The water used by 85% of the Asian population originates in Tibetan Plateau. During April and May of 2006, water samples were collected from four major Asian rivers in the Plateau (i.e. the Salween, Mekong, Yangtze River and Yarlung Tsangpo) and analyzed for Cu, Pb, Zn, Ag, Mo, Cd, Co, Cr, Ni, Li, Mn, Al, Fe, Mg and Hg. The results showed that elements such as Mg were rather high in Tibetan rivers, giving a mean electrical conductance of 36 mS/m. In a few locations, the results also showed relatively high concentrations of Al and Fe (>1 mg/L). However, the concentrations of Cu, Zn, Ag, Cd, and Cr were generally low. Contamination with Pb was identified at a few locations in the Salween and Ni at a few sites in the Yangtze River. For the first time, total dissolved metal contents in source water of four major Asian rivers were evaluated at the same time.

We examined acute (2 h exposure of 5-day-old larvae) and subchronic (exposure from fertilization up to an age of 11 days) effects of NiCl2·6H2O on embryos and larvae of zebrafish (Danio rerio), both alone and in combination with oxygen depletion. The following endpoints were recorded: acute exposure: locomotory activity and survival; subchronic exposure: hatching rate, deformations, locomotory activity (at 5, 8 and 11 days) and mortality. In acute exposures nickel chloride (7.5-15 mg Ni/L) caused decreasing locomotory activity. Oxygen depletion (<=2.45 ± 0.16 mg O2/L) also resulted in significantly reduced locomotory activity. In the subchronic test, exposure to >=10 mg Ni/L resulted in delayed hatching at an age of 96 h, in decreased locomotory activity at an age of 5 days, and increased mortality at an age of 11 days (LC20 = 9.5 mg Ni/L). The observed LOEC for locomotory activity (7.5 mg Ni/L) is in the range of environmentally relevant concentrations. Since locomotory activity was already affected by acute exposure, this parameter is recommended to supplement commonly recorded endpoints of toxicity. Increasing concentrations of nickel chloride and decreasing concentrations of oxygen lead to reduced vitality and locomotory activity in Danio rerio embryos and larvae.

Two types of polar organic chemical integrative samplers (pharmaceutical POCIS and pesticide POCIS) were examined for their sampling efficiency of selected endocrine disrupting compounds (EDCs). Laboratory-based calibration of POCISs was conducted by exposing them at high and low concentrations of 14 EDCs (4-alkyl-phenols, their ethoxylate oligomers, bisphenol A, selected estrogens and synthetic steroids) for different time periods. The kinetic studies showed an integrative uptake up to 28 days. The sampling rates for the individual compounds were obtained. The use of POCISs could result in an integrative approach to the quality status of the aquatic systems especially in the case of high variation of water concentrations of EDCs. The sampling efficiency of POCISs under various field conditions was assessed after their deployment in different aquatic environments. Calibration and field performance of polar organic integrative samplers for monitoring EDCs in aquatic environments.

Laboratory tests of fipronil and its degradation products have revealed acute lethal toxicity at very low concentrations (LC50) of <0.5 μg/L to selected aquatic macroinvertebrates. In streams draining basins with intensive rice cultivation in southwestern Louisiana, USA, concentrations of fipronil compounds were an order of magnitude larger than the LC50. The abundance (ρ = -0.64; p = 0.015) and taxa richness (r2 = 0.515, p < 0.005) of macroinvertebrate communities declined significantly with increases in concentrations of fipronil compounds and rice-cultivation land-use intensity. Macroinvertebrate community tolerance scores increased linearly (r2 = 0.442, p < 0.005) with increases in the percentage of rice cultivation in the basins, indicating increasingly degraded stream conditions. Similarly, macroinvertebrate community-tolerance scores increased rapidly as fipronil concentrations approached about 1 μg/L. Pesticide toxicity index determinations indicated that aquatic macroinvertebrates respond to a gradient of fipronil compounds in water although stream size and habitat cannot be ruled out as contributing influences. Aquatic macroinvertebrate commmunities in southwestern Louisiana streams respond to a gradient of fipronil compounds in water.

The objective of this study was to investigate the accumulation of selenium in lakes downstream of a uranium mine operation in northern Saskatchewan, Canada. Selenium concentrations in sediment and biota were elevated in exposure areas even though water concentrations were low (<5 μg/L). The pattern (from smallest to largest) of selenium accumulation was: periphyton < plankton and filterer invertebrates < detritivore and predator invertebrates < small bodied (forage) fish and predatory fish. Biomagnification of selenium resulted in an approximately 1.5–6 fold increase in the selenium content between plankton, invertebrates and forage fish. However, no biomagnification was observed between forage fish and predatory fish. Selenium content in organisms from exposure areas exceeded the proposed 3–11 μg/g (dry weight) dietary toxicity threshold for fish, suggesting that the selenium released into these aquatic systems has the potential to bioaccumulate and reach levels that could impair fish reproduction. Selenium bioaccumulation patterns in a north temperate, cold water aquatic ecosystem were similar to those reported from warm water systems.

