Marine Recipients Research Articles

Nitrogen and Phosphorus Export After Flooding of Agricultural Land by Coastal Managed Realignment

Climate-driven sea level rise has severe consequences for drained agricultural areas near coasts. The least productive of these can be restored into marine wetlands of high ecological quality by managed realignment. This study assessed the nitrogen (N) and phosphorus (P) balance in a 214 ha coastal lagoon formed after flooding of agricultural land by managed realignment. N and P loss from the soils was monitored over a 5-year period after flooding using three independent approaches: (1) temporal changes in N and P inventories of the soil; (2) flux of dissolved inorganic N and P from the flooded soil; and (3) tidal N and P exchange across the outer boundary in the form of particulate and dissolved nutrients. All three approaches showed similar initial release and tidal export of N and P the first year(s) after flooding followed by decreasing rates. The annual loss ranged from 157 to 299 kg N ha−1 yr−1 and 29 to 63 kg P ha−1 yr−1 during the first year. N loss decreased rapidly after the first 2 years and reached a level of 28–65 kg N ha−1 yr−1, while P loss declined after the first year and remained stable and relatively high at 18–32 kg P ha−1 yr−1 thereafter. High N and P export after implementing managed realignment of agricultural land may deteriorate environmental conditions in the adjacent marine recipients for at least 5 years. Particularly small and stagnant water bodies vulnerable to eutrophication should be avoided as recipients.

Treating urban stormwater in constructed wetlands in Kalmar, Sweden, for improved water quality and biodiversity

Stormwaters’ heavy loads of nutrients, metals and oil etc, via urban ditches / streams, are increasingly treated in engineered shallow wetlands/ponds. Such approaches are still only remedying a minor part of affected storm waters, urban streams, and freshwater and marine recipients. In Kalmar, a middle-sized Swedish town at the Baltic Sea, > 10 such wetlands / ponds are established for reduction of such heavily polluted waters. Aiming at determining the effectiveness in reduction of nutrients and metals, and the facilitation of the aquatic biodiversity (primarily in the wetlands), monitoring programs were initiated. Regular in/outflow water sampling, water flow and biology, were followed for 1-2-3 years (varied with parameter) after construction in two of these wetlands. Skälby Dämme, constructed 14 years ago (2000), showed ca 40 % nutrient reduction figures, less for TSS and metals, while Hagbygärde Dämme, constructed two years ago (2012), attained only much lower results. Reasons for this difference might be that Hagbygärde is less surrounded by forested land, also that less than one year had elapsed before evaluation commenced, while two-three years in Skälby. More recent monitoring in Skälby Dämme is also compared with. Moreover, this kind of wetlands/ponds is shown to favour the biodiversity of benthic invertebrates, (aquatic) plants and birds, although with trends to decline in species richness some years after the initial colonization period.

Reprint of “Mapping of nitrogen risk areas”

Loading of nitrogen (N) from diffuse sources to Danish marine waters was reduced by 41% in the period 1990–2012 by a suite of general measures. However, further reductions in N loading are required if the ambitious quality goals of the EU Water Framework Directive are to be achieved. Measures will be more effective if they are implemented in N loss hot spots or risk areas. Additionally, the highly variable N reduction in groundwater and surface waters needs to be taken into account as this strongly influences the resulting effect of mitigation measures. The objectives of this study were to develop and apply an N risk tool to the entire agricultural land area in Denmark. The purpose of the tool is to identify high risk areas, i.e. areas which contribute disproportionately much to diffuse N losses to the marine recipient, and to suggest cost-effective measures to reduce losses from risk areas. In the N risk mapping part of the tool, we combined a modelled root zone N leaching with a catchment-specific N reduction factor which in combination determines the N load to the marine recipient. N leaching was calculated using detailed information of agricultural management from national databases as well as datasets of percolation and soil parameters as input parameters to an empirical N leaching model. The developed N risk tool showed that the Danish agricultural area is distributed almost evenly between N retention classes (N retention being divided into classes of <40%; 40–60%; 60–80% and >80% N retention). Hot spots for marine N loading are, however, mainly located in catchments with N retention less than 80%. Hot spots for N leaching from the root zone are mainly located in the western part of Jutland, while hot spots for marine N loading are found in all regions and especially in small catchments close to the coast. In a case study for the catchment of the Danish Odense Fjord estuary, we demonstrated how the tool facilitates cost-effective implementation of measures and how measures can be combined to reach a given reduction target for an estuary.

