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In this article, numerical experiments are performed to investigate the effects of increasing atmospheric moisture on the precipitation depth (PD) produced by Hurricane Ivan (2004) over a target area, chosen as the drainage basin of the city of Asheville, NC. Atmospheric moisture was increased indirectly by increasing the sea surface temperature (SST) in the simulation initial conditions, and by letting the regional atmospheric model adjust the atmospheric fields to the SST perturbation. The SST was increased in two ways: 1) using spatially constant increments and 2) using a climate change perturbation field obtained from a climate projection. For each SST scenario, the PD over the target area was maximized by using a physically based storm transposition method. Although the mean PD, that was obtained by averaging over all shifting increments, increased with SST, the maximum PD was obtained for the case of no SST increase. It was found that, in the case of no SST increase, the worst-case tropical cyclone track was significantly different than in the SST increase scenarios. In particular, in this case, the storm spent a longer time in the simulation inner domain, thus spawning a larger PD over the target area.

Urbanization can dramatically alter stormwater, both the quantity and quality, by engendering larger peak flows and through the introduction of contaminants into runoff. The current study builds on previous research that developed relationships between a suite of nonpoint source contaminants, known as trace organic contaminants (TOrCs), and hydrologic measurements for a series of storms (one site had 15 storms and the other had 19 storms) in Madison, WI, by creating statistical and deterministic models. Correlations and regressions were calculated between TOrC loads and hydrologic measurements for a series of storms for both a commercial site and a high-density residential site. From the regressions, it became evident that loading responses to precipitation were not the same between the two land covers for some TOrCs, indicating varying load responses for TOrCs depending on land cover. The regressions were utilized in the Source Loading and Management Model for Windows (WinSLAMM), an event-based hydrologic and water-quality model, to demonstrate that it can be used to model novel contaminants. The regressions were also used to estimate mean annual loads of TOrCs from all commercial and high-density residential areas in Madison, WI, for the watersheds to which Madison discharges its stormwater. The mean annual loads varied between grams per year to tens of thousands of grams per year depending on the TOrC and watershed. This work will ultimately allow managers to simulate the presence of, establish total maximum daily loads for, and mitigate the loads of TOrCs through stormwater best management practices.

Tropical cyclones (TCs) are intense atmospheric vortices that form over the warm tropical oceans. They are recognized for their ability to generate intense precipitation that may in turn create disastrous floods. This article first assesses the suitability of a regional atmospheric model, the Weather Research and Forecasting (WRF) model, to simulate the intense precipitation depth (PD) fields of six North Atlantic TCs that affected the eastern United States during 2002–2016. Due to the strong nonlinearity involved in tropical cyclones' dynamics and thermodynamics, which causes tropical cyclones' tracks to be very sensitive to the different modeling choices, placing the PD fields in the observed locations was challenging. This involved trying several simulation start dates and combinations of the WRF model's parameterization schemes for each storm simulated. Model performance was evaluated by comparing the simulated PD fields with the observed PD fields obtained from the NCEP Stage IV precipitation dataset. In addition to qualitative comparisons, three quantitative metrics were used to quantify the WRF model performance in simulating a PD field's location, structure and intensity. The sensitivity of the simulation results to the choice of the parameterization schemes was then illustrated using Hurricane Gustav (2008). Eventually, the most satisfactory simulations were used to investigate the mechanisms responsible for the generation of intense precipitation in these TCs. More specifically, the vertically integrated vapor transport field and its divergence were calculated using the model outputs, and it was found that horizontal moisture convergence played a central role in the generation of intense precipitation in these TCs.

Changing weather patterns, droughts and competing water demands are dramatically altering the landscape and creating conditions conducive to the production of wind-blown dust and dust storms. In California, such factors are leading to the rapid shrinking of the Salton Sea, a 345 mile2 land-locked “sea” situated near the southeastern rural border region known as the Imperial Valley. The region is anticipated to experience a dramatic increase in wind-blown dust and existing studies suggest a significant impact on the health and quality of life for nearby residents of this predominantly low-income, Mexican-American community. The discussion calls attention to the public health dimensions of the Salton Sea crisis. We know little about the possible long-term health effects of exposure to mobilized lakebed sediments or the numerous toxic contaminants that may become respirable on entrained particles. We draw on existing epidemiological literature of other known sources of wind-blown dust, such as desert dust storms, and related health effects to begin to understand the potential public health impact of wind-blown dust exposure. The increased production of wind-blown dust and environmental exposures to such non-combustion related sources of particulate matter are a growing health threat, due in part to drought coupled with increasing pressures on limited water resources. Recent population-based studies have linked dust storms with cardiovascular mortality, asthma hospitalization and decrease in pulmonary function in both adults and children. A growing number of studies provide evidence of the acute health effects of wind-blown dust exposures among children, which with repeated insults have the potential to influence respiratory health over time. The shrinking of the Salton Sea illustrates a public health and environmental justice crisis that requires action and attention to protect the health and well-being of local communities.

Per- and polyfluoroalkyl substances (PFAS) are presently essential ingredients in aqueous film forming foam (AFFF) used for fire-fighting, but are also pervasive environmental contaminants. The use and subsequent release and transport of AFFF in the ocean environment from marine vessels has not been studied to date. A numerical model (Delft3D) was rigorously calibrated and validated for the hydrodynamics, and used to predict the transport of PFAS released instantaneously into a large harbour (Halifax Harbour, Nova Scotia) that is representative of coastal environments in eastern Canada and other parts of the world. The numerical model results indicate that PFAS released in the presence of strong winds and waves during a storm will travel up to 31 km in 2 days, approximately 40% farther than PFAS release during a time period dominated by tidal currents with light winds and small waves (1 m). After a 10 day simulation, PFAS levels from release sites in the Inner Harbour were higher (40-60 μg/L) compared to PFAS levels from the Outer Harbour release site which had decreased to low levels (1 μg/L) during a non-storm period. Along shorelines within the Harbour, PFAS concentrations remained elevated after 12 h (40-500 μg/L) and 48 h (2-300 μg/L). These concentrations are within the range of PFAS guidance values for recreational water use. The methods described here are relevant to studies of PFAS dispersion and transport in other coastal areas, and could be used to determine best practices for applications of AFFF in the coastal environment.

China has a long history of building hard engineered coastal defences for storm protection, which enables us to examine the economic effects of the hard engineering to mitigate storm damage. Examining historical storm impacts between 1989 and 2016, a significant negative relationship exists between the relative economic damages (i.e., TD/GDP) by storm and the length of existing hard engineering within the storm swath. This indicates that hard engineered defences play a critical role in storm mitigation. We estimated that the storm protection value provided by hard engineered defences in China is CNY 3.18 million/km [US$0.50 million/km] on average, with a median of CNY 1.69 million/km [US $0.27 million]. They provide an annual economic value of CNY 6.04 billion on average. Despite their great contribution to reduce total economic damages from storms, hard engineered defences are not as efficient as coastal wetlands. Coastal wetlands are more cost effective based on comparison from China and USA. This study highlights the need for the Chinese government to transfer focus from prevailing hard engineered defences to ecosystem-based measure or the combination of both measures to prevent storm damage in the future.

