Recycled iron phosphate as a fertilizer raw material for tree stands on drained boreal peatlands

Fertilization of drained peatland forests with easily soluble or slow-release apatite fertilizers can increase phosphorus (P) export to water courses, especially when the soil is low in aluminum (Al) and iron (Fe) hydroxides and oxides. Application of Al and Fe together with P increases P adsorption to the soil and decreases the risk of leaching. The aim of this study was to investigate the use of recycled iron phosphate (rFePO₄) as forest fertilizer raw material from environmental and forest production perspectives. Trial fertilizers with different mixtures of rFePO₄ and Russian Kola apatite (Kap) were applied on 15 mini-catchments (area 100 m²), where the discharge at the outlet was collected, sampled and analyzed throughout the about 4-year measurement period. The foliage P content and height growth of the trees on the mini-catchments were measured. The biomass growth of the extramatrical mycorrhizal mycelia (EMM) was studied with a separate in-growth mesh bag experiment conducted on the same site. The results indicated no increase in phosphorus export to surface waters after application of rFePO₄ and 25/75 and 50/50 mixtures of rFePO₄ and Kap. In contrast to earlier studies showing a relatively high P export with different types of apatite fertilizers, the Kap fertilizer showed only minor phosphorus export. The height growth measurements and needle analyses of the juvenile Scots pine stands indicated poor P availability from pure rFePO₄, but the P availability from the 50/50 and 25/75 mixtures of rFePO₄ and Kap was similar to pure Kap. The mixtures of Kap and rFePO₄ enhanced the EMM biomass by 2- to 3-fold, whereas Kap and rFePO₄ alone, and high P availability (superphosphate) had no significant effect compared to non-P controls. The increase in EMM biomass as induced by concurrent application of Kap and rFePO₄ was not clearly reflected in tree growth and P acquisition. However, longer follow-up studies than in this one may be needed in order to verify the effect of increased EMM biomass on mycorrhizal mycelia mediated nutrient uptake and tree growth.     

Evaluation of fly ash,apatite and rice straw derived-biochar in varying combinations for in situ remediation of soils contaminated with multiple heavy metals

ABSTRACT

In

-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.     

磷灰石和石灰稳定化修复对污染土壤铜和镉垂直迁移的影响

大量改良材料被用于重金属污染土壤的稳定化修复,但是不同用量的改良材料长期田间修复后重金属总量和有效态在不同土层的垂直分布特征鲜有研究涉及。本研究采集不同剂量的磷灰石和石灰稳定化修复的0~13、13~30和30~50 cm土层污染土壤,考察铜和镉总量及有效态含量在不同土层的分布特征。结果表明:随着磷灰石和石灰用量的增加,显著降低了0~13 cm土层土壤交换性酸和交换性铝,增加了土壤全钙的含量,且磷灰石处理提高了土壤全磷和速效磷含量。0~13 cm土层土壤pH、总铜和总镉含量均随着磷灰石和石灰用量的增加而逐渐增加,但是降低了13~30和30~50 cm土层土壤总铜和总镉含量。3个土层中铜和镉有效态含量均随着磷灰石和石灰用量的增加而显著降低,其中23.2 g/kg磷灰石处理和4 g/kg石灰处理土壤有效态铜含量降低85.1%和92.0%,有效态镉降低18.8%和23.5%。相关性分析表明,土壤pH和铜镉总量是影响铜镉有效性的主要因素。可见,磷灰石和石灰的应用使铜和镉较好地固定在土壤表层,减少铜和镉向下层土壤的淋溶,降低了铜和镉的有效性。     

Renal Calculi in Dogs and Cats: Prevalence, Mineral Type, Breed, Age, and Gender Interrelationships (1981–1993)

Three hundred seventeen specimens of urinary calculi of renal origin from 214 female dogs and 103 male dogs, and 71 specimens of urinary calculi of renal origin from 38 female cats and 33 male cats were submitted for mineral analysis between July 1, 1981, and December 31, 1993. Among dogs, 45 breeds were affected with renal calculi. Thirty-three breeds and a crossbred group were represented among females, but 8 breeds and the crossbred group accounted for 81% of the total. Among male dogs, 30 breeds and a crossbred group were represented, but 7 breeds and the crossbred group accounted for 69% of the total. Among cats, 10 breeds and a crossbred group were represented. Dogs and cats with renal calculi were older than those of 2 comparison population groups. More than one-half of the renal calculi in both dogs and cats were from the 1st known episode of urolithiasis. The risk of formation of renal calculi was found to be higher for cats than for dogs, when compared to other stone-forming cats and dogs (approximately 4.95 per 100 stone-forming cats and 2.88 per 100 stone-forming dogs). Among dogs, breeds at highest risk of developing renal calculi were Miniature Schnauzers, Shih Tzus, Lhasa Apsos, Yorkshire Terriers, and female Pugs. Also at high risk were male Dalmatians and male Basset Hounds. Among small dogs, females generally were at higher risk of developing renal calculi than were males. Regardless of size, terrier breed males generally were at higher risk of developing renal calculi. Breeds of dogs at low risk for development of renal calculi included crossbreds, German Shepherd Dogs, Labrador Retrievers, Golden Retrievers, and female Dachshunds. When only 1 kidney was involved, the risk of left renal calculus was greatest for both dogs and cats, but bilateral renal involvement was relatively common in both species (19% and 9%, respectively). Among dogs, specimens composed of 1 mineral substance (eg, struvite) occurred more often in males (58.3%) than in females (37.9%). Female dogs formed renal calculi containing struvite or oxalate more often than did males; males formed calculi containing urate more often than did females. Calculi containing oxalate, apatite, or some combination of these minerals predominated among cats; only 1 specimen from 38 female cats and only 4 specimens from 33 male cats contained neither oxalate nor apatite. Crossbred cats were significantly less likely to have renal calculi than were other breeds. A single renal calculus specimen was identified in several uncommon breeds including Tonkinese and Birman cats, and Affenpinscher, Clumber Spaniel, English Shepherd, and Field Spaniel dogs. No significant differences were observed between male and female dogs or between male and female cats with regard to mineral type of the specimen and the presence of urinary tract infection.     

