About 170 million tons of phosphogypsum (PG) are annually generated worldwide as a by-product of phosphoric acid factories. Agricultural uses of PG could become the main sink for this waste, which usually contains significant radionuclide (from the ²³⁸U-series) and toxic metals concentrations. To study PG effects on pollutant uptake by crops, a completely randomised greenhouse experiment was carried out growing Lycopersicum esculentum Mill L. on a reclaimed marsh soil amended with three PG rates (treatments), corresponding to zero (control without PG application), one, three and ten times the typical PG rates used in SW Spain (20 Mg ha⁻¹). The concentrations of Cd, Pb, U (by inductively coupled plasma mass spectroscopy) and ²²⁶Ra and ²¹⁰Po (by γ-spectrometry and α-counting, respectively) were determined in soil, vegetal tissue and draining water. Cadmium concentrations in fruit increased with PG rates, reaching 44 ± 7 μg kg⁻¹ formula weight with ten PG rates (being 50 μg kg⁻¹ the maximum allowed concentration by EC 1881/2006 regulation). Cd transfer factors in non-edible parts were as high as 4.8 ± 0.5 (dry weight (d.w.)), two orders of magnitude higher than values found for lead, lead, uranium and radium concentrations in fruit remained below the corresponding detection limits--0.5 and 0.25 mg kg⁻¹ and 0.6 mBq kg⁻¹, respectively (in a d.w. basis). ²³⁸U (up to 7 μg kg⁻¹ d.w.) and ²¹⁰Po (up to 0.74 Bq kg⁻¹ d.w.) could be measured in some fruit samples by α-spectrometry. Overall, the concentrations of these metals and radionuclides in the draining water accounted for less than 1% of the amount applied with PG.

Fecal pollution from human and natural sources enters soil or watercourses, mixes, then reemerges as a nuisance of unknown origin. Before remediation is attempted, the sources and identities of pollution must be identified. Previous microbial source tracking studies have relied on traditional methods of microbiology such as selective media and biochemical characteristics to quantify fecal bacteria in water samples. This is successful when single sources are responsible for pollution. However, when multiple sources are present, numbers must be subdivided into categories of pollution to define relative importance and select appropriate methods of remediation which are very different for examples such as humans and avifauna pollution. Rather than depending on a single method, we recommend a tiered approach which takes advantage of ecological parameters and conventional microbiology to provide context for more precise DNA data and related statistics.

This paper presents the development of a filtered stepwise clustering (FSC) method for facilitating the pump-and-treat (PAT) designs in groundwater remediation programs. To investigate the performances of different remediation strategies, a subsurface model is employed to simulate contaminant transport. Multivariate relationships between decision variables and selected modeling outputs are developed through the FSC method. Based on the developed statistical relationships, a set of possible outcomes for the remediation design can be presented; the solution space has been confined to a narrowed range. The proposed method can aid the PAT design by (a) quickly providing predicted outcomes given different remediation strategies and (b) directly locating the optimum remediation strategy for any outcome. The FSC method is examined through its application to a real-world aquifer remediation case in western Canada. The prediction results can help decision makers to evaluate the remediation design in an explicit way.

