Climate dynamics and extreme precipitation and flood events in Central Europe

Past changes and possible future variations in the nature of extreme precipitation and flood events in Central Europe and the Alpine region are examined from a physical standpoint. An overview is given of the following key contributory physical processes: (1) the variability of the large-scale atmospheric flow and the associated changes of the North-Atlantic storm track; (2) the feedback process between climate warming and the water cycle, and in particular the potential for more frequent heavy precipitation events; and (3) the catchment-scale hydrological processes associated with variations in major river flooding events and that are related to land-use changes, river training measures, and shifts in the proportion of rain to snowfall. In this context an account is provided of the possible future forecasting and warning methodologies based upon high-resolution weather prediction and runoff models. Also consideration is given to the detectability of past (future) changes in observed (modeled) extreme events. It is shown that their rarity and natural fluctuation largely impedes a detection of systematic variations. These effects restrict trend analysis of such events to return periods of below a few months. An illustration using daily precipitation from the Swiss Alps does yield evidence for pronounced trends of intense precipitation events (return period 30 days), while trends of stronger event classes are not detectable (but nevertheless can not be excluded). The small detection probability for extreme events limits possible mitigation of future damage costs through an abatement of climate change alone, and points to the desirability of developing improved early forecasting/warning systems as an additional no-regret strategy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Environmental and socioeconomic assessment of impacts by mining activities—a case study in the Certej River catchment,Western Carpathians,Romania

Background, aim and scope

In the region of the Apuseni Mountains, part of the Western Carpathians in Romania, metal mining activities have a long-standing tradition. These mining industries created a clearly beneficial economic development in the region. But their activities also caused impairments to the environment, such as acid mine drainage (AMD) resulting in long-lasting heavy metal pollution of waters and sediments. The study, established in the context of the ESTROM programme, investigated the impact of metal mining activities both from environmental and socioeconomic perspectives and tried to incorporate the results of the two approaches into an integrated proposition for mitigation of mining-related issues.

Study site

The small Certej catchment, situated in the Southern Apuseni Mountains, covers an area of 78 km². About 4,500 inhabitants are living in the basin, in which metal mining was the main economic sector. An open pit and several abandoned underground mines are producing heavy metal-loaded acidic water that is discharged untreated into the main river. The solid wastes of mineral processing plants were deposited in several dumps and tailings impoundment embodying the acidic water-producing mineral pyrite.

Methods

The natural science team collected samples from surface waters, drinking water from dug wells and from groundwater. Filtered and total heavy metals, both after enrichment, and major cations were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Major anions in waters, measured by ion chromatography, alkalinity and acidity were determined by titration. Solid samples were taken from river sediments and from the largest tailings dam. The latter were characterised by X-ray fluorescence and X-ray diffraction. Heavy metals in sediments were analysed after digestion. Simultaneously, the socioeconomic team performed a household survey to evaluate the perception of people related to the river and drinking water pollution by way of a logistic regression analysis.

Results and discussion

The inputs of acid mine waters drastically increased filtered heavy metal concentrations in the Certej River, e.g. Zn up to 130 mg L⁻¹, Fe 100 mg L⁻¹, Cu 2.9 mg L⁻¹, Cd 1.4 mgL⁻¹ as well as those of SO₄ up to 2.2 g L⁻¹. In addition, river water became acidic with pH values of pH 3. Concentrations of pollutant decreased slightly downstream due to dilution by waters from tributaries. Metal concentrations measured at headwater stations reflect background values. They fell in the range of the environmental quality standards proposed in the EU Water Framework Directive for dissolved heavy metals. The outflow of the large tailing impoundment and the groundwater downstream from two tailings dams exhibited the first sign of AMD, but they still had alkalinity.

Most dug wells analysed delivered a drinking water that exhibited no sign of AMD pollution, although these wells were a distance of 7 to 25 m from the contaminated river. It seems that the Certej River does not infiltrate significantly into the groundwater.

Pyrite was identified as the main sulphide mineral in the tailings dam that produces acidity and with calcite representing the AMD-neutralising mineral. The acid–base accounting proved that the potential acid-neutralising capacity in the solid phases would not be sufficient to prevent the production of acidic water in the future. Therefore, the open pits and mine waste deposits have to be seen as the sources for AMD at the present time, with a high long-term potential to produce even more AMD in the future.

The socioeconomic study showed that mining provided the major source of income. Over 45% of the households were partly or completely reliant on financial compensations as a result of mine closure. Unemployment was considered by the majority of the interviewed persons as the main cause of social problems in the area. The estimation of the explanatory factors by the logistic regression analysis revealed that education, household income, pollution conditions during the last years and familiarity with environmental problems were the main predictors influencing peoples’ opinion concerning whether the main river is strongly polluted. This model enabled one to predict correctly 77% of the observations reported. For the drinking water quality model, three predictors were relevant and they explained 66% of the observations.

