Atmospheric contribution to eutrophication of the Adriatic Sea

Abstract. Many alpine areas are experiencing deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, atmospheric deposition sources may be an important source of C and nutrients for these environments. We evaluated the magnitude of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long-term dataset (2002–2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were 1.12 ± 0.19 mg l−1, and weekly concentrations reached peaks as high at 6–10 mg l−1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. To investigate potential sources of C in atmospheric deposition, we evaluated the chemical quality of dissolved organic matter (DOM) and relationships between DOM and other solutes in wet deposition. Relationships between DOC concentration, fluorescence, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring, which may reflect an association of DOM with dust. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples. Our C budget estimates for the Green Lake 4 catchment illustrated that wet deposition (9.9 kg C ha−1 yr−1) and dry deposition (6.9 kg C ha−1 yr−1) were a combined input of approximately 17 kg C ha−1 yr−1, which could be as high as 24 kg C ha−1 yr−1 in high dust years. This atmospheric C input approached the C input from microbial autotrophic production in barren soils. Atmospheric wet and dry deposition also contributed 4.3 kg N ha−1 yr−1, 0.15 kg P ha−1 yr−1, and 2.7 kg Ca2+ ha−1 yr−1 to this alpine catchment.

The chemical composition and fluxes of atmospheric wet deposition at four sites in South Africa

(pp. 47–52) The wet deposition of nitrogen compounds in the intensive dairy farming area and its environs in the northern part of the Kanto region in central Japan was investigated from April 2003 to April 2005. Open-bulk samplers were used to collect open-bulk precipitation, which approximates the sum of wet and dry deposition. Furthermore, wet-only samplers were applied to collect the precipitation for every 1 mm in a rainfall, termed the wet sample. The concentrations of total nitrogen and ammonium ions in the open-bulk precipitation were high in the central part of the dairy farming area and low in the remote mountainous area more than 15 km away the concentrations were generally high during winter and spring, and low during summer and autumn. There was a large difference in the annual deposition of nitrogen between the farming area and the surrounding area. The annual deposition of nitrogen in the farming area was significantly high compared to the values of existing data in Japan and Europe. The concentrations of respective nitrogen compounds in the wet sample, which accounted for 40 of the total rainfalls events, were notably high at the beginning of precipitation and rapidly decreased by 8 mm of continuous precipitation. The nitrogen concentrations at the beginning of precipitation were high in the farming area, and relatively low in the surrounding area. It was thought that the cause of the large wet deposition in the farming area was due to ammonia emissions, mainly from cattle manure produced at dairy farms. The factors of the seasonal changes were considered to be the frequency and the amount of precipitation, and the change in ammonia emissions from manure management performed by dairy farmers.

Carbon (C), nitrogen (N), and sulfur (S) are elements strongly influenced by biological cycling and redox reactions in soils, but few comparative analyses have investigated the behaviors of these elements with time. Thus, we examined changes in content and isotope composition of soil profiles along a chronosequence (58–212 kyr) of marine terraces on the central California coast, in an area with significant background geochemical research. Unlike in other chronosequences in more humid locations, the total C, N, and S in these soils did not vary strongly with age, possibly due to the retention of phosphorus (P). The total pools of soil N and S cannot be explained by wet deposition of NO3 and SO4 alone, suggesting other sources of atmospheric inputs such as NH4+ and dimethyl sulfide. Total C and N declined in a characteristic logarithmic pattern with depth, while S did not. The ratio of extractable soil nitrate (NO3) to total N declined with depth, suggesting strong biological demand via various avenues. In contrast, the ratio of extractable sulfate (SO4) to total S increased with depth, suggesting that S was in biological excess. We used a simple reactive transport model to integrate the depth profiles of total C and N and their isotope values. The depth trends of total concentrations suggested one-pool residence times of approximately 500 to 1000 y, consistent with turnover times calculated by mass balance. Depth trends of stable isotope values indicated that N is isotopically fractionated at a magnitude twice that of C, consistent with observed 15N-depleted nitrous oxide (N2O) emissions during the dry summer months. The isotope composition of S (total and SO4) suggests some isotope enrichment during biogeochemical cycling, but far less than observed for N. Thus, despite significant chemical weathering and elemental loss over time, the biogeochemical cycles of C, N, and S remain relatively unaffected by soil age in this climatic setting.

This study reports the only recent characterisation of two contrasted wet deposition events collected during the PEACETIME cruise in the Mediterranean open seawater, and their impact on trace metals (TMS) marine stocks. Rain samples were analysed for Al, 12 trace metals (TMs hereafter, including Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrients (N, P, DOC) concentrations. The first rain sample collected in the Ionian Sea (rain ION) was a wet typical regional background deposition event whereas the second rain collected in the Algerian Basin (rain FAST) was a Saharan dust wet deposition. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, suggesting either less anthropogenic influence in the remote Mediterranean environment, or decreased emissions during the last decades in the Mediterranean Sea. The TMs inventories in the surface microlayer and mixed layer (0–20 m) at ION and FAST stations before and after the events, compared to atmospheric fluxes, showed that the atmospheric inputs were a significant source of particulate TMs for both layers. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as marine stocks within the ML for dissolved Fe, Co and Zn, underlining the role of the atmosphere in their biogeochemical cycle in the stratified Mediterranean Sea. In case of intense wet dust deposition event, the contribution of atmospheric inputs could be critical for dissolved stocks of the majority of TMs.