Storms impact coastal areas often causing damages and losses at occupied areas. On a scenario of increasing human occupation at coastal zones and under climate change conditions (including sea level rise and increasing frequency of extreme sea levels), the consequences of storms arc expected to be amplified if no adaptation or further management actions are implemented. The selection of the best possible coastal management measures, considering both costs and effectiveness, will be mandatory in the future, in order to optimise resources. This work analyses the performance of risk reduction measures (beach nourishment and receptors - house and infrastructures - removal), using a decision support system comprised by a morphodynamic numerical model (XBeach) and a Bayesian network based on the source-pathway-receptor concept. The effectiveness of the risk reduction measures is then assessed by a simple index expressing the consequences to the receptors. The approach was tested at Faro Beach by evaluating its performance for a particular storm, Emma (Feb/March 2018), which fiercely impacted the southern coast of Portugal. The output results from the modelling were compared to field observations of the actual damages caused by the storm. The combined use of both measures or the solely use of the nourishment would avoid almost all observed impacts from this storm. The work is pioneer on demonstrating the use of a decision support system for coastal regions validated against observed impacts for a high-energy storm event. The methodology and the proposed index arc adaptable to any sandy coastal region and can be used to test (and improve) management options at a broad number of coastal areas worldwide, minimizing implementation costs and reducing the risk to the occupation and to the people. (C) 2018 Elsevier B.V. All rights reserved. FCT Investigator program [IF/01047/2014] European Union 7th Framework ProgrammeEuropean Union (EU) [603458] project EVREST [PTDC/MAR-EST/1031/2014] project EW-COAST [G-LISBOA-01-145-FEDER-028657] Portuguese Science and Technology Foundation (FCT)Portuguese Foundation for Science and Technology [UID/MAR/00350/2013] research group RNM-328 of the Andalusian Research Plan (PAI) info:eu-repo/semantics/publishedVersion

There are very few reports about the effect of PM2.5 particles carried by the Middle East dust storms on lung cells. This study aimed to investigate the chemical properties and in-vitro cytotoxic effects of PM2.5 extracts. Water-soluble fraction and organic solvent-extractable components of the samples collected from the city of Ahvaz, Khuzestan Province, Iran, during the normal and dust storm days of the winter of 2016 were analyzed and then applied on the human lung epithelial cell line (A549). The chemical properties and the cytotoxicity were analyzed by ICP-OES and Lactase Dehydrogenase (LDH) assay, respectively. The results of the independent t-test showed significantly higher mean cytotoxicity in the samples of normal days than that of dust storm days. It could be due to the fact that the cells were exposed to the same amount of water-soluble extract, whether it be from a normal day or a dust storm day, and since the normal air of Ahvaz is severely affected by traffic and industrial pollutants, its normal day samples showed stronger cytotoxic effect. The results of the Kruskal-Wallis test showed that cytotoxic effect increased with the particulate concentration. The highest cytotoxicity levels observed at 62, 125, and 250 μg/mL concentrations after 24-h incubation were 17% (belonging to a dust storm day), 37% (belonging to a normal day), and 47% (belonging to a dust storm day), respectively Since PAH compounds were measured in the particulate phase, their amount was naturally correlated with the quantity of particulates. However, it was observed that the samples of normal days contained the species with stronger human carcinogens ΣPAHs = 0.82 ng/m3.The results of one-way ANOVA showed a significant difference between the incubation times regarding the resulted cytotoxicity levels. In general, as the incubation duration increased, so did the cytotoxicity level. Although normal day particulates had a greater cytotoxic effect on A549 cell line, dust storm days are associated with higher levels of health risk; simply because during dust storms, people inhale much larger amounts of particulates.

Anthropogenic activities have caused N saturation in many terrestrial ecosystems. The transfer of nutrients and sediments to freshwater environments has resulted in water quality impairments including eutrophication, increased turbidity, ecosystem acidification, and loss of biodiversity. Storm events account for the transport of a large proportion of nutrients and sediments found in watersheds on an annual basis. To implement effective water-quality management strategies, the importance of surface and subsurface flow paths during storm events and low flow conditions need to be quantified. The increased availability of optical in-situ sensors makes high-frequency monitoring of catchment fluxes practical. In this study, we present a high-resolution nitrate monitoring record over a 10-year period in the Neuse River Basin near Clayton, North Carolina. The relationship between discharge and nitrate concentration for 365 storm events are categorized into hysteresis classes that indicate different transport mechanisms into the river. Storm events over the entire period of this study are divided between clockwise, counter-clockwise, and complex hysteresis patterns, indicating multiple nitrate flow paths during different seasons and years. Logistic regression of a suite of environmental variables demonstrates that antecedent soil moisture is a significant factor in determining the storm hysteresis class, with the odds of counter-clockwise hysteresis increasing by 10.3% for every 1 percentage point increase in the soil moisture. There is also an overlying seasonal effect, which indicates that dry soil conditions and frequent small storms during summer leads to greater nitrate transport on the rising limb, in contrast to slower, groundwater-driven inputs during the rest of the year.

The aim of this paper is to better understand the functioning of the River Selle (northern France) during dry weather and storm events, to assess the impact of a town on the surface water quality and to suggest qualitative assumptions on the vulnerability of water quality to weather conditions. Two high-frequency monitoring stations covering the Cateau-Cambrésis town were deployed during 4 months in 2016. River flow, water temperature, pH, dissolved oxygen, turbidity, conductivity, total organic carbon, nitrates and phosphates were monitored every 10 min. The water supply of the River Selle is mainly dominated by groundwater as shown by the behaviour of the river flow, the water temperature and the nitrate concentrations in both surface water and groundwater. The reference station located at the upstream of the river (Saint Souplet) exhibits low anthropogenic pressure during dry weather but is significantly impacted during storm events. At the downstream of the Cateau-Cambrésis town, the water quality is severely impacted by phosphates during dry weather mainly due to wastewater inputs into the river. An additional load of pollution is highlighted during storm events. According to our results, the water quality of the River Selle would degrade if actions to reduce dry-weather and storm events pollution sources are not undertaken rapidly. Moreover, nutrients, particularly phosphates, are clearly in excess in this system. Efforts to combat soil leaching and the revision of sewage systems and urban wastewater treatment in the catchment are two key points to tackle. Finally, this study shows the importance of understanding the current behaviour of a given river towards dry weather and storm events before suggesting local scenarios of the impact of climate change on surface water quality.

This study evaluates the performance of a suite of stormwater green infrastructure (GI) practices at the Belknap Campus, University of Louisville. In lack of instrumentation within individual GIs, and detailed drainage and sewer information, data mining procedures and artificial neural networks (ANN) were used. Two separate Back Propagation Neural Network Models (BPNNMs) were developed to estimate the reductions of flow volume and peak flow rates within the combined sewer system. The results from developed BPNNMs showed that following the construction of stormwater GIs at the Belknap campus, downstream wet-weather related flow decreased. The developed BPNNMs showed that the flow volume reduction and the peak flow attenuation rates had averages of approximately 33% and 61% per storm event, respectively. The flow reduction rates generally were lower for larger storms. Similarly, the peak flow rates decreased by increase of maximum intensity values per storm. However, further analysis indicated that even for large storm events, with long durations, the GIs had a positive impact on mitigation of combined sewer flows. Additionally, using rainfall data and downstream sewer flow in conjunction with artificial neural network modeling, was determined to be an effective technique for evaluating the combined hydrological performance of a suite of stormwater GIs.

In some cold regions up to 97% of the chloride (Cl-) entering rivers and lakes is derived from road salts that are applied to impervious surfaces to maintain safe winter travel conditions. While a portion of the Cl- applied as road salt is quickly flushed into streams during melt events via overland flow and flow through storm sewer pipes, the remainder enters the subsurface. Previous studies of individual watersheds have shown that between 28 and 77% of the applied Cl- is retained on an annual basis, however a systematic evaluation of the spatial variability in Cl- retention and potential driving factors has not been carried out. Here we used a mass balance approach to estimate annual Cl- retention in 11 watersheds located in southern Ontario, Canada, which span a gradient of urbanization. We evaluated the influence of multiple landscape variables on the magnitude of Cl- retention as well as the long-term rate of change in stream Cl-concentration for the same systems. We found that mean annual Cl- retention ranged from 40 to 90% and was higher for less urbanized watersheds and for watersheds with urban areas located farther from the stream outlet. This result suggests that less urbanized watersheds and ones with longer flow pathways have more Cl- partitioned into storage and hence the potential for legacy Cl- effects on aquatic organisms. While we did measure statistically significant increasing trends in stream Cl- concentration in some watersheds, there was no consistent relationship between the long-term rate of change in stream Cl- concentrations and patterns of urbanization and the magnitude of Cl- retention. Based on our results we present a detailed conceptual model of watershed Cl- dynamics that can be used to guide future research into the mechanisms of Cl- retention and release within a watershed.