磷灰石联合黑麦修复铜污染土壤研究

通过田间试验研究了不同剂量磷灰石(10、20、30、50 g/kg,编号分别为LH1、LH2、LH3和LH4)与黑麦联合作用对Cu污染土壤的修复效果,重点考察了磷灰石对黑麦生物量及Cu吸收、土壤pH及Cu形态转化、土壤酶活性、植物生理指标等的影响。试验结果表明,磷灰石显著提高了土壤pH、黑麦生物量及其Cu吸收量,显著降低了黑麦地上部分及根系Cu含量,其中LH3处理黑麦Cu吸收量最高,达到对照处理的33.38倍;与对照相比,LH1、LH2、LH3和LH4处理土壤可交换态Cu含量显著降低了37.0%、58.9%、89.0%和83.3%,碳酸盐结合态Cu含量显著增加了46.6%、63.1%、78.0%和93.3%;与对照相比,LH2、LH3和LH4处理显著提高了土壤磷酸酶、过氧化氢酶和脲酶活性,显著提高了黑麦SOD和POD酶活性,显著降低了黑麦MDA含量。综合而言,施用30 g/kg的磷灰石并种植黑麦能够很好地修复Cu污染土壤。     

Changes in soil phosphorus fractions across a toposequence in the estuary plains of Pakistan

Understanding the regional dynamics of soil phosphorus (P) chemistry is essential for developing the best fertilizer management practices aimed at enhancing P use efficiency in cropping systems. The soil content of apatite, an important P-containing lithogenic mineral, can be influenced by its position in the local relief of a landscape. The objective of this study was to determine quantitative distribution of various P-forms in estuary plains of southern Pakistan in relation to soil genesis. Soils at different positions within the estuary plain were sampled at various genetic horizons. Apatite-P was the most abundant inorganic P constituent (380-590 mg kg^?1) in all cases, followed in decreasing abundance by iron oxides surfaces adsorbed phosphorus (Fe-P), octacalcium phosphates (Ca₈-P), aluminum oxides with surface bound P (Al-P) and the least abundant was the phosphorus occluded in iron oxides mineral (Occl-P). The abundance of apatite-P and these other forms of secondary phosphate varied for the soils at different relief positions in these estuary plain landscapes.     

Soil and sediment phosphorus fractions in a forested watershed at Acadia National Park,ME, USA

Phosphorus (P) is often the critical limiting nutrient controlling the productivity of natural waters. Understanding the linkages between terrestrial and aquatic P dynamics is essential to defining the mechanisms governing P availability in the ecosystem. We used P fractionation techniques to investigate landscape patterns of P distribution in soils, and associated stream and lake sediments, in a forested watershed at Acadia National Park, ME, USA. Specifically, we investigated the chemical and spatial distribution of P in primary and secondary mineral phases along a topographic and bathymetric transect based on distance from the stream for soils and lake sediments. The dominant P fraction was associated with aluminum (Al) hydroxides, a fraction that also included some iron (Fe) hydroxides and organic P. The Al–P fraction accounted for 62% and 66% of total P in all soil and lake samples, respectively. These results suggest that secondary Al, and to a lesser extent Fe, dominate P dynamics in these soils and lakes. Stream sediments appear to originate from deeper, less weathered portions of the soil with lower accumulations of secondary Al and Fe. As a result, stream sediments have little capacity for adsorbing P, relative to soil or lake sediments. Phosphorus fractionation results also suggested that both exposed and occluded primary apatite-P still persists in these soils, stream sediments, and lake sediments. Extractable apatite-P concentrations increased progressively with decreasing distance from the stream in the watershed and with increasing distance from the stream and depth in the lake. These trends were attributed to spatial patterns in the intensity of pedogenesis in the watershed and the influence of winnowing and sedimentation on lake sediment composition.