Non-interactive effects drive multiple stressor impacts on the taxonomic and functional diversity of atlantic stream macroinvertebrates.

Freshwaters are considered among the most endangered ecosystems globally due to multiple stressors, which coincide in time and space. These local stressors typically result from land-use intensification or hydroclimatic alterations, among others. Despite recent advances on multiple stressor effects, current knowledge is still limited to manipulative approaches minimizing biological and abiotic variability. Thus, the assessment of multiple stressor effects in real-world ecosystems is required. Using an extensive survey of 50 stream reaches across North Portugal, we evaluated taxonomic and functional macroinvertebrate responses to multiple stressors, including marked gradients of nutrient enrichment, flow reduction, riparian vegetation structure, thermal stress and dissolved oxygen depletion. We analyzed multiple stressor effects on two taxonomic (taxon richness, Shannon-diversity) and two trait-based diversity indices (functional richness, functional dispersion), as well as changes in trait composition. We found that multiple stressors had additive effects on all diversity metrics, with nutrient enrichment identified as the most important stressor in three out of four metrics, followed by dissolved oxygen depletion and thermal stress. Taxon richness, Shannon-diversity and functional richness responded similarly, whereas functional dispersion was driven by changes in flow velocity and thermal stress. Functional trait composition changed along a major stress gradient determined by nutrient enrichment and oxygen depletion, which was positively correlated with organisms possessing fast-living strategies, aerial respiration, adult phases, and gathering-collector feeding habits. Overall, our results reinforce the need to consider complementary facets of biodiversity to better identify assembly processes in response to multiple stressors. Our data suggest that stressor interactions may be less frequent in real-word streams than predicted by manipulative experiments, which can facilitate mitigation strategies. By combining an extensive field survey with an integrative consideration of multiple biodiversity facets, our study provides new insights that can help to better assess and manage rivers in a global change context.

Combined effects of land-use intensification and plant invasion on native communities.

Land-use intensification (LUI) and biological invasions are two of the most important global change pressures driving biodiversity loss. However, their combined impacts on biological communities have been seldom explored, which may result in misleading ecological assessments or mitigation actions. Based on an extensive field survey of 445 paired invaded and control plots of coastal vegetation in SW Spain, we explored the joint effects of LUI (agricultural and urban intensification) and invasion on the taxonomic and functional richness, mean plant height and leaf area of native plants. Our survey covered five invasive species with contrasting functional similarity and competitive ability in relation to the native community. We modeled the response of native communities for the overall and invader-specific datasets, and determined if invader-native functional differences could influence the combined impacts of LUI and invasion. Overall, we found that urban intensification reduced taxonomic richness more strongly at invaded plots (synergistic interactive effects). In contrast, functional richness loss caused by urban intensification was less pronounced at invaded plots (antagonistic interactive effects). Overall models showed also that urban intensification led to reduced mean leaf area, while agriculture was linked to higher mean plant height. When exploring invader-specific models, we observed that the combined effects of agricultural and urban intensification with invasion were heterogeneous. At invaded plots, invader-native functional differences accounted for part of this variability. Our findings demonstrate the importance of considering the interactive effects of global change pressures for a better assessment and management of ecosystems.

[A preliminary experience in the laparoscopic approach to bowel obstruction]. / Experiencia inicial en el abordaje laparoscópico de la obstrucción intestinal.

BACKGROUND: The laparoscopic approach to bowel obstruction is still controversial. OBJECTIVE: To evaluate our initial results in the laparoscopic treatment of bowel obstruction. MATERIAL AND METHODS: A retrospective study on patients diagnosed with bowel obstruction that underwent laparoscopic surgery within the time frame of January 2008 to June 30, 2012. The variables employed were: age, sex, occlusion etiology, previous surgeries, clinical progression, pneumoperitoneum creation, use of an auxiliary incision, anesthesia duration, conversion rate, postoperative hospital stay, time needed to tolerate liquids, and complications. RESULTS: Twenty-six patients, 18 women (69.2%) and 8 men (30.8%), with a mean age of 64.35 years (range: 21-92 years) were analyzed. The most frequent obstruction etiology was secondary to adhesions and presented in 12 cases. Nine patients (34.6%) underwent a completely laparoscopic approach and laparoscopy was complemented by an auxiliary incision in another 9 patients (34.6%), resulting in 18 cases (69.2%) of successful laparoscopic approach. Eight patients (30.8%) required conversion to open surgery. The mean anesthesia duration was 95min (range: 55-165min), mean postoperative hospital stay was 6 days (range: 3-72 days), and the mean amount of time needed to tolerate liquids was 3 days (range: 1-10 days). The patients that underwent complete laparoscopic approach presented with shorter hospital stay, they were able to ingest liquids earlier, and they presented with a lower number of postoperative complications; this latter variable was the only one that was statistically significant. CONCLUSIONS: The initial results of our experience were good, although more patients are needed in order to standardize and extend the use of this technique.

