The disposal of flue gas desulphurisation waste: sulphur gas emissions and their control

Flue gas desulphurisation (FGD) equipment to be fitted to UK coal-fired power stations will produce more than 0.8 Mtonnes of calcium sulphate, as gypsum. Most gypsum should be of commercial quality, but any low grade material disposed as waste has the potential to generate a range of sulphur gases, including H₂S, COS, CS₂, DMS and DMDS. Literature data from the USA indicates that well-oxidised waste with a high proportion of calcium sulphate (the main UK product of FGD) has relatively low emissions of sulphur gases, which are comparable to background levels from inland soils. However, sulphur gas fluxes are greatly enhanced where reducing conditions become established within the waste, hence disposal strategies should be formulated to prevent the sub-surface consumption of oxygen.     

Modeling seasonal course of carbon fluxes and evapotranspiration in response to low temperature and moisture in a boreal Scots pine ecosystem

Environmental conditions act above and below ground, and regulate carbon fluxes and evapotranspiration. The productivity of boreal forest ecosystems is strongly governed by low temperature and moisture conditions, but the understanding of various feedbacks between vegetation and environmental conditions is still unclear. In order to quantify the seasonal responses of vegetation to environmental factors, the seasonality of carbon and heat fluxes and the corresponding responses for temperature and moisture in air and soil were simulated by merging a process-based model (CoupModel) with detailed measurements representing various components of a forest ecosystem in Hyytiälä, southern Finland. The uncertainties in parameters, model assumptions, and measurements were identified by generalized likelihood uncertainty estimation (GLUE). Seasonal and diurnal courses of sensible and latent heat fluxes and net ecosystem exchange (NEE) of CO₂ were successfully simulated for two contrasting years. Moreover, systematic increases in efficiency of photosynthesis, water uptake, and decomposition occurred from spring to summer, demonstrating the strong coupling between processes. Evapotranspiration and NEE flux both showed a strong response to soil temperature conditions via different direct and indirect ecosystem mechanisms. The rate of photosynthesis was strongly correlated with the corresponding water uptake response and the light use efficiency. With the present data and model assumptions, it was not possible to precisely distinguish the various regulating ecosystem mechanisms. Our approach proved robust for modeling the seasonal course of carbon fluxes and evapotranspiration by combining different independent measurements. It will be highly interesting to continue using long-term series data and to make additional tests of optional stomatal conductance models in order to improve our understanding of the boreal forest ecosystem in response to climate variability and environmental conditions.     

Spatial variations in the N2O emissions and denitrification potential of riparian buffer strips in a contaminated urban river

Spatial variations in the N₂O emissions and denitrification potential of riparian buffer strips (RBS) in a polluted river were examined. The river received large pollutant inputs from urban runoff and wastewater discharge, resulting in impaired water quality in the river and downstream reservoir. The potential for nitrogen removal by RBS was evaluated by measuring in situ N₂O emission fluxes in static closed chambers and sediment denitrification potentials with acetylene inhibition techniques. The results showed that N₂O emission fluxes decreased from the upstream (16.39 μg/(m²·h)) to downstream (0.30 μg/(m²·h)) sites and from the water body to upland sites. The trend in decreasing N₂O emission fluxes in the downstream direction was mainly associated with sediment/soil textures (clay loam→sandy soil) and sediment/soil water contents and was also related to the vegetation along the RBS and nutrients in the sediments/soils. The correlation coefficient was highest (r=0.769) between the N₂O emission flux and sediment/soil water content. Sediment/soil denitrification potentials under N-amended and ambient conditions were higher (highest 32.86 mg/(kg·h)) for the upstream sites, which were consistent with in situ N₂O flux rates.     