Mapping of nitrogen risk areas

Loading of nitrogen (N) from diffuse sources to Danish marine waters was reduced by 41% in the period 1990–2012 by a suite of general measures. However, further reductions in N loading are required if the ambitious quality goals of the EU Water Framework Directive are to be achieved. Measures will be more effective if they are implemented in N loss hot spots or risk areas. Additionally, the highly variable N reduction in groundwater and surface waters needs to be taken into account as this strongly influences the resulting effect of mitigation measures. The objectives of this study were to develop and apply an N risk tool to the entire agricultural land area in Denmark. The purpose of the tool is to identify high risk areas, i.e. areas which contribute disproportionately much to diffuse N losses to the marine recipient, and to suggest cost-effective measures to reduce losses from risk areas. In the N risk mapping part of the tool, we combined a modelled root zone N leaching with a catchment-specific N reduction factor which in combination determines the N load to the marine recipient. N leaching was calculated using detailed information of agricultural management from national databases as well as datasets of percolation and soil parameters as input parameters to an empirical N leaching model. The developed N risk tool showed that the Danish agricultural area is distributed almost evenly between N retention classes (N retention being divided into classes of <40%; 40–60%; 60–80% and >80% N retention). Hot spots for marine N loading are, however, mainly located in catchments with N retention less than 80%. Hot spots for N leaching from the root zone are mainly located in the western part of Jylland, while hot spots for marine N loading are found in all regions and especially in small catchments close to the coast. In a case study for the catchment of the Danish Odense Fjord estuary, we demonstrated how the tool facilitates cost-effective implementation of measures and how measures can be combined to reach a given reduction target for an estuary.

Drug-resistant and hospital-associated Enterococcus faecium from wastewater, riverine estuary and anthropogenically impacted marine catchment basin

BackgroundEnterococci, ubiquitous colonizers of humans and other animals, play an increasingly important role in health-care associated infections (HAIs). It is believed that the recent evolution of two clinically relevant species, Enterococcus faecalis and Enterococcus faecium occurred in a big part in a hospital environment, leading to formation of high-risk enterococcal clonal complexes (HiRECCs), which combine multidrug resistance with increased pathogenicity and epidemicity. The aim of this study was to establish the species composition in wastewater, its marine recipient as well as a river estuary and to investigate the antimicrobial susceptibility of collected isolates. Molecular methods were additionally applied to test the presence of HiRRECC-related E. faecium.ResultsTwo wastewater treatment plants (WWTPs), their marine outfalls and Vistula river that influence significantly the quality of waters in Gulf of Gdansk were sampled to investigate the presence of Enterococcus spp. Four-hundred-twenty-eight isolates were obtained, including E. faecium (244 isolates, 57.0%), E. hirae (113 isolates, 26.4%) and E. faecalis (63 isolates, 14.7%); other species (E. gallinarum/casseliflavus, E. durans and E. avium) accounted for 1.9%. Antimicrobial susceptibility testing revealed the presence of isolates resistant to erythromycin, tetracycline, amipicillin, fluoroquinolones and aminoglycosides (high-level resistance), especially among E. faecium, where such isolates were usually characterized by multilocus sequence types associated with nosocomial lineages 17, 18 and 78 of this species representing HiRECC, formerly called CC17. These isolates not only carried several resistance determinants but were also enriched in genes encoding pathogenicity factors (Esp, pili) and genes associated with mobile genetic elements (MGE), a feature also typical for nosocomial HiRECC.ConclusionsOur data show that WWTPs constitute an important source of enterococcal strains carrying antimicrobial resistance determinants, often associated with the presence of MGE, for the recipient water environment, thus increasing a pool of such genes for other organisms. The presence of HiRECCs in wastewaters and marine/river environment may indicate that adaptations gained in hospitals may be also beneficial for survival of such clones in other settings. There is an obvious need to monitor the release and spread of such strains in order to elucidate better ways to curb their dissemination.

