Mobilization of arsenic and other trace elements of health concern in groundwater from the Salí River Basin, Tucumán Province, Argentina

The Salí River Basin in north-west Argentina (7,000 km²) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality problems, including arsenic (concentrations in the range of 12.2–1,660 μg L⁻¹), fluoride (50–8,740 μg L⁻¹), boron (34.0–9,550 μg L⁻¹), vanadium (30.7–300 μg L⁻¹) and uranium (0.03–125 μg L⁻¹). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate concentrations (50.0–1,260 mg L⁻¹) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L⁻¹ in shallow groundwater, 129–250 μg L⁻¹ in deep groundwater and 110–218 μg L⁻¹ in artesian groundwater. All exceed the WHO guideline value of 50 μg L⁻¹. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions.     

Effects of ambient ammonia levels on blood ammonia, ammonia excretion and heart and scaphognathite rates of Nephrops norvegicus

During commercial handling of Nephropsnorvegicus (L.) there are a number of situations when the prawns may be exposed to very high ambient ammonia levels. These experiments evaluated the effects of increased levels of ambient total ammonia (TA = NH₃ + NH₄ ⁺) on␣blood ammonia, ammonia efflux rates and on the cardio-ventilatory performance of N. norvegicus. When prawns were taken from <1 to 2000 μmol TA l⁻¹ medium, blood TA concentrations increased rapidly for the first 2 h but tended to drop thereafter. Original blood TA levels were restored 6 h after the prawns were transferred back from seawater containing 2000 to <1 μmol TA l⁻¹. Sudden exposure to 500, 1000, 2000 or 4000 μmol TA l⁻¹ medium induced blood TA concentrations to increase respectively to 50, 30, 33 and 36% of external concentrations (normally, internal TA values are much higher than external levels). Immediately after transfer back to seawater with low ammonia concentration ( <1 μmol TA l⁻¹), excretion rates were higher than those of control prawns, and the absolute amounts of TA excreted were considerably higher than those calculated to have accumulated in the haemolymph. Heart rate (HR) and scaphognathite rate (SR) were not altered when prawns were subjected to sudden alterations in ambient ammonia ( <1 to 2000 to <1 μmol TA l⁻¹). When water ammonia concentrations were altered more gradually, both rates increased, but only at 4000 μmol TA l⁻¹. These results show that N. norvegicus is able to remove ammonia from the haemolymph and/or transform ammonia into some other substance when subjected to increased levels of ambient ammonia. Possible mechanisms involved (e.g. active transport across the gills; storage in some other tissue; glutamate synthe sis) are discussed. Received: 20 May 1996 / Accepted: 1 July 1996     

Clearance rates of the great scallop (<Emphasis Type="Italic">Pecten maximus</Emphasis>) and blue mussel (<Emphasis Type="Italic">Mytilus edulis</Emphasis>) at low natural seston concentrations

Great scallop, Pecten maximus, and blue mussel, Mytilus edulis, clearance rate (CR) responses to low natural seston concentrations were investigated in the laboratory to study (1) short-term CR variations in individual bivalves exposed to a single low seston diet, and (2) seasonal variations in average CR responses of bivalve cohorts to natural environmental variations. On a short temporal scale, mean CR response of both species to 0.06 μg L⁻¹ chlorophyll a (Chl a) and 0.23 mg L⁻¹ suspended particulate matter (SPM) remained constant despite large intra-individual fluctuations in CR. In the seasonal study, cohorts of each species were exposed to four seston treatments consisting of ambient and diluted natural seston that ranged in mean concentration from 0.15 to 0.43 mg L⁻¹ SPM, 0.01 to 0.88 μg L⁻¹ Chl a, 36 to 131 μg L⁻¹ particulate organic carbon and 0.019 to 0.330 mm³ L⁻¹ particle volume. Although food abundance in all treatments was low, the nutritional quality of the seston was relatively high (e.g., mean particulate organic content ranged from 68 to 75%). Under these low seston conditions, a high percentage of P. maximus (81–98%) and M. edulis (67–97%) actively cleared particles at mean rates between 9 and 12 and between 4 and 6 L g⁻¹ h⁻¹, respectively. For both species, minimum mean CR values were obtained for animals exposed to the lowest seston concentrations. Within treatments, P. maximus showed a greater degree of seasonality in CR than M. edulis, which fed at a relatively constant rate despite seasonal changes in food and temperature. P. maximus showed a non-linear CR response to increasing Chl a levels, with rates increasing to a maximum at approximately 0.4 μg L⁻¹ Chl a and then decreasing as food quantity continued to increase. Mean CR of M. edulis also peaked at a similar concentration, but remained high and stable as the food supply continued to increase and as temperatures varied between 4.6 and 19.6°C. The results show that P. maximus and M. edulis from a low seston environment, do not stop suspension-feeding at very low seston quantities; a result that contradicts previous conclusions on the suspension-feeding behavior of bivalve mollusks and which is pertinent to interpreting the biogeographic distribution of bivalve mollusks and site suitability for aquaculture.     