秋季羰基硫在植物与大气间的交换

利用静态箱法研究了秋季羰基硫(COS)在六种北京常见树种与大气间的交换．结果表明：法国梧桐、槐树、龙爪槐、玉兰、柳树对COS有吸收,油松没有吸收,树木与大气间COS的交换通量受树种、环境温度、光照、COS初始浓度等因素的影响．一般来说．温度高、光照强时,以上树种与大气间COS的交换强;空气中COS初始浓度高时,植物对COS的吸收通量高,植物对COS的吸收达到饱和较植物对CO2的吸收以及异戊二烯的排放持续时间长．     

Interaction of leaves and roots of Ruppia maritima in the uptake of phosphate,ammonia and nitrate

Leafy shoots of Ruppia maritima were incubated in two-compartment chambers, with the roots in one compartment and the leaves in the other. Rates of phosphate and ammonia uptake were compared when roots and leaves were supplied with these nutrients separately and simultaneously. Uptake of phosphate and ammonia by leaves was reduced when these nutrients were supplied to the roots, but uptake by roots was not affected by the availability of these nutrients to leaves. This response suggested root-to-shoot translocation predominated. V_max for leaf uptake of phosphate was decreased by 31% when roots were supplied with phosphate simultaneously. Leaf uptake of ammonia was not affected by the availability of ammonia to roots unless the plants were starved for nitrogen. V_max for plants starved for nitrogen was two times greater than for unstarved plants. When roots and leaves of starved plants were exposed simultaneously to ammonia, V_max for ammonia uptake by leaves did not change but K_s increased by 97% to a value similar to that for unstarved plants. Ammonia supplied to leaves or roots inhibited nitrate uptake by leaves by an average of 52%. Ammonia supplied to leaves, however, had no influence on the rate of nitrate uptake by roots.Contribution No. 579 of the Environmental Research Laboratory, US Environmental Protection Agency. Use of product names does not imply endorsement by USEPA     

Nutrient regeneration in shallow-water sediments of the estuarine plume region of the nearshore Georgia Bight,USA

Benthic community respiration and the cycling of N and P were seasonally investigated in the unprotected, sandy sediments (Z5m) of the nearshore zone of the Georgia Bight, USA in 1981 and 1982. Nutrient exchange across the sediment-water interface was calculated from a diffusive model, measured by in-situ enclosure experiments and estimated from whole core incubations. Seasonally changing pore water profiles indicated that the sediments were not in steady-state with respect to N and P and showed the characteristics of enhanced interstitial water movement by benthic animals. Over an annual period the total flux of nitrogen measured in situ averaged 1812 mol m^-2 d^-1 from the sediments. NH ₄ ⁺ flux accounted for the vast majority of the total directly measured N flux (77%), followed by nitrate + nitrite (14%), and dissolved organic nitrogen (9%). Phosphorus flux averaged 537 mol m^-2 d^-1. A large ratio of in-situ fluxes to calculated diffusive fluxes (5.2:1) indicated flux enhancement due to benthic animal activity. ammonium fluxes measured in situ did not agree well with the rate of NH ₄ ⁺ produced in incubated whole cores (11.7 mmol m^-2 d^-1). Relative rates of C, N and P release throughout the year fluctuated considerably. Generally, nutrient fluxes were not simply related to respiration or temperature. As respiration was highly correlated with temperature, however, this suggested that respiration-regeneration was temporarily decoupled from exchange across the sediment-water interface. The annual C-N-P flux stoichiometry was 130:3.1:1. Using the rate at which NH ₄ ⁺ was produced in incubated cores the stoichiometry was 120:21:1. The anomalously low N flux measured in situ was attributed to a combination of denitrification and wave-and current-induced sediment nutrient flushing. The potential for sediment flushing is high as experiments showed that sediments were fluidized or resuspended down to 25 cm during large storms. Benthic nutrient flux contributed 40% to the annual P but only 11% to the annual N requirements of the pelagic primary producers.This is Contribution No. 558 from the University of Georgia Marine Institute. This work was supported by the Georgia Sea Grant College Program maintained by the National Oceanic and Atmospheric Administration, US Department of Commerce, under Grant No. NA80AA-D-00091     

