An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord,Western Sweden

In a 2.5-year-long environmental engineering experiment in the By Fjord, surface water was pumped into the deepwater where the frequency of deepwater renewals increased by a factor of 10. During the experiment, the deepwater became long-term oxic, and nitrate became the dominating dissolved inorganic nitrogen component. The amount of phosphate in the water column decreased by a factor of 5 due to the increase in flushing and reduction in the leakage of phosphate from the sediments when the sediment surface became oxidized. Oxygenation of the sediments did not increase the leakage of toxic metals and organic pollutants. The bacterial community was the first to show changes after the oxygenation, with aerobic bacteria also thriving in the deepwater. The earlier azoic deepwater bottom sediments were colonized by animals. No structural difference between the phytoplankton communities in the By Fjord and the adjacent Havsten Fjord, with oxygenated deepwater, could be detected during the experiment.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0524-9) contains supplementary material, which is available to authorized users.     

Arsenic Background Concentrations in Florida,U.S.A. Surface Soils: Determination and Interpretation

Background concentrations of soil arsenic have been used as an alternative soil cleanup criterion in many states in the U.S. This research addresses issues related to the interpretation of background concentrations of arsenic in near pristine soils in Florida. Total arsenic was measured in 448 taxonomic and geographic representative surface soil samples using USEPA Method 3052 (HCl-HNO 3 -HF, microwave digestion) and graphite furnace atomic absorption spectrophotometry analysis procedure. Values were log-normally distributed, with geometric mean and baseline concentration (defined as 95% of the expected range of background concentrations) providing the most satisfactory statistical results. An upper baseline concentration of 6.21 mg As/kg was estimated for undisturbed soils (n=267) compared to 7.63 mg As/kg for disturbed soils (n=181). Temporal trend of total soil arsenic concentrations from 1967 to 1989 paralleled decreased usage of arsenic in U.S. agriculture. Soil arsenic background concentrations were generally higher in south Florida than in north and central Florida, and associated with wet soils. Individual high arsenic sites were scattered throughout the state, but the most highly concentrated of these occurred in the Leon-Lee belt along the Ocala uplift district extending to the southwestern flatwoods district. Extrapolation of the data using a single arsenic value regardless of the taxonomic and geographical differences in soil arsenic distribution would underestimate potential arsenic contamination in upland soils.     

土壤-水稻/小麦重金属吸收机制与安全调控

为掌握我国水稻和小麦作物的重金属污染情况,收集了我国粮食主产区水稻/小麦-土壤系统中的砷(As)、镉(Cd)、铬(Cr)和铅(Pb)含量,综述了其吸收、转运、积累机制和有效的修复措施.结果表明,我国粮食主产区水稻及小麦籽粒的Cd超标率达31.3％和22.2％,Pb的超标率达26.2％和32.1％,污染情况较为突出;降低...     

Speciation and quantification of Hg in sediments contaminated by artisanal gold mining in the Gualaxo do Norte River,Minas Gerais,SE, Brazil

The Iron Quadrangle in SE Brazil was, in the eighteenth century, one of the most important Au producing regions of Brazil. In this region, gold is produced, even today, by artisanal methods that use Hg to increase the extraction efficiency with no control of Hg release to water systems and the atmosphere. In this context, the Gualaxo do Norte River is of particular interest; its springs are located in the Doce River basin, an important Brazilian basin that supplies water for 3.5 million people. The main goal of this work was to quantify and speciate the Hg in the sediments of the Gualaxo do Norte River using a direct mercury analyzer and gas chromatography-pyrolysis-atomic fluorescence detection system. Statistical analyses consisted of principal component analysis, aiming to assess interactions among elements and species and to group the variables in factors affecting the properties of sediment. The results show that total Hg (THg) and methylmercury (CH₃Hg⁺) concentrations in samples ranged from 209 to 1207 μg kg^?1 and from 0.07 to 1.00 μg kg^?1, respectively (methylation percentages from 0.01 to 0.27%). Thermal desorption analysis showed that mercury is mainly present in the oxidized form, and correlation analyses pointed to a relationship between THg and MnO, indicating that manganese can oxidize and/or adsorb Hg. Together, MO and CH₃Hg⁺ are important parameters in the third principal component, indicating the influence of OM on the methylation process. This first investigation on Hg methylation in this small-scale gold mining area points to the possibility of Hg bioaccumulation and to the need of better understanding the biogeochemical cycle of Hg in this area. Samples were collected in 2012, prior to the 2015 Fundão Dam disaster. The results are also a record of the characteristics of the sediment prior to that event.     

