Epiphytic lichens as sentinels for heavy metal pollution at forest ecosystems (central Italy)

The results of a study using epiphytic lichens (Parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central Italy are reported. The woods investigated are characterized by holm oak (Quercus ilex), turkey oak (Quercus cerris) and beech (Fagus sylvatica) and represent the typical forest ecosystems of central Italy at low, medium and high elevations, respectively. The results showed that levels of heavy metals in lichens were relatively low and consequently no risk of heavy metal air pollution is expected for the six forest ecosystems investigated. However, for two of them there are indications of a potential risk: the beech forest of Vallombrosa showed signs of contamination by Pb as a consequence of vehicle traffic due to the rather high touristic pressure in the area, and the holm oak forest of Cala Violina showed transboundary pollution by Mn, Cr and Ni originating from the steel industry in Piombino. Epiphytic lichens proved to be very effective as an early warning system to detect signs of a changing environment at forest ecosystems.     

Aquatic leeches (Hirudinea) as bioindicators of organic chemical contaminants in freshwater ecosystems

Freshwater leeches from an industrially polluted creek were found to contain very high residues of chlorophenols, when compared with fish, tadpoles and most other benthic invertebrates. Leeches are recommended as possible bioindicators of aquatic organic contamination.     

Historical changes in arctic freshwater ecosystems

Various types of ecosystem-based climate proxies have been used to assess past arctic change. Although lotic records are relatively poor because of the constant reworking of riverine material, high-quality lentic data have been assembled back to the end of the Pleistocene and deglaciation of the circumpolar Arctic. In general, climatic variations in the Holocene, partly due to changes in the shrinking effect of glacier coverage, produced significant temporal and spatial variations in arctic hydrology and freshwater ecosystems. Of particular note were the vast expansions of northern peatlands during major protracted periods of wetting. More recent lake biota and sedimentiological data reflect the general warming trend that has occurred over the last one to two centuries and indicate major changes to freshwater characteristics such as ice-cover duration and thermal stratification. Such data provide an excellent baseline against which future effects of climate change can be both projected and measured.     

Aquatic plants and ecotoxicological assessment in freshwater ecosystems: a review

Environmental Science and Pollution Research - This paper reviews the current state-of-the-art, limitations, critical issues, and new directions in freshwater plant ecotoxicology. We selected...     

Lichens as sentinels for air pollution at remote alpine areas (Italy)

The present study was undertaken with the aim of using epiphytic lichens as sentinels for air pollution at two remote alpine sites (1,400 and 1,800 m above sea level (asl)) of NW Italy. The results indicated that the site at 1,800 m prompted for early warning indications of biological changes. Although levels of the many elements assayed in samples of the lichen Pseudevernia furfuracea (L.) Zopf, ranging from minor elements (e.g., Al) to ultra-trace (e.g., Pt), were at normal levels, indications of a slowly worsening environment were given by the lichen biodiversity and by damage to cell membranes. The analysis of Pb isotopic ratios suggested that the origin of Pb accumulated in lichens is not local, but linked to the long-range transport by air masses. It was concluded that the origin of pollutants is from air mass coming from the Po plain of Italy and from densely populated areas of Switzerland and France.     

General features of the arctic relevant to climate change in freshwater ecosystems

Large variations exist in the size, abundance and biota of the two principal categories of freshwater ecosystems, lotic (flowing water; e.g., rivers, streams, deltas and estuaries) and lentic (standing water; lakes, ponds and wetlands) found across the circumpolar Arctic. Arctic climate, many components of which exhibit strong variations along latitudinal gradients, directly affects a range of physical, chemical and biological processes in these aquatic systems. Furthermore, arctic climate creates additional indirect ecological effects through the control of terrestrial hydrologic systems and processes, particularly those associated with cryospheric components such as permafrost, freshwater ice and snow accumulation/ablation. The ecological structure and function of arctic freshwater systems are also controlled by external processes and conditions, particularly those in the headwaters of the major arctic rivers and in the adjacent marine environment. The movement of physical, chemical and biotic components through the interlinked lentic and lotic freshwater systems are major determinants of arctic freshwater ecology.     