Diffusive gradient in thin-film (DGT) models Cd and Pb uptake by plants growing on soils amended with sewage sludge and urban compost

Food contamination by Cd and Pb is of increasing concern because contaminated composts and sewage sludges are used as soil fertilizers. Indeed, Cd and Pb from sewage sludge and compost can be transferred to plants and, in turn, to food. Predicting the quantity of metals transferred to plants is difficult and actual models are unable to give accurate concentrations. Therefore, new techniques are needed. For instance, diffusive gradient in thin-film (DGT) is commonly used to measure metal bioavailability in waters, sediments and soils, but DGT has not been well studied for metal uptake in plants. Moreover, actual models for soil–plant transfer are too complex and require many soil parameters. Here, we simplified the modelization of metal uptake by plants by considering only DGT fluxes and roots surfaces. We grew durum wheat in a greenhouse on sandy soils amended with urban compost or sewage sludge. Results show that Cd uptake was slightly underestimated when whole roots were considered as an absorbing surface. For Pb, the best estimation was found by using root tip surface. Overall, our model ranks correctly the samples but underestimates Pb uptake by 15 % and Cd uptake by 45 %. It is nonetheless a simpler way of modelling by using only DGT fluxes and root system morphology.     

Seasonal variations in nitrogen-fixation (acetylene reduction) and sulphate-reduction rates in the rhizosphere of Zostera noltii: nitrogen fixation by sulphate-reducing bacteria

Nitrogen-fixation (acetylene reduction) rates were measured over an annual cycle in meadows of the seagrass Zostera noltii Hornem in the Bassin d'Arcachon, south-west France, between March 1994 and February 1995, using both slurry and whole-core techniques. Measured rates using the slurry technique consistently overestimated those determined on whole cores, probably due to the release of labile organic carbon sources as a result of root damage during preparation of the slurries. Thus, the whole-core technique may provide a more accurate estimate of in situ activity, since disturbance of physicochemical gradients of oxygen, sulphide, nutrients and the relationship between the plant roots and the rhizosphere microflora is minimised. Rates measured by the whole-core method were 1.8- to 4-fold greater (dependent upon season) in the light than those measured during dark incubations, indicating that organic carbon diffusing from the plant roots during photosynthesis was an important factor in regulating nitrogen fixation in the rhizosphere. Additions of sodium molybdate, a specific inhibitor of sulphate-reducing bacteria (SRB) inhibited acetylene-reduction activity by >80% as measured by both the slurry and whole-core techniques throughout the year, inferring that SRB were the dominant component of the nitrogen-fixing microflora. A mutualistic relationship between Z. noltii and nitrogen-fixing SRB in the rhizosphere, based on the exchange of organic carbon and fixed nitrogen is proposed. Acetylene- and sulphate-reduction rates showed distinct summer peaks which correlated with a reduced availability of ammonium in the sediment and the annual growth cycle of Z. noltii in the basin. Overall, these data indicate that acetylene reduction (nitrogen fixation) activity in the rhizosphere of Z. noltii was regulated both by the availability of organic carbon from the plant roots and maintenance of a low NH ₄ ⁺ concentration in the vicinity of the plant roots due to efficient assimilation of NH ₄ ⁺ by Z. noltii during the growth season. Nitrogenfixation rates determined from acetylene-reduction rates measured using the whole-core technique ranged from 0.1 to 7.3 mg N m^-2d^-1, depending on season, and were calculated to contribute between 0.4 and 1.1 g N m^-2yr^-1, or 6.3 to 12% of the annual fixed nitrogen requirement of Z. noltii.     