Characterizing the antibiotic resistance genes in a river catchment: Influence of anthropogenic activities

<p>A severe weather events hit Italy on July 9-10, 2019 causing heavy damages by the falling of large-size hail. A trough from Northern Europe affected Italy and the Balkans advecting cold air on the Adriatic Sea. The intrusion of relatively cold and dry air on the Adriatic Sea, in a first stage through the "Bora jets" generated by the Dinaric Alps gave rise to a frontal structure on the ground, which rapidly moved from North to South Adriatic. The large thermal gradient (also with the sea surface), the interaction with the complex orography and the coastal zone, generated several storm structures along the eastern Italian coast.  In particular, on 10 July 2019 between 8UTC and 12UTC a deep convective cell (probably a supercell) developed along the coast North of the city of Pescara, producing intense rainfall (accumulated rainfall reaching 130 mm/3h) and a violent hailstorm with hailstones larger than 10 cm in diameter. The storm quickly moved southward, evolving into a complex multicellular structure clearly visible by observing radar data.  In this work the frontal dynamics and the genesis of the storm cell are investigated using the numerical model WRF (Weather Research and Forecasting system). Numerical experiments are carried out using a 1 km grid on Central Italy, initialized using the ECMWF dataset and the Sea Surface Temperature (SST) taken by MFS-CMEMS Copernicus dataset. The sensitivity study investigated both the impact of the initial conditions, the quality and the anomaly of the SST on the Adriatic basin in those days. Furthermore, in order to quantify the importance of the use of different microphysics, Planetary boundary Layer (PBL) and radiative schemes, several experiments are performed. The role of orography in the development and location of the convective cell is also investigated. Preliminary results show that initialization and SST played a fundamental role. In particular, the initialization several hours before the event, coupled with a detailed SST allows to correctly reproduce the atmospheric fields. The microphysics scheme turned out to play a key role for this event by showing a significant greater impact than the PBL, in terms of frontal genesis on both the synoptic and local scale.</p>

Contrasting wet deposition composition between three diverse islands and coastal North American sites

Modelling deposition and air concentration of reduced nitrogen in Poland and sensitivity to variability in annual meteorology

Estimates of the sources and wet deposition fluxes of inorganic nutrients (PO43−, NO3−, NO2−, NH4+) have been made using a long‐term wet atmospheric deposition measurement at three sites along the Mediterranean coast of Israel. The nutrient composition in rainwater indicated a dominant anthropogenic source for NO3− and NH4+ and a continental, natural, and anthropogenic, rock/soil source for PO43−. The calculated long‐term dissolved inorganic N (IN) and inorganic P (IP) fluxes were 0.28 and 0.009 g m−2 yr−1 to the coastal zone and estimated as 0.24 and 0.008 g m−2 yr−1 to the Southeast (SE) Mediterranean, with a possible increasing pattern of the annual dissolved IN fluxes. Concentration of total and seawater leachable IP (LIP) from dust was examined on 20 Whatman 41 filters collected during 1996. The mean total IP concentration in dust was 0.13 ± 0.11% (geomean = 0.09%), with a mean of 387 ± 205 μg IP per g of dust leached by seawater. LIP from dust varies between 6 and 85% (mean of 38%) of the dry total IP. Dust of desert‐type (Saharan) events exhibited lower LIP solubility in seawater (∼25%, median) than air masses of European origin (∼45%, median). The calculated ratio of wet deposition to total (wet and dry) deposition here of 0.2 showed the importance of dry deposition of P in the SE Mediterranean basin compared to atmospheric inputs into the northwestern basin. The total IP and seawater LIP fluxes from dry deposition were estimated as 0.04 and 0.01 g m−2 yr−1, respectively. Atmospheric inputs of bioavailable N and P represent an imbalanced contribution to the new production of 8–20 and 4–11%, respectively, and reinforce the unusual N:P ratios (∼27) and possible P limitation in the SE Mediterranean.