Watersheds Nutrient Loss and Eutrophication of the Marine Recipients: A Case Study of the Jiaozhou Bay, China

Industrialization and urbanization along the coastal population centers have brought great changes in the land cover and material fluxes from watersheds to receiving bays and estuaries. We have embarked a multiyear research project on “Watersheds Nutrient Loss and Eutrophication of Jiaozhou Bay” for the period of 2000 to 2004, funded by the Natural Science Foundation of China to examine human influence on the marine sector of ecosystem. Jiaozhou Bay, located in the southern part of Shandong Peninsula, was selected because of the existence of long-term hydrographic and meteorological records since the 1930s and recent observations on the marine ecological variables. We have made extensive and periodic measurements on the water movement, nutrients, phytoplankton, and microbe in water column and bottom sediments. Box and 3-dimensional hydrodynamic models were developed and utilized to understand the evolution of eutrophic status with time. It was found that primary productivity has suffered from silica depletion followed by phosphate, and the dominance of large phytoplankton has been replaced by small-size communities. These ecosystem changes were brought by the changes in the relative contribution among major pathways and concentrations, owing to the human activities in the watershed. Eight articles in this volume reported various aspects of the linkage between watershed human activities and ecosystem for the Jiaozhou Bay as the initial outcome of this project.

Spatial and temporal variability of trace metals in aerosol from the desert region of China and the Yellow Sea

From spring to early summer of 1995 and 1996, about 180–190 aerosol samples were collected from three observatories at Northwest China desert region (i.e., Minqin), coastal suburb area (i.e., Qingdao), and an island in the Yellow Sea (i.e., Qianliyan), respectively. The samples were analyzed to determine the concentrations of trace metals (Al, Fe, Mn, Na, Cr, Zn, Cu, Co, Ni, Pb, V, Sr, and Cd). Data are examined to understand the distribution of trace metals in aerosols at an upwind desert region and downwind marine recipient under westerly flow. The result shows that trace metal composition of aerosols vary considerably in time and space. Trace metal levels display a drastic seasonal change at both Qingdao and Qianliyan, with concentrations generally 2–3 times higher in spring than summer. Daily variation of trace metal concentrations at Minqin is more significant than Qingdao and Qianliyan, however. The enrichment factors for the crustal source (EFcrust) at Minqin are relatively low and unimportant compared with those at Qingdao and Qianliyan. Some of the trace species like Pb, Zn, and Cd have relatively high contributions from the anthropogenic source (Rp), and &gt;98% are found at Qingdao and Qianliyan, with EFcrust values 1–2 orders of magnitude higher than Minqin. Manganese is mainly from low‐temperature weathering products and the contribution from crustal source (Rc) is &gt;70% at Qingdao and Qianliyan. The coastal atmosphere responds to the episodic dust storms in the desert region (i.e., Minqin) by an increase in aerosol level and a higher concentration of crust‐dominated materials. The percentage contributions from the crustal source (Rc) of trace metals, such as Pb, Cd, and Zn, could be increased considerably by 5–10 folds higher during the passage of cold fronts than during calm weather period over the Yellow Sea.