Respiratory quotient and calcification of Nautilus macromphalus (Cephalopoda: Nautiloidea)

Respiration and calcification were investigated in the ectocochleate cephalopod Nautilus macromphalus Sowerby. Specimens were collected off New Caledonia, in October 1991, and kept at the Nouméa Aquarium until December 1991. The respiratory quotient and calcification rate of 5 individuals were measured during 14 short term incubations (63 to 363 min). Oxygen uptake was recorded with a polarographic oxygen sensor. CO₂ flux and calcification were calculated from changes in pH and alkalinity (alkalinity-anomaly technique). Several methods were used to compute the respiratory quotient (RQ); a functional regression indicated an RQ of 0.74. CaCO₃ exchange rates were linearly related to respiratory quotient, calcification occurring in individuals with a low RQ. CaCO₃ uptake from the surrounding water was noncontinuous. From the highest CaCO₃ uptake, maximum growth rate was estimated as 7.1 mg shell wt h^- (=61 g yr^-1).     

Nitrogen accretion,and the nature and possible significance of N2 fixation (Acetylene reduction) in a Nova Scotian Spartina alterniflora stand

Total aboveground nitrogen accretion through the 1975 growing season at a short Spartina alterniflora stand was estimated as 78 kg N ha^-1, compared to estimated N₂ fixation on the mud surface of 22 kg N ha^-1 and subsurface N₂ fixation of 93 kg N ha^-1. Subsurface N accretion was estimated to be of the order of 77 kg N ha^-1. Mudsurface ARA (acetylene-reducing activity) exhibited a pronounced mid-season maximum, while subsurface ARA exhibited a general trend of increase from May to September, and then a decline as a function of falling temperature. Various experiments suggested that mud-surface ARA was associated largely with non-heterocystous blue-green algae and photosynthetic bacteria, while subsurface ARA was associated mainly with vital activity of S. alterniflora. Counts of various groups of bacteria indicated an enrichment of anaerobic (glucose-utilizing) and microaerophilic (malateutilizing) N₂-fixing bacteria in the rhizosphere in comparison to non-rhizosphere soil. Treatment of roots with chloramine-t for 2 h reduced total numbers (plate count), anaerobic N₂ fixers, and microaerophilic N₂ fixers by factors of 357, 172, and 22, respectively, suggesting a relative enrichment of microaerophiles in the interior or endorhizosphere of the roots. ARA of excised roots was correlated with ¹⁴C-activity for roots from a plant previously exposed to ¹⁴CO₂, and with branching and age of the roots.     

Benthic oxygen uptake and carbon cycling under aphotic and resource-limiting conditions in a submarine cave

To establish relationships between organic input to the benthos and decreases in benthic population biomass and density, benthic oxygen uptake was measured in an oligotrophic submarine cave in the northwestern Mediterranean Sea (Marseille, France), on seven separate occasions in 1987, using an in situ bell-jar respirometer. Oxygen uptake was measured in both the outer twilight section and the dark inner section of the cave during an annual survey (seven recording periods from February 1987 to November 1988). The mean annual benthic oxygen uptake was 80.9 litres O₂ m^–2 yr^–1 for the twilight outer section and 15.5 litres O₂ m^–2 yr^–1 for the dark inner section. The results are discussed and the biogeochemical budget for particulate organic carbon at the sediment-water interface calculated. Respiration rates (expressed as carbon equivalents), together with previously published data on vertical fluxes and burial of organic carbon, revealed that anaerobic pathways accounted for 14% and aerobic pathways for 86% of the total benthic metabolism in the outer part of the cave. In the inner section of the cave, degradation of organic carbon occurred only through aerobic degradation, indicating a strongly carbon-limited ecosystem. The low respiration rates recorded in the dark section were similar to values recorded for some oligotrophic deep-sea environments (1 000 to 2 000 m). Such budgets are essential preliminary steps in order to accurately model benthic metabolic pathways. The determination of annual fluxes linked to the acquisition of long-term data will yield better knowledge of the recycling processes at the water-sediment interface.     

