The negative health effects of simulated acid mists and fluoranthene on juvenile Japanese red pine were investigated, and the methods of protection from these pollutants were examined. The needle gas exchange, chlorophyll fluorescence, chemical contents and visual damage to needles caused by acid mist applied alone or its conjunction with fluoranthene were investigated over 60 d and 20 d, respectively. Acid mist at pH 2 and 3 caused physiological and visual damage, which was enhanced by the addition of fluoranthene to the mist. However, fluoranthene and acid mist at pH 4 and 5 showed only minor effects. These findings indicate that acid mist may be more harmful to pine trees if it occurs in conjunction with polycyclic aromatic hydrocarbons. Moreover, suppression of the singular and additive effects of these compounds was achieved using mannitol, which may be widely applicable to suppression of reactive oxygen species-mediated plant damage.

The Berre lagoon receives freshwater from two natural rivers but the implementation of the hydroelectric power plant led to strong changes in the ecosystem structure and functioning. Sediments are important sites for nitrogen cycling because the O2 sharp gradient allows oxic nitrification as well as anoxic denitrification and anammox to operate in close proximity. Seasonal and short-term variations in the coastal nitrogen processes were quantified at two stations: SA1 located in the northern part of the lagoon directly under the inflows of freshwater and SA3 in the southern part of the lagoon influenced mainly by the marine water inflows. Results revealed that most of the nitrate formed by nitrification was denitrified. Total denitrification was the main N2 removal process. The high primary production based on N–NH4+ might be explained by mineralization rates, while the primary production based on N–NO3- was not fully explained by nitrification.

We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r2=0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production “saturated”. The δ15N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast.

We studied the role of small, highly stratified, sulfate and nutrient enriched estuaries, as a source or sink of inorganic nitrogen species, using the Qishon estuary at the Mediterranean coast of Israel, as a case study. Measurements of nutrient concentrations, δ15N and δ18O of nitrate+nitrite, δ13CDIC and δ18OH2O were performed during 2008–2009 along the upper-fresh and lower-saline water masses, as well as sediment porewater depth-profiles. Such estuaries are characterized by relatively low removal flux of NO3- (via sedimentary denitrification) and enhanced (×3) upward flux of NH4+ (via sulfate reduction), attributed to the penetration of seawater of low NO3- and high dissolved oxygen and sulfate concentrations. The role of such small estuaries in releasing dissolved inorganic nitrogen, especially in sensitive oligotrophic areas as the Levantine basin and in the long-term, as a result of enhanced seawater penetration due to the expected sea level rise, has important environmental policy implications.

MC252 oil:sand aggregates, termed surface residue balls (SRBs), were sampled for physical, chemical and microbial characteristics from different tidal zones on a coastal headland beach in Louisiana, USA. Supratidal SRBs were smaller, had low moisture content, and salinities that were <2ppt. Intertidal SRBs were hypersaline and had higher N and sulfate concentrations, consistent with regular tidal inundation. Crude oil components were highest in the intertidal “oil mat” SRBs with C1- and C2-phenanthrenes, C2- and C3-dibenzothiophenes comprising the majority of the PAH concentrations. In the other SRB categories, PAHs and alkanes were depleted and profiles were skewed toward higher molecular weight compounds. Oxygen microelectrode measurements demonstrated that saturated O2 is present immediately after wetting, but O2 consumption in the interior of the aggregate occurs after a few days. Microbial populations varied with position on the beach but sequences similar to known PAH-degrading taxa (Mycobacterium sp. and Stenotrophomonas sp.) were observed.

In laboratory experiments, the cold-water coral Lophelia pertusa was exposed to settling particles. The effects of reef sediment, petroleum drill cuttings and a mix of both, on the development of anoxia at the coral surface were studied using O2, pH and H2S microsensors and by assessing coral polyp mortality. Due to the branching morphology of L. pertusa and the release of coral mucus, accumulation rates of settling material on coral branches were low. Microsensors detected H2S production in only a few samples, and sulfate reduction rates of natural reef sediment slurries were low (<0.3nmolScm−3d−1). While the exposure to sediment clearly reduced the coral’s accessibility to oxygen, L. pertusa tolerated both partial low-oxygen and anoxic conditions without any visible detrimental short-term effect, such as tissue damage or death. However, complete burial of coral branches for >24h in reef sediment resulted in suffocation.