Heavy metals in potable groundwater of mining-affected river catchments,northwestern Romania

Groundwater, accessed using wells and municipal springs, represents the major source of potable water for the human population outside of major urban areas in northwestern Romania, a region with a long history of metal mining and metallurgy. The magnitude and spatial distribution of metal contamination in private-supply groundwater was investigated in four mining-affected river catchments in Maramureş and Satu Mare Counties through the collection of 144 groundwater samples. Bedrock geology, pH and Eh were found to be important controls on the solubility of metals in groundwater. Peak metal concentrations were found to occur in the Lapuş catchment, where metal levels exceed Dutch target and intervention values in up to 49% and 14% of samples, respectively. A 700 m wide corridor in the Lapuş catchment on either side of the main river channel was identified in which peak Cd (31 μg l⁻¹), Cu (50 μg l⁻¹), Pb (50 μg l⁻¹) and Zn (3,000 μg l⁻¹) concentrations were found to occur. Given the generally similar bedrock geologies, lower metal levels in other catchments are believed to reflect differences in the magnitude of metal loading to the local environment from both metal mining and other industrial and municipal sources. Sampling of groundwater in northwestern Romania has indicated areas of potential concern for human health, where heavy metal concentrations exceed accepted environmental quality guidelines. The presence of elevated metal levels in groundwater also has implications for the implementation of the EU Water Framework Directive (WFD) and achieving ‘good’ status for groundwater in this part of the Danube River Basin District (RBD).     

Automated method for the determination of total arsenic and selenium in natural and drinking water by HG-AAS

A multicommutated flow system was designed and evaluated for the determination of total arsenic and selenium by Hydride Generation Atomic Absorption Spectrometry (HG-AAS). It was applied to the determination of arsenic and selenium in samples of natural and drinking water. Detection limits were 0.46 and 0.08 μg l⁻¹ for arsenic and selenium, respectively; sampling frequency was 120 samples h⁻¹ for arsenic and 160 samples h⁻¹ for selenium. Linear ranges found were 1.54–10 μg l⁻¹ (R = 0.999) for arsenic and 0.27–27 μg l⁻¹ (R = 0.999) for selenium. Accuracy was evaluated by spiking various water samples and using a reference material. Recoveries were in the range 95–116%. Analytical precision (s _r (%), n = 10) was 6% for both elements. Compared with the Standard Methods, APHA, 3114B manual method, the system consumes at least 10 times less sample per determination, and the quantities of acid and reducing agent used are significantly lower with a reduction in the generation of pollutants and waste. As an additional advantage, the system is very fast, efficient and environmentally friendly for monitoring total arsenic and selenium levels in waters.     