Seasonal variations of organic-carbon and nutrient transport through a tropical estuary (Tsengwen) in southwestern Taiwan

This paper reports the fluvial fluxes and estuarine transport of organic carbon and nutrients from a tropical river (Tsengwen River), southwestern Taiwan. Riverine fluxes of organic carbon and nutrients were highly variable temporally, due primarily to temporal variations in river discharge and suspended load. The sediment yield of the drainage basin during the study period (1995–1996, 616 tonne km^–2 year^–1) was ca. 15 times lower than that of the long-term (1960–1998) average (9379 tonne km² year^–1), resulting mainly from the damming effect and historically low record of river water discharge (5.02 m³ s^–1) in 1995. The flushing time of river water in the estuary varied from 5 months in the dry season to >4.5 days in the wet season and about 1 day in the flood period. Consequently, distributions of nutrients, dissolved organic carbon (DOC) and particulate organic carbon (POC) were of highly seasonal variability in the estuary. Nutrients and POC behaved nonconservatively but DOC behaved conservatively in the estuary. DOC fluxes were generally greater than POC fluxes with the exception that POC fluxes considerably exceeded DOC fluxes during the flood period. Degradation of DOC and POC within the span of flushing time was insignificant and may contribute little amount of CO₂ to the estuary during the wet season and flood period. Net estuarine fluxes of nutrients were determined by riverine fluxes and estuarine removals (or additions) of nutrients. The magnitude of estuarine removal or addition for a nutrient was also seasonally variable, and these processes must be considered for net flux estimates from the river to the sea. As a result, nonconservative fluxes of dissolved inorganic phosphorus (DIP) from the estuary are –0.002, –0.09 and –0.59 mmol m^–2 day^–1, respectively, for dry season, wet season and flood period, indicating internal sinks of DIP during all seasons. Due to high turbidity and short flushing time of estuarine water, DIP in the flood period may be derived largely from geochemical processes rather than biological removal, and this DIP should not be included in an annual estimate of carbon budget. The internal sink of phosphorus corresponds to a net organic carbon production (photosynthesis–respiration, p–r) during dry (0.21 mmol m^–2 day^–1) and wet (9.5 mmol m^–2 day^–1) seasons. The magnitude of net production (p–r) is 1.5 mol m^–2 year^–1, indicating that the estuary is autotrophic in 1995. However, there is a net nitrogen loss (nitrogen fixation–denitrification < 0) in 1995, but the magnitude is small (–0.17 mol m^–2 year^–1).     

Seasonal Changes in Soil Atmospheric Co2 Concentrations in Two Upland Catchments and Associated Changes in River Water Chemistry

Seasonal changes in river water chemistry and in soil atmospheric CO₂ concentrations at two depths and drainage water solute composition at two upland peaty podzol sites in north east Scotland were monitored over 12 months. the CO₂ concentrations were controlled by changes in soil temperature and moisture status. Highest CO₂ concentrations were observed in late summer 1988 when both soil temperatures and the moisture status of the soils were high. Then maximum CO₂ concentrations of 4% (v/v) were recorded for one of the sites. No significant correlations between seasonal changes in soil CO₂ concentrations and river water solute composition were observed. Nevertheless the field results and laboratory experiments indicated that in upland areas, where soils with acid surface horizons are common, soil CO₂ substantially influences river water chemistry at baseflow, increasing the pH and cation concentration of the soil water draining into the river. the results suggest that transfer of carbon as dissolved CO₂ in drainage water is a significant pathway for CO₂ transfer to the atmosphere.     

