A pot experiment was conducted to study the effect of 7 intercrops on Cd uptake by maize. The intercrops included cowpea (V. unguiculata (L.) Walp.), purple haricot (L. purpureus (L.) Sweet.), chickpea (C. arietinum L.), alfalfa (M. sativa L.), teosinte (E. mexicana Schrad.), amaranth (A. paniculatus L.) and rape (B. napus L.). The results showed that most legumes substantially increased Cd uptake by maize during vegetative growth. Leaf tissue of maize grown with legumes averaged 5.05 mg kg⁻¹ higher Cd than that grown with nonlegumes, or 2.42 mg kg⁻¹ higher than the control. However, the effect of intercrops on Cd uptake by maize became small during reproductive growth. Since chickpea resulted in a relatively large maize bioconcentration factor of 2.0 and large transfer factor of 0.55, it is regarded as the most valuable intercrop for enhancing Cd extraction from soil by maize. The results suggest that intercropping might be a feasible practice in facilitating phytoremediation.

The chemical, mineralogical, and leaching behavior of three dominant Greek forest species ashes (Pinus halepensis, Pistacia lentiscus, and Olea europaea), before and after treating forest species with diammonium phosphate (DAP) 5% and 10% weight to weight, have been studied using a new five-step shake leaching method at pH = 6. For the analysis of ashes (prior and after leaching) and leachants, the following analytical techniques were used: atomic absorption spectroscopy, X-ray diffraction, and scanning electron microscopy with energy dispersive X-ray fluorescence analysis. The presence of DAP obstructs the extraction process of some metal ions (i.e., Na, K) contained in ashes by converting the soluble carbonate salts to the less soluble phosphates (i.e., Na₂CO₃ [rightward arrow] Na₃PO₄). On the contrary, DAP enhances the mobility of some other metals (i.e., Ca) by forming more soluble compounds [i.e., CaCO₃ [rightward arrow] Ca₃(PO₄)₂]. In addition, the presence of DAP lowers the pH of leachates, causing dissolution of some toxic elements (i.e., Mn, Pb, Zn). Unexpectedly, DAP prevents the leachability of Cr from ash. The above study concerns the environmental effects (soil and ground and underground water streams) caused by the use of chemical retardants on forest fires.

Chemical processes in the rhizosphere play a major role in the availability of metals to plants. The objective of this study was to assess the potential of white lupin (Lupinus albus L.) for the phytoimmobilisation of heavy metals in a calcareous soil with high levels of Zn and Pb (2,058 and 2,947 μg g⁻¹, respectively) by evaluating the chemical changes in the rhizosphere, relative to bulk soil, which modify the solubility of heavy metals. Plants were cultivated for 74 days in specially designed pots (rhizopots) in which rhizosphere was sampled easily under controlled conditions. White lupin accumulated high concentrations of Mn in the shoots (average of 4,960 μg g⁻¹), well above the normal concentration in plants (300 μg g⁻¹). But the metal concentrations found in shoots were not at toxic levels. Rhizosphere soil showed a significantly greater redox potential (245 mV) and water-soluble organic carbon content (34.6 μg C g⁻¹) than bulk soil (227 mV; 27.6 μg C g⁻¹). Root activity decreased EDTA-extractable Pb, Zn and Fe and promoted their precipitation as insoluble compounds in the residual fraction (acid digestion), hardly available to plants. These results indicate the suitability of this annual N₂-fixing species for the initial phytoimmobilisation of heavy metals in contaminated soils.

Lake Koumoundourou is a shallow meromictic lake located ∼11 km NW of Athens. It is surrounded by various industries and oil refineries, which contaminate the lake by oil spills and leakage. Moreover, the lake receives freshwater from underwater springs, plus drainage from industrialized catchment and Athens landfill. Potential contamination of the lakes' sediments in heavy metals and metalloids was assessed by means of enrichment factors (EFs) estimated against local preindustrial core sediment; elements were normalized to loss on ignition. EFs revealed that surface sediments were enriched in Pb (×10.2), Cu (×6.7), V (×5.1), Ni (×4.1), and other heavy metals. The use of EFs is recommended as a reliable method for heavy metal contamination assessment, provided that (1) element contents are corrected following a careful normalization procedure, (2) local preindustrial sediment is used as reference, and (3) reference sediment should be unaffected by diagenetic alterations.

Episodic acidification of surface waters has been observed in the Great Smoky Mountains National Park, similar to other forested watersheds with base-poor bedrock in the eastern US receiving acids from atmospheric deposition. Three remote, forested, high-elevation streams were selected in the Little Pigeon River watershed for study; two of which brook trout have extirpated, and believed to have resulted from severe acidity during stormflows. This research characterized stream chemistry during episodes in order to better understand potential factors that contribute to rapid drops in pH and acid neutralizing capacity (ANC) during stormflows. Autosamplers initialized by sondes, collected samples during storm events for analysis of pH, ANC, cations, and anions over a 15-month period. ANC and pH depressions, and increased concentrations in sulfate, nitrate, and organic acids were observed for all storms at each study site. ANC contribution analysis indicated sulfate was the strongest contributor to ANC depressions, but nitrate, cation dilution, and organic acids were also significant in some cases. Acidic deposition appears to be the primary source of episodic acidification, supported also by the finding that larger stormflows preceded by long, dry periods resulted in significantly larger pH depressions. It appears stream acidification episodes may be driven by acid deposition. However, this study documents the variability of several ion contributors to observed stormflow ANC depressions illustrating the spatial and temporal complexity of watershed processes that influence this phenomenon.