Smoggiest days like heavy rainfall, tornadic and hail storms are considered as weather extremes. The method of anomaly-based meteorological variable analysis has been recently used to analyze and predict weather extremes. Thus, in this study, the same method was also applied to analyze ten severe haze episodes with PM2.5 exceeding 300 micrograms per cubic metre (μg/m3) for >24 h occurred during 2015–2016 in Beijing or North China. The anomalous spatial features of tropospheric meteorological variables show that the haze intensity indicated by PM2.5 concentration is strengthened gradually following the five factors of (1) an anomalous temperature inversion in the lower troposphere, (2) negative geopotential anomaly near the surface, (3) positive geopotential anomaly at the upper troposphere, (4) southwesterly wind anomaly and (5) positive anomaly of specific humidity in the lower troposphere. The correlation coefficient between the geopotential anomaly factor at the upper troposphere and PM2.5 concentration at Beijing is 0.56 reaching the level of 95% confidence in December 2016. Forecast evaluation analyses reveal that the European Centre for Medium-Range Weather Forecasts (ECMWF) model is able to predict most anomalous temperature-pressure structures related to haze episodes and to indicate haze intensities for leading about one week.

Accidental leakage of radionuclides from the Fukushima Nuclear Power Plant (FNPP1) took place in the aftermath of the catastrophic tsunamis associated with the Great East Japan Earthquake that occurred on March 11, 2011. Significant amount of radionuclides released into the atmosphere were reportedly transported and deposited on land located near FNPP1. The Niida River, Fukushima, Japan, has been recognized as a terrestrial source of highly contaminated suspended radiocesium adhering to sediment particles in the ocean through the river mouth as a result of hydrological processes. Remaining scientific questions include the oceanic dispersal and inventories of the sediments and suspended radiocesium in the ocean floor derived from the Niida River. Complementing limited in situ data, we developed a quadruple nested 3D ocean circulation and sediment transport model in an extremely high-resolution configuration to quantify the transport processes of the suspended radiocesium. Particularly, we investigated the storm and subsequent floods associated with Typhoon 201326 (Wipha) that passed off the Fukushima coast in October 2013, and subsequently promoted precipitation to a considerable extent and associated riverine freshwater discharge along with sediment outfluxes to the ocean. Using in situ bed sediment core data obtained from regions near the river mouth, we conducted a quantitative assessment of the accumulation and erosion of the sediments and explored the resultant suspended radiocesium distribution around the river mouth and nearshore areas along the Fukushima coast. We identified three major accumulative areas, near the river mouth within an area

Microplastics (MP) are a commonly reported pollutant in the freshwater, marine, and soil environment. Few studies to date have reported MP concentrations and polymer types observed in stormwater, particularly not for catchments with separate storm sewers. The objectives of this study were to determine the microplastic concentration, polymer fingerprints, and the inter-storm variation of MP in two stormwater outfalls and a bioretention basin. Composite stormwater samples were collected at each site across three rain events each in catchments with urban and suburban land use. Particles 250 to 2000 μm were collected, separated into two sizes classes, treated with a wet peroxide oxidation, density separated with NaCl, and buoyant particles (fragments, films, and spheres) were collected for analysis with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Significant differences were observed in the total polymer concentrations and profiles between the sampling sites, potentially due to differences in land use within the catchments sampled, but not between size classes. The highest MP concentrations were observed in samples from the bioretention basin compared to the stormwater outfalls sampled, indicating the potential for green infrastructure to capture MP in the size range studied here. A weak but significant negative correlation was observed between cumulative rainfall (1.5 to 4.5 cm) and MP concentrations but no correlation was observed between antecedent dry days and MP concentrations. These data represent a conservative measure of MP concentrations given that fibers, particles250 μm, and non-buoyant particles (i.e., density 1.2 g/mL) were not targeted, but all targeted particles were analyzed with ATR-FTIR. Overall, these results presented provide insight into the loading and character (size, morphology, polymer type) of buoyant MP particles in stormwater that may be useful in designing mitigation strategies.

Concentrated animal feeding operations (CAFOs) pose wide ranging environmental risks to many parts of the US and across the globe, but datasets for CAFO risk assessments are not readily available. Within the United States, some of the greatest concentrations of CAFOs occur in North Carolina. It is also one of the only states with publicly accessible location data for classes of CAFOs that are required to obtain water quality permits from the U.S. Environmental Protection Agency (EPA); however, there are no public data sources for the large number of CAFOs that do not require EPA water quality permits. We combined public records of CAFO locations with data collected in North Carolina by the Waterkeeper and Riverkeeper Alliances to examine the distribution of both permitted and non-permitted CAFOs across the state. Over half (55%) of the state's 6646 CAFOs are located in the Coastal Plain, a low-lying region vulnerable to flooding associated with regular cyclonic and convective storms. We identified 19% of CAFOs ≤ 100 m of the nearest stream, and some as close as 15 m to the nearest stream, a common riparian buffer width for water quality management. Future climate scenarios suggest large storm events are expected to become increasingly extreme, and dry interstorm periods could lengthen. Such extremes could exacerbate the environmental impacts of CAFOs. Understanding the potential impacts of CAFO agroecosystems will require remote sensing to identify CAFOs, fieldwork to determine the extent of environmental footprints, and modeling to identify thresholds that determine environmental risk under changing conditions.

Climate change is likely to increase the frequency and intensity of tropical storms. However, the impacts of major storms on nutrient cycling processes in the river-estuary-coast continuum are poorly understood. Continuous observations were made at lower river stations and on a transect down the Jiulong River Estuary in south east China for three storms in 2013–2014. There were major increases in both dissolved nutrients and suspended particulate matter (SPM) brought down the river during storms. Strong Estuarine Turbidity Maxima (ETM) were observed during major storms and were the result of SPM brought down rivers augmented by sediment scoured within the Upper Estuary (salinity = 0 psu) and possibly also from behind the dikes opened for flood control. There were major increases in dissolved nutrients (nitrate, ammonium and phosphate) in the Upper Estuary particularly during major Storms C (July 2013) and D (May 2014). These increases were probably due to river inflows with surrounding runoff, pore water supply and nutrients desorbed from scoured sediment. During major Storm D there were greater nutrient fluxes through the estuary-coast interface compared to the nutrients supplied through the river-estuary interface while the opposite pattern was observed during normal flow. The increased supply of ammonium and phosphate to the coastal region caused increased chlorophyll a once the light inhibiting SPM had been removed from the water column. This is likely to increase the potential of eutrophication. Storm induced increases in N:P:Si supplied from the estuary to the coastal region increased the degree of P limitation.

