Differences in the growth response of three bryophyte species to nitrogen

The effect of nitrogen on biomass production, shoot elongation and relative density of the mosses Pleurozium schreberi, Hylocomium splendens and Dicranum polysetum was studied in a chamber experiment. Monocultures were exposed to 10 N levels ranging from 0.02 to 7.35 g N m⁻² during a 90-day period. All the growth responses were unimodal, but the species showed differences in the shape parameters of the curves. Hylocomium and Pleurozium achieved optimum biomass production at a lower N level than Dicranum. Pleurozium had the highest biomass production per tissue N concentration. Tolerance to N was the widest in Dicranum, whereas Hylocomium had the narrowest tolerance. Dicranum retained N less efficiently from precipitation than the other two species, which explained its deviating response. All species translocated some N from parent to new shoots. The results emphasize that the individual responses of bryophytes to N should be known when species are used as bioindicators.     

用次磷酸钠废渣制备饲料级磷酸三钙

采用高温煅烧工艺，以工业生产次磷酸钠的废渣为原料，制备饲料级磷酸三钙，并对最佳工艺条件进行探讨。最佳工艺条件：煅烧温度600℃、煅烧时间20min。制得的饲料级磷酸三钙中磷的质量分数为16％～18％，符合Q／YHY01—2003《饲料级磷酸三钙》产品质量企业标准。     

Rock phosphate solubilizing and cellulolytic actinomycete isolates of earthworm casts

Four microbial isolates, OP2, OP3, OP6, and OP7, of earthworm casts ofPontoscolex corethrurus were found to be acid tolerant actinomycetes and efficient rock phosphate (RP) solubilizers that could grow fast on NH₄Cl-enriched or N-free carboxymethyl cellulose or glucose as sole carbon source. CMC (carboxymethyl cellulose) induced production of extracellular cellulase enzyme and the production of reducing sugar in all the isolates. RP solubilizing power was observed to be inversely related to glucose consumption. The most efficient RP solubilizer was found to consume the least glucose. Growth was faster on cellulose than on glucose media. N-free CMC induced greater glucose production than NH₄Cl-enriched CMC medium. Both CMC and glucose media were acidified by all the isolates, however, RP solubilizing power decreased with acidification. Solubilization power was greatest with isolate OP7, which also produced the greatest amount of reducing sugar per gram CMC. Both RP solubilizing power and the cellulolytic efficiency varied among isolates. A minimum of 631 μg P/0.1 g RP and a maximum of 951.4 μg P/0.1 g RP was recorded.     

UV/H2O2 oxidation of tri(2-chloroethyl) phosphate: Intermediate products, degradation pathway and toxicity evaluation

Tri(2-chloroethyl) phosphate (TCEP) with the initial concentration of 5 mg/L was degraded by UV/H₂O₂ oxidation process. The removal rate of TCEP in the UV/H₂O₂ system was 89.1% with the production of Cl^? and PO₄^3? of 0.23 and 0.64 mg/L. The removal rate of total organic carbon of the reaction was 48.8% and the pH reached 3.3 after the reaction. The oxidative degradation process of TCEP in the UV/H₂O₂ system obeyed the first order kinetic reaction with the apparent rate constant of 0.0025 min^?1 (R²=0.9788). The intermediate products were isolated and identified by gas chromatography-mass spectrometer. The addition reaction of HO? and H₂O and the oxidation reaction with H₂O₂ were found during the degradation pathway of 5 mg/L TCEP in the UV/H₂O₂ system. For the first time, environment risk was estimated via the “ecological structure activity relationships” program and acute and chronic toxicity changes of intermediate products were pointed out. The luminescence inhibition rate of photobacterium was used to evaluate the acute toxicity of intermediate products. The results showed that the toxicity of the intermediate products increased with the increase of reaction time, which may be due to the production of chlorine compounds. Some measures should be introduced to the UV/H₂O₂ system to remove the highly toxic Cl-containing compounds, such as a nanofiltration or reverse osmosis unit.     