Hydroides elegans, a worldwide fouling polychaete, can spawn throughout the year, but its recruitment drops during summer when hypoxia prevails. Here, the influence of hypoxia on larval development and settlement of H. elegans was investigated. Results showed that larval development was compromised at 1mg O2 l−1 with a lower proportion of competent larvae and a higher proportion of malformed larvae, probably due to reduction in clearance rate. Regarding larval settlement, although most of the larvae were reluctant to settle at 1mg O2 l−1, regardless of the biofilm nature, they settled quickly within 24h in response to the resumption of dissolved oxygen. Furthermore, only about 5% of the larvae settled on the biofilms developed under hypoxia, regardless of dissolved oxygen levels of the seawater. The delayed larval development and potential alteration of biofilm nature owing to hypoxia explained why the recruitment of H. elegans declines during summer.

The effects of Si on growth, the anatomy of the roots, radial oxygen loss (ROL) and Fe/Mn plaque on the root surface were investigated in Avicennia marina (Forsk.) Vierh. seedlings under Cd stress. Si prompted the growth of seedlings and reduced the Cd concentration in the root, stem and leaf of A. marina. Si prompted the development of the apoplastic barrier in the roots, which may be related to the reduction of Cd uptake. The higher amount of ROL and Mn plaque on the root surface due to Si were also related to the promotion of Cd tolerance in A. marina seedlings. Therefore, it is concluded that the alteration of the anatomy of the roots, the increase of ROL and Mn plaque of A. marina seedlings play an important role in alleviation of Cd toxicity due to Si.

Arsenic (As) toxicity and the effects of nitric oxide (NO), supplied as sodium nitroprusside (SNP), were analyzed in Pistia stratiotes. The plants, which were grown in nutrient solution at pH 6.5, were exposed to four treatments for 24 h: control; SNP (0.1 mg L-1); As (1.5 mg L-1); and As + SNP (1.5 and 0.1 mg L-1). As accumulated primarily in the roots, indicating the low translocation factor of P. stratiotes. The As accumulation triggered a series of changes with increasing production of reactive oxygen intermediates and damage to cell membranes. The application of SNP was able to mitigate the harmful effects of As. This attenuation was probably due to the action of the SNP as an antioxidant, reducing the superoxide anion concentration, and as a signaling agent. Acting as a signal transducer, SNP increased the activity of enzymatic antioxidants (POX, CAT, and APX) in the leaves and stimulated the entire phytochelatins biosynthetic pathway in the roots (increased sulfate uptake and synthesis of amino acids, non-proteinthiols, and phytochelatins). The As also stimulated the phytochelatins biosynthesis, but this effect was limited, probably because plants exposed only to pollutant showed small increments in the sulfate uptake. Thus, NO also may be involved in gene regulation of sulfate carriers. © 2013 Springer Science+Business Media Dordrecht.

Volatile organic compounds (VOCs) are ubiquitous in marine areas in many parts of the world. Effect of environmental factors (light intensity, temperature, oxygen levels, and presence of sensitizer) on photodegradation of VOCs present in water-soluble fraction of Kuwait crude oil was investigated in laboratory conditions. The results showed that all factors investigated had significant effects on photo degradation rates. Higher temperatures produced faster degradation rates. At 15 °C, most of the volatile optimally degraded when light intensity was set at 750 W/m². Oxygen level of 7 ppm and presence of sensitizer was also required. Oxygen level of 4 ppm and light intensity of 500 W/m² and presence of a sensitizer produced optimal degradation rates for most of the compounds at 30 °C. At 40 °C, deoxygenated water-soluble fraction and light intensity of 500 W/m² produced the fastest degradation for many of the volatile compounds. Linear regression indicated that for most of the compounds temperature had the greatest effect on degradation rates.