharge of these antibiotics into rivers. Consumption data showed surprising variations, up to 200-fold in the popularity of different antibiotics across different European nations. Using the water resources model GWAVA which has a spatial resolution of approximately 6 × 9 km, river water concentrations throughout Europe were predicted based on 31-year climate data. The modelled antibiotic concentrations were within the range of measurements reported previously in European effluents and rivers. With the expected scenario, the predicted annual-average antibiotic concentrations ranged between 0 and 10 ng/L for 90% by length of surface waters. In the worst case scenario concentrations could reach between 0.1 and 1 μg/L at the most exposed locations. As both predicted and observed sewage effluent concentrations were below reported effect levels for the most sensitive aquatic wildlife, no direct toxicity in rivers is expected. Predicted river concentrations for CIP and ERY were closest to effect levels in wildlife, followed by SUF which was 2–3 orders of magnitude lower. TRI appeared to be of the least concern with around 6 orders of magnitude difference between predicted and effect levels. However, mixture toxicity may elevate this risk and antibiotic levels of 0.1–1 μg/L in hotspots may contribute to local environmental antibiotic resistance in microorganisms

Nano silver and nano zinc-oxide in surface waters - exposure estimation for Europe at high spatial and temporal resolution

Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ~6 × 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production. Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng/L nano silver and 1.5 ng/L nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng/L and 150 ng/L, respectively. Predicted concentrations were usually highest in July

Do concentrations of ethinylestradiol, estradiol and diclofenac in European rivers exceed proposed EU environmental quality standards?

This study used a geographic based water model to predict the environmental concentrations of three pharmaceuticals, 17α-ethinylestradiol (EE2), 17β-estradiol (E2), and diclofenac throughout European rivers. The work was prompted by the proposal of the European Community (COM(2011)876) to consider these chemicals as candidates for future control via environmental quality standards (EQS). National drug consumption information, excretion, national water use, and sewage removal rates, were used to derive per capita sewage effluent values for the European countries . For E2, excretion rates of the natural hormone and national demographics were also included. Incorporating this information into the GWAVA model allowed water concentrations throughout Europe’s rivers to be predicted. The mean concentration from the expected sewage discharge scenario indicated that 12% by length of Europe’s rivers would reach concentrations greater than the proposed 0.035 ng/L EQS for EE2. For several countries, between a quarter and a third of their total river length would fail such an EE2 EQS. For E2, just over 1% by length of rivers would reach concentrations greater than the 0.4 ng/L proposed EQS, while just over 2% by length of rivers would reach concentrations greater than the proposed EQS of 100 ng/L for diclofenac

3D bite modeling and feeding mechanics of the largest living amphibian, the Chinese Giant Salamander Andrias davidianus (Amphibia:Urodela)

Biting is an integral feature of the feeding mechanism for aquatic and terrestrial salamanders to capture, fix or immobilize elusive or struggling prey. However, little information is available on how it works and the functional implications of this biting system in amphibians although such approaches might be essential to understand feeding systems performed by early tetrapods. Herein, the skull biomechanics of the Chinese giant salamander, Andrias davidianus is investigated using 3D finite element analysis. The results reveal that the prey contact position is crucial for the structural performance of the skull, which is probably related to the lack of a bony bridge between the posterior end of the maxilla and the anterior quadrato-squamosal region. Giant salamanders perform asymmetrical strikes. These strikes are unusual and specialized behavior but might indeed be beneficial in such sit-and-wait or ambush-predators to capture laterally approaching prey. However, once captured by an asymmetrical strike, large, elusive and struggling prey have to be brought to the anterior jaw region to be subdued by a strong bite. Given their basal position within extant salamanders and theirPeer ReviewedPostprint (published version

Future trends in emissions of N2O from rivers and estuaries

Emissions of nitrous oxide (N2O) from aquatic systems such as rivers and estuaries are enhanced as a result of human activities on land resulting in enhanced nitrogen availability in aquatic systems. These human activities include agricultural activities such as fertilizer use, as well as industrial activities resulting in nitrogen (N) losses to the environment. In this article, we analyze past and future trends in global emissions of N2O from rivers and estuaries. We calculate aquatic N2O emissions from trends in the export of nitrogen to coastal waters by world-wide rivers. These trends in riverine N exports are from the Global NEWS models, which are global, regionally explicit models developed in the NEWS (Nutrient Export from WaterShed) framework. The NEWS models calculate nutrient exports from land to coastal waters, taking into account different human activities on the land, as well as biological N2 fixation and different ways in which nitrogen is retained in watersheds, including the effect of dams. We present global total emissions of N2O for the years 1970, 2000, and for four scenarios for 2050, as well as regional patterns

Modelling water scarcity across Europe in terms of water quantity and quality

The need for integrated and sustainable water resources management has become an important driver behind large-scale gridded modelling. Such modelling has traditionally focused on water quantity. However, reduced water quality can also limit water resources, particularly for drinking water. The water availability model GWAVA has been further developed to include a water quality module. This module will initially focus on biochemical oxygen demand (BOD). The module considers drivers of BOD loading from land, such as agriculture and urban runoff, and transport and loss of BOD through sewage treatment and river networks. In an exploratory assessment, GWAVA was used to produce maps of water scarcity across Europe. The new module enhanced those maps with effects of BOD on water resources. This enhancement increased the modelled proportion of Europe experiencing water scarcity, which indicates that it is important to include both water quantity and quality in model estimates of water scarcity