Conclusions

Coupling the findings from the natural science and socioeconomic approaches, we may conclude that the impact of mining on the Certej River water is high, while drinking water in wells is not significantly affected. The perceptions of the respondents to pollution were to a large extent consistent with the measured results.

Recommendations and perspectives

The results of the study can be used by various stakeholders, mainly the mining company and local municipalities, in order to integrate them in their post-mining measures, thereby making them aware of the potential long-term impact of mining on the environment and on human health as well as on the local economy.

     

Integrated rice-fish culture: Coupled production saves resources

Rice is a key component in global food security, as it is the main ingredient in the daily diets of around 3 billion people, especially in Asia. Like all agricultural production, rice cultivation depends on scarce natural resources. This article briefly outlines the utilization of land and water in rice production, and suggests an approach for optimizing use efficiency, namely through the combination of rice and fish culture. The authors argue that the utilization of land and fresh water is optimized through integrated and complementary production of rice and fish — two basic foods items in daily local diets. The article reviews currently available scientific literature on integrated rice‐fish systems. Rice‐fish culture systems are briefly characterized, and respective yield potential and interactions between rice and fish are discussed. Results of socio‐economic surveys regarding the adoption of integrated rice‐fish culture are summarized. The article also reviews literature on the impact of fish culture on rice field ecology as outlined in studies on weed infestation, insect populations, and greenhouse gas emissions. The article concludes that rice‐fish culture can be an option to help rice producing countries keep pace with soaring domestic demand for food, especially fish. Integrated rice and fish culture optimizes the benefits of scarce land and water resources through complementary use, and exploits the synergies between fish and plant.     

Impact of Urban Sprawl on Water Quality in Eastern Massachusetts,USA

A study of water quality, land use, and population variations over the past three decades was conducted in eastern Massachusetts to examine the impact of urban sprawl on water quality using geographic information system and statistical analyses. Since 1970, eastern Massachusetts has experienced pronounced urban sprawl, which has a substantial impact on water quality. High spatial correlations are found between water quality indicators (especially specific conductance, dissolved ions, including Ca, Mg, Na, and Cl, and dissolved solid) and urban sprawl indicators. Urbanized watersheds with high population density, high percentage of developed land use, and low per capita developed land use tended to have high concentrations of water pollutants. The impact of urban sprawl also shows clear spatial difference between suburban areas and central cities: The central cities experienced lower increases over time in specific conductance concentration, compared to suburban and rural areas. The impact of urban sprawl on water quality is attributed to the combined effects of population and land-use change. Per capita developed land use is a very important indicator for studying the impact of urban sprawl and improving land use and watershed management, because inclusion of this indicator can better explain the temporal and spatial variations of more water quality parameters than using individual land use or/and population density.     

Streamflow Responses to Climate Change: Analysis of Hydrologic Indicators in a New York City Water Supply Watershed

Recent works have indicated that climate change in the northeastern United States is already being observed in the form of shorter winters, higher annual average air temperature, and more frequent extreme heat and precipitation events. These changes could have profound effects on aquatic ecosystems, and the implications of such changes are less understood. The objective of this study was to examine how future changes in precipitation and temperature translate into changes in streamflow using a physically based semidistributed model, and subsequently how changes in streamflow could potentially impact stream ecology. Streamflow parameters were examined in a New York City water supply watershed for changes from model‐simulated baseline conditions to future climate scenarios (2081‐2100) for ecologically relevant factors of streamflow using the Indicators of Hydrologic Alterations tool. Results indicate that earlier snowmelt and reduced snowpack advance the timing and increase the magnitude of discharge in the winter and early spring (November‐March) and greatly decrease monthly streamflow later in the spring in April. Both the rise and fall rates of the hydrograph will increase resulting in increased flashiness and flow reversals primarily due to increased pulses during winter seasons. These shifts in timing of peak flows, changes in seasonal flow regimes, and changes in the magnitudes of low flow can all influence aquatic organisms and have the potential to impact stream ecology.     

