亚硒酸钠对蚯蚓的毒性及蚓体富硒作用的研究

以100mgkg^-1,200mgkg^-1,300mg kg^-1等不同质量分数（w)的亚硒酸钠（NaSeO2)添加到蚯吲饵料中,研究了亚硒酸钠处理对蚯蚓生长发育及死亡的影响和蚯蚓的富硒作用,结果表明,3个w(NaSeO2)处理对蚯蚓生长发育和富硒量的影响都达到极显著水平,w(NaSeO2)越高,用其处理饲养的蚯蚓死亡率也较高,富硒量也较大,二者存在一定的正相关性,在200mg kg^-1的w(NaSeO2)处理下,当蚯蚓饲养到84d时,蚯蚓的富硒量可达到332．5mg kg^-1,同时死亡率高达90％。     

Alterations of biochemical parameters in malformed Indian rice frogs, Rana limnocharis from Southern Taiwan

The purpose of this study is to investigate the factors that cause malformed frogs in upstream Kaoping river (KP site) and Tungkang river (T site) of Southern Taiwