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We describe continental-scale increases in lake and stream total phosphorus (TP) concentrations, identified through periodic probability surveys of thousands of water bodies in the conterminous U.S. The increases, observed over the period 2000-2014 were most notable in sites in relatively undisturbed catchments and where TP was initially low (e.g., less than 10 µg L-1). Nationally, the percentage of stream length in the U.S. with TP ≤ 10 µg L-1 decreased from 24.5 to 10.4 to 1.6% from 2004 to 2009 to 2014; the percentage of lakes with TP ≤ 10 μg L-1 decreased from 24.9 to 6.7% between 2007 and 2012. Increasing TP concentrations appear to be ubiquitous, but their presence in undeveloped catchments suggests that they cannot be entirely attributed to either point or common non-point sources of TP. [ABSTRACT FROM AUTHOR]

Assessments of acidic deposition effects on aquatic ecosystems have often been hindered by complications from naturally occurring organic acidity. Measurements of pH and ANCG, the most commonly used indicators of chemical effects, can be substantially influenced by the presence of organic acids. Relationships between pH and inorganic Al, which is toxic to many forms of aquatic biota, are also altered by organic acids. However, when inorganic Al concentrations are plotted against ANC (the sum of Ca2+, Mg2+, Na+, and K+, minus S042, N03-, and CI-), a distinct threshold for Al mobilization becomes apparent. If the concentration of strong organic anions is included as a negative component of ANC, the threshold occurs at an ANC value of approximately zero, the value expected from theoretical charge balance constraints. This adjusted ANC is termed the base-cation surplus. The threshold relationship between the base-cation surplus and Al was shown with data from approximately 200 streams in the Adirondack region of New York, during periods with low and high dissolved organic carbon concentrations, and for an additional stream from the Catskill region of New York. These results indicate that (1) strong organic anions can contribute to the mobilization of inorganic Al in combination with S042- and N03-, and (2) the presence of inorganic Al in surface waters is an unambiguous indication of acidic deposition effects. [ABSTRACT FROM AUTHOR]

Inorganic aluminum (Al) concentrations are critical for defining the biological effects of acidification. The landscape's role in controlling the spatial variability of Al and its speciation has received only limited attention. We analyzed the speciation of stream Al at 14 sites within a 68 km² boreal catchment during spring snowmelt, a period of episodic acidity. Three factors that influenced Al at these sites were landscape type (specifically the proportion of wetland areas), stream pH, and dissolved organic carbon (DOC). Forested catchment sites underlain by mineral soils had higher total Al concentrations and greater inorganic Al proportions than catchments with larger wetland areas, despite significantly higher pH. We suggest that this difference results from source limitation of Al in the peat wetlands. The control of Al solubility was dominated by organic complexes, with the organic carrying capacity exceeding Al in the majority of samples. When assessing the inorganic phase, only four percent of the samples were oversaturated with regards to commonly forming secondary Al minerals, with no samples showing supersaturation higher than 10 times with respect to any given solid phase. Inorganic Al rarely exceeded biological thresholds, except for short periods during peak flow in forested areas, despite two-thirds of the streams having minimum pH values below 4.9. Streams with a high percentage of wetland area were associated with lower Al:DOC ratios. The Al:DOC ratios were quite stable in each stream before, during, and after snowmelt, with the exception of isolated spikes in the Al:DOC ratio associated with particulate Al at a downstream site during high flow. [ABSTRACT FROM AUTHOR]

This article focuses on the reasons of decline in fish catches in Swiss rivers. The decline in the inland fish catches has become a topical issue in many countries. In Switzerland, the reported fish catch in streams and rivers has declined by 60% since the early 1980s. This trend has also been accompanied by deterioration in fish health. The authorities and the public were alerted to the first indications of fish decline in the country in the 1970s. The Swiss researchers and authorities initiated Fischnetz (Netzwerk Fischrückgang Schweiz; Project on declining fish catches in Switzerland) in 1998. This nationwide research was conducted for five years until the project's completion in January 2004. At the end of the project, the researchers agreed that more than one factor is responsible for the vanishing of fishes. Some of these factors were: impairment in health and fitness of fishes; the poor morphological quality and longitudinal connectivity of rivers; and harmful effects of chemical pollution.

The article features the 2,300-mile-long Mississippi river that flows through 10 U.S. states and serves millions of Americans. The river serves as a channel for commercial shipping. This means that this river is a source of drinking water and a home to diverse wildlife species. According to a report from the National Research Council committee that when it comes to keeping the river free from pollution, the Big Muddy is just an orphan. The river suffers from lack of oversight, in which states regard the Mississippi as a federal responsibility.