Low frequency, high magnitude storm events can dramatically alter coastlines, helping to relocate large volumes of sediments and changing the configuration of landforms. Increases in the number of intense cyclones occurring in the Northern Hemisphere since the 1970s is evident with more northward tracking patterns developing. This brings added potential risk to coastal environments and infrastructure in northwest Europe and therefore understanding how these high-energy storms impact sandy coasts in particular is important for future management. This study highlights the evolution of Storm (formally Hurricane) Ophelia in October 2017 as it passed up and along the western seaboard of Ireland. The largest ever recorded Hurricane to form in the eastern Atlantic, we describe, using a range of environmental measurements and wave modelling, its track and intensity over its duration whilst over Ireland. The impact on a stretch of sandy coast in NW Ireland during Storm Ophelia, when the winds were at their peak, is examined using terrestrial laser scanning surveys pre- and post-storm to describe local changes of intertidal and dune edge dynamics. During maximum wind conditions (>35 knots) waves no >2 m were recorded with an oblique to parallel orientation and coincident with medium to low tide (around 0.8 m). Therefore, we demonstrate that anticipated widespread coastal erosion and damage may not always unfold as predicted. In fact, around 6000 m3 of net erosion occurred along the 420 m stretch of coastline with maximum differences in beach topographic changes of 0.8 m. The majority of the sediment redistribution occurred within the intertidal and lower beach zone with some limited dune trimming in the southern section (10% of the total erosion). Asynchronous high water (tide levels), localised offshore winds as well as coastline orientation relative to the storm winds and waves plays a significant role in reducing coastal erosional impact.

Background There is little work in assessing the impact of storm events combined with power outage (PO). In this study, we evaluated the individual and synergistic impacts of wind events and PO on overall and subtypes of injuries in New York State (NYS) and by demographics. Methods The emergency department (ED) visit data were obtained from the NYS Department of Health from November–April 2005–2013 to identify injury cases, length of stay and care costs. Wind event was defined according to high wind, strong wind or thunderstorm wind defined by NOAA. PO occurrence was defined when PO coverage exceeded the 50th percentile of its distribution. By comparing non-event days, we used distributed lag nonlinear models to evaluate the impacts of wind events, PO, and their combined effect on injuries during the cold season over a 0-3-day lag period, while controlling for time-varying confounders. The differences in critical care indicators between event and non-event days were also evaluated. Results Overall injuries ED visits (16,628,812) significantly increased during the wind events (highest Risk Ratio (RR): 1.05; 95% CI: 1.02–1.08), and were highest when wind events cooccurred with PO (highest RR: 1.14; 95% CI: 1.10–1.18), but not during PO alone (RR: 1.00; 95%CI: 0.96–1.04). The increase was also observed with all subgroups through Day 2 after the event. Greater risks exist for older adults (≥65 years) and those on Medicaid. After the joint occurrences of wind events and PO, average visits are 0.2 days longer, and cost 13% more, compared to no wind/no PO days. Conclusion There is a significant increase in ED visits, length of stay and cost of injuries during wind events, especially when they coupled with PO and especially among older cases and Medicaid holders. Our findings may be used for planning disaster preparedness and recovery efforts.

Seasonal rainfall events reinforce the link between terrestrial and fluvial domains and are crucial for assessing hydrological control over riverine nutrient dynamics and pollutant source behaviors, especially in a semi-arid watershed. Taking the Qingshuihe river basin, a semi-arid mountainous basin in China, as an example, this paper investigated storm effects on riverine nitrogen (N) and phosphorus (P) dynamics (i.e. concentration, load, and composition changes) through continuous sampling of four storm events of the 2019 rainy season, including one small storm, two moderate storms, and a large storm. Pollutant sources and transport pathways were then examined over the storm sequence via hysteresis analysis. The results revealed a strong linkage between N/P dynamics and hydrological processes. Storm runoff caused a 6-fold increase in particulate-P (PP) and a 4-fold increase in ammonia-N (NH4-N) fluxes through four storms (most sensitive nutrients to storms). On average, PP shared 86% of P exports, and nitrate-N (NO3-N) contributed 79% of N exports. PP and NH4-N were delivered primarily from overland sources and transported by surface runoff. Nonetheless, mobilization of channel sediment reserves was also an important way of PP supply during storms. The results suggested groundwater as the principal NO3-N source in the watershed, and subsurface flow was important for NO3-N and total dissolved-P (TDP) delivery during storms. The large storm (>20 mm) often registered the highest N/P load exports. However, there were other influencing factors/processes on stormflow N/P dynamics in the semi-arid watershed, which complicate/override the effects of different storm magnitudes. Total suspended solids (TSS)/PP source availability and inter- and intra-storm export trends influenced P behaviors through storms. Moreover, impacts of mobilization processes on NO3-N behavior appeared over the storm sequence. These findings enhance our understanding of storm events induced N/P exports in water-scarce regions and provide references for water quality predictions and control in flood seasons.

On September 14, 2018, Hurricane Florence delivered ~686 mm rainfall to a 106 km2 watershed in coastal North Carolina, USA. A forested land treatment site comprises one third of the watershed wherein municipal wastewater effluent is spray-irrigated onto 8.9 km2 of forest. This communication provides insight for land treatment function under excess water duress as well as changes in organic chemical composition in on- and off-site waters before (June 2018) and after (September & December 2018) Hurricane Florence's landfall. We compare the numbers and relative abundances of chemical features detected using suspect screening high resolution mass spectrometry in waste-, ground-, and surface water samples. Values for upstream and receiving waters in September were lower than for sampling events in June and December, indicating an expected dilution effect across the watershed. Chemical diversity was greatest for all surface water samples in December, but only upstream surface water showed a dramatic five-fold increase in relative chemical abundance. Chemical abundance in on-site water and downstream surface water was equal to or lower than the September storm dilution effect. These data suggest that the land treatment system is functionally and hydrologically robust to extreme storm events and contributed to dilution of upstream chemical reservoirs for downstream receiving waters for months after the storm. Similar systems may embody one water reuse strategy robust to the increasing occurrence of extreme precipitation events.

Low-frequency high-magnitude storms can flush disproportionate amounts of terrigenous dissolved organic carbon (DOC) and particulate organic carbon (POC) into rivers during a short period. However, previous studies focused on the impacts of storms on organic carbon transport in headwater streams that are minimally influenced by human activities and are far from lakes. To better estimate the lake carbon budget and manage lake water environments, we need to understand the transport of storm-induced organic carbon into lakes by eutrophic rivers. Based on daily and hourly time-series monitoring data, this paper systematically studied the influences of storm precipitation on DOC and POC transport in the eutrophic Tiaoxi River entering Lake Taihu, the 3rd largest freshwater lake in China. The results showed that seven storms transported 59% of the annual total organic carbon into Lake Taihu in 2019, and all storms resulted in transport peaks. During the storm period on August 9-16, 2019, DOC was negatively related to the water level (r = -0.44, p0.05), but POC responded positively (r = 0.52, p0.05); allochthonous organic carbon contents were elevated, but the autochthonous components were diluted. Moreover, the storm-induced input of riverine organic carbon influenced the lake water environment across a large region, and the impacts lasted more than 10 days. These findings have important implications for accurately estimating riverine organic carbon fluxes into lakes and making better-informed decisions about when to pump drinking water from lakes.