Effect of acclimatization to low temperature and reduced light on the response of reef corals to elevated temperature

This study tested the effects of acclimatization on the response of corals to elevated temperature, using juvenile massive Porites spp. and branching P. irregularis from Moorea (W149°50′, S17°30′). During April and May 2006, corals were acclimatized for 15 days to cool (25.7°C) or ambient (27.7°C) temperature, under shaded (352 μmol photons m⁻² s⁻¹) or ambient (554 μmol photons m⁻² s⁻¹) natural light, and then incubated for 7 days at ambient or high temperature (31.1°C), under ambient light (659 μmol photons m⁻² s⁻¹). The response to acclimatization was assessed as biomass, maximum dark-adapted quantum yield of PSII (F _v/F _m), and growth, and the effect of the subsequent treatment was assessed as F _v/F _m and growth. Relative to the controls (i.e., ambient temperature/ambient light), massive Porites spp. responded to acclimatization through increases in biomass under ambient temperature/shade, and low temperature/ambient light, whereas P. irregularis responded through reduced growth under ambient temperature/shade, and low temperature/ambient light. Acclimatization affected the response to thermal stress for massive Porites spp. (but not P. irregularis), with an interaction between the acclimatization and subsequent treatments for growth. This interaction resulted from a lessening of the negative effects of high temperature after acclimatizing to ambient temperature/shade, but an accentuation of the effect after acclimatizing to low temperature/shade. It is possible that changes in biomass for massive Porites spp. are important in modulating the response to high temperature, with the taxonomic variation in this effect potentially resulting from differences in morphology. These results demonstrate that corals can acclimatize during short exposures to downward excursions in temperature and light, which subsequently affects their response to thermal stress. Moreover, even con-generic taxa differ in this capacity, which could affect coral community structure. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Feeding of Clausocalanids (Calanoida,Copepoda) on naturally occurring particles in the northern Gulf of Aqaba (Red Sea)

A total of 12 feeding experiments were conducted in the northern Gulf of Aqaba during spring (March/April) and autumn (September/October) 2002 at the Marine Science Station (MSS) in Aqaba. Females of three species of clausocalanids were selected: Clausocalanus farrani, C. furcatus and Ctenocalanus vanus. Natural occurring particle (NOP) larger than 5 μm were investigated as food source. The ambient chlorophyll a concentration at sampling depth (∼70 m) ranged between 0.15 and 1.00 μg chl a l⁻¹ and NOP concentrations ranged between 1.78 and 14.0 × 10³ cells l⁻¹ during the sampling periods. The division of particles into five size classes (5–10, 10–20, 20–50, 50–100 and >100 μm) revealed that most of the particles were found in the size classes below 50 μm (81–98%), while most of the natural occurring carbon (NOC) was concentrated in the size classes larger than 20 μm (70–95%). Ingestion rates were food density dependent rather than size dependent ranging between 0.02 and 1.65 × 10³ NOP ind⁻¹ day⁻¹ and 0.01 and 0.41 μg NOC ind⁻¹ day⁻¹, respectively, equivalent to a body carbon (BC) uptake between 0.4 and 51.8% BC day⁻¹. The share of the size classes to the total ingestion resembled in most cases the size class composition of the natural particle community.     

Effect of an organophosphorus insecticide, fenitrothion, on survival and osmoregulation of various developmental stages of the shrimp Penaeus japonicus (Crustacea: Decapoda)