The effect of female arrivals on mate monopolization in the yellow dung fly

The degree of resource monopolization relates to the distribution of resources in space and time. In general, monopolization is predicted to be high when resources (food or mates) are clumped in space, dispersed in time, and predictable in space or time. Using the yellow dung fly, Scathophaga stercoraria (Diptera: Scathophagidae), we qualitatively tested a general model that predicts the distribution of mating success among competing males based on the temporal pattern of female arrivals relative to mating time and a ranking of males in priority of access to the resource (here by body size). In a laboratory experiment approximating the natural mating situation, a constant number of males of various sizes were allowed to compete for females. As predicted, mate monopolization decreased as the temporal clumping of female arrivals increased, mediated by either a decrease in the mean or an increase in the variance of female inter-arrival times, which were manipulated independently. Males appeared to adjust their behavior to variation in female arrivals in a manner consistent with the marginal value theory of Parker and associates: forcible take-overs of females were rarer, and copula durations shorter, when females arrived regularly at short intervals. Therefore, a complex interaction of variation in intrinsic characteristics affecting male resource holding potential, mating time and stochastic, extrinsic variables increasing temporal clumping of mates generally reduces the variance in mating success among competing males and thus ultimately the opportunity and intensity of sexual selection on traits influencing male success. This theory extends operational sex ratio theory at the mechanistic, behavioral level.     

Methane emissions and related physicochemical soil and water parameters in rice–fish systems in Bangladesh

Lowland rice fields constitute a semi aquatic environment, which is potentially suitable for fish production. Little is known about the effect of fish on greenhouse gas emissions from integrated rice–fish systems. An experiment was carried out at the Bangladesh Agricultural University to assess the effect of the stocking of fish on methane emissions from rice fields. Common carp, Cyprinus carpio L., and Nile Tilapia, Oreochromis niloticus (L.) were stocked in a mixed culture and subjected to three different input regimes: (1) urea fertilization according to the recommendation of the Bangladesh Rice Research Institute (BRRI), (2) supplementary feeding at 2 × maintenance level and (3) an elevated feeding schedule where 4 × maintenance level was fed initially and 2 × maintenance level towards the end of the growth period. Rice only with urea fertilization according to BRRI-recommendation was included as the control. The presence of fish increased methane emissions in all three rice–fish treatments. Average emission over the cropping season was 34, 37, and 32 mg m⁻² h⁻¹ in the rice–fish treatments, respectively, and 20 mg m⁻² h⁻¹ in rice only. Apart from an increase in methane emission, a significant drop (p < 0.05) in floodwater pH and dissolved oxygen concentration was observed in the rice–fish plots. Both parameters were the lowest in the treatment where a higher feeding rate was provided. Due to the fish activity, floodwater in the rice–fish treatments was more turbid, as reflected in higher particulate inorganic matter (PIOM). An elevated level of dissolved methane was observed in the floodwater of the feed supplemented rice–fish plots. Methane emissions showed negative correlation with morning and afternoon pH of the floodwater (r = −0.46; r = −0.56, p < 0.001) and morning and afternoon dissolved oxygen level (r = −0.53; r = −0.46, p < 0.001). Positive correlations were recorded between morning and afternoon floodwater temperature (r = 0.49; r = 0.44, p < 0.001) and with air temperature (r = 0.54, p < 0.001). The results suggest that the stocking of fish has an increasing effect on methane emissions from rice fields.     

Cropland patchiness strongest agricultural predictor of bird diversity for multiple guilds in landscapes of Ontario,Canada

The potential for agricultural landscapes to support biodiversity may vary greatly based on agricultural land use. Current knowledge suggests that agricultural composition and intensity are dominant drivers of biodiversity in agricultural landscapes, with variable effects of agricultural configuration and landscape diversity. The aim of this study was to determine the relative effects of agricultural composition, intensity, configuration, and landscape diversity on the species diversity of six distinct bird guilds on the landscape scale in a large and complex landscape in Ontario, Canada. We found that agricultural configuration, specifically patchiness of croplands, and to a lesser degree forage lands, was the strongest predictor of bird diversity for three of the six bird guilds considered (forest, shrubland, and town). The effects of increased cropland patchiness were variable, with forest and shrubland bird diversity increasing from small to moderate patchiness, and town bird diversity declining from moderate to high patchiness. Grassland birds, a group of considerable conservation concern, increased near linearly with increased agricultural land cover in the landscape, highlighting the need to consider agricultural lands in conservation planning for this species group. Woodland bird diversity declined significantly with all increasing measures of agricultural intensity, including the proportion of high-intensity agriculture and larger patches of agricultural land. Wetland birds were unique from the other guilds, showing primarily a strong association between diversity of land cover types and guild-level bird diversity. Surprisingly, increased cover of agricultural lands, which we predicted to be a dominant driver of guild-level bird diversity declines due to habitat loss, had weak, non-significant effects relative to the other land use variable being tested, except for the positive association with grassland birds. Our findings suggest that a mix of management strategies should be employed to consider the varying effects of agricultural lands on different bird guilds, such as the inclusion of agricultural land in conservation strategies for grassland species and further managing the configuration of agricultural lands to enhance biodiversity of agricultural landscapes.