7 p., In several countries, hail is considered as the most harmful climatic phenomenon from an agricultural perspective. The surroundings of the Gallocanta Lake (North-East Spain), is one of the areas where the storms affecting the Ebro Valley are formed. For this reason, silver iodide from hail suppression systems has been emitted to the atmosphere for half a century. Nowadays, there is an increasing social concern about the potential environmental consequences of this activity, which has promoted the analysis of the influence of hail suppression systems regarding the amount of silver concentration in the ecosystem. This study focuses on silver atmospheric deposition and its accumulation in soils. To this end, silver concentrations in rainfall (5 gauges, 16 samples per site, from April 2017 to March 2019) and soils (72 samples) distributed across the hail suppression network managed by the Anti-hail Consortium of Aragón, were analysed. The results show that the amount of silver is much higher in rainfall gauges and soils close to ground-based silver iodide generators (85 μg/m2·day and 10 mg/kg soil, respectively), but concentrations considerably decrease when samples are collected far from them (downing to 0.3 μg/m2·day and 0.1 mg/kg soil). Apart from the samples obtained nearby silver iodide generators, most of the other soil samples display silver concentrations below the legal threshold established for the most vulnerable activities (1 mg/kg soil in agricultural and forestry land uses). Nevertheless, silver content, both in precipitation and in soils, is higher in regions where hail suppression has been developed for decades when compared to nearby areas in which silver iodide emissions did not occur. Silver content observed in soils is not high, but their cumulative effect in sediments and biota should be analysed, which is the aim of the second part of the present study., Unidad de Zaragoza, Instituto Geologico y Minero de España, España, Agencia Aragonesa para la Investigación y el Desarrollo, España, Instituto Pirenaico de Ecología, España, Unidad de Tres Cantos, Instituto Geológico y Minero de España, España

The Tibetan Plateau (TP) plays important roles in global climate and environment. This study combines in-situ BC measurements in the Himalayas and the Indo-Gangetic Plain (IGP) with a regional dynamical and chemical model (WRF-Chem model) to investigate the effect of the trans-Himalayas on black carbon (BC) from the IGP to the TP during Indian summer monsoon. To determine topographic effects of the trans-Himalayas on BC concentrations over the TP, sensitive experiments were conducted by applying the WRF-Chem model. The results showed that the reduction of the altitude of the Himalayas had an important effect on the trans-Himalayas transport of BC. There was an obvious increase in BC concentration over the trans-Himalayas region, but no significant increase over the TP because the TP (a.m.s.l ~ 4 km) always acted as a wall to prevent BC transport from the IGP to the TP. The trans-Himalayas transport of BC was strongly dependent upon meteorological conditions over the IGP. During summer monsoon, there were three types of cyclones at different locations and one kind of convergent circulation in the IGP. Under the condition of convergent airflows, a strong northeastward wind produced the trans-Himalayas transport of BC. As a result, BC concentrations in the southeastern TP significantly increased to 0.6–0.8 μg m − 3 . When the cyclone located in the eastern IGP, high BC concentrations over the IGP were transported along the foothill of the Himalayas, resulting in a significant reduction of the trans-Himalayas transport. When the cyclone moved to the west, the dynamical perturbations for the trans-Himalayas transport were weaker than the eastern cyclone, and the trans-Himalayas transport were enhanced in the middle and eastern Himalayas. This study will be helpful to assess the impacts of BC particles emitted from South Asia on regional climate change and ecological environment over the TP in the future.

Traditionally, the Universal Soil Loss Equation (USLE) and the revised version of it (RUSLE) have been applied to predicting the long term average soil loss produced by rainfall erosion in many parts of the world. Overtime, it has been recognized that there is a need to predict soil losses over shorter time scales and this has led to the development of WEPP and RUSLE2 which can be used to predict soil losses generated by individual rainfall events. Data currently exists that enables the RUSLE2, WEPP and the USLE-M to estimate historic soil losses from bare fallow runoff and soil loss plots recorded in the USLE database. Comparisons of the abilities of the USLE-M and RUSLE2 to estimate event soil losses from bare fallow were undertaken under circumstances where both models produced the same total soil loss as observed for sets of erosion events on 4 different plots at 4 different locations. Likewise, comparisons of the abilities of the USLE-M and WEPP to model event soil loss from bare fallow were undertaken for sets of erosion events on 4 plots at 4 different locations. Despite being calibrated specifically for each plot, WEPP produced the worst estimates of event soil loss for all the 4 plots. Generally, the USLE-M using measured runoff to calculate the product of the runoff ratio, storm kinetic energy and the maximum 30-minute rainfall intensity produced the best estimates. As to be expected, ability of the USLE-M to estimate event soil loss was reduced when runoff predicted by either RUSLE2 or WEPP was used. Despite this, the USLE-M using runoff predicted by WEPP estimated event soil loss better than WEPP. RUSLE2 also outperformed WEPP.

Vegetation phenology changes have been widely applied in the disaster risk assessments of the spring dust storms, and vegetation green-up date shifts have a strong influence on dust storms. However, the effect of earlier vegetation green-up dates due to climate warming on the evaluation of dust storms return periods remains an important, but poorly understood issue. In this study, we evaluate the spring dust storm return period (February to June) in Inner Mongolia, Northern China, using 165 observations of severe spring dust storm events from 16 weather stations, and regional vegetation green-up dates as an integrated factor from NDVI (Normalized Difference Vegetation Index), covering a period from 1982 to 2007, by building the bivariate Copula model. We found that the joint return period showed better fitting results than without considering the integrated factor when the actual dust storm return period is longer than 2years. Also, for extremely severe dust storm events, the gap between simulation result and actual return period can be narrowed up to 0.4888years by using integrated factor. Furthermore, the risk map based on the return period results shows that the Mandula, Zhurihe, Sunitezuoqi, Narenbaolige stations are identified as high risk areas. In this study area, land surface is extensively covered by grasses and shrubs, vegetation green-up date can play a significant role in restraining spring dust storm outbreaks. Therefore, we suggest that Copula method can become a useful tool for joint return period evaluation and risk analysis of severe dust storms.

Data are analyzed in terms of daily average ozone, its diurnal variation and its relation with meteorological parameters like dry bulb temperature (T), wet bulb temperature (Tw), atmospheric pressure and wind speed based on measurement of these parameters at two Indian Antarctic stations (Larsemann Hills, and Maitri) during 28th Indian Scientific Expedition of Antarctica (ISEA) organized during Antarctic summer of the year 2008-09. The work has been carried out to investigate summer time ozone level and its day-to-day and diurnal variability at these coastal locations and to highlight possible mechanism of ozone production and destruction. The result of the analysis indicates that daily average ozone concentration at Larsemann Hills varied from ~13 and ~20ppb with overall average value of ~16ppb and at Maitri, it varied from ~16 and ~21ppb with overall average value of ~18ppb. Photochemistry is found to partially contribute occasionally to the surface layer ozone at both the stations. Lower concentration of ozone at Maitri during beginning of the observational days may be due to destruction of ozone through activated halogens, whereas higher ozone on latter days may be due to photochemistry and advective transport from east to south-east areas. Ozone concentration during blizzard episodes at both the stations is reduced due to slow photochemical production of ozone, its photochemical removal and removal through deposition of ozone molecules on precipitation particles. Diurnal variation of ozone at Larsemann Hills and Maitri has been found to be absent.

International audience; Contaminants found in watercourses are not only the result of anthropogenic activities but also depend on river's seasonal hydrodynamics. This is particularly true in Mediterranean climate regions where long dry periods are interrupted by strong rainfalls. Storm events remobilize particles from soils and sediments and, as a consequence, the load of particulate matter in rivers can be quite considerable, severely affecting water quality. Nevertheless, an absence of fieldwork studies exists concerning the simultaneous dynamics of mixtures of pollutants in river waters, particularly during strong rainfalls and floods. Our study assessed the concentrations of six families of pollutants, including pesticides, at these events, and compared them to those observed at drought sampling periods. We have used as model a typical Mediterranean coastal river from Southeast France, the Têt River, whose hydrodynamics and major elements fluxes have been fairly investigated. As expected, our results show that chemical mixtures due to human activities occur and that they are particularly relevant during storm events. But the results of our study argue that exceptional multicontamination phenomena actually happen more often than expected because they are linked to recurrent sudden intense rainfall events in the Mediterranean. In particular, combined sewer overflows are responsible for this major issue in urbanized areas, whereas runoff and leaching will be the most important sources of pollutant mixtures occurring at flood flow peak. After an overview of the sources responsible for chronic multiple stressors events in regions under a Mediterranean climate regime worldwide, we revisit best management measures to reduce risks from the presence of chemical mixtures in the environment.