The toxicity of fenitrothion was determined in larvae (nauplii, Zoeae 1 to 3, Mysis 1 to 3), postlarvae (PL stages) and juvenile shrimp (Penaeus japonicus Bate), in two media, seawater (SW) and diluted seawater (DSW) (1100 and 550 mosM kg⁻¹, ≃ 37 and 19‰ S). The effects of fenitrothion on the osmoregulatory capacities (OC) of juveniles were recorded. A gill and epipodite histopathological study was also conducted. For larvae in seawater, 24 and 48 h LC₅₀s ranged from 32.9 μg l⁻¹ (Zoeae 2) to 10.7 μg l⁻¹ (Mysis 3), and from 3.9 μg l⁻¹ (Zoeae 3) to 2.0 μg l⁻¹ (Mysis 3), respectively; 48 and 96 h  LC₅₀s in postlarvae (PL) at the same salinity ranged from 1.8 μg l⁻¹ (PL1) to 0.6 μg l⁻¹ (PL5), and from 0.3 μg l⁻¹ (PL7) to 0.4 μg l⁻¹ (PL15). In juveniles, 96 h LC₅₀s were 0.8 μg l⁻¹ in seawater and 1.5 μg l⁻¹ in diluted seawater. From hatching to juvenile stages, the overall trend was a rapid decrease (from nauplii to PL5–PL7) followed by a slight increase (from PL7 to PL15 and juveniles) in the shrimp's ability to tolerate the insecticide. In juveniles kept in seawater and in diluted seawater, fenitrothion decreased the osmoregulatory capacity (OC = difference between the hemolymph osmotic pressure and the osmotic pressure of the medium) at both lethal and sublethal concentrations. This effect was time- and dose-dependent. In SW, the decrease in hypo-OC was ˜ 25% at sublethal concentrations and ˜ 35% at the 96 h LC₅₀. In DSW, the decrease in hyper-OC was ˜ 10 to 15% at sublethal concentrations. In SW, shrimp were able to recover their OC in less than 48 h when transferred to water free of pesticide. In DSW, recovery at 48 h was only possible after exposure to the lowest tested sublethal concentration. Haemocytic congestions (thrombosis) of the gills, lamellae necrosis and other alterations of gills and epipodites (breakage of the cuticle, reduction of the hemolymph lacunae) were noted in juveniles exposed to lethal and sublethal concentrations of fenitrothion. Received: 7 October 1996 / Accepted: 13 November 1996     

Modification of light utilization for skeletal growth by water flow in the scleractinian coral <Emphasis Type="Italic">Galaxea fascicularis</Emphasis>

In this study, we tested the hypothesis that the importance of water flow for skeletal growth (rate) becomes higher with increasing irradiance levels (i.e. a synergistic effect) and that such effect is mediated by a water flow modulated effect on net photosynthesis. Four series of nine nubbins of G. fascicularis were grown at either high (600 μE m⁻² s⁻¹) or intermediate (300 μE m⁻² s⁻¹) irradiance in combination with either high (15–25 cm s⁻¹) or low (5–10 cm s⁻¹) flow. Growth was measured as buoyant weight and surface area. Photosynthetic rates were measured at each coral’s specific experimental irradiance and flow speed. Additionally, the instantaneous effect of water flow on net photosynthetic rate was determined in short-term incubations in a respirometric flowcell. A significant interaction was found between irradiance and water flow for the increase in buoyant weight, the increase in surface area, and specific skeletal growth rate, indicating that flow velocity becomes more important for coral growth with increasing irradiance levels. Enhancement of coral growth with increasing water flow can be explained by increased net photosynthetic rates. Additionally, the need for costly photo-protective mechanisms at low flow regimes could explain the differences in growth with flow.     

Heavy metal contamination of paddy soils and rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) from Kočani Field (Macedonia)

This research focuses on the heavy metal contamination of the paddy soils and rice from Kočani Field (eastern Macedonia) resulting from irrigation by riverine water impacted by past and present base-metal mining activities and acid mine drainage. Very high concentrations of As, Cd, Cu, Pb and Zn were found in the paddy soils (47.6, 6.4, 99, 983 and 1,245 μg g⁻¹) and the rice (0.53, 0.31, 5.8, 0.5 and 67 μg g⁻¹) in the western part of Kočani Field, close to the Zletovska River, which drains the mining facilities of the Pb–Zn mine in Zletovo. In terms of health risk, the observed highest concentrations of these elements in the rice could have an effect on human health and should be the subject of further investigations.     

Phytoaccumulation prospects of cadmium and zinc by mycorrhizal plant species growing in industrially polluted soils

