The majority of oil from oceanic oil spills (e.g. the recent accident in the Gulf of Mexico) converges on coastal ecosystems such as mangroves. Microorganisms are directly involved in biogeochemical cycles as key drivers of the degradation of many carbon sources, including petroleum hydrocarbons. When properly understood and managed, microorganisms provide a wide range of ecosystem services, such as bioremediation, and are a promising alternative for the recovery of impacted environments. Previous studies have been conducted with emphasis on developing and selecting strategies for bioremediation of mangroves, mostly in vitro, with few field applications described in the literature. Many factors can affect the success of bioremediation of oil in mangroves, including the presence and activity of the oil-degrading microorganisms in the sediment, availability and concentration of oil and nutrients, salinity, temperature and oil toxicity. More studies are needed to provide efficient bioremediation strategies to be applicable in large areas of mangroves impacted with oil. A major challenge to mangrove bioremediation is defining pollution levels and measuring recuperation of a mangrove. Typically, chemical parameters of pollution levels, such as polycyclic aromatic hydrocarbons (PAHs), are used but are extremely variable in field measurements. Therefore, meaningful mangrove monitoring strategies must be developed. This review will present the state of the art of bioremediation in oil-contaminated mangroves, new data about the use of different mangrove microcosms with and without tide simulation, the main factors that influence the success of bioremediation in mangroves and new prospects for the use of molecular tools to monitor the bioremediation process. We believe that in some environments, such as mangroves, bioremediation may be the most appropriate approach for cleanup. Because of the peculiarities and heterogeneity of these environments, which hinder the use of other physical and chemical analyses, we suggest that measuring plant recuperation should be considered with reduction in polycyclic aromatic hydrocarbons (PAHs). This is a crucial discussion because these key marine environments are threatened with worldwide disappearance. We highlight the need for and suggest new ways to conserve, protect and restore these environments.

Limnologists have regarded temporal coherence (synchrony) as a powerful tool for identifying the relative importance of local-scale regulators and regional climatic drivers on lake ecosystems. Limnological studies on Asian reservoirs have emphasized that climate and hydrology under the influences of monsoon are dominant factors regulating seasonal patterns of lake trophic status; yet, little is known of synchrony or asynchrony of trophic status in the single reservoir ecosystem. Based on monthly monitoring data of chlorophyll a, transparency, nutrients, and nonvolatile suspended solids (NVSS) during 1-year period, the present study evaluated temporal coherence to test whether local-scale regulators disturb the seasonal dynamics of trophic state indices (TSI) in a giant dendritic reservoir, China (Three Gorges Reservoir, TGR). Reservoir-wide coherences for TSICHL, TSISD, and TSITP showed dramatic variations over spatial scale, indicating temporal asynchrony of trophic status. Following the concept of TSI differences, algal productivity in the mainstream of TGR and Xiangxi Bay except the upstream of the bay were always limited by nonalgal turbidity (TSICHL−TSISD <0) rather than nitrogen and phosphorus (TSICHL−TSITN <0 and TSICHL−TSITP <0). The coherence analysis for TSI differences showed that local processes of Xiangxi Bay were the main responsible for local asynchrony of nonalgal turbidity limitation levels. Regression analysis further proved that local temporal asynchrony for TSISD and nonalgal turbidity limitation levels were regulated by local dynamics of NVSS, rather than geographical distance. The implications of the present study are to emphasize that the results of trophic status obtained from a single environment (reservoir mainstream) cannot be extrapolated to other environments (tributary bay) in a way that would allow its use as a sentinel site.

The objective of this study was to develop an index of biological integrity (IBI) for national-level monitoring of watersheds as an ecosystem health assessment methodology for the South Korean government. A 10-metric IBI model (IBIKW) was developed for watershed management and then applied to 76 streams in four major watersheds in Korea. The model assessments showed that 32.9% of all streams were judged to be in ‘excellent–good’ condition, whereas 67.1% were in ‘fair–poor’ condition, indicating severely impaired ecological health. Nutrient analyses of stream water revealed a two- to fivefold increase in nutrient and biological oxygen demand (BOD) levels in urban- and cropland-dominant streams compared to forest-dominant streams. The guild structure within the watersheds indicated that tolerant species were predominant in severely degraded regions (BOD > 6 mg L−1), and sensitive species were distributed in regions with BOD < 2 mg L−1. Factors affecting ecosystem health (IBIKW scores) included chemical water quality parameters, physical habitat parameters and land use around the stream. In particular, land use was one of the major factors influencing ecosystem health, as indicated by the strong relationships between the percentages of urban and forest streams and the IBIKW scores. The integrated ecosystem health assessment technique developed here can be applied for both regular bioassessments and post-restoration assessments.

This study investigated the storage of nitrogen (N) and phosphorus (P) in the biomass, bed sediments and water column of representative reaches of a sub-tropical river, the upper Brisbane River (UBR), Queensland, Australia, and contrasted instream storage with total wet season exports. In reaches which contained accumulated fine sediments, more than 87% of total P and between 50% and 92% of total N were stored in the surface sediments. The lower proportion of N in sediment at some sites was attributed to substantial differences in the N/P ratios of sediments and macrophytes. At one site, the riverbed was dominated by cobbles and boulders and total nutrient stocks were comparatively low and dominated by the biomass. In reaches with a narrow channel and intact riparian cover, biomass N and P were stored predominately in leaf litter, while in wider unshaded reaches, macrophytes dominated. Total instream storage in the mid to lower reaches of the UBR was ∼50.9 T for N and ∼18.1 T for P. This was considerably higher than total wet season N (∼15.6 T) and P (∼2.7 T) exports from the UBR. The first flow event in the river after a prolonged period of no flow resulted in the export of free-floating, emergent species Azolla. The estimated biomass of Azolla in the mid to lower reaches of the river was equivalent to approximately 24% and 9% of the total N and P flux, indicating that this may be a significant, previously unaccounted for, source at peak flow.