The relation among the mean slope angle of a watershed, the stream water quality, and the chemical composition of the plagioclase component of granite was examined for 17 watersheds located in the southern part of the Northern Japan Alps in central Japan. The 17 watersheds were mainly composed of the granite. The ionic composition of the stream water can be classified into two patterns: the Ca-HCO₃-type and the Ca·Na-HCO₃-type. In all the watersheds, Na⁺ and Ca²⁺ occur in the groundwater that flows into the stream mainly due to the kaolinization of plagioclase. As compared to the watersheds with Ca-HCO₃-type stream water, the Na⁺/Ca²⁺ ratio for stream water in watersheds with Ca·Na-HCO₃-type stream water was closer to that for plagioclase in granite. This implies that the groundwater flowing in the Ca·Na-HCO₃-type watersheds is deeper than that in the Ca-HCO₃-type watersheds. The mean slope angle of Ca·Na-HCO₃-type watersheds was less acute as compared to that of Ca-HCO₃-type watersheds. The mean slope angle of the watersheds is negatively correlated with the Na⁺/Ca²⁺ ratio for stream water (r = -0.78, P <= 0.001). It is suggested that the groundwater quality at greater depths, which is comparable with the Na/Ca ratio of plagioclase, contributes more to the stream water quality in the gently sloping watersheds than in the steep watersheds. This study clarified that there is a close relation between the mean slope angle of watersheds and the depth of groundwater discharged to the stream. Moreover, it is believed that the relationship between the mean slope angle of watersheds and the Na⁺/Ca²⁺ ratio for stream water is an effective and simple index for understanding the relative depth of groundwater.

The recurrence of reports citing water quality impairments in watersheds is evidence that tools are needed to identify pollution sources and facilitate restoration efforts such as implementing total maximum daily limits (TMDLs) or best management practices (BMPs). Fecal bacteria in surface waters are one of the most commonly cited impairments to water quality. This study evaluated microbial source tracking (MST), specifically multiple antibiotic resistance (MAR) analysis, as a management tool to differentiate nonpoint source pollution into source groups. A library containing Escherichia coli (E. coli, EC) and fecal streptococci (FS) isolates from poultry (EC n = 282, FS n = 650), human (EC n = 152, FS n = 240), wildlife (EC n = 17, FS n = 43), horse (EC n = 79, FS n = 82), dairy cattle (EC n = 38, FS n = 42), and beef cattle (EC n = 49, FS n = 46) sources was created. The MAR analysis was conducted on the isolates using a profile of seven antibiotics. The antibiotic signatures of unknown source isolates from Elkhorn and Hickman Creek watersheds were evaluated against the library to determine the contributions of potential fecal inputs from the respective sources. Correct classification was >60% when analyzed at the human and non-human-level of classification. On a watershed basis, both watersheds produced similar results; inputs from non-human sources were the greatest contributors to nonpoint source pollution. The results from the multiple antibiotic resistance (MAR) analysis revealed that the information produced, coupled with knowledge of the watershed and its associated land uses, would be helpful in allocating resources to remediate impaired water quality in such watersheds.

The purpose of this study is to evaluate the combined Cr(VI) removal capacities of nonliving (untreated rubber wood sawdust, URWS) and living biomass (URWS-immobilized Acinetobacter haemolyticus) in a continuous laboratory scale downward-flow two column system. Synthetic solutions of Cr(VI) between 237 and 320 mg L⁻¹ were mixed with 1 g L⁻¹ brown sugar in a nonsterile condition. Final Cr(VI) of between 0 and 1.6 mg L⁻¹ indicate a Cr(VI) removal capacity of 99.8-100%. The bacterial Cr(VI) reduction capacity increased with column length. This study shows the feasibility of using the two column system consisting of living (bacteria) and nonliving biomass (URWS) as a useful alternative treatment for Cr(VI) contamination in the aqueous system.

The degradation of benzene in groundwater at concentrations as high as 2,000 mg L⁻¹ was studied using a four-column trickling-flow fixed-film biological reactor with recirculation. A decrease in the content of benzene was achieved, its concentration falling to 0.55 µg L⁻¹. On the contrary, high levels of diesel fuel were not diminished sufficiently with this mode of operation of the reactor. Thus, a submerged reactor was tested as a modification to the conventional trickling-flow configuration. This modified fixed-film reactor was effective when high loadings of diesel were present as an emulsion. The concentration of diesel was reduced from 2,000 to 0.12 mg L⁻¹ after 8 days of treatment. In both cases, the reactors were packed with a carbonaceous material and were operated in semibatch mode with recirculation. The final concentration of benzene fell below the permissible limit established by Mexican law, and the results for both pollutants also met the concentration limits required by the German law for drinking water, 0.001 mg L⁻¹ for benzene and 0.1 mg L⁻¹ for total hydrocarbons.

Gypsum-rich coatings found on buildings constructed with granitic rock ashlars have been studied, from both an urban and a rural area of the NW of Spain. Previous works have attributed gypsum to rock weathering by atmospheric pollution. Mineralogical, chemical, and physical data of coatings have allowed us to distinguish six different types of coatings formed in several ways. In most cases, they are originated by the deterioration calcium-rich plaster building materials. Sulfation of Ca-rich coatings, in situ gypsum dissolution and precipitation, and deposition of air pollution particles are the most important agents related to genesis of coatings. In fact, remains of plasters practically intact were found in some studied buildings. Also, data from coatings and rock ashlars suggest that gypsum-rich coatings are not formed by environment-rock interaction. Coatings located on different parts and façades of the buildings and submitted to different environmental conditions decay in a different way.