This study characterizes the effects of water-soil flooding volume ratio and flooding time on copper (Cu) desorption and toxicity following multiple floodings of field-collected soils from agricultural sites acquired under the Comprehensive Everglades Restoration Plan (CERP) in south Florida. Soils from four field sites were flooded with three water-soil ratios (2, 4, and 6 [water] to 1 [soil]) and held for 14 days to characterize the effects of volume ratio and flooding duration on Cu desorption (volume ratio and flooding duration study). Desorption of Cu was also characterized by flooding soils four times from seven field sites with a volume ratio of 2 (water) to 1 (soil) (multiple flooding study). Acute toxicity tests were also conducted using overlying waters from the first flooding event to characterize the effects of Cu on the survival of fathead minnows (Pimephales promelas), cladocerans (Daphnia magna), amphipods (Hyalella azteca), midges (Chironomus tentans), duckweed (Lemna minor), and Florida apple snails (Pomacea paludosa). Acute tests were also conducted with D. magna exposed to overlying water from the second and third flooding events. Results indicate that dissolved Cu concentrations in overlying water increased with flooding duration and decreased with volume ratio. In the multiple flooding study, initial Cu concentrations in soils ranged from 5 to 223 mg/kg (dw) and were similar to Cu concentration after four flooding events, indicating retention of Cu in soils. Copper desorption was dependent on soil Cu content and soil characteristics. Total Cu concentration in overlying water (Cuw) was a function of dissolved organic carbon (DOC), alkalinity, and soil Cu concentration (Cus): log(Cuw) = 1.2909 + 0.0279 (DOC) + 0.0026 (Cus) - 0.0038 (alkalinity). The model was validated and highly predictive. Most of the desorbed Cu in the water column complexed with organic matter in the soils and accounted for 99% of the total dissolved Cu. Although total dissolved Cu concentrations in overlying water did not significantly decrease with number of flooding events, concentrations of free Cu²⁺ increased with the number of flooding events, due to a decrease in DOC concentrations. The fraction of bioavailable Cu species (Cu²⁺, CuOH⁺, CuCO₃) was also less than 1% of the total Cu. Overlying water from the first flooding event was only acutely toxic to the Florida apple snail from one site. However, overlying water from the third flooding of six out of seven soils was acutely toxic to D. magna. The decrease in DOC concentrations and increase in bioavailable Cu²⁺ species may explain the changes in acute toxicity to D. magna. Results of this study reveal potential for high Cu bioavailability (Cu²⁺) and toxicity to aquatic biota overtime in inundated agricultural lands acquired under the CERP.

Current-year, 1-year-old, and 2-year-old needles were collected separately on 37 black spruce (Picea mariana Mill. B.S.P.) trees located on a heavy metal contamination gradient around the smelter in Murdochville, Québec (Canada). Needles were analyzed separately by year for the concentrations of Pb and Cu, a nonessential and an essential metal, respectively. Lead concentrations increased significantly with needle age in the highly contaminated area near the smelter. In contrast, Cu concentrations decreased with needle age in the same area. Our results support the hypothesis that the passive sequestration of toxic metals in the senescing foliage is a detoxification process contrasting with the active translocation of essential metals in the nonsenescent part of the foliage.

Impairment of water quality is a major concern for streams and rivers in the central USA. Total maximum daily loads (TMDLs) establish a watershed framework and set management targets to alleviate pollution from both point and nonpoint sources. For this study, we have used a hydrologic modeling approach to holistically examine the effect of land use management, urban development, and agricultural practices on sediment and nutrient loadings in an agricultural watershed. Annualized Agricultural Nonpoint Source (AnnAGNPS) simulation indicates that while point source dischargers contribute 8% of total nitrogen (TN) and 24% of total phosphorus (TP) loadings to the Marmaton River, agricultural nonpoint sources are the leading pollution source contributing 55% of TN and 49% of TP loading. Based on TMDL analysis and model simulation, 3% of the watershed area (3,244 ha) needs to be targeted to control TN loading whereas 1% of the total area (1,319 ha) is required for TP reduction management. Managing the TN areas alone can achieve a 57% reduction in the TP load required for the TMDL, whereas managing the targeted TP areas can only provide 30% of the required TN reduction. Areas required both TN and TP management comprise 469 ha. Targeting these areas can achieve approximately 22% of the required TN reduction and 29% of the required TP reduction. Overall, 4,094 ha will require management to achieve water quality goals. This study demonstrates that a modeling approach is needed to effectively address TMDL issues and help identify targeted areas for management.