Phytoextraction by arsenic hyperaccumulator Pteris vittata L. from six arsenic-contaminated soils: Repeated harvests and arsenic redistribution

This greenhouse experiment evaluated arsenic removal by Pteris vittata and its effects on arsenic redistribution in soils. P. vittata grew in six arsenic-contaminated soils and its fronds were harvested and analyzed for arsenic in October, 2003, April, 2004, and October, 2004. The soil arsenic was separated into five fractions via sequential extraction. The ferns grew well and took up arsenic from all soils. Fern biomass ranged from 24.8 to 33.5 g plant(-1) after 4 months of growth but was reduced in the subsequent harvests. The frond arsenic concentrations ranged from 66 to 6,151 mg kg(-1), 110 to 3,056 mg kg(-1), and 162 to 2,139 mg kg(-1) from the first, second and third harvest, respectively. P. vittata reduced soil arsenic by 6.4-13% after three harvests. Arsenic in the soils was primarily associated with amorphous hydrous oxides (40-59%), which contributed the most to arsenic taken up by P. vittata (45-72%). It is possible to use P. vittata to remediate arsenic-contaminated soils by repeatedly harvesting its fronds.     

Sequential sorption of lead and cadmium in three tropical soils

It is important to examine mechanisms of Pb and Cd sorption in soils to understand their bioavailability. The ability of three tropical soils to retain Pb, Cd, and Ca was evaluated. The objectives of this study were to (1) determine the extent to which soil sorption sites are metal specific, (2) investigate the nature of reactions between metals and soil surfaces, and (3) identify how metals compete for sorption sites when they are introduced to soils sequentially or concurrently. Lead was shown to be much less exchangeable than Cd and inhibited Cd sorption. Cadmium had little effect on Pb sorption, though both Ca and Cd inhibited the adsorption of Pb at exchange sites. Lead appears to more readily undergo inner-sphere surface complexation with soil surface functional groups than either Cd or Ca. Thus, regardless of when Pb is introduced to a soil, it should be less labile than Cd.     

Smart regulation for water innovation – the case of decentralized rainwater technology

“Lead-markets”, “environmental innovations”, and “low-carbon technologies” are some of the modern buzz-words surrounding environmental regulation. But how can governments set the stage for industrial innovation, new and improved products, and the implementation of new, cleaner processes, products and services? The article explores this question with reference to sustainable water technologies, specifically the purchase of decentralized rainwater facilities. It is more ecologically sustainable to process rainwater locally than expanding drainage into the centralized system. However, the market for decentralized water technologies is still a niche one compared to centralized infrastructure. The article therefore evaluates regulative instruments in “smart” support of decentralized technologies.     

Occurrence of Norovirus GIV in Environmental Water Samples from Belém City,Amazon Region,Brazil

Noroviruses are the major cause of non-bacterial acute gastroenteritis outbreaks in humans, with few reports about the occurrence of the norovirus GIV strain. We investigated the presence of norovirus GIV in surface water (river, bay, and stream) and untreated sewage, and we determined a positivity rate of 9.4 % (9/96). The strains genotyped were GIV.1. To our knowledge, this is the first report of GIV in Brazil.     

The uptake and translocation of selected elements by cole (Brassica) grown using oasis soils in pot experiments

Pot experiments were conducted on cole (Brassica) grown in soils jointly treated with traces of two heavy metals cadmium (Cd) and zinc (Zn). As the concentration of heavy metals in the soil increased, the uptake of these metals by the plants rose. However, the ratio of heavy metal concentration in soil to uptake by plants increased at a slower rate. Bioavailability of heavy metals considered between the roots and soil using non-linear regressions was shown to be statistically significant. Similarly, the bioavailability of these two heavy metals between leaves and roots using a linear regression was also statistically significant. The bioconcentration factors (BCFs) for Cd and Zn were 0.282 and 4.289, respectively. Significant variation of BCF with the heavy metal bioavailability in soil was noted from non-linear models. The transfer factors (TFs) were 4.49 for Cd and 1.39 for Zn. The Zn concentration in leaves under all treatments did not exceed threshold set standards, but Cd levels exceeded these standards when the concentration of Cd in the soil was more than 1.92 mg kg^?1 dry weight (dw). Data indicate that cole (Brassica) is not a suitable crop for oasis soils because of plant contamination with heavy metals, especially Cd.