The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-β-estradiol (E2), and 17-α-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75 ± 3.89 ng/g. E2 was also found, with its concentration ranging from 0.90 ± 0.03 to 39.77 ± 1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO2 and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic.

Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil–water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil–water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the feasibility of bioremediation technology, in general, and its applicability for remediating LNAPLs polluted lands under aforesaid environments, in particular.

Agricultural runoff is a major non-point source pollutant and is the leading impairment of streams and rivers in the USA. This study examined the effects of agricultural, forest and urban land cover on water quality at the watershed level. Forty-three catchments ranging from 12 to 50 km2 were selected based on a land cover gradient within Lower Kaskaskia River Watershed in Illinois. Grab samples were collected and analyzed for nutrients, bacteria, and total suspended solids (TSS). Forest land cover was included in six of the ten regression models produced. Four of these regression models were for base flow conditions, suggesting that forest land cover had a significant impact on base flow water quality. Urban land cover was also included in six of the regression models. However, the majority were during storm flow conditions implying urban land cover had a greater impact on storm flow conditions. Watersheds were further categorized into agriculture, village, and urban watersheds. During base flow conditions agriculture watersheds had significantly higher TSS concentrations and urban watersheds had significantly higher ortho-P concentrations. In all watersheds, ortho-P concentrations were above the statewide 95th percentile for Illinois streams. Escherichia coli levels during storm conditions exceeded the national US EPA criteria.

A multiphase model based on the Mackay-type level II fugacity model has been used to predict the behaviour and final environmental concentrations of some of the more consumed pharmaceuticals in Spain. The model takes into account the mean rate of consumption of pharmaceuticals, the percentage of pharmaceutical metabolised, the formation of the corresponding glucuronide, which is assumed to be hydrolysed back to the parent molecule, the partial degradation of each pharmaceutical in a conventional sewage treatment plant, and the fate of these substances in a regional model environmental system. Predicted environmental concentrations in air, water, soil, sediments and suspended matter, and the corresponding residence time for each pharmaceutical have been obtained by application of the model. The predicted concentrations of pharmaceuticals in the water phase are of the same order than the measured experimentally, showing that the simple model used to predict the environmental concentrations is suitable for modelling the environmental fate of high water soluble and low volatile organic compounds such as pharmaceuticals products.

Lake Hallstättersee is a holomictic alpine lake, which is influenced by salt mining since the middle Bronze Age. Beside the constant saline waste water load, two massive brine spills loaded the lake with additional 16,900 tons sodium chloride (≈10,250 tons Cl−) from 1977 to 1979 and 3,000 tons salt (≈1,820 tons Cl−) in 2005. The effect of waste water intrusions from salt mining on stratification of Lake Hallstättersee was analysed over a period of 40 years. Water density, dissolved oxygen and total phosphorus (TP) concentrations were measured and an exponential model was fitted to describe the wash-out of chloride from Lake Hallstättersee after the brine spills. Furthermore, the time required returning to holomixis and steady chloride content after the second brine spill was estimated. During the whole sampling period the minimum and maximum volume-weighted annual mean chloride concentrations were 23.58 mg/L in 1979 and 3.19 mg/L in 1998. However, the mixing regime of Lake Hallstättersee, as well as the chloride concentrations, varied considerably and exhibited three holomictic and three meromictic periods between 1970 and 2009. Holomictic periods were observed when the yearly density gradient was below 0.06 kg/m3, deepwater oxygen in spring above 4 mg/L and consequently declining TP concentration in the deepest water layer below 60 mg/m3, otherwise meromictic periods were observed. Our study showed that Hallstättersee was 13 years ectogenic meromictic and 27 years holomictic during the study period.

The effects of municipal sewage sludge applied on topsoil and understory vegetation (Molinia caerulea (L.) Moench) were studied in a maritime pine forest located in the South West of France (Landes of Gascogne). Understory response to sludge application is important as sludge addition to forest could increase competition with pine and affect herbivorous wildlife through incorporation of heavy metals in the food chain. The experiment was conducted in a young stand of maritime pines. The experimental design consisted of three 0.1-ha plots. One plot received composted sludge, one plot received liquid sludge, and one control plot received no sludge. Liquid sludge and composted sludge were applied on the basis of 3 tons dry matter sludge per hectare and per year. After 2 years of sludge application, we observed the following: (1) a significant increase in total concentrations of the following major and trace elements in the topsoil (layer 0–20 cm) [organic carbon (+140%), nitrogen (+140%), and lead (+80%)] and (2) no significant accumulation of trace elements in M. caerulea except nickel, which increased moderately (+40%) following application of composted sludge. These initial results need to be completed (1) by the assessment of long-term effects and dynamics of trace elements with additional applications of sludge and (2) by analyzing secondary understory species to determine if understory response to sludge application is more dependant on species than on soil parameters and sludge type.