Cd Kg-1 Research Articles

Effect of soil cadmium application and pH on growth and cadmium accumulation in roots, leaves and fruit of strawberry plants (Fragaria × ananassa Duch.)

Three strawberry (Fragaria × ananassa Duch.) cultivars Rainier, Totem and Selva were grown under greenhouse conditions in a Parkhill sandy loam soil with a background DTPA-extractable Cd concentration of 0.18 mg kg-1 and a pH of 5.1. Experimental treatments included combinations of 4 Cd applications (0, 15, 30 and 60 mg Cd kg-1 soil) applied as CdSO4 and 2 soil pH values 5.1 and 6.8. Both the application of Cd and pH of the soil significantly affected plant growth, yield and Cd accumulation in plant tissue anf fruit. Although roots accumulated the highest concentrations of Cd of all plant parts investigated, increased soil Cd application reduced leaf weight more than root weight. In general, yield of strawberries was decreased by an increase in amount of soil-applied Cd, however the yield response varied among cultivars. At 60 mg Cd kg-1 soil, yield of Rainier cultivar was reduced to 17.6% of control plants. Over 90% of total Cd taken up by plants grown in Cd-treated soil accumulated in roots, regardless of the Cd level in the soil. Root Cd concentrations ranged from 2.6 mg kg-1 (control plants) to 505.7 mg kg-1 (Totem plants grown in soil at highest Cd and a soil pH 5.1) and were directly related to soil Cd concentrations. Cd translocation from roots to leaves and fruit was very limited, resulting in a maximum Cd concentration in root leaf tissue of 10.2 mg kg-1. Accumulation of Cd in fruit was found to correlate well with leaf Cd, although even at the highest amount of applied Cd, fruit Cd concentration did not exceed 700 μg kg-1 of fresh weight.

Cadmium distribution in hill pastures as influenced by 20 years of phosphate fertilizer application and sheep grazing

Cadmium (Cd) accumulating in the kidneys of older grazing animals threatens the continued access of New Zealand offal products to traditional markets. Phosphatic fertilizers represent the largest input of Cd into pastoral farming systems. Little research has been conducted on the cycling of Cd in grazed pastures. To estimate the distribution of Cd in grazed pastures, soil samples were collected from self-contained farmlets which had received either high superphosphate (HF) inputs (765 kg P ha-1), low superphosphate (LF) inputs (113 kg P ha-1) or no phosphate fertilizer (UF) inputs over the previous 20 years. The average total Cd concentration in the surface soil (0-30 mm; bulk density 0.64 g cm-3) of the farmlets which had received HF inputs was 0.40 mg kg-1 soil (range 0.18-0.60 mg kg-1), whereas farmlets which had received LF or no fertilizer inputs had an average Cd concentration of 0.10 mg kg-1 (range 0.02-0.19 mg kg-1). Cadmium concentration decreased with soil depth. The concentration of Cd in mixed herbage reflected the difference in soil Cd between the HF (mean � standard error = 0.321 � 0.033 mg Cd kg(-1) dry matter) and LF (0.063 � 0.004 mg Cd kg(-1) dry matter) farmlets. Soil Cd accumulation was highest on low slopes (0-12�) and lowest on high slopes (> 26�) in both LF and HF farmlets, whereas pasture Cd concentration in the HF farmlet increased with slope from 0.178 � 0.035 mg Cd kg-1 on low slopes to 0.487 � 0.053 mg Cd ha-1 on high dopes. A strong relationship was obtained between soil Cd and P in the 0-30 mm layer of the HF farmlet, demonstrating the link between phosphate fertilizer use and Cd accumulation. Zinc to Cd ratios were much lower in this layer compared with those in LF and UF sites, providing further evidence of the contribution of phosphate fertilizer to soil Cd. A model originally developed to explain the distribution of soil P in sheep-grazed fertilized hill pastures gave good predictions of present day soil Cd distribution in the HF farmlet. The model predicts Cd accumulation in soil by using the amounts of Cd applied in fertilizer per unit surface area of land and functions which calculate the redistribution of Cd by animal grazing and camping behaviour. The model on an average overpredicted the measured soil Cd by 17% in the high slope sites and by 10% in the low slope sites.