This research evaluated the efficiency of a mesocosm scale bioreactor to remove Mn from a synthetic mine drainage in the presence of selected organic and inorganic substrate combinations that could enhance sulfate reduction and induce Mn sulfide precipitation. The mine drainage tested was slightly acidic (pH 6.2) and had average Mn and SO₄ concentrations of 90 and 1,500 mg/L, respectively. The substrates used were creek sediment amended with either wood mulch or a wood mulch and biosolid mixture. Greater than 90% of Mn and 70% of sulfate was removed over a 65-day test period. The results suggested multiple Mn removal mechanisms including sorption, complexation, and Mn sulfide, Mn oxide, and/or Mn carbonate precipitation.

The distribution and geochemical behavior of nonylphenol (NP) in suspended and settling particles were studied in Lake Biwa, Japan. The vertical distribution of the particulate nonylphenol (PNP)/particulate organic carbon (POC) ratio showed a characteristic and hitherto unreported profile. The ratio was low at the surface, increased with depth to the middle layer before reaching a maximum at a depth of 45 or 65 m, and decreased toward the bottom. This profile is thought to have been due to the particulate organic matter (POM) in the lake being either freshly produced or aged POM and because the aged POM has a relatively higher affinity for NP compared to freshly produced POM. This idea was supported by the statistical analysis of physicochemical data (PNP, POC and chlorophyll a) and because the average PNP/POC ratio in the aged POM (2.24 x 10⁻⁵ g/g) was approximately four times higher than that of the freshly produced POM (0.63 x 10⁻⁵ g/g). The settling flux was estimated to be 2.2-6.4 μg/m²/day.

The need for solutions to minimize the negative environmental impacts of anthropogenic activities Fhas increased. Sewage sludge is composed of predominantly organic matter and can be used to improve soil characteristics, such as fertility. Therefore, its application in agriculture is an adequate alternative for its final disposal. However, there is a lack of information on its long-term effects on soil changes in tropical areas. Thus, the objectives of this study were to determine (i) the effect of sewage sludge application on heavy metal build-up in soil and maize grains and leaves, and (ii) the effects of soil amendment with sewage sludge on the chemical properties of a Brazilian oxisol. Besides the increasing levels of Zn, Cu, Ni, and Cr, amending soil with sewage sludge also alters the distribution of these metals by increasing the mobile Phases, which correlated significantly with the increase in metal extraction with two single extractants, Mehlich 1 and DTPA (Diethylene triamine pentaacetic acid). The levels of Fe, Mn, Zn, and Cu in maize grains and leaves increased with the type and rate of sewage sludge application. Nevertheless, metal build-up in soil and plants was within the allowed limits. Significant differences were also found in soil characteristics like humic fractionation with the applied sewage doses. The data obtained does not indicate any expressive drawbacks in the use of sewage sludge as a soil amendment, as the heavy metal concentrations observed are unlikely to cause any environmental or health problems, even overestimated loadings, and are in accordance with the Brazilian regulations on farming land biosolid disposal.

Roe deer (Capreolus capreolus) antlers are a useful tool for historical biomonitoring because they accumulate potential bone-seeking pollutants (Pb) and are naturally standardized environmental samples. Lead concentrations were measured in 45 antlers of roe deer, shot in the period 1925-2003 in the Upper Meža Valley, Slovenia, where lead production started at the end of the nineteenth century. Extremely high levels of lead were determined in the antlers (mean (SD) 54.7 (33.5) mg/kg, dry weight; range 2.69-554 mg/kg), exceeding previously reported levels of Pb in roe deer antlers from Europe. After the cessation of primary lead production in 1989, lead levels in antlers have been declining but are still high (period 2000-2003: mean (SD) 5.81 (6.60) mg/kg; range 2.69-7.74 mg/kg) compared with other areas of Slovenia. Spatial comparison confirmed that the lead contamination declines with distance from the emission source. The study confirmed the exceptional potential of roe deer antlers as a bioindicator of lead contamination of the environment.