In order to estimate acute-to-chronic toxicity ratios (ACRs) relevant to a coldwater stream community, we exposed rainbow trout (Oncorhynchus mykiss) to cadmium (Cd), lead (Pb), and zinc (Zn) in 96-h acute and 60+ day early-life stage (ELS) exposures. We also tested the acute and sublethal responses of a mayfly (Baetis tricaudatus) and a midge (Chironomus dilutus, formerly C. tentans) with Pb. We examine the statistical interpretation of test endpoints and the acute-to-chronic ratio concept. Increasing the number of control replicates by 2 to 3x decreased the minimum detectable differences by almost half. Pb ACR estimates mostly increased with increasing acute resistance of the organisms (rainbow trout ACRs <[almost equal to] mayfly < Chironomus). The choice of test endpoint and statistical analysis influenced ACR estimates by up to a factor of four. When calculated using the geometric means of the no- and lowest-observed effect concentrations, ACRs with rainbow trout and Cd were 0.6 and 0.95; Zn about 1.0; and for Pb 3.3 and 11. The comparable Pb ACRs for the mayfly and Chironomus were 5.2 and 51 respectively. Our rainbow trout ACRs with Pb were about 5-20x lower than earlier reports with salmonids. We suggest discounting previous ACR results that used larger and older fish in their acute tests.

Adenoviruses are emerging pathogens which may represent new indicators of microbial water quality. In the present study, environmental samples of seawater, estuarine water, and influents of sewage treatment plants underwent both standard bacteriological and viral analyses (adenovirus identification, typing and quantification) in order to evaluate the role of surface water contamination as a possible vehicle for the transmission of adenovirus, and the relevance of adenoviruses as an additional tool in water quality assessment. Qualitative PCR methods were used for the detection and typing of adenoviruses. This was done through the sequencing and phylogenetic analysis of segments of the hexon- and fiber-coding regions of the viral genome. Subsequently, quantitative PCR assays based on TaqMan probe hydrolysis technology were used to assess virus concentrations in environmental samples. Results showed a widespread presence of adenovirus in the environment, even in the absence of bacterial indicators, confirming the relevance of evaluating these viruses as possible indicators of viral contamination of water.

Historic and current agricultural and industrial activities have resulted in accumulation of Cd, Cu, Pb and Zn in soil. To estimate potential risks for ecosystems, agriculture and water quality, an integrated risk assessment was performed for The Netherlands. Risks of metal contamination were assessed on a national scale by comparing present soil concentrations of Cd, Pb, Cu and Zn with critical concentrations of those metals in view of agricultural impacts, ecological impacts and impacts on the quality of groundwater and surface waters. Results show that present soil metal concentrations cause few risks for agriculture or ecosystems; for less than 2% of the surface area present metal levels exceed critical limits. Critical limits for groundwater are only significantly exceeded for Pb (17% of the area), but critical limits for surface water are exceeded throughout the country for Cu and Zn. Taking critical limits used in The Netherlands, the area where exceedances take place is nearly negligible for Cd and low for Pb (less than 3%), but much larger (between 40% and 50%) for both Cu and Zn. Results from this study suggest that accumulation of heavy metals in Dutch soils at present primarily affects the quality of surface waters. This stresses the need for harmonization of soil and water policy. Measures to reduce the load in surface waters to meet target levels, under conditions like those prevailing in The Netherlands, are bound to have an impact on land management.

Inorganic nitrogen deposition and leaching in stream water were monitored from January, 2001 to December, 2004 in a subtropical evergreen mixed forest in central-south China. The seasonal concentration and flux of inorganic nitrogen in bulk precipitation and stream water, seasonal mean net retention of nitrogen and net flux of H⁺ transformed by nitrogen were estimated and quantified in Shaoshan forest. The research results show that the correlation coefficient of fluxes between bulk precipitation and stream water is significant, with a coefficient 0.916 at the 0.01 level. Mean fluxes of inorganic nitrogen input are 2.62 g m⁻² a⁻¹ and 0.516 g m⁻² a⁻¹ in form of bulk precipitation and dry deposition respectively, and output in stream water is around 0.22 g m⁻² a⁻¹, which indicates that most of nitrogen input is reserved in the forest. Net retention of nitrogen reaches 2.916 g m⁻² a⁻¹, just higher than other study plots over the world. Along with the translating of nitrogen ( [graphic removed] and [graphic removed] ), H⁺ is imported to the forest ecosystem at the same time. At our study plots, net flux of H⁺ transformed by nitrogen is about 73.57 mmol m⁻² a⁻¹. The positive value suggests that Shaoshan forest is still a finer buffering system to nitrogen deposition and it is far from nitrogen saturation in spite of the high nitrogen deposition.

Intensive cultivation of fen peat soils (Eutric Histosols) for agricultural purposes, started in Europe about 250 years ago, resulting in decreased soil fertility, increased oxidation of peat and corresponding CO₂-emissions to the atmosphere, nutrient transfer to aquatic ecosystems and losses in the total area of the former native wetlands. To prevent these negative environmental effects set-aside programs and rewetting measures were promoted in recent years. Literature results and practical experiences showed that large scale rewetting of intensively used agricultural Histosols may result in the mobilisation of phosphorus (P), its transport to adjacent surface waters and an accelerated eutrophication risk. The paper summarises results from an international European Community sponsored research project and demonstrates how results obtained at different scales and from different scientific disciplines were compiled to derive a strategy to carry out rewetting measures. A decision support system (DSS) for a hydrologically sensitive area in the Droemling catchment in north-eastern Germany was developed and is presented as a tool to regulate rewetting in order to control P release. It is demonstrated that additional laboratory experiments to identify essential processes of P release during rewetting and the site-specific management of the water table, the involvement of specific knowledge and experience of the stakeholders are necessary to develop an applicable DSS. The presented DSS is practically used to prevent freshwater resources from diffuse P pollution.