A nonurban base line has been established for nine trace element constituents of aerosol particles as a function of particle size at ground level sampling stations in north Florida up to 50 km from the Gulf of Mexico. The particle size range 0.25- to >4-μm aerodynamic diameter was investigated by cascade impactor sampling and elemental analysis by proton-induced X ray emission. By using a strategy of sampling at urban, forest, and coastal locations and by choosing approximately 48-hour sample averaging intervals the potential dependence of the base line levels both on local pollution and natural sources and on local particle size specific aerosol removal processes could be evaluated. It is found that elements contained in the largest particles, especially those of >4 μm, display the greatest degree of average concentration difference between sites, a result suggesting short atmospheric residence times and the importance of local dispersion sources and atmospheric cleansing processes in regulating the particle concentrations in air. Elements contained in particles of <2-μm diameter show little average concentration difference between sites unless they are influenced by local pollution sources, a finding suggesting that their concentrations in air are regulated by large-scale sources and transport processes. Sulfur in the smallest particles shows a marked constancy of concentration, but it may be modified in the largest particle size ranges in relation to proximity to the seacoast. No evidence is found for dependence of particulate sulfur concentrations on local pollution sources. K, Ca, Ti, Fe, and Zn appear to be regulated in the main by terrestrial source processes, and Cl by marine source processes, but Br and Pb appear to be accounted for adequately by assuming automotive fuel combustion as their major source. Limited data obtained for V indicate that it may vary considerably with fluctuations in aerosol transport from oil-fired electric power plant sources in the region. Limited additional data also suggest that Mn is derived from sources of natural terrestrial composition. In view of these findings, certain criteria may be set for the design of a meaningful nonurban aerosol monitoring network.

The Mediterranean basin continuously receives anthropogenic aerosols from industrial and domestic activities from the European region, as well as high rates of aeolian material in the form of mineral dust from northern Africa. Moreover, combustion dominates over natural dust, whereas vegetation fires frequently burn throughout the Mediterranean coastal zone, especially during hot and dry summers. Once in the atmosphere, aerosols become an important external source of nutrients but also of toxins to the marine ecosystem through atmospheric deposition (AD), affecting the quality and quantity of organic matter (OM) produced by phytoplankton in the photic zone, and altering the CO2 uptake. AD onto sea surface cannot be completely understood without considering the interfacial processes within the sea surface microlayer (SML). As the uppermost millimeter of the sea surface, the SML represents the natural interface of the major environmental importance. It could serve as the first indicator of increasing human impact and climate change due to fast response of its biological and physico-chemical properties. However, surprisingly little research assessed the impact of AD on surface plankton communities, distinguishing between the SML and the water column bellow.This work is designed to assess the magnitude and temporal variability of atmospheric concentrations and deposition fluxes of nutrients and trace metals, and to gain insight into the AD impacts on the nature of enrichments of organic compounds within surface layers in a typical Mediterranean coastal environment. The field campaign was conducted during the period of retrieval of sea surface oligotrophic conditions (February-July 2019) at the Adriatic coastal area. On-line black carbon (BC) concentrations were measured while the aerosol particles (PM10), wet and total deposition samples as well as the SML and underlying water (ULW; 0.5 m depth) samples were collected simultaneously. The first comprehensive insight into concentration levels of macro nutrients (N, P) and trace metals (e.g. Cu, Pb, Cd, Ni, Zn, Co) in atmospheric samples, their transport history, source apportionment and deposition fluxes to the coastal Adriatic area will be presented. The temporal dynamics of SML biology as well as concentrations of inorganic and organic constituents enabled the assessment of their sources and the nature of the enrichments taking place within the SML. Due to their significance throughout the Mediterranean coastal area, open-fire episodes and Saharan dust inputs were especially considered. In order to better understand the impacts of ambient AD from diverse sources on the physiology and biomass of the natural plankton population and consequently on the chemistry of the surface layers (SML and ULW), we further conducted the first in situ bioassay incubation experiment of its kind at the Adriatic Sea. We experimentally examined the impact of locally collected anthropogenic aerosols, that had different levels of biologically important nutrients, trace metals and organic pollutants, in contrast to the material mimicking biomass burning events.Acknowledgment: This work has been supported by the Croatian Science Foundation under the IP-2018-01-3105 project: Biochemical responses of oligotrophic Adriatic surface ecosystems to atmospheric deposition inputs.

Distribution of polycyclic aromatic hydrocarbons (PAH) in recent sediments of two transversal transects in the middle part of the adriatic sea

Two classes of organophosphorus compounds, OP pesticides and phosphate esters used for industrial purposes were investigated in a monitoring program carried out at the mouth of the river Po and along the Adriatic coast. Contamination by OP pesticides resulted rather low and of land based origin. Non‐pesticides, on the contrary, can reach considerable contamination levels both in river and in sea water. Local sources of pollution seem to be present along the coast and to cause in some cases a more severe pollution in sea than in river water.

Seven series of global radiation measurements, totaling 190 stationyears, were analyzed from sites covering the world-wide range of insolation regimes. All were remote from any local surface sources of atmospheric pollution. Global radiation decreased linearly with year of measurement at all sites and at six of them the decreases were statistically significant, averaging annually 17.67 MJ m−2 yr−1 (0.56 W m−2). Observations of daytime cloud cover made at five of the sites showed no large or significant changes over the same periods. There was some indication that the rates of decline in global radiation were larger at sites and during years with greater-than-average cloud cover. The results confirm an earlier finding of a large-scale decline in insolation, derived from an analysis of data from the World Radiation Network and show that this cannot only be attributed to local sources of pollution. Temporal variations in the rate of insolation decline were small; spatial variations were large and unexplained.