[Ictal nystagmus: acquired nystagmus of infrequent cause in pediatrics]. / Nistagmo ictal: causa infrecuente de nistagmo adquirido en pediatría.

Ictal nystagmus is a rare phenomenon secondary to an epileptic seizure, usually in the temporo- occipital region. For its characterization, we must rely on clinical history, examination, and ideally observation of the episodes. OBJECTIVES: To describe a case of this unusual entity and highlight the characteristics that should increase diagnostic suspicion in order to avoid treatment delay. CLINICAL CASE: An 8-year-old schoolboy, with no relevant history, consulted due to 5-6 episodes a day in the last year of conjugate horizontal eye movements with rapid jerks and associated slight miosis, lasting 5-10 seconds, with doubtful disconnection from the environment or consciousness impairment in some of the episodes, with no other accompanying signs or symptoms. Neurological examination between episodes was normal. He was evaluated by ophthalmology and otolaryngology, which ruled out pathology in these areas. Video-electroencephalogram showed electro-clinical correlations, with epileptiform activity in the left temporal and occipital region, which subsequently generalized during episodes. Brain MRI showed no pathological findings. After initiation of carbamazepine treatment, the patient had a good evolution, without recurrence of the episodes at 2 years of follow-up. CONCLUSIONS: When faced with a case of acquired nystagmus, epileptic etiology should be included in the differential diagnosis, especially if the frequency of episodes is high, of short duration, and associated with consciousness impairment. The diagnosis is based on a video-electroencephalogram with electro-clinical correlations and a good response to treatment with antiepileptic drugs is expected.

Remote sensing depicts riparian vegetation responses to water stress in a humid Atlantic region.

Riparian areas in the Cantabrian Atlantic ecoregion (northwest Portugal) play a key role in soil formation and conservation, regulation of nutrient and water cycle, creation of landscape aesthetic value and the preservation of biodiversity. The maintenance of their ecological integrity is crucial given the ever increase in multiple anthropogenic (water demand and agriculture) and climatic pressures (droughts and extreme events). We developed a transferable remote sensing approach, taking advantage of the latest freely available technologies (Sentinel-2 and Copernicus Land products), to detect intra-annual and inter-annual changes in riparian vegetation productivity at the river basin scale related to water stress. This study has used the normalized difference vegetation index (NDVI) to investigate riparian vegetation productivity dynamics on three different vegetation types (coniferous, broadleaved and grassland) over the past 5 years (2015-2019). Our results indicated that inter-annual seasonality differed between drier (2017) and wetter (2016) years. We found that intra-annual dynamics of NDVI were influenced by the longitudinal river zonation. Our model ranked first (r2m = 0.73) showed that the productivity of riparian vegetation during the dry season was positively influenced by annual rainfall and by the type of riparian vegetation. The emergent long lags between climatic variation and riparian plant productivity provides opportunities to forecast early warnings of climatically-driven impacts. In addition, the different average productivity levels among vegetation types should be considered when assessing climatic impacts on riparian vegetation. Future applications of Sentinel 2 products could seek to distinguish riparian areas that are likely to be more vulnerable to changes in the annual water balance from those that are more resistant under longer-term changes in climate.

Pit lakes from Southern Sweden: natural radioactivity and elementary characterization.

Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation-reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks was measured by XRF and SEM-EDX in some specific cases. A non-negligible number of pit lakes (26%) with enhanced U levels in water was found. At some sites, rocks contained up to 4% of U in areas with high degree of interaction with local population. Concerning the elementary perspective, another popular site (due to its turquoise water) was found to have elevated dissolved heavy metal levels. Results obtained in this work prove that measurement of natural radioactivity is another component that should be included in routine analysis of characterization in mining areas, especially if restauration of post-mining sites is intended for human recreational.