The natural vegetation growing along a wastewater channel was subjected to analyze the uptake of Cadmium (Cd) and Zinc (Zn) and their subsequent accumulation in aboveground and underground plant parts. Species which were mycorrhizal and growing in soils receiving industrially contaminated wastewater were collected along with their rhizospheric soil samples. The nearby uncontaminated control (reference) area was also subjected to sampling on similar pattern for comparison. Both Cd and Zn concentrations were significantly higher in soils of the study area as compared to the reference site. Five plant species i.e. Desmostachya bipinnata, Dichanthium annulatum, Malvastrum coromandelianum, Saccharum bengalense, and Trifolium alexandrinum were analyzed for metal uptake. The maximum phytoaccumulation of Cd was observed in Desmostachya bipinnata (20.41 μg g⁻¹) and Dichanthium annulatum (15.22 μg g⁻¹) for shoot and root tissues, respectively. However, Malvastrum coromandelianum revealed maximum Zn accumulation for both the shoot and the root tissues (134 and 140 μg g⁻¹, respectively). The examination of cleared and stained roots of the plants from both the areas studied revealed that all of them were colonized to a lesser or a greater degree by arbuscular mycorrhizal (AM) fungi. The Cd hyperaccumulating grasses i.e. Desmostachya bipinnata and Dichanthium annulatum, from study area had smaller root:shoot (R/S) ratio as compared to those growing on reference area indicating a negative pressure of soil metal contamination. The lower R/S ratio in the mycorrhizal roots observed was probably due to increased AM infection and its mediatory role in soil plant transfer of heavy metals. Furthermore, comparatively lower soil pH values in the study areas may have played a key role in making the overall phytoavailability of both the metals. Consequently variations in Cd and Zn tissue concentration among species were observed that also indicate the phytoaccumulation potential of the native species.     

Production and fate of copepod fecal pellets across the Southern Indian Ocean

The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 μg C m⁻³ day⁻¹. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg m⁻² day⁻¹).     

Nitrate uptake by the reef coral Diploria strigosa: effects of concentration, water flow, and irradiance

The effects of several environmental variables on net nitrate uptake by the scleractinian coral Diploria strigosa were investigated under controlled flow conditions. D. strigosa exhibited nitrate uptake rates ranging from 1 to 5 nmol cm⁻² h⁻¹ at ambient concentrations of 0.1–0.3 μM that are typical of oligotrophic reefs such as Bermuda. Net uptake ceased at approximately 0.045 μM. The uptake was positively correlated with concentration up to a saturation concentration of approximately 3 μM. The uptake was also positively correlated with water velocity at 1 μM, but not at 6 μM, suggesting diffusional limitation at low concentrations and kinetic limitation at higher concentrations. Nitrate uptake by D. strigosa was not affected by light intensity or time of day, but was almost completely inhibited by 48 h exposure to ammonium levels found on many reefs.     

Fluoride in Antarctic marine crustaceans

The concentration of fluoride in the body parts of a range of Antarctic crustaceans from a variety of habits was examined with the aim of determining whether fluoride concentration is related to lifestyle or phylogenetic grouping. Euphausiids had the highest overall fluoride concentrations of a range of Antarctic marine crustaceans examined; levels of up to 5477 μg g⁻¹ were found in the exoskeleton of Euphausia crystallorophias. Copepods had the lowest fluoride levels (0.87 μg g⁻¹ whole-body); some amphipods and mysids also exhibited relatively high fluoride levels. There was no apparent relationship between the lifestyle of the crustaceans and their fluoride level; benthic and pelagic species exhibited both high and low fluoride levels. Fluoride was concentrated in the exoskeleton, but not evenly distributed through it; the exoskeleton of the head, carapace and abdomen contained the highest concentrations of fluoride, followed by the feeding basket and pleopods, and the eyes. The mouthparts of E.␣superba contained almost 13 000 μg F g⁻¹ dry wt. Antarctic krill tail muscle had low levels of fluoride. After long-term (1 to 5 yr) storage in formalin, fluoride was almost completely lost from whole euphausiids. Received: 1 April 1998 / Accepted: 29 July 1998     

Geographic patterns of non-carpeted floor dust loading in Syracuse, New York (USA) homes