Transfer and expression of a hydrocarbon-degrading plasmid pHCL from Pseudomonas putida to marine bacteria

Transfer of a catabolic plasmid from Pseudomonas putida to indigenous marine bacteria and obligate halophilic bacteria was carried out under both in vitro and in situ conditions. The marine recipients, which could not otherwise grow on hydrocarbon substrates, were able to degrade them after the horizontal transfer of the catabolic plasmid from P. putida. Mating conducted on nutrient plates yielded comparatively more transconjugants than in broth mating under laboratory conditions (106 c.f.u./ml). The transconjugants stably maintained the plasmid when they were maintained in seawater amended with selective pressure (antibiotics/Hg (25 μg/μl) even after 30 days, whereas under non-selective conditions they progressively lost the plasmid after 24 days. The expression of the plasmid in the marine recipients was investigated by gas chromatographic analysis. The overall objective of this study is to evolve a novel strategy for bioremediation of oil spills and the results of the present study suggest that the present approach would offer a better solution for the removal of harmful substances from the environment by avoiding serious interference with the microbial flora of the ecosystem.

The Effect of Riverine Nitrate Loads on Winter Concentrations in the Great Belt, Denmark

This paper presents a method that models the fraction of the NOx concentrations (nitrate and nitrite) in a marine recipient resulting from riverine runoff from land. The analysis is performed on the surface waters in the Great Belt, Denmark, during winter seasons. The method is based on simulation of two independent NOx fractions: First, the “background” fraction, which results from the oceanographic mixing in the Belt Sea between Kattegat water and Baltic Sea water, and second, the nutrient load from land. The calculation of the background fraction is based on the finding that the Kattegat water has high salinity and high NOx contents whereas the Baltic Sea water has low salinity and low NOx contents. By means of an empirical relation between salinity and NOx a specific salinity measurement in the mixing zone can be related to a “background” NOx concentration. Measurements in the Great Belt show to be higher than the calculated “background” concentrations, which indicates the presence of a second NOx fraction. The second fraction is defined as the difference between the calculated background concentration and the measured NOx concentration. The hypothesis of the present paper is that this second fraction is dominated by the river runoff. Cross correlation analysis between the time series of the river NOx load and the time series of surplus concentration in the Great Belt reveals a time lag between maximum river load and maximum surplus concentration during winter seasons of approx. 1 month. An empirical transfer function has been developed in order to connect the daily NOx river loads with the surplus concentration in the Great Belt. The development of the NOx-concentration in the Great Belt due to river run off is modelled for 8 specific winter periods of 3 months (December - February) between 1988/1989 and 1995/1996. The model simulates concentrations on a weekly basis and quantifies the NOx-increase during each winter based on the river load data. The analysis indicates that the NOx concentration can be doubled during winters with high runoff, giving rise to an increase of approx. 60 μgN/1 at the end of February. In winters with minimal runoff no significant increase above the background level is found.

96/06707 Speciation of 137Cs and 90Sr in discharges from the pulp industry and the marine recipient

96/06707 Speciation of 137Cs and 90Sr in discharges from the pulp industry and the marine recipient

Speciation of 137Cs and 90Sr in discharges from the pulp industry and the marine recipient

The concentrations and size distribution pattern of radionuclides in waste-water discharges from a pulp industry located at the Oslo fjord, Norway, have been studied. The annual discharge to the fjord amounts to about 1.9 GBq for 137Cs and 2.7 G Bq 90Sr. Information on the size-distribution pattern of 137Cs and 90Sr in discharge waste water and the marine recipient was obtained using tangential cross-flow ultrafiltration technique. Caesium-137 was measured with Ge-detectors, while 90Sr was determined using a low-level scintillation spectrometer. Almost all 137Cs in discharge waste water was found to be present in the low molecular weight fraction. The major fraction of 90Sr in discharge waste water was present in the low molecular weight fraction, while a significant fraction was found as colloids. Almost all 90Sr in seawater was present in the low molecular weight fraction. Due to transporting currents and dilution, no radiological impact on the receiving coastal waters could be observed.