226Ra, 210Po and lead isotopes in a pit lake water profile in Sweden.

A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These water bodies may be enriched in hazardous stable contaminants and/or in naturally occurring radionuclides depending on the local geological conditions. Mining legacy in Sweden produced hundreds of these pit lakes and most of them are used for recreational purposes in the southern part of the country. In this paper, one pit lake was selected for having enhanced levels of natural radionuclides. Physico-chemical parameters (temperature, pH, oxidation-reduction potential, dissolved oxygen and depth), elemental composition (via Inductive Coupled Plasma Mass Spectrometry) and radiometric characterization (via alpha spectrometry of 226Ra, 210Po and 210Pb) were carried along the depth of a 60 m depth pit lake, with the main aim to describe how natural radionuclides and elements behaves with depth in a non-uraniferous pit lake. Based on observed changes in physico-chemical parameters, a thermocline and a chemocline region were identified at around 10 and 30 m depth respectively. Concerning radionuclides, 226Ra ranged from 75 ± 3 up to 360 ± 12 mBq/kg while 210Po ranged from 11 ± 1 up to 71 ± 3 mBq/kg. 210Pb distribution with depth was also determined via secular equilibrium with 210Po after 2 years and also stable Pb was measured. Disequilibrium 226Ra-210Pb was found and the residence time of 210Pb in the water column was assessed. Additionally, different vertical distributions between 210Pb and Pb were found which points out different sources for different lead isotopes in the water body.

Causes and impacts of a mine water spill from an acidic pit lake (Iberian Pyrite Belt).

In May 2017, a spill from La Zarza pit lake (SW Spain) resulted in the release of approximately 270,000 m3 of extremely acidic waters to the Odiel River. Around 780 × 103 kg of Fe, 170 × 103 kg of Al, 2.15 × 103 kg of As and high amounts of other trace metals and metalloids were spilled. The purpose of this study is to explain the causes, consequences and impacts of the mine spill on the receiving water bodies. To this end, an extensive sampling along the mine site, river and estuary as well as a hydrological model of the pit lake was performed. Around 53 km of the Odiel River's main course, which was already contaminated by acid mine drainage (AMD), were affected. The mine spill resulted in an incremental impact on the Odiel River water quality. Thus, dissolved concentrations of some elements increased in the river up to 450 times; e.g. 435 mg/L of Fe and 0.41 mg/L of As. Due to low pH values (around 2.5), most metals (e.g., Cu, Zn, Mn, Cd) were transported in the dissolved phase to the estuary, exhibiting a conservative behavior and decreasing their concentration only due to dilution. However, dissolved concentrations of Fe, Cr, Pb, Se, Sb, Ti, V and especially As decreased significantly along the river due to Fe precipitation and sorption/coprecipitation processes. At the upper zone of the estuary, a noticeable increment of metal concentrations (up to 77 times) was also recorded. The water balance illustrates the existence of groundwater inputs (at least 16% of total) to the pit lake, due probably to local infiltration of rainwater at the mining zone. The probable existence of an ancient adit connected to the pit lake indicates that potential releases could occur again if adequate prevention measures are not adopted.

From floodplain to aquatic sediments: Radiogeochronological fingerprints in a sediment core from the mining impacted Sancho Reservoir (SW Spain).

The Sancho Reservoir (SW Spain) was built in 1962, about the time of maximum 137Cs fallout, and it has been affected by acid mine drainage (AMD) particularly since the mining cease in 2001. This is a unique scenario for studying the radiogeochronological fingerprints in AMD-affected sediments deposited over the former flood plain. A sediment core sampled in 2011 was analysed for bulk density, 137Cs, 239Pu, 240Pu, 210Pb, 226Ra, 228Ra, 234Th (238U) and 40K, and studied with various radiometric dating models. Bulk density revealed unsteady compaction and likely depositional events. The activity concentrations of 226Ra, 228Ra, 234Th (238U) and 40K were uniform down-core, but declining overall in the upper 0-25cm, revealing changes in provenance except for 238U, which increased in the top 10cm likely due to its supply by AMD. The AMD fingerprint was also found in the 239+240Pu/137Cs activity ratio, which increased in the top sediment layers. The 137Cs and 239+240Pu profiles show well defined peaks at the same depth, with inventories being about four times higher than the expected integrated atmospheric deposition in the area. The unsupported 210Pb (210Pbexc) showed a complex non-monotonic profile interrupted at several sections, particularly around the 137Cs peak. The whole dataset cannot be interpreted in terms of continuous sedimentation processes. Based upon correlated features in the bulk density and 210Pbexc profiles, a series of depositional events (likely linked to peaks in the rainfall records) have been identified in the core. These events date back to the period comprised since the construction of the dam until its increase in height in 1972, which likely displaced upstream the main depositional area of riverine loads, as inferred from sediment trap data. The CRS (with a reference date) and (a piecewise) CIC models have been used for complementing and discussing the chronology.