Sediment processes and mercury transport in a frozen freshwater fluvial lake (Lake St. Louis, QC, Canada)

An open-bottom and a closed-bottom mesocosm were developed to investigate the release of mercury from sediments to the water column in a frozen freshwater lake. The mesoscosms were deployed in a hole in the ice and particulate mercury (Hg_P) and total dissolved mercury (TDHg) were measured in sediments and in water column vertical profiles. In addition, dissolved gaseous mercury (DGM) in water and mercury water/airflux were quantified. Concentrations of TDHg, DGM, and mercury flux were all higher in the open-bottom mesocosm than in the closed-bottom mesocosm. In this paper we focus on the molecular diffusion of mercury from the sediment in comparison with the TDHg accumulation in the water column. We conclude that the molecular diffusion and sediment resuspension play a minor role in mercury release from sediments suggesting that solute release during ebullition is an important transport process for mercury in the lake.     

Half a century of changing mercury levels in Swedish freshwater fish

The variability of mercury (Hg) levels in Swedish freshwater fish during almost 50 years was assessed based on a compilation of 44 927 observations from 2881 waters. To obtain comparable values, individual Hg concentrations of fish from any species and of any size were normalized to correspond to a standard 1-kg pike [median: 0.69 mg kg^?1 wet weight (ww), mean ± SD: 0.84 ± 0.67 mg kg^?1 ww]. The EU Environmental Quality Standard of 0.02 mg kg^?1 was exceeded in all waters, while the guideline set by FAO/WHO for Hg levels in fish used for human consumption (0.5–1.0 mg kg^?1) was exceeded in 52.5 % of Swedish waters after 2000. Different trend analysis approaches indicated an overall long-term decline of at least 20 % during 1965–2012 but trends did not follow any consistent regional pattern. During the latest decade (2003–2012), however, a spatial gradient has emerged with decreasing trends predominating in southwestern Sweden.     

Bacterial periphytic communities related to mercury methylation within aquatic plant roots from a temperate freshwater lake (South-Western France)

Environmental Science and Pollution Research - Macrophyte floating roots are considered as hotspots for methylmercury (MeHg) production in aquatic ecosystems through microbial activity....     

Assessment of copper and zinc levels in fish from freshwater ecosystems of Moldova

Purpose

The aim of this work was to assess the levels of copper and zinc in fish from the main freshwater ecosystems of Moldova, in relation with species, habitat, age, sex, season, and development stage.

Methods

Fish from Cyprinidae and Percidae families (Cyprinus carpio, Carassius auratus gibelio, Rutilus rutilus heckeli, Abramis brama, Aristichthys nobilis, Hypophtalmichthys molitrix, Sander lucioperca) were collected from Prut and Dniester rivers, Cuciurgan, Dubasari, and Costesti-Stanca reservoirs, and ponds of farms in the Dniester delta. The Cu and Zn content of fish tissues (skeletal muscles, liver, gonads, gills, skin, and scales) was determined by flame atomic absorption spectrophotometer AAS-3, of water by graphite furnace HGA 900 of AAnalist 400.

Results

The level of heavy metals accumulation in muscles of immature fish follows their dynamics in water. The highest concentration of zinc was registered in the gonads of mature fish, and of copper??in the liver. The lowest Cu and Zn contents were recorded in the muscles and are in the United Nations Food and Agriculture Organization safety-permissible levels for human consumption. Cu and Zn contents in muscles of fish depend on specimen age. Their level in fish gonads was sharply increasing during pre-spawning period. During the early developmental stages, the metal concentration in fish eggs and larvae varies within wide limits, but the accumulation pattern is similar in the investigated species.

Conclusions

The fish represent one of the most indicative factors for the estimation of trace metals pollution in freshwater systems and this is important not only for monitoring purposes, but also for the fish culture ones.     

Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems

In the mid-1800s, the agricultural chemist Justus von Liebig demonstrated strong positive relationships between soil nutrient supplies and the growth yields of terrestrial plants, and it has since been found that freshwater and marine plants are equally responsive to nutrient inputs. Anthropogenic inputs of nutrients to the Earth's surface and atmosphere have increased greatly during the past two centuries. This nutrient enrichment, or eutrophication, can lead to highly undesirable changes in ecosystem structure and function, however. In this paper we briefly review the process, the impacts, and the potential management of cultural eutrophication in freshwater, marine, and terrestrial ecosystems. We present two brief case studies (one freshwater and one marine) demonstrating that nutrient loading restriction is the essential cornerstone of aquatic eutrophication control. In addition, we present results of a preliminary statistical analysis that is consistent with the hypothesis that anthropogenic emissions of oxidized nitrogen could be influencing atmospheric levels of carbon dioxide via nitrogen stimulation of global primary production.     