A Study on Transfer Factors of 60Co and 65Zn from Soil to Plants in the Tropical Environment of Bangladesh

Soil to plant transfer factor (TF) of⁶⁰Co and ⁶⁵Zn was determined fromradioisotope experiments on plants grown in pots underoutdoor ambient tropical conditions for three growingseasons (1995–1998). The TFs were obtained fordifferent plants/crops such as, rice, bean, peanutspineapple, cabbage, tomato, spinach and grass. Theaverage TF values of ⁶⁰Co are found to be 0.087,0.15, 0.12, 0.67, 0.28, 0.79, 1.03 and 0.34respectively for the above mentioned plants/crops. Incase of ⁶⁵Zn, the average TF values are found tobe 2.24, 1.17, 0.89, 1.09, 0.78, 1.34, 2.92 and 1.78,respectively, for the above mentioned plants/crops. Thedata will be useful to assess the radiation exposureto man associated with the releases of radionuclidesfrom nuclear facilities by means of radiologicalassessment models that require transfer factors asinput parameters to predict the contamination ofradionuclides in foodchain.     

氨基酸法现场快速测定废水中的磷酸盐

通过磷酸盐与钼酸盐、氨基酸反应使样品呈淡蓝色,讨论了在事故现场快速测定水中磷的方法。试验表明方法灵敏,操作简单快速。检测范围0～15mg/L。     

有机磷酸酯诱导迟发性神经毒性及其对神经毒性酯酶（NTE）活性影响的动态研究

以成年产卵来航母鸡为试验动物，研究了三甲基苯基磷酸酯（Ｔｒｉ－ｏ－ＣｒｅｓｙｌＰｈｏｓ－ｐｈａｔｅ，ＴＯＣＰ）诱导的迟发性神经毒性．试验发现，母鸡口服ＴＯＣＰ（７５０ｍｇ／ｋｇ）后，经过大约８－１０ｄ的潜伏期开始出现中毒症状，其表现为以步态失调为主要特征的运动障碍呈进行性加重，至第２１ｄ开始便发展为瘫痪，对鸡脑神经病损靶标酯酶（ＮｅｕｒｏｐａｔｈｙＴａｒｇｅｔＥｎｚｙｍｅ，ＮＴＥ）活性的测定表明，有机械诱导的迟发性神经毒性（Ｏｒｇａｎｏｐｈｏｓｐｈａｔｅ－ＩｎｄｕｃｅｄＤｅｌａｙｅｄＰｏｌｙｎｅｕｒｏｐａｔｈｙ，ＯＰＩＤＰ）与ＮＴＥ活性抑制之间的关系不平行，其毒性症状的轻重与ＮＴＥ活性被抑制的强弱也不呈正相关，很可能，在给药后２４ｈ，体内ＯＰＩＤＰ已被触发，此外，实验观察到给予ＴＯＣＰ后被试鸡的体重明显下降。     

Effects of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils

In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3--N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3--N leaching significantly, whereas ammonium (NH4 -N) leaching increased slightly. In case of total N (NO3--N NH4 -N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea DMPP), 108.10 mg (ASN), 60.70 mg (ASN DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea DMPP), 37.86 mg (ASN), 31. 09 mg (ASN DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4 -N and low levels of NO3--N in soil, and nitrification was slower. DMPP supplementation also resulted in potassium leached less, but the difference was not significant except the treatment ASN and ASN DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.     

溶解氧对水质变化和沉积物吸磷过程的影响

通过室内模拟实验,研究有光和黑暗条件下,富氧和缺氧环境对东太湖沉积物吸收磷酸盐过程的影响.研究结果表明沉积物能够吸收上覆水中高质量浓度的磷酸盐,但吸收量和吸收速度随环境条件的不同而不同;缺氧环境上覆水中的pH高于或略高于相同光照条件下的富氧环境;实验开始的前20d,富氧环境有利于沉积物吸附上覆水中的磷酸盐,并快速达到吸附平衡,缺氧环境则相反;实验开始20d后,有光缺氧组上覆水中磷酸盐质量浓度开始迅速下降,且明显低于其他实验条件;富氧环境沉积物中总磷的增加量高于缺氧环境,其含量顺序为无光富氧＞有光富氧＞有光缺氧＞无光缺氧;溶解氧对沉积物中铁结合态磷和钙结合态磷含量的影响较大,对有机磷含量的影响不大.