Once established, biocrusts (known also as biological soil crusts or microbiotic crusts) are thought to be relatively resilient to wind erosion, with crust burial being considered as the main mechanism responsible for crust death. Thus far, to the best of our knowledge, crust flaking and rupture under natural conditions were not reported. We report herein a two-year study during two severe drought years (2010 − 2012) in a dunefield in the Negev Desert during which in addition to crust burial, crust rupture and flaking also took place. As for crust burial, it took place under sand sheets or coppice dunes (mounds). Subsequent removal of the coppice dunes by wind resulted in crust disintegration and erosion of the formerly buried crust and the formation of patches devoid of crusts termed herein ‘erosion cirques’. As for crust flaking and rupture, it is explained by a large change in the properties of the extracellular polymeric substances (EPS) composing the crust. The EPS adherence and viscoelastic properties were monitored using a quartz crystal microbalance with dissipation monitoring (QCD-M) technology. EPS adherence and viscoelastic properties deduced from the QCM-D experiments suggest that crust coherence and elasticity, mediated by the EPS, were affected by droughts. Although crust flaking affected up to 25% of the interdunal surface, it is suggested that with continuous rain shortage, further crust flaking is likely to take place under continuous drought-driven dry surface conditions. This positive feedback mechanism, during which initially eroded crusts trigger additional crust erosion, may have severe consequences on the structure and function of drought-prone ecosystems, and may endanger the stability of dunefields, causing dust storms, triggering dune encroachment and declining air quality.

A quantitative analysis of the impacts of particulate matter transported from Central and South Asia on winter surface PM2.5 concentrations in China is investigated from 2013 to 2017. The chemical boundary conditions generated by the MOZART4 global model (MOZ-CBC) are used to drive WRF-Chem regional model as the long-range transport inflow to China. The long-range transport effects of PM2.5 were estimated by the difference caused by primary aerosol (PA), secondary aerosol (SIA), and dust separately from the corresponding component changes in MOZ-CBC. On the five-year average, the long-range transports of particulate matter increase the winter surface dust concentrations by 6–30 μg/m3, PA concentrations by 0–2 μg/m3, and SIA concentrations by 0–1.2 μg/m3. Except for Xinjiang, which is closest to the western border, North China Plain is the most significant region in the mainland of China that could be affected by the long-range transport, indicated by the average increase at 1.6 μg/m3 (4.5%) in PA, 0.9 μg/m3 (1.8%) in SIA, and 16 μg/m3 (35%) in dust. The average increment in PA, SIA, and dust is decreased during El Nino and increased during La Nina. Wind anomalies in the El Nino event weaken prevailing westerly wind but favor the meridional circulation, increasing the precipitation and wet scavenging contribution in the eastern seaboard and resulting in the decrease of the PM2.5 concentration in China caused by long-range transport, while these phenomena are opposite in La Nina events. However, the MOZART4 model might overestimate the frequency of dust storms in winter and the vertical height that dust could reach.

Estimating the influence of dust aerosol on clouds, especially deep convective clouds which is closely related to heavy precipitation, still has large uncertainties due to the lack of adequate direct measurements. In this study, a typical dust storm along with thunderstorm (referred to dust-rain storm), occurred in Northwest India on May 2, 2018, was selected to explore the possible effects of dust aerosol on deep convective cloud by combining a series of satellite retrievals and reanalysis data. Results showed that dust aerosol and moisture were carried to Northwest India by southwesterly wind at 700 hPa and easterly wind along south foothill of Himalayas at 850 hPa, respectively, and then were lifted to upper level of the cloud by robust updraft induced by the deep convection and secondary circulation driven by the upper-level westerly jet. The injection of dust is likely to transfer supercooled water cloud into ice cloud as effective ice nuclei, hence increasing the cloud ice water path and cloud optical depth but decreasing ice particle radius in the cloud. The latent heat released by this phase-change process would enhance the deep convection and further cause heavy rainfall in northern India by drawing moisture from surrounding region. Although we cannot eliminate the effect of large-scale dynamics, this study highlighted the role of dust aerosol in invigorating the deep convective clouds as ice nuclei, providing observation evidence for the investigation of aerosol-cloud-precipitation interaction.

Hurricanes affect the structure and function of forests by removing leaf area, reducing biomass, and causing plant mortality. Quantifying the effects of hurricanes on the phenological processes of forests can help to develop a better understanding of the responses of these systems to natural disasters. On October 10, 2018 Hurricane Michael made landfall in the northern Gulf of Mexico causing extensive damage to forests within its path. Using a phenology model, we evaluated the short-term response and recovery of phenological processes of two subtropical forests that were affected by the storm. Our results suggest that the hurricane accelerated senescence in autumn following the storm, leading to a shorter growing season. The response was dependent on the structure of the forest prior to the storm and the degree of damage; the forest with a taller canopy had greater damage, and the recovery period was prolonged compared to the forest with a shorter canopy. In the summer of the first year following the hurricane, ecosystem physiological function began to return to pre-hurricane levels which corresponded to a recovery in growing season length. The functional diversity in the understory may have aided recovery of post-hurricane spring phenology. While summer phenology was synchronized with the rate of vegetation coverage and mainly driven by increase in canopy leaf area, these forests have not completely recovered during the study. As extreme weather events and disasters induced by global climate change may become more frequent, our research can provide a reference for post-disaster forest management practices which can be adapted to local conditions and contribute to restoration efforts.

The floc size distribution of suspended sediment is a critical driver for in-channel sedimentation and sediment-associated contaminant and nutrient transfer and fate in river catchments. Real-time, in situ, floc size characterisation is possible using available technology but, to date, limited high resolution floc data have been published for fluvial systems draining upland extensive grassland catchments. To that end, suspended sediment floc size distribution and turbidity were characterised at 15-minute intervals using Laser In-Situ Scattering and Transmissometry (LISST) diffraction and a YSI turbidity sonde for six storm events in the upper River Taw (15 km2) catchment in SW England. Maximum event discharges (Q) ranged between 4.3 and 20.0 m3 s−1, with clockwise hysteretic responses (HI = 0.18–0.48) of total suspended solid concentrations (TSS) and Q. The sediment flushing index was highest in the early autumn (0.93) and storm event TSS fluxes varied from 0.04 to 2.9 t km−2. This suggests a change in sources or composition of sediment during higher Q and highly variable patterns of sediment flux from event-to-event. The proportion of particulate organic matter (POM) to TSS was highly variable (5–89%) and did not increase with Q, indicating POM source limitation. The fine-grained tail (D10 and D16) of the floc size distributions decreased during hydrograph rising limbs, with the finest floc sizes associated with the highest TN and TP concentrations at peak Q. The results suggest that dynamic interactions between wet ground and extreme rainfall events can flush significant amounts of sediment from the relatively undisturbed extensive grassland upland catchment. We strongly encourage a sensors-based approach to reveal the spatio-temporal complexity of floc size and associated pollutant export during high Q generated by extreme rainfall since this can help to elucidate processes and mechanisms and generate high-resolution data for water quality modelling without significant user intervention., Graphical abstract Unlabelled Image, Highlights • In situ flocs size and turbidity were studied in sequential high discharge events. • Hydrographs characterised by clockwise hysteresis with a secondary sediment peak. • Proportion of POM to TSS in the physical samples was highly variable (5–89%). • Fine (D10 and D16) floc size diameter was lowest during peak discharges. • Floc size exerted less influence on TP and TN concentrations.