Vibrio anguillarum: Prevalence of typical and atypical strains in marine recipients with special reference to carbohydrate pollution

Primary isolates of Vibrio anguillarum-like organisms could be separated into typical V. anguillarum (VA) and atypical V. anguillarum (AVA) by biochemical tests. The prevalence of the fish pathogenic V. anguillarum was highly influenced by carbohydrate pollution as compared to the AVA. Water an sediment counts of VA generally increased at the polluted sites during April-May and persisted at a level of approx. 100/ml water and 1,000/g sediment until October-November. A further increase in VA counts could be registered locally at the time when the sugar beet processing season started (September-October). At the control site VA counts increased during June-July to a level of 10/ml persisting until August, while the only increase in sediment counts occurred in September (100/g). The maximum counts in water and sediment were at the control site 10/ml and 100/g and the polluted sites 100,000/ml and 50,000/g, respectively.

Vibrio anguillarum: Prevalence in three carbohydrate loaded marine recipients and a control

A bacteriological study of prevalences of Vibrio anguillarum like organisms (VLO) in three marine recipients, polluted with effluents from sugar and cellulose factories, showed some characteristic features. In the winter period very low counts of VLO were recorded. During temperature rise in spring the VLO values rise to a characteristic level persisting from June to September. A decline occurs at this time, except in sites polluted from sugar plants, where there is a delay of appr. one month. In the relatively stable period the prevalence of VLO in the recipients is appr. 10–100 per ml water and 1.000–10.000 per gram sediment while the corresponding values for the control are 1–10 per ml and 100–1000 per gram, respectively. Thus fish living in these recipients are exposed to a ten times higher risk from VLO, which is reflected in a higher prevalence of an ulcus disease in cod. The complicated nature of pollution induced diseases makes it impossible directly to correlate VLO and disease prevalence. Prevalence studies of VLO in marine recipients give valuable information on growth conditions (“organic pollution”) for marine vibrios and the risk to fish, wild living and cultured. Therefore this group of bacteria should to be added to the list of marine indicator organisms, where the indication is based on the environmental risk.

Growth of Mytilus edulis in net bags transferred to different localities in a eutrophicated Danish fjord

The growth rate has been measured in Mytilus edulis transferred in net bags to seven localities in the brackish Danish fjord, Limfjorden, in which certain areas are heavily eutrophicated. The increase in shell length, shell weight and flesh body weight was measured after growth periods of 14–18 days. The increase in, e.g., flesh dry weight ranged from twice the start weight to a four-fold increase of the start weight. The net growth efficiencies were estimated to be between 54 and 73%. Algal concentration was in no case the limiting growth factor, but low growth rates were observed in areas with seasonal oxygen depletion and release of toxic H 2S from the sediments. It is suggested that measurements of actual growth in M. edulis can be a useful technique in the study of biological effects in marine recipients.

Estimation of heavy metal pollution in two Norwegian fjord areas by analysis of the brown alga Ascophyllum nodosum

The usefulness of trace element analysis of seaweeds for determining the distribution of heavy metals in fjord areas was investigated. Concentrations of zinc, copper, lead, cadmium and mercury were determined in the brown alga Ascophyllum nodosum from two Norwegian fjords, Trondheimsfjord and Hardangerfjord. In both areas marked local variations in heavy metal concentrations in the seaweeds were observed, and in the Hardangerfjord maximum concentrations as high as 20–50 times normal levels were found for Zn, Cu, Pb and Cd. The highest value observed for mercury was 20 ppm of dry matter, while the normal level was below 0·1 ppm. In the narrow Hardangerfjord, levels of zinc, cadmium and mercury higher than normal were observed 90 km from the main source, while copper and lead reached normal levels 35 km from the source. The results indicate that trace element analysis of seaweeds is a useful and inexpensive method for evaluating the state of a marine recipient with regard to heavy metal contamination.