Effect of nitrogen supply on nitrogen uptake,accumulation and assimilation in Porphyra perforata (Rhodophyta)

Porphyra perforata J. Ag. was collected from a rocky land-fill site near Kitsilano Beach, Vancouver, British Columbia, Canada and was grown for 4 d in media with one of the following forms of inorganic nitrogen: NO ₃ ^- , NH ₄ ⁺ and NO ₃ ^- plus NH ₄ ⁺ and for 10 d in nitrogen-free media. Internal nitrogen accumulation (nitrate, ammonium, amino acids and soluble protein), nitrate and ammonium uptake rates, and nitrate reductase activity were measured daily. Short initial periods (10 to 20 min) of rapid ammonium uptake were common in nitrogen-deficient plants. In the case of nitrate uptake, initial uptake rates were low, increasing after 10 to 20 min. Ammonium inhibited nitrate uptake for only the first 10 to 20 min and then nitrate uptake rates were independent of ammonium concentration. Nitrogen starvation for 8 d overcame this initial suppression of nitrate uptake by ammonium. Nitrogen starvation also resulted in a decrease in soluble internal nitrate content and a transient increase in nitrate reductase activity. Little or no decrease was observed in internal ammonium, total amino acids and soluble protein. The cultures grown on nitrate only, maintained high ammonium uptake rates also. The rate of nitrate reduction may have limited the supply of nitrogen available for further assimilation. Internal nitrate concentrations were inversely correlated with nitrate uptake rates. Except for ammonium-grown cultures, internal total amino acids and soluble protein showed no correlation with uptake rates. Both internal pool concentrations and enzyme activities are required to interpret changes in uptake rate during growth.     

Influence of soil-extractable aluminium and pH on the uptake of aluminium from soil into the soybean plant (Glycine max)

The effects of soil pH and other soil properties on the uptake of AI by soybean plants have been investigated in a greenhouse experiment. Six soils were compared that were developed over six contrasting bedrock types ranging widely in their AI content and other chemical and physical characteristics, namely Oxford Clay, Chalk, Lower Lias Clay, Devonian Shale, Granite and Lower Greensand. Soil pH varied naturally between soil types and each soil was also amended to give two other pH levels using elemental sulphur and/or calcium carbonate. AI concentrations in various parts of the soybean plants were determined by ICP-AES after acid digestion. The AI solubility in the soils and hence its availability to the plants was estimated using a number of different reagents designed to extract different forms of AI. The AI concentration measured in the soybean leaves was found to be predicted most accurately by the ‘available’ AI extracted from soils by 0.02 M CaCl₂. The relationship appears to the linear, with a correlation coefficient of 0.97 (p <0.01). The AI content of the leaves increases with decreasing soil pH. The relationship is non-linear with a marked increase in leaf AI for soils with pH <4.4. The amounts of ‘plant-available’ AI in the soils extracted with 0.02 M CaCl₂ was much less than that extracted with 0.05 M EDTA, although both increased markedly with decreasing soil pH. The amount of AI measured in the soybean plants was directly related to both the ‘available’ forms of AI in the soils, and also to the pH of the soils. Soil pH was identified as a major factor that controls the uptake of Al from soil into the soybean plant.     

Simulation of NO and N2O emissions from a spruce forest during a freeze/thaw event using an N-flux submodel from the PnET-N-DNDC model integrated to CoupModel

The amount of nitrogen gases (N₂O, NO and N₂) emitted from forest soils depends on interactions between soil properties, climatic factors and soil management. To increase the understanding of nitrogen processes in soil ecosystems, two dynamic models, CoupModel (coupled heat and mass transfer model for soil–plant–atmosphere systems) and the denitrification–decomposition (DNDC) model were selected. Both are dynamic models with different submodels for soil, vegetation, hydrology and climate system. CoupModel has a higher degree of detail on soil physical and abiotic components, whereas the DNDC model contains details of microbiological processes involved in production of nitrogen gases. To improve the previous simple submodel of nitrogen emission in CoupModel, we included a submodel corresponding to the forest version of DNDC containing photosynthesis/evapotranspiration-nitrogen (PnET-N-DNDC model).     