Residential floor dust loading was measured on the smooth floor surface of 488 houses in Syracuse, New York, during the summers of 2003 and 2004. Using U.S. Environmental Protection Agency (EPA) wipe methods, pre-weighed Ghost Wipes, Lead Wipes, or Whatman Filters were employed to collect duplicate samples from (predominantly) kitchens. The collection efficiency of the various media was determined from multiple wipe tests and side-by-side comparisons. The results were normalized and aggregated at the census tract level to determine whether spatial patterns of dust loading could be observed. Loading was found to be log-normally distributed, with a geometric mean value of 0.311 g m⁻² (29 mg of dust per square foot of floor); 95% of the observations fell in the range of 0.042–2.330 g m⁻² (4–216 mg foot⁻²). The sampling for floor dust loading shows some bias for day of the week in which visits to the residential properties were made. After a first-order correction for this effect, results were aggregated by census tract and mapped in a geographic information system (GIS); strong spatial patterns can be identified in an inverse distance weighted mapping. The geographic patterns exhibit a strong correlation with socio-economic/demographic covariates extracted from the 2000 census summaries. Dust mass on the floors is positively correlated with renter-occupied properties and family size; it is negatively correlated with measures of household income.     

Effects of chronic copper exposure on the green mussel Perna viridis

The effects of chronic copper exposure on growth and physiological responses of the green mussel Perna viridis were investigated by exposing the mussels to 50 μg l⁻¹ Cu for 3 mo at 17 and 25 °C. These temperatures represent, respectively, the winter and summer seawater temperatures in Hong Kong. Differences in the level of response between mussels exposed for 3 mo to 50 μg Cu l⁻¹ generally increased with duration of exposure. The tissue concentration of copper had increased by 280 and 450% after 3 mo exposure at 17 and 25 °C, and growth performances were reduced, with the 25 °C sets suffering from larger negative impact of copper in most responses. The inhibitory effects of copper on production of the various body components generally followed the order linear shell growth (greatest) > tissue production > byssus production > shell production. There were also decreases in the condition index (43 and 35% reductions at 17 and 25 °C), clearance rates (10.3 and 18.5%), faeces production (11 and 16.3%), assimilation efficiency (6.8 and 9.2%) and oxygen consumption rate (12.8 and 24.8%). In contrast, the organic content of the faeces (9.2 and 13.2% increases at 17 and 25 °C) and rate of ammonia excretion (21 and 28.6%), increased upon chronic copper exposure. Many of the responses (e.g. changes in tissue copper content, body dry wt, shell organic content, clearance rate and oxygen consumption rate) exhibited fluctuating levels of impact during prolonged copper exposure, while others (e.g. faecal production rate, assimilation efficiency, tissue organic content) demonstrated steady decreasing trends with increasing exposure time. Received: 17 September 1999     

Life cycle of <Emphasis Type="Italic">Oithona</Emphasis> <Emphasis Type="Italic">similis</Emphasis> (Copepoda: Cyclopoida) in Kola Bay (Barents Sea)

The annual population dynamics (nauplii, old copepodites CIV–CV and adults) and seasonal variations in reproductive parameters of the cyclopoid copepod Oithona similis were investigated on the basis of the data 1999–2006 in Kola Bay, a large subarctic fjord in the Barents Sea. Population density of O. similis ranged from 110 to 9,630 ind m⁻³ and averaged 1,020 ± 336 ind m⁻³. The relative abundance of adults was high during winter (~60%). At the end of winter (mid-March), the population included a large percentage of later-stage copepodites (stage CIV 23% and stage CV 57%). There were two periods of mass spawning, in late June and September. Autumn and summer generations strongly differed in abundance, average prosome length (PL), clutch size (CS), egg diameter (D), egg production rates (EPR and SEPR) and female secondary production. Average PL decreased with increasing water temperature, while D and CS were strongly correlated with PL but unaffected by temperature. Annual average EPR and SEPR were 0.55 ± 0.18 eggs female⁻¹ day⁻¹ and 0.0011 ± 0.003 day⁻¹, respectively. Female secondary production averaged 0.8 ± 0.3 μg C m⁻³ day⁻¹ (range 0.001–3.58). There were positive relationships between abundance, EPR, SEPR, production and water temperatures. Reproductive parameters appeared to be controlled by hydrological factors and food conditions.     