Factors influencing concentrations of dissolved gaseous mercury (DGM) and total mercury (TM) in an artificial reservoir

The effects of various factors including turbidity, pH, DOC, temperature, and solar radiation on the concentrations of total mercury (TM) and dissolved gaseous mercury (DGM) were investigated in an artificial reservoir in Korea. Episodic total mercury accumulation events occurred during the rainy season as turbidity increased, indicating that the TM concentration was not controlled by direct atmospheric deposition. The DGM concentration in surface water ranged from 3.6 to 160 pg/L, having a maximum in summer and minimum in winter. While in most previous studies DGM was controlled primarily by a photo-reduction process, DGM concentrations tracked the amount of solar radiation only in winter when the water temperature was fairly low in this study. During the other seasons microbial transformation seemed to play an important role in reducing Hg(II) to Hg(0). DGM increased as dissolved organic carbon (DOC) concentration increased (p-value < 0.01) while it increased with a decrease of pH (p-value < 0.01).     

Water balances in intensively monitored forest ecosystems in Europe

A soil hydrological model based on Darcy's law was used to calculate hydrological fluxes for 245 intensively monitored forest plots in Europe. Local measured input data for the model were rather limited and input was partly based on generic data. To obtain the best results, the model was calibrated on measured throughfall at the plots. Median transpiration fluxes are 350 mm; median leaching fluxes are 150 mm yr(-1) with the highest values in areas with high rainfall. Uncertainty analyses indicate that the use of local meteorological data instead of generic data leads to lower leaching fluxes at 70% of the plots due to an overestimation of the wind speed on basis of main meteorological stations. The underestimation of the leaching fluxes is confirmed by the median Cl fluxes which were slightly positive for the considered plots.     

Complex interactions between autotrophs in shallow marine and freshwater ecosystems: implications for community responses to nutrient stress

The relative biomass of autotrophs (vascular plants, macroalgae, microphytobenthos, phytoplankton) in shallow aquatic ecosystems is thought to be controlled by nutrient inputs and underwater irradiance. Widely accepted conceptual models indicate that this is the case both in marine and freshwater systems. In this paper we examine four case studies and test whether these models generally apply. We also identify other complex interactions among the autotrophs that may influence ecosystem response to cultural eutrophication. The marine case studies focus on macroalgae and its interactions with sediments and vascular plants. The freshwater case studies focus on interactions between phytoplankton, epiphyton, and benthic microalgae. In Waquoit Bay, MA (estuary), controlled experiments documented that blooms of macroalgae were responsible for the loss of eelgrass beds at nutrient-enriched locations. Macroalgae covered eelgrass and reduced irradiance to the extent that the plants could not maintain net growth. In Hog Island Bay, VA (estuary), a dense lawn of macroalgae covered the bottom sediments. There was reduced sediment-water nitrogen exchange when the algae were actively growing and high nitrogen release during algal senescence. In Lakes Brobo (West Africa) and Okeechobee (FL), there were dramatic seasonal changes in the biomass and phosphorus content of planktonic versus attached algae, and these changes were coupled with changes in water level and abiotic turbidity. Deeper water and/or greater turbidity favored dominance by phytoplankton. In Lake Brobo there also was evidence that phytoplankton growth was stimulated following a die-off of vascular plants. The case studies from Waquoit Bay and Lake Okeechobee support conceptual models of succession from vascular plants to benthic algae to phytoplankton along gradients of increasing nutrients and decreasing under-water irradiance. The case studies from Hog Island Bay and Lake Brobo illustrate additional effects (modified sediment-water nutrient fluxes, allelopathy or nutrient release during plant senescence) that could play a role in ecosystem response to nutrient stress.     