Hydrogeochemical characteristics of the Tinto and Odiel Rivers (SW Spain). Factors controlling metal contents.

The Tinto and Odiel Rivers are strongly affected by acid mine drainage (AMD) due to the intense sulphide mining developed in their basins over the past 5000 years. In this study the results obtained from a weekly sampling in both rivers, before their mouth in the Ría of Huelva, over three and a half years of control are analysed. In the Tinto River, the concentrations of sulphates, Al, Cd, Co, Li and Zn are double to those of the Odiel as a consequence of lower dilution. However, the concentration of Fe in the Odiel River is 20 times lower, since the precipitation of Fe oxyhydroxysulphates caused by neutralisation processes is more intense. Lower As, Cr, Cu and Pb concentrations are also found in the Odiel River as, to a greater or lesser extent, they are sorbed and/or coprecipitated with Fe. Other elements such as Be, Mn, Ni and Mg show similar values in both systems, which is ascribed to lithological factors. The seasonal evolution of contaminants is typical of rivers affected by AMD, reaching a maximum in autumn due to the dissolution of evaporitic salts precipitated during the summer. Nevertheless, in the Tinto River, Ca, Na and Sr show a strong increase during the summer, probably due to a greater water interaction with marly materials, through which the last reach of the river flows. Barium has a different behaviour from the rest of the metals and its concentration seems to be controlled by the solubility of barite. Iron, As and Pb show different behaviours in both rivers, those for Fe and As possibly linked to the prevalence of different dissolved species of Fe. The different Pb pattern is probably due to the control of Pb solubility by anglesite or other minerals rich in Pb in the Tinto River.

[Subcutaneous seeding of hepatocellular carcinoma after fine-needle percutaneous biopsy]. / Implante subcutáneo de un carcinoma hepatocelular tras la punción aspiración con aguja fina.

Subcutaneous tumor seeding after fine-needle percutaneous biopsy for hepatocellular carcinoma is a rarely seen complication. The authors describe a case of subcutaneous neoplastic seeding in a 70-year-old woman with chronic hepatitis C virus complicated by hepatocellular carcinoma. Ultrasonically guided fine-needle aspiration biopsy was performed in segment II of the liver. The neoplastic seeding developed along the needle track used to carry out the fine-needle biopsy. The subcutaneous tumor was excised, and histological examination revealed a well-differentiated hepatocellular carcinoma.

Prediction of temperature and thermal inertia effect in the maturation stage and stockpiling of a large composting mass.

A macroscopic non-steady state energy balance was developed and solved for a composting pile of source-selected organic fraction of municipal solid waste during the maturation stage (13,500 kg of compost). Simulated temperature profiles correlated well with temperature experimental data (ranging from 50 to 70 degrees C) obtained during the maturation process for more than 50 days at full scale. Thermal inertia effect usually found in composting plants and associated to the stockpiling of large composting masses could be predicted by means of this simplified energy balance, which takes into account terms of convective, conductive and radiation heat dissipation. Heat losses in a large composting mass are not significant due to the similar temperatures found at the surroundings and at the surface of the pile (ranging from 15 to 40 degrees C). In contrast, thermophilic temperature in the core of the pile was maintained during the whole maturation process. Heat generation was estimated with the static respiration index, a parameter that is typically used to monitor the biological activity and stability of composting processes. In this study, the static respiration index is presented as a parameter to estimate the metabolic heat that can be generated according to the biodegradable organic matter content of a compost sample, which can be useful in predicting the temperature of the composting process.