Tropical cyclones (TCs) are one of the most devastating storm systems with high socioeconomic impacts around the world. The drivers of long-term changes in TC frequency and intensity, including the recent global climatic changes, are, however, poorly understood due to short instrumental measurements and a lack of accurate proxy records. Here we present the long-term impacts of large volcanic eruptions on TC activity in northeast Asia. For this purpose, we performed a reconstruction of the frequency and intensity of landfalling TCs based on tree-ring oxygen isotope ratios over the past 350 years. Our results revealed markedly depleted δ18O values (P

The 2019 pandemic of Severe Acute Respiratory Syndrome-Corona Virus Diseases (COVID-19) has posed a substantial threat to public health and major global economic losses. The Northern Emirates of the United Arab Emirates (NEUAE) had imposed intense preventive lockdown measures. On the first of April 2020, a lockdown was implemented. It was assumed, due to lower emissions, that the air quality and Surface Urban Heat Island Intensity (SUHII) had been strengthened significantly. In this research, three parameters for Nitrogen Dioxide (NO2), Aerosol Optical Depth (AOD), and SUHII variables were examined through the NEUAE. we evaluated the percentage of the change in these parameters as revealed by satellite data for 2 cycles in 2019 (March 1st to June 30th) and 2020 (March 1st to June 30th). The core results showed that during lockdown periods, the average of NO2, AOD, and SUHII levels declined by 23.7%, 3.7%, and 19.2%, respectively, compared to the same period in 2019. Validation for results demonstrates a high agreement between the predicted and measured values. The agreement was as high as R2=0.7, R2=0.6, and R2=0.68 for NO2, AOD, and night LST, respectively, indicating significant positive linear correlations. The current study concludes that due to declining automobile and industrial emissions in the NEUAE, the lockdown initiatives substantially lowered NO2, AOD, and SUHII. In addition, the aerosols did not alter significantly since they are often linked to the natural occurrence of dust storms throughout this time of the year. The pandemic is likely to influence several policy decisions to introduce strategies to control air pollution and SUHII. Lockdown experiences may theoretically play a key role in the future as a possible solution for air pollution and SUHII abatement., Graphical abstract Unlabelled Image, Highlights • COVID-19 pandemic impact lockdown events in NEUAE greatly reduced the NO2, AOD and SUHII concentrations. • All Emirates in NEUAE showed decline in NO2, AOD and SUHII concentrations during lockdown period. • The average NO2, AOD and SUHII concentrations were decreased by 23.7%, 3.7% and 19.2%, respectively. • Validation for results showed a significant linear correlations between estimated and measured values.

Since the 1940's, rapid shoreline and dunefield changes have been ongoing at Salmon Hole, an embayment situated near Beachport in the SE of South Australia. Storm induced erosion has nearly removed the entire dunefield and created a lagoon confined by a calcarenite reef. This study examines the progress, dynamics and causes of the erosion to determine why it has been so severe, using historical aerial imagery, wave reanalyses data, Digital Surface Models (DSM's) from drone surveys and through the volumetric analysis of topographic profiles. The results gained through analysing shoreline change at Salmon Hole are then discussed based on Phillips (2009) change assessment system. This study found that a combination of the formation of the ‘lagoon’ between the mainland/dune system and the offshore reef and the resultant breakthrough of the tombolo that have led to the acceleration of the erosion processes seen at Salmon Hole. The formation of the lagoon initiated a divergent evolution that continues in the form of a significant geologically controlled longshore current and terminal rip that enhances removal of sediment during and following erosion of the dunes. It appears that each time the lagoon widened post storm erosion it resulted in an increase in the efficiency of the current, resulting in a positively reinforcing feedback loop furthering the erosion level during each successive storm. The profiles taken from the drone survey DEM's reveal the processes involved in scarping and demonstrate how dune systems with zero sediment supply will respond to future climate and wave conditions. Coastal systems experiencing a deficit in sediment supply will not be able to translate landwards/upwards resulting in their removal. If the current rate of erosion at Salmon Hole is maintained into the future, the entire system is likely to be fully eroded within the next 30 years.

Dust storms are one of the major disasters in arid and semi-arid regions. Understanding the impact factors is crucial for early warning and disaster mitigation. Many factors have been affecting the spatiotemporal patterns of dust storms. However, the relative importance of those factors to dust emissions in recent 40 years over the whole dust belt has not been well documented. This study explored the relative importance of those factors to the interannual variation in dust emissions over the whole dust belt. The difference in the primary contributors over two global warming phases was compared to investigate the association of dust emission trend with global warming. The results indicated that the wind regimes, such as the nocturnal low-level jet, were key factors to the wintertime dust emissions over the Sahel. The springtime dust storms related to cold air and cyclones primarily occurred in the southern coast of the Mediterranean and northwestern China. The cold high and heat low were typical mechanisms for the summertime dust emissions, which frequently formed in western North Africa, the Middle East, and northwestern Indian subcontinent. Whereas the land cover and drought conditions play significant roles in the relatively wetter regions, i.e., the southern coast of the Mediterranean, the Ustyurt Plateau, the northwest coast of Indian Ocean, the Thar desert and the Taklimakan desert. The wintertime global warming coincided well with the decreasing trend of dust emissions over the dust sources inland with a more significant effect seen in Asia. The positive anomalies of summertime dust emissions were primarily found over the dust sources in the low-lying coastal areas on the foot of high mountains. Understanding the relative importance of those drivers to dust emission trends and their variation under different warming periods can improve the prediction of dust storm evolutions and mitigate their impacts under future climate change.

Dust aerosol, one of the important light-absorbing impurities in snow and ice sheets in the Tibet Plateau (TP), can significantly affect the magnitude and timing of snow melting and glacier recession by altering the surface albedo. It is thus of great importance to understand the potential source and transport mechanism of the dust aerosol over the TP. A typical dust storm case, erupted from the Thar Desert (ThD) in South Asia on 1 to 4 May 2018, was selected to understand synoptic causes and a transport mechanism to the TP using the latest Second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) reanalysis data. Comparing with active/passive satellite-based and AERONET-based observations, the MERRA-2 data provide both the spatio-temporal distribution and evolution process of the dust aerosol more accurately. This study also found that the entire Indian-Gangetic Plain (IGP), Southern India, the Bay of Bengal, and even the TP were influenced by the dust event. The synoptic analysis showed that the dust storm was caused jointly by an upper-level jet stream (ULJS), an upper trough and the subtropical high. A typical south-north secondary circulation adjacent its exit zone, mainly triggered by the ULJS, promoted much stronger and higher vertical uplift of the dust aerosols over the ThD. Consequently, those uplifted dust particles were easily transported to the TP across the majestic Himalayas by the southerly airflows in front of the low-pressure trough over Afghanistan and the southern branch trough over the Bengal Bay. These results indicate that dust aerosol and anthropogenic pollutions constrained and driven by the typical atmospheric circulation condition from South Asia are likely to be transported to the TP. Therefore, it is necessary to further pay attention to the influence of dust aerosols from South Asia on the weather and climate in the TP and its downstream areas.