Effect of Phosphate Fertilizers and Atmospheric Deposition on Long-Term Changes in the Cadmium Content of Soils and Crops

Trends are reported in the Cd content of herbage collected and stored from the Park Grass Experiment at Rothamsted Experimental Station, a semirural location in the U.K. Samples from 1861 to 1992 were bulked for 5-year periods from two phosphate fertilizer-treated plots, now with soil pH 4.9 (unlimed) and 6.5 (limed), respectively. Analysis of Cd was by Zeeman correction GFAAS following a nitric acid digestion. The data are compared with those from control plots which have not received superphosphate. On the unlimed plots, levels of Cd in the herbage from the phosphate-treated plot were very similar to those on the control for the years to 1930; whereas from 1940 to the present, the Cd concentrations in herbage were considerably greater on the phosphate-treated plot. On the limed plots, Cd concentrations in the herbage from both the phosphate-treated and control plots have remained similar to each other, although both plots exhibit a small increase of about 1 Mg of Cd kg-1 year-1 since the beginning of the liming treatment in 1903

Populations of Cd-tolerant microorganisms in soils polluted with heavy metals

Abstract In order to estimate the effect of heavy metal pollution on soil microorganisms, field surveys were carried out in paddy fields, upland fields, and fallow paddy fields located in two areas with heavy metal pollution in Japan (Izuhara area, where the soil samples contained 0.2–15.0 mg Cd kg-1, 11–696 mg Zn kg-1, 0.8–16.2 mg Cu kg-1; Toyama area, where the soil samples contained 0.2–3.9 mg Cd kg-1, 4.7–146 mg Zn kg-1, 0.5–21 mg Cu kg-1). There was no significant correlation between the viable counts of microorganisms and heavy metal content of the soils. The dominance value of the bacteria tolerant to 10 mg kg-1 Cd (D 10 value; D c =log(VC c /VC0), where VC c is the viable count on the plates containing c mg L-1 of Cd, VC0 is the viable count on the plates without Cd) increased significantly with the increase of the heavy metal content in the paddy fields. However, there was no significant correlation between the D100 value of the bacteria or the D10 value of the fungi and the heavy metal content o...

Distribution of Copper and Cadmium Fractions in Two Forest Soils.

Pollution of soil by Cu and Cd seems to be increasing in Switzerland. To know the background concentration in low polluted soil we have measured their concentrations in every horizon and calculated the total amounts. The concentrations were low: the largest concentrations of Cu and Cd occurred in the topsoil of a Typic Dystrochrept (acid brown soil) (13.5 mg kg-1 Cu and 437 μg kg-1 Cd) and in the Oi-Oa-Al and Bh horizons of a Typic Haplorthod (podzol) (up to 16 mg kg-1 Cu and 460 μg kg-1 Cd in Oi), though when corrected by density, concentrations were higher in Al horizon of the Haplorthod and Al and BC of the Dystrochrept. The Dystrochrept was found to contain more of the metals than the Haplorthod. The soil is the main storage compartment of both ecosystems. A six step sequential extraction was applied to evaluate the affinity of metals for the soil constituents and the binding strength to the solid matrix. Water, 0.1 M NaNO3 , 0.1 M hydroxylamine, 1 M hydroxylamine plus acetic acid, H2 O2 and aqua regia were used as successive reagents. Patterns of Cu and Cd distribution in a given soil are different and, to a lesser extent, for a given element the distribution patterns depend on the soil type. Organic matter or Fe and Mn oxides seem to immobilize Cu whereas Cd is associated mainly with Fe and Mn oxides. If the sequential extraction is considered as succession of reagents of increasing strength, then Cd seems to be less strongly bound to soil than Cu and thus more readily solubilized and translocated within soil. The results show the limitations of multistep sequential extraction as a technique for studying metal fractions.

Effects of heavy metals in soil on microbial diversity and activity as shown by the sensitivity-resistance index, an ecologically relevant parameter

A sensitivity-resistance index was developed, and proved to be a very sensitive biomonitor of soil pollution with heavy metals. The index was developed by a step-by-step approach. Ultimately, the bacterial soil microflora was divided into three groups, senstivive, tolerant, and resistant microflora. Zn and Cd sensitivity was defined as no growth occurring in the presence of 5 and 0.5 mg l-1 of these metals, respectively, while resistance was defined as distinct growth in the presence of 50 and 16 mg l-1, respectively. The sensitivity: resistance ratio of a referent clay soil (0.57 mg Cd kg-1 and 140 mg Zn kg-1) was 0.53, but for polluted (6 mg Cd kg-1 + 670 mg Zn kg-1) clay soil, the ratio was 0.24. For a referent (0.06 mg Cd kg-1 + 12 mg Zn kg-1) sandy soil the sensitivity: resistance ratio was 1.50 whereas polluted (2.3 mg Cd kg-1 + 252 mg Zn kg-1) sandy soil had a ratio 0.19. The ecological value of the sensitivity-resistance lies in its capacity to reflect potential deradation of aromatic compounds. It has been shown repeatedly that sensitive bacteria grow significantly better on a range of selected aromatic compounds. It has been speculated that resistance fo heavy metals may reduce the bioremediation capacity of soil towards chlorinated aromatics and polyaromatic hydrocarbons.