Status and trends of mercury pollution of the atmosphere and terrestrial ecosystems in Poland

The goal of this paper is to assess the current status and trends of total mercury (THg) contamination of the atmosphere and terrestrial ecosystems in Poland. The study shows that the reduced domestic and worldwide atmospheric emission of Hg resulted in decreased THg level in the terrestrial biotope and biosphere. Considering that Poland is one of the main Hg emitters in Europe, the THg concentrations in its abiotic environment are still elevated. However, the THg level in terrestrial organisms is relatively low, which is because a large proportion of Hg deposited on land is accumulated in organic-rich soils. Regarding the THg concentration, consumption of wildlife and livestock from Poland is safe for humans. Nevertheless, the authors indicate the need for effective environmental monitoring, based on selected bioindicators, which is crucial considering the slowing reduction of Hg emission combined with the consequences of the changing climate.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01505-1.     

MODELKEY. Models for assessing and forecasting the impact of environmental key pollutants on freshwater and marine ecosystems and biodiversity (5 pp)

BACKGROUND: Triggered by the requirement of Water Framework Directive for a good ecological status for European river systems till 2015 and by still existing lacks in tools for cause identification of insufficient ecological status MODELKEY (http:// www.modelkey.org), an Integrated Project with 26 partners from 14 European countries, was started in 2005. MODELKEY is the acronym for 'Models for assessing and forecasting the impact of environmental key pollutants on freshwater and marine ecosystems and biodiversity'. The project is funded by the European Commission within the Sixth Framework Programme. OBJECTIVES: MODELKEY comprises a multidisciplinary approach aiming at developing interlinked tools for an enhanced understanding of cause-effect-relationships between insufficient ecological status and environmental pollution as causative factor and for the assessment and forecasting of the risks of key pollutants on fresh water and marine ecosystems at a river basin and adjacent marine environment scale. New modelling tools for risk assessment including generic exposure assessment models, mechanistic models of toxic effects in simplified food chains, integrated diagnostic effect models based on community patterns, predictive component effect models applying artificial neural networks and GIS-based analysis of integrated risk indexes will be developed and linked to a user-friendly decision support system for the prioritisation of risks, contamination sources and contaminated sites. APPROACH: Modelling will be closely interlinked with extensive laboratory and field investigations. Early warning strategies on the basis of sub-lethal effects in vitro and in vivo are provided and combined with fractionation and analytical tools for effect-directed analysis of key toxicants. Integrated assessment of exposure and effects on biofilms, invertebrate and fish communities linking chemical analysis in water, sediment and biota with in vitro, in vivo and community level effect analysis is designed to provide data and conceptual understanding for risk arising from key toxicants in aquatic ecosystems and will be used for verification of various modelling approaches. CONCLUSION AND PERSPECTIVE: The developed tools will be verified in case studies representing European key areas including Mediterranean, Western and Central European river basins. An end-user-directed decision support system will be provided for cost-effective tool selection and appropriate risk and site prioritisation.     

Identification of multixenobiotic defence mechanism (MXR) background activities in the freshwater bivalve Dreissena polymorpha as reference values for its use as biomarker in contaminated ecosystems

The biological defence mechanism called MXR or MXD for multixenobiotic resistance or defence protects cells against the entry and the accumulation of xenobiotics. As the defence is modulated by man made chemicals, MXR is used as a biomarker of organisms' exposure to environmental contamination. However, to reliably assess and evidence MXR induction, the use of a reference level is required. In this context, we focused on MXR background level in a freshwater bivalve, the zebra mussel Dreissena polymorpha, in order to propose its use as a reference during MXR evaluation. We monitored the MXR transport activity in mussels collected either in a natural population or in a caged population and then transplanted to clean water in the laboratory. The results showed that MXR activity was decreased to its baseline level after an eight to nine day depuration period (13.1+/-3.1; 7+/-2.6; 13.7+/-3.9 pmol RB min(-1)org(-1) after three experiments of laboratory depurations). Moreover, significant MXR induction was measured in depurated zebra mussels exposed to contaminated sites (39.6+/-3.7; 59.2+/-20.3 pmol RB min(-1)org(-1) after two experiments of field exposure), showing that the laboratory depuration did not affect the induction potential. The MXR responses (decrease as well as increase) occurred in few days and were highly significant, highlighting its reactivity in zebra mussels. Finally, this paper confirms the usefulness of MXR as a tool in biomonitoring studies and provides a protocol for field experiments that enables to establish and use the background level of MXR activity as a reference.     

Microplastics in freshwater ecosystems: a recent review of occurrence,analysis, potential impacts,and research needs

Environmental Science and Pollution Research - The utilization of plastics has now become a threat to the environment as it generates microplastic particles (&lt;5 mm in size). The increasing...