Effect of the nitrification inhibitor dicyandiamide on microbial communities and N<Subscript>2</Subscript>O from an arable soil fertilized with ammonium sulphate

Nitrous oxide (N₂O) affects climate change as a greenhouse gas and indirectly contributes to stratospheric ozone depletion. The main source of N₂O in soils is denitrification which requires high soil moisture, carbon and nitrate. Nitrification inhibitors can be used to mitigate emissions of N₂O from soils. In Portugal, fertilisers are often applied when soils are still relatively warm and moist conditions conducive to denitrification. A Portuguese arable soil was inhibited with dicyandiamide, a nitrification inhibitor and the effect on soil microbiological activity and composition was determined after 46 days. Soils were then incubated and received carbon and ammonium under high soil water conditions and mineral N and N₂O fluxes were measured during 22 days. We found that dicyandiamide decreased microbial populations and activity, but did not alter composition. Pre-conditioning of the soil with dicyandiamide was 80% more effective in reducing fluxes of N₂O than simultaneous application with fertiliser.     

Nitrogen fixation (acetylene reduction) in the phyllosphere of Thalassia testudinum

N₂ fixation (C₂H₂ reduction) associated with the leaves of the sea grass Thalassia testudinum was investigated at 5 sites in South Florida (Biscayne Bay) and one site in the Bahamas (Bimini Harbor). Significant activities were correlated with the occurrence of a heterocystous blue-green alga (Calothrix sp.) on the leaves. C₂H₂ reduction was not stimulated by organic compounds, either aerobically or anaerobically in the light or dark. Therefore, other physiological types of microbes were not important in N₂ fixation. Diurnal and seasonal variations in N₂ fixation occurred, with maximal rates during the daytime and in the late spring and early summer. N₂ fixation was negligible at four stations in Biscayne Bay. At the fifth station, near Fowey Rock, about 5 kg N ha^-1 year^-1 was fixed. In the summer, the N₂ fixed per day (4–5 mg N m^-2) could provide 4 to 23% of the foliar productivity demands of T. testudinum at this site and the station in Bimini Harbor. N₂ fixation at the periphery of a sea-grass patch, near Fowey Rock, could provide 8 to 38% of the daily nitrogen requirement for leaf production, and thereby might compensate for a less effective trapping and recycling of nitrogen from dead leaves in such regions.     

Effects of Cadmium on Nutrient Uptake and Translocation by Indian Mustard

Plants that hyperaccumulate metals are ideal subjects for studying the mechanisms of metal and mineral nutrient uptake in the plant kingdom. Indian Mustard (Brassica juncea) has been shown to accumulate moderate levels of Cd, Pb, Cr, Ni, Zn, and Cu. In this experiment, 10 levels of Cd concentration treatments were imposed by adding 10–190 mg Cd kg^–1 to the soils as cadmium nitrate [Cd(NO₃)₂]. The effect of Cd on phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and the micronutrients iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in B. juncea was studied. Plant growth was affected negatively by Cd, root biomass decreased significantly at 170 mg Cd kg^–1 dry weight soils treatment. Cadmium accumulation both in shoots and roots increased with increasing soil Cd treatments. The highest concentration of Cd was up to 300 mg kg^–1 d.w. in the roots and 160 mg kg^–1 d.w. in the shoots. The nutrients mainly affected by Cd were P, K, Ca, Fe, and Zn in the roots, and P, K, Ca, and Cu in the shoots. K and P concentrations in roots increased significantly when Cd was added at 170 mg kg^–1, and this was almost the same level at which root growth was inhibited. Zn concentrations in roots decreased significantly when added Cd concentration was increased from 50 to 110 mg kg^–1, then remained constant with Cd treatments from 110 to 190 mg kg^–1. However, Zn concentrations in the shoots seemed less affected by Cd. It is possible that Zn uptake was affected by the Cd but not the translocation of Zn within the plant. Ca and Mg accumulation in roots and shoots showed similar trends. This result indicates that Ca and Mg uptake is a non-specific process.