Metal and acidity fluxes controlled by precipitation/dissolution cycles of sulfate salts in an anthropogenic mine aquifer.

Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in derelict mines worldwide.

Functional redundancy as a tool for bioassessment: A test using riparian vegetation.

There is an urgent need to track how natural systems are responding to global change in order to better guide management efforts. Traditionally, taxonomically based metrics have been used as indicators of ecosystem integrity and conservation status. However, functional approaches offer promising advantages that can improve bioassessment performance. In this study, we aim to test the applicability of functional redundancy (FR), a functional feature related to the stability, resistance and resilience of ecosystems, as a tool for bioassessment, looking at woody riparian communities in particular. We used linear mixed-effect models to investigate the response of FR and other traditional biomonitoring indices to natural (drought duration) and anthropogenic stress gradients (flow regulation and agriculture) in a Mediterranean basin. Such indices include species richness, a taxonomic index, and the Riparian Quality Index, which is an index of ecological status. Then, we explored the ability of FR and the other indices to discriminate between different intensities of human alteration. FR showed higher explanatory capacity in response to multiple stressors, although we found significant negative relationships between all the biological indices (taxonomic, functional and ecological quality) and stress gradients. In addition, FR was the most accurate index to discriminate among different categories of human alteration in both perennial and intermittent river reaches, which allowed us to set threshold values to identify undisturbed (reference condition), moderately disturbed and highly disturbed reaches in the two types of river. Using these thresholds and the best-fitting model, we generated a map of human impact on the functional redundancy of riparian communities for all the stretches of the river network. Our results demonstrate that FR presents clear advantages over traditional methods, which suggests that it should be part of the biomonitoring toolbox used for environmental management so as to obtain better predictions of ecosystem response to environmental changes.

Water acidification trends in a reservoir of the Iberian Pyrite Belt (SW Spain).

Scarcity of waters is the main limiting factor of economic development in most arid and semi-arid regions worldwide. The construction of reservoirs may be an optimal solution to assure water availability if the drainage area shows low disturbances. This is the quandary of mining areas where economic development relies on water accessibility. Water acidification trends were investigated in the Sancho Reservoir (SW Spain) in the last 20 years. The acidity (pH3-5) and high dissolved metal concentrations (e.g., 4.4 mg/L of Al, 2.1mg/L of Mn, 1.9 mg/L of Zn) observed in the Sancho, together with the large volume stored (between 37 and 55 Mm(3)), makes this reservoir an extreme case of surface water pollution worldwide. A progressive acidification has been observed since 2003, as evidenced by decreasing pH values and increasing dissolved metal concentrations, especially noticeable after 2007. The increase in the net acidity in the reservoir originates from the higher input of metals and acidity due to the rebound effect after the mining closure in 2001. This trend was not detected in the river feeding the reservoir due to its great hydrological and hydrochemical variability, typical of the Mediterranean climate. Chemical analysis and absolute dating of sediments identified a progressive enrichment in S and metals (i.e., Fe, Zn Cu, Ni, Co and Cd) in the upper 20 cm, which reinforce the year 2002/03 as the onset of the acidification of the reservoir. The decrease of pH values from 4-5 to 3-4 occurred later than the increase in sulfate and metals due to pH-buffering by Al. The acid mine drainage (AMD) pressure has caused an increment of dissolved Fe and other metals, as well as a change in the pH buffering role, exerted now by Fe. These processes were simulated by PHREEQC, which confirms that the acidification trend will continue, causing pH values to reach 2.5 if AMD pressure persists.

Seasonal water quality variations in a river affected by acid mine drainage: the Odiel River (South West Spain).

