Assessing the impact of inland navigation on the faecal pollution status of large rivers: A novel integrated field approach.

The contribution of ships to the microbial faecal pollution status of water bodies is largely unknown but frequently of human health concern. No methodology for a comprehensive and target-orientated system analysis was available so far. We developed a novel approach for integrated and multistage impact evaluation. The approach includes, i) theoretical faecal pollution source profiling (PSP, i.e., size and pollution capacity estimation from municipal vs. ship sewage disposal) for impact scenario estimation and hypothesis generation, ii) high-resolution field assessment of faecal pollution levels and chemo-physical water quality at the selected river reaches, using standardized faecal indicators (cultivation-based) and genetic microbial source tracking markers (qPCR-based), and iii) integrated statistical analyses of the observed faecal pollution and the number of ships assessed by satellite-based automated ship tracking (i.e., automated identification system, AIS) at local and regional scales. The new approach was realised at a 230 km long Danube River reach in Austria, enabling detailed understanding of the complex pollution characteristics (i.e., longitudinal/cross-sectional river and upstream/downstream docking area analysis). Faecal impact of navigation was demonstrated to be remarkably low at regional and local scale (despite a high local contamination capacity), indicating predominantly correct disposal practices during the investigated period. Nonetheless, faecal emissions were sensitively traceable, attributable to the ship category (discriminated types: cruise, passenger and freight ships) and individual vessels (docking time analysis) at one docking area by the link with AIS data. The new innovative and sensitive approach is transferrable to any water body worldwide with available ship-tracking data, supporting target-orientated monitoring and evidence-based management practices.

Significance testing of rank cross-correlations between autocorrelated time series with short-range dependence.

Statistical dependency measures such as Kendall's Tau or Spearman's Rho are frequently used to analyse the coherence between time series in environmental data analyses. Autocorrelation of the data can, however, result in spurious cross correlations if not accounted for. Here, we present the asymptotic distribution of the estimators of Spearman's Rho and Kendall's Tau, which can be used for statistical hypothesis testing of cross-correlations between autocorrelated observations. The results are derived using U-statistics under the assumption of absolutely regular (or ß-mixing) processes. These comprise many short-range dependent processes, such as ARMA-, GARCH- and some copula-based models relevant in the environmental sciences. We show that while the assumption of absolute regularity is required, the specific type of model does not have to be specified for the hypothesis test. Simulations show the improved performance of the modified hypothesis test for some common stochastic models and small to moderate sample sizes under autocorrelation. The methodology is applied to observed climatological time series of flood discharges and temperatures in Europe. While the standard test results in spurious correlations between floods and temperatures, this is not the case for the proposed test, which is more consistent with the literature on flood regime changes in Europe.

Shifts in flood generation processes exacerbate regional flood anomalies in Europe.

Anomalies in the frequency of river floods, i.e., flood-rich or -poor periods, cause biases in flood risk estimates and thus make climate adaptation measures less efficient. While observations have recently confirmed the presence of flood anomalies in Europe, their exact causes are not clear. Here we analyse streamflow and climate observations during 1960-2010 to show that shifts in flood generation processes contribute more to the occurrence of regional flood anomalies than changes in extreme rainfall. A shift from rain on dry soil to rain on wet soil events by 5% increased the frequency of flood-rich periods in the Atlantic region, and an opposite shift in the Mediterranean region increased the frequency of flood-poor periods, but will likely make singular extreme floods occur more often. Flood anomalies driven by changing flood generation processes in Europe may further intensify in a warming climate and should be considered in flood estimation and management.

Current European flood-rich period exceptional compared with past 500 years.

There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way1. Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe2. However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560-1580 (western and central Europe), 1760-1800 (most of Europe), 1840-1870 (western and southern Europe) and 1990-2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.

Detecting Flood-Rich and Flood-Poor Periods in Annual Peak Discharges Across Europe.

This paper proposes a method from Scan statistics for identifying flood-rich and flood-poor periods (i.e., anomalies) in flood discharge records. Exceedances of quantiles with 2-, 5-, and 10-year return periods are used to identify periods with unusually many (or few) threshold exceedances with respect to the reference condition of independent and identically distributed random variables. For the case of flood-rich periods, multiple window lengths are used in the identification process. The method is applied to 2,201 annual flood peak series in Europe between 1960 and 2010. Results indicate evidence for the existence of flood-rich and flood-poor periods, as about 2 to 3 times more anomalies are detected than what would be expected by chance. The frequency of the anomalies tends to decrease with an increasing threshold return period which is consistent with previous studies, but this may be partly related to the method and the record length of about 50 years. In the northwest of Europe, the frequency of stations with flood-rich periods tends to increase over time and the frequency of stations with flood-poor periods tends to decrease. In the east and south of Europe, the opposite is the case. There appears to exist a turning point around 1970 when the frequencies of anomalies start to change most clearly. This turning point occurs at the same time as a turning point of the North Atlantic Oscillation index. The method is also suitable for peak-over-threshold series and can be generalized to higher dimensions, such as space and space-time.

Changing climate both increases and decreases European river floods.