Field studies of cadmium in potatoes (Solanum tuberosum L.) I. Effects of lime and phosphorus on cv. Russet Burbank

Field experiments were conducted at three sites on basaltic krasnozems to examine cadmium (Cd) responses of Russet Burbank potatoes to different rates of broadcast lime and banded phosphorus (P). Double superphosphate (DSP, containing 15 and 90 mg Cd kg-1) and triple superphosphate (TSP, 12 mg Cd kg-1)) were the sources of P. In a fourth experiment, lime was banded with the basal fertilizer. Despite producing a range of topsoil pH (1:5 H20) of 5.2 to 7.1, broadcast lime had no effect on tuber Cd concentrations. Lime had no effect when banded with the basal fertilizer, and the practice did not adversely affect yields. With broadcast lime, Cd availability from the fertilizer band may have been unaffected. However, there were also no lime x P interactions at any site, suggesting that lime also had no effect on the availability of Cd in the soil. It is possible that Tasmanian krasnozems, with their high organic matter and iron oxide content, restrict the availability of Cd in the soil such that pH change exerts little net influence on Cd availability. Increasing amounts of Cd applied in P fertilizer increased tuber Cd concentrations significantly, but the increases were less per unit of P than those found previously when TSP with 151 mg Cd kg-1) was used.

Accumulation of cadmium and selected elements in flax seed grown on a calcareous soil

Seed of flax (Linum usitatissimum L.) grown on calcareous and neutral soils sometimes accumulates relatively high concentrations of Cd. The influence of a post-flowering application of NH4NO3 (115 mg N kg-1), CdSO4 (1 mg Cd kg-1), FeEDDHA (2 mg Fe kg-1), NaH2PO4 (120 mg P kg-1) and ZnSO4 (8 mg Zn kg-1) on seed accumulation of Cd, Fe, N, Mn, P and Zn by flax grown on a Calciaquoll was studied in two experiments under greenhouse conditions. Seed yields were increased by the N and Zn treatments, and the N×Zn interaction was positive. Zinc deficiency delayed flowering and boll formation by up to 20 days and reduced seed size. In the absence of added Cd, seed accumulated up to 0.33 mg Cd kg-1. This Cd accumulation was reduced by approximately 50 and 17% by added Zn and Fe, respectively, but was little affected by P fertilizer and post-flowering N stress. In the presence of added Cd, seed Cd exceeded 3.3 mg Cd kg-1, and the antagonistic effects of Fe and Zn on seed Cd were absent. Seed N, P, Fe and Zn concentrations were increased on average by 10, 45, 31 and 97% by the N, P, Fe and Zn fertilizer treatments, respectively. FeEDDHA reduced seed Mn concentration by approximately 58%. However, seed Mn concentration was much less than that found in vegetative tissue at flowering. Soil-applied Zn may reduce seed Cd concentration in flax under field conditions, and may increase marketability of flax for food use.

Field studies of cadmium in potatoes (Solanum tuberosum L.). Response of cvv. Russet Burbank and Kennebec to two double superphosphates of different cadmium concentration

Separate field experiments were conducted with Russet Burbank and Kennebec potatoes on a basaltic krasnozem where tuber cadmium (Cd) responses were examined over three rates of banded phosphorus (P), supplied as double superphosphate (DSP) containing either 15 or 90 mg Cd kg-1. In both cultivars, tuber Cd concentrations increased with rate of DSP. This response was due more to the amount of P supplied in the DSP than the amount of Cd supplied in the DSP and may be a result of banded P encouraging root proliferation in the fertilizer band. Even with DSP at 15 mg Cd kg-1, Cd additions at rates of DSP needed for high yields were 6-20 times higher than corresponding rates of Cd removal in tubers. Examination of data from all studies of Cd in Russet Burbank on Tasmanian krasnozems showed a significant relationship between petiole and tuber Cd concentrations, but the estimation of a petiole concentration associated with the critical tuber Cd concentration in Australia was subject to unacceptable uncertainty due to variation between sites.