This paper intends to analyse seasonal variations of the quality of the water of the Odiel River. This river, together with the Tinto River, drains the Iberian Pyrite Belt (IPB), a region containing an abundance of massive sulphide deposits. Because of mining activity dating back to prehistoric times, these two rivers are heavily contaminated. The Odiel and Tinto Rivers drain into a shared estuary known as the Ría of Huelva. This work studies dissolved contaminant data in water of the Odiel River collected by various organisations, between October 1980 and October 2002, close to the rivers entry into the estuary. Flow data for this location were also obtained. The most abundant metals in the water, in order of abundance, are zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu). Arsenic (As), cadmium (Cd) and lead (Pb) are also present but in much lower quantities. The quality of the river water is linked to precipitation; the maximum sulphate, Fe, Zn, Mn, Cd and Pb concentrations occur during the autumn rains, which dissolve the Fe hydroxysulphates that were precipitated during the summer months. In winter, the intense rains cause an increase in the river flow, producing a dilution of the contaminants and a slight increase in the pH. During spring and summer, the sulphate and metal concentration (except Fe) recover and once again increase. The Fe concentration pattern displays a low value during summer due to increased precipitation of ferric oxyhydroxides. The arsenic concentration displays a different evolution, with maximum values in winter, and minimum in spring and summer as they are strongly adsorbed and/or coprecipitated by the ferric oxyhydroxides. Mn and sulphates are the most conservative species in the water. Relative to sulphate, Mn, Zn and Cd, copper displays greater values in winter and lower ones in summer, probably due to its coprecipitation with hydroxysulphates during the spring and summer months. Cd and Zn also appear to be affected by the same process, although to a lower degree than Cu, experiencing a slight reduction in summer with respect to Mn and sulphates.

Perceptual accuracy as measured by the Rorschach: are American norms applicable for cross-cultural assessment?

Cross-cultural applications of Rorschach's test assume that American norms may be applied, but this assumption has little empirical basis. In fact, several such investigations have indicated that culture-specific norms must be employed on key variables employed to assess subjects' perceptual accuracy. The current study compared responses of 19 Spanish children who scored low on a reading measure and were considered by their teachers to experience significant reading problems with 19 peers who scored significantly higher on that reading measure and who experienced no apparent reading problems. Perceptual accuracy of both groups, as measured by the F+ and X+ percents, was virtually identical. Results are discussed in the context of other research which has questioned the cross-cultural applicability of American norms with respect to perceptual accuracy.

Trace metal partitioning over a tidal cycle in an estuary affected by acid mine drainage (Tinto estuary, SW Spain).

The Tinto River estuary is highly polluted with the acid lixiviates from old sulphide mines. In this work the behaviour of dissolved and particulate trace metals under strong chemical gradients during a tidal cycle is studied. The pH values range from 4.4 with low tide to 6.9 with high tide. Precipitation of Fe and Al is intense during rising tides and As and Pb are almost exclusively found in the particulate matter (PM). Sorption processes are very important in controlling the mobility (and hence bioavailability) of some metals and particularly affect Cu below pH 6. Above pH~6 Cu is desorbed, probably by the formation of Cu(I)-chloride complexes. Although less pronounced than Cu, also Zn desorption above pH 6.5 seems to occur. Mn and Co are affected by sorption processes at pH higher than ca. 6. Cd behaves conservatively and Ni is slightly affected by sorption processes.

Geochemical behavior of metals and metalloids in an estuary affected by acid mine drainage (AMD).

The Tinto and Odiel rivers in southwest Spain drain the world's largest sulfide mineral formation: the Iberian Pyrite Belt which has been worked since 2,500 BC. The Tinto and Odiel estuarine zones include both an extensive area of salt marsh and an intensively industrialized urban area. As a consequence of pyrite oxidation, the Tinto and Odiel rivers are strongly acidic (pH < 3) with unusually high and quite variable metal concentrations. In this study, seasonally varying concentrations of dissolved major and trace elements were determined in the acid mine drainage affected estuary of the Ría de Huelva. During estuarine mixing, ore-derived metal concentrations exhibit excellent correlations with pH as the main controlling parameter. As pH increases, concentrations of dissolved ore-associated elements are attenuated, and this process is enhanced during the summer months. The decrease in Fe and Al concentrations ranged from 80 to 100 % as these elements are converted from dissolved to sediment-associated forms in the estuary. Coprecipitation/adsorption processes also removed between 60 and 90 % of the originally dissolved Co, Cu, Mn, Pb, Zn, and Th; however, Cd and Ni exhibited a greater propensity to remain in solution, with an average removal of approximately 60 %. On the other hand, As and U exhibited a different behavior; it is likely that these elements remain in dissolved forms because of the formation of U carbonates and soluble As species. Concentrations of As remain at elevated levels in the outer estuary (average = 48 µg L(-1)) which exceeds concentrations present in the Tinto River. Nevertheless, the estuary has recently witnessed improvements in water quality, as compared to results of several previous studies reported in the 1990s.