The relationship between nitrogen and discharge (N-Q) in a stream can be captured with high frequency nitrate nitrogen (NO3--N) samplers. In Austria, the Raab catchment (998 km2) has high frequency NO3--N data measured with a spectrometer probe. This study evaluated if the widely-used and typically calibrated eco-hydrological model Soil and Water Assessment Tool (SWAT) can reproduce the hysteresis loop direction and the dilution or accretion effects of NO3--N dynamics during storm events in this agricultural catchment. The daily aggregated NO3--N measurements were compared with the daily SWAT simulated discharge and NO3--N concentrations of 14 storm events by computing hysteresis indices - loop direction and area (h index), loop direction (HInew) and solute gradient (∆C). Overall, the SWAT model was able to replicate the predominant anticlockwise hysteresis and dilution effect of NO3--N in the Raab catchment. The loop direction was simulated correctly in 9 and 10 events, for the h and HInew indices, respectively. The hysteresis direction inferred from both indices did not always concur due to the differences in the calculation methods. The dilution or accretion effect was simulated correctly in 9 of the events. However, the SWAT model only correctly simulated the N-Q relationships for all three hysteresis criteria in 5 of the 14 events. Due to the aggregation of measured data to the daily time step, information pertaining to the hysteresis shape was sometimes lost, particularly if the storm event was

We used a numerical model to analyze the impact of combined sewer overflows (CSOs) in the hydrodynamics and water quality of the Chicago Area Waterway System (CAWS). We coupled the Environmental Fluid Dynamics Code (EFDC) with the Water Quality Analysis Simulation Program (WASP) to perform three-dimensional simulations of the hydrodynamics and water quality in CAWS. The analysis was performed for two different storms: (i) May 6, 2009 representing a 6-hour duration 4-month return period, and (ii) September 12, 2008 representing a 48-hour duration 100-year return period. Results from the simulations show distinct differences between the two storms. During the May 2009 storm there was only one major CSO pumping event with negligible impact on the water quality of CAWS. During the September 2008 storm there were several CSOs that impacted the hydrodynamics and water quality of CAWS. In particular, CSOs during the September 2008 event induced a reversal flow in CAWS, with a plume of constituents that traveled in the opposite direction as water does under normal conditions. However, the simulation results show that CSOs events in CAWS take place during periods of high rainfall, thus the discharge of CSOs is significantly diluted along the CAWS. As a result, the concentrations of organic matter and inorganic nutrients observed at the downstream boundary in CAWS were significantly lower than those recorded at the CSOs outfalls and are within the limits established in the regulation for regular effluents. These results suggest that even during storms events with significant CSOs into the CAWS there is a significant dilution that reduce the impact in the water quality at the system boundaries.

Despite extensive efforts to reduce nitrate transfer in agricultural areas, limited response is often observed in the nitrate concentration in rivers. To investigate the reasons for this limited response, nitrate dynamics in a 100km(2) agricultural catchment in eastern Germany was analysed from sub-hourly to decadal time-scales. Sub-hourly analysis of storm event dynamics during a typical hydrological year (2005-2006) was performed to identify periods of the year with high leaching risk and to link the latter to agricultural management practices in the catchment. Dynamic Harmonic Regression analysis of a 32-year (1982-2014) record of nitrate and discharge revealed that i) the long-term trend in nitrate concentration was closely related to that in discharge, suggesting that large-scale weather and climate patterns were masking the effect of improved nitrogen management on nitrate trends; ii) a persistent seasonal pattern with winter concentration maxima and summer minima could be observed, which was interpreted in terms of a dynamic nitrate concentration profile in the soil and subsoil; and iii) the catchment progressively changed from chemodynamic to more chemostatic behaviour over the three decades of study, which is a sign of long-term homogenisation of nitrate concentrations distribution over depth. This study shows that detailed physical understanding of nitrate dynamics across time scales can be obtained only through combined analysis of long-term records and high-resolution sensor data. Hence, a joint effort is advocated between environmental authorities, who usually perform long-term monitoring, and scientific programmes, which usually perform high-resolution monitoring.

Extreme rainfall events are predicted to become more frequent with climate change and can have a major bearing on instream solute and pollutant transport in mineralised catchments. The Coledale Beck catchment in north-west England was subject to an extreme rainfall event in December 2015 that equated to a 1 in 200-year event. The catchment contains the UK's first passive metal mine water treatment system, and as such had been subject to intense monitoring of solute dynamics before and after commissioning. Due to this monitoring record, the site provides a unique opportunity to assess the effects of a major storm event on (1) catchment-scale solute transport, and (2) the resilience of the new and novel passive treatment system to extreme events. Monitoring suggests a modest decline in treatment efficiency over time that is not synchronous with the storm event and explained instead by changes in system hydraulic efficiency. There was no apparent flushing of the mine system during the event that could potentially have compromised treatment system performance. Analysis of metal transport in the catchment downstream of the mine suggests relatively subtle changes in instream chemistry with modest but statistically-significant reductions in zinc in the lower catchment irrespective of flow condition after the extreme event, but most parameters of interest show no significant change. Increased export of colloidal iron and aluminium is associated with major landslips in the mid-catchment after the storm and provide fresh sorption sites to attenuate dissolved zinc more rapidly in these locations, corroborated by laboratory experiments utilising site materials to investigate the attenuation/release of metals from stream and terrestrial sediments. The data are important as they show both the resilience of passive mine water treatment systems to extreme events and the importance of catchment-scale monitoring to ensure continued effectiveness of treatment initiatives after major perturbation.

Fecal contamination is observed downstream of municipal separate storm sewer systems in coastal North Carolina. While it is well accepted that wet weather contributes to this phenomenon, less is understood about the contribution of the complex hydrology in this low-lying coastal plain. A quantitative microbial assessment was conducted in Beaufort, North Carolina to identify trends and potential sources of fecal contamination in stormwater receiving waters. Fecal indicator concentrations were significantly higher in receiving water downstream of a tidally submerged outfall compared to an outfall that was permanently submerged (p 0.001), though tidal height was not predictive of human-specific microbial source tracking (MST) marker concentrations at the tidally submerged site. Short-term rainfall (i.e.12 h) was predictive of E. coli, Enterococcus spp., and human-specific MST marker concentrations (Fecal Bacteroides, BacHum, and HF183) in receiving waters. The strong correlation between 12-hr antecedent rainfall and Enterococcus spp. (r = 0.57, p 0.001, n = 92) suggests a predictive model could be developed based on rainfall to communicate risk for bathers. Additional molecular marker data indicates that the delivery of fecal sources is complex and highly variable, likely due to the influence of tidal influx (saltwater intrusion from the estuary) into the low-lying stormwater pipes. In particular, elevated MST marker concentrations (up to 2.56 × 10

Various water transmitting media are related to highly variable water source compositions, which limit the understanding of the aquifer structure and hydrological processes in a karst catchment. This study aims to understand the variation in water contribution by matrix, fissure, and conduit flows during storm and seasonal scales based on discharge, electrical conductivity (EC), and nitrate measurements of stream water in a typical dolomite catchment during 2017-2018 and discusses the hydrological response mechanism of a karst aquifer to rainfall characteristics. Time-series analyses of discharge and EC indicated that the rapid response time (mean lag time 1 h) was mainly controlled by rainfall intensity, and the lag time decreased significantly when the rainfall intensity was lower than 15 mm/h. However, the mean discharge was dominated by the rainfall amount and antecedent moisture state. Hydrograph separation based on nitrate indicates that the contribution of soil water was irrelevant for recharging the stream during a non-rain period, whereas epikarst water contributed more than 83.2% of the total flow during a rainfall event. As indicated by the EC frequency distribution analyses, the contribution ratios of the surface, conduit, fissure, and matrix flows were 1:1.8:2.1:7.1, 1:1.6:5.3:6.3, and 0:0:0:1 during stormy, heavy, and light rainfall events, respectively. These parameters indicate that the degree of karstification was low in the karst aquifer. Seasonal frequency distribution analyses of EC indicate that higher rainfall amounts and rainfall intensities during the wet season promoted the contribution of conduit flow to approximately 11.4% of the total flow; however, matrix flow dominated the recharge of the streamflow and its contribution was more than 55.6% during each season. Our results suggest that the permeability of the epikarst matrix dominates the storage and transfer functions in dolomite karst aquifers with low karstification.