Influence of cadmium, copper, and pentachlorophenol on growth and sexual development of Eisenia andrei (Oligochaeta; Annelida)

In the existing guidelines for earthworm toxicity testing, mortality is the only test criterion. Mortality is, however, not a very sensitive parameter, and from an ecological point of view growth and reproduction are more important for a proper risk assessment of chemicals in soil. In this study the growth and sexual development of juvenile earthworms were considered as test criteria in a standardized earthworm toxicity test. The effect of Cd, Cu, and pentachlorophenol on the growth and sexual development of juveniles of the species Eisenia andrei was studied in an artificial soil substrate. Two tests with Cd were carried out to study the effects of the mode of application of the food source (cow dung). EC50 (50% effective concentration) values for the effect of Cd, Cu and pentachlorophenol on the growth of E. andrei were 33–96, >100, and >32 mg kg-1 dry soil, respectively, and there was no observed effect at 18–32, 56, and ≥32 mg kg-1 dry soil, respectively. Sexual development of the earthworms was inhibited at 10 mg Cd kg-1 and 100 mg Cu kg-1 dry soil, but was not affected at the highest pentachlorophenol concentration tested (32 mg kg-1 dry soil). The results were the same whether the food was applied in a hole in the middle of the soil or mixed homogeneously through the soil.

Crassostrea virginica as an indicator of cadmium pollution

As much as 89, 176 and 292 μg Cd g-1 dry weight were accumulated by adult Crassostrea virginica after treatment for 40 wk with 5, 10 and 15 μg Cd kg-1, respectively, in flowing seawater at ambient salinity and temperature without mortalities. Cadmium accumulation increased with increased concentration of cadmium in seawater; greater amounts were accumulated during the summer months. Uptake patterns measured as cadmium content were similar among the total soft parts, gill, mantle and visceral mass. A continuous increase of cadmium concentration in the visceral mass was observed. This differed from the uptake patterns observed as cadmium concentration in gill, mantle and total soft parts. Although cadmium accumulation in the total soft parts and the tissues was curvilinear over the entire study period, significant linear relations between cadmium concentration and time indicated a general increasing trend. At seawater temperatures below 6°C, when oysters were not actively feeding, cadmium concentrations in the total soft parts varied significantly between treatments, but not within treatments. In the tissues, the rate of uptake expressed as cadmium concentrations was visceral mass>gill≥mantle. Cadmium concentration in the total soft parts varied inversely with dry weight, whereas cadmium concentration in the total soft parts increased, whereas the content decreased. Cadmium concentration decreased in mantle and gill but increased in the visceral mass during spawning, whereas cadmium content decreased in all tissues. Regression analyses indicated that during spawning dry weight decreased at the same rate in gill and mantle, but they lost less weight and lost it more slowly than visceral mass. Also, during spawning, cadmium content decreased in mantle and gill at the same rate but more slowly than in the visceral mass. In mid-August, Cd concentration decreased despite the continuous addition of cadmium to the seawater; however, Cd content increased, suggesting that organism weight was responsible for fluctuations in cadmium concentrations.

Variability in the composition of commercial pig diets with particular reference to minerals

Samples of 28 pig diets fed to grower pigs in 24 commercial piggeries in Victoria were analysed for proximate constituents, fibre components, energy, Ca, P, K, Mg, Na, Cu, Zn, Fe, Cd, Pb and As. Vitaminmineral premixes, salts used in the premixes, and some other additives were analysed for Cd and Pb. There was a wide variability in the composition of all components in the diets except gross energy. 'Home mix' diets tended to have lower contents of ash and fibre, compared with diets supplied by feed manufacturers. Comparisons with recommended nutrient requirements showed that 8 diets were apparently deficient in crude protein (less than 16%) and only 7 diets contained sufficient crude protein to meet the requirements of pigs up to 50 kg liveweight (20% or more). However, amino acid contents were not determined. One diet was deficient in Na, six diets were deficient in Ca, and eight diets had Ca : P ratios less than 1:1. Seven diets contained Cu at levels recommended for growth promotion (125-250 mg kg-1) ; 20 diets contained added Cu but at levels insufficient for growth promotion. All diets contained excessive amounts of Zn and Fe (up to 317 and 701 mg kg-1 respectively) ; the mean concentration of Zn was three times the recommended requirement and the mean concentration of Fe was six times the recommended requirement. Concentrations of Cd occurred up to 0.61 mg kg-1 and of Pb up to 5.53 mg kg-1. One diet contained 32.41 mg As kg-1 but the next highest concentration was 1.07 mg kg-1. Vitamin-mineral premixes contained up to 81 mg Cd kg-1 and up to 1292 mg Pb kg-1. Copper sulphate contained 376 mg Cd kg-1; copper oxide contained 2550 mg Pb kg-1; zinc oxide contained 114 mg Pb kg-1.