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere1. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe2. Any changes in river floods would have lasting implications for the design of flood protection measures and flood risk zoning. However, existing studies have been unable to identify a consistent continental-scale climatic-change signal in flood discharge observations in Europe3, because of the limited spatial coverage and number of hydrometric stations. Here we demonstrate clear regional patterns of both increases and decreases in observed river flood discharges in the past five decades in Europe, which are manifestations of a changing climate. Our results-arising from the most complete database of European flooding so far-suggest that: increasing autumn and winter rainfall has resulted in increasing floods in northwestern Europe; decreasing precipitation and increasing evaporation have led to decreasing floods in medium and large catchments in southern Europe; and decreasing snow cover and snowmelt, resulting from warmer temperatures, have led to decreasing floods in eastern Europe. Regional flood discharge trends in Europe range from an increase of about 11 per cent per decade to a decrease of 23 per cent. Notwithstanding the spatial and temporal heterogeneity of the observational record, the flood changes identified here are broadly consistent with climate model projections for the next century4,5, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management.

Causative classification of river flood events.

A wide variety of processes controls the time of occurrence, duration, extent, and severity of river floods. Classifying flood events by their causative processes may assist in enhancing the accuracy of local and regional flood frequency estimates and support the detection and interpretation of any changes in flood occurrence and magnitudes. This paper provides a critical review of existing causative classifications of instrumental and preinstrumental series of flood events, discusses their validity and applications, and identifies opportunities for moving toward more comprehensive approaches. So far no unified definition of causative mechanisms of flood events exists. Existing frameworks for classification of instrumental and preinstrumental series of flood events adopt different perspectives: hydroclimatic (large-scale circulation patterns and atmospheric state at the time of the event), hydrological (catchment scale precipitation patterns and antecedent catchment state), and hydrograph-based (indirectly considering generating mechanisms through their effects on hydrograph characteristics). All of these approaches intend to capture the flood generating mechanisms and are useful for characterizing the flood processes at various spatial and temporal scales. However, uncertainty analyses with respect to indicators, classification methods, and data to assess the robustness of the classification are rarely performed which limits the transferability across different geographic regions. It is argued that more rigorous testing is needed. There are opportunities for extending classification methods to include indicators of space-time dynamics of rainfall, antecedent wetness, and routing effects, which will make the classification schemes even more useful for understanding and estimating floods. This article is categorized under:Science of Water > Water ExtremesScience of Water > Hydrological ProcessesScience of Water > Methods.

The synthesis of planar chiral pseudo-gem aminophosphine pre-ligands based on [2.2]paracyclophane.

The synthesis of three planar chiral pseudo-gem disubstituted [2.2]paracyclophane-derived P,N-pre-ligands is reported along with preliminary results of their activity in the amination of aryl bromides and chlorides. The pseudo-gem aminophosphines were capable of mediating the coupling reaction at a loading of 1 mol%.

The synthesis of substituted amino[2.2]paracyclophanes.

Two methodologies for the formation of substituted amino[2.2]paracyclophane derivatives were developed. The first involves the direct amination of bromo[2.2]paracyclophanes with sodium azide. This permits the synthesis of simple mono- and disubstituted derivatives but fails to give sterically congested pseudo-gem derivatives. A 'one-pot' oxidation-Lossen rearrangement of [2.2]paracyclophane oximes provides access to a range of amino[2.2]paracyclophanes including the most efficient synthesis of the pseudo-gem planar chiral amino acid yet reported.

A general thermolabile protecting group strategy for organocatalytic metal-organic frameworks.

We present a general strategy for incorporating organocatalytic moieties into metal-organic frameworks (MOFs). The organocatalytic units are protected by a thermolabile protecting group during MOF synthesis and then unveiled by a simple postsynthetic heating step. The strategy is exemplified using a thermolabile tert-butoxycarbonyl (Boc) protecting group for a proline moiety, the removal of which endows the resulting cubic zinc(II) IRMOF with catalytic activity for asymmetric aldol reactions. The bulky Boc groups also prevent framework interpenetration, producing open MOFs that can admit relatively large substrates.

Surface-active fungicidal D-peptide inhibitors of the plasma membrane proton pump that block azole resistance.

A 1.8-million-member D-octapeptide combinatorial library was constructed in which each member comprised a diversity-containing N-terminal pentapeptide and a C-terminal amidated triarginine motif. The C-terminal motif concentrated the library members at the fungal cell surface. A primary screen for inhibitors of Saccharomyces cerevisiae and Candida albicans growth, together with an in vitro secondary screen with the S. cerevisiae plasma membrane ATPase (Pma1p) as a target, identified the antifungal D-octapeptide BM0 (D-NH(2)-RFWWFRRR-CONH(2)). Optimization of BM0 led to the construction of BM2 (D-NH(2)-RRRFWWFRRR-CONH(2)), which had broad-spectrum fungicidal activity against S. cerevisiae, Candida species, and Cryptococcus neoformans; bound strongly to the surfaces of fungal cells; inhibited the physiological activity of Pma1p; and appeared to target Pma1p, with 50% inhibitory concentrations in the range of 0.5 to 2.5 microM. At sub-MICs (<5 microM), BM2 chemosensitized to fluconazole (FLC) S. cerevisiae strains functionally hyperexpressing fungal lanosterol 14alpha-demethylase and resistance-conferring transporters of azole drugs. BM2 chemosensitized to FLC some FLC-resistant clinical isolates of C. albicans and C. dubliniensis and chemosensitized to itraconazole clinical isolates of C. krusei that are intrinsically resistant to FLC. The growth-inhibitory concentrations of BM2 did not cause fungal cell permeabilization, significant hemolysis of red blood cells, or the death of cultured HEp-2 epithelial cells. BM2 represents a novel class of broad-spectrum, surface-active, Pma1p-targeting fungicides which increases the potencies of azole drugs and circumvents azole resistance.