Cadmium accumulation in the female shore crab Carcinus maenas during the moult cycle and ovarian maturation

 The influence of moulting and ovarian maturation on cadmium accumulation in the tissues of female shore crabs Carcinus maenas exposed to 1 mg Cd l⁻¹ in the water was investigated. Cadmium accumulation in all tissues examined was markedly increased in crabs in the postmoult stages (A and B) compared to crabs in all other moult stages. During the moult cycle, average cadmium accumulation in the midgut gland ranged from 29 μg Cd g⁻¹ dw at premoult stage (D₂) to 589 μg Cd g⁻¹ dw at postmoult stage (A). Average cadmium concentrations in the haemolymph ranged from 0.56 μg Cd ml⁻¹ at intermoult stage (C₄) to 4.6 μg Cd ml⁻¹ at postmoult stage (A), while the gills accumulated from 103 μg Cd g⁻¹ dw in intermoult stage (C₃) to 352 μg Cd g⁻¹ dw in postmoult stage (A). Cadmium concentration in gills and haemolymph was also significantly higher in crabs in late premoult stage (D₃) compared to C₄-crabs, while midgut gland cadmium concentration remained elevated in C₁- and C₃- intermoult stages relative to C₄. During ovarian maturation the cadmium accumulation in midgut gland, gills, ovaries and haemolymph decreased. Average cadmium concentration in the midgut gland decreased from 63 μg g⁻¹ dw in ovarian Stage I to 19 μg g⁻¹ dw in ovarian Stage VI. The same pattern was observed for gills, haemolymph and ovaries. The present study demonstrates that cadmium accumulation in the female shore crab strongly depends on the physiological status of the animal. A possible association between physiological calcium requirements and cadmium accumulation during moulting is discussed. Received: 20 January 2000 / Accepted: 20 July 2000     

Assessment of acute toxicity of ��-cyhalothrin to a freshwater catfish, Clarias batrachus

Acute static bioassays were conducted for 96 h period with λ-cyhalothrin to determine its acute toxicity to a freshwater catfish, Clarias batrachus. The 96 h LC₅₀ value was estimated to be 5.00 μg l⁻¹ (95% confidence limit: 4.114–5.712). The alterations in behavioral pattern, such as change in the color of skin, hyperactivity, loss of balance, rapid swimming, increased surfacing activity, enhanced rate of opercular activity, as well as prominent rates of convulsions in treated fish were observed with the increasing concentrations of insecticide as compared to the control fish. The results indicate that λ-cyhalothrin is highly effective even at very low concentrations.     

Concentrations of inorganic elements in 20 municipal waters in Sweden before and after treatment – links to human health

The water chemistry of 20 municipal water treatment plants in southern Sweden, representing various bedrock situations, and water qualities, were investigated. Four water samples, raw and treated, were collected from each plant and analyzed by predominantly ICP-OES and ICP-MS at four occasions from June to December, 2001. The concentrations of Ca, Mg, K, Na, HCO₃ and a number of micronutrients, varied considerably in treated waters from the studied plants (ranges; Ca: 9.1–53.7 mg L⁻¹, Mg: 1.4–10.9 mg L⁻¹, K: 1.1–4.8 mg L⁻¹, Na; 5.4–75.6 mg L⁻¹, HCO₃: 27–217 mg L⁻¹). The elimination of Fe and Mn from raw water was efficient in all treatments investigated, giving concentrations in treated waters below the detection limits at some plants. Softening filters gave waters with Ca-concentrations comparable to the softest waters in this study. Adjustment of pH by use of chemicals like lye, soda or lime, modified the consumer water composition significantly, besides raising the pH. It was estimated that drinking water contributed to approximately 2.2–13% of the daily Ca uptake, if the gastrointestinal uptake efficiency from food and water was estimated to be around 50%. The corresponding figures for Mg was 1.0–7% and for F 0–59%. None of the studied elements showed any significant time trends in raw or treated waters during the follow-up period. The concentrations of potentially toxic metals such as Al, Pb and U were low and did not indicate risks for adverse health effects (ranges; Al: 0.5–2.3 μg L⁻¹, Pb: 0–0.3 μg L⁻¹, U: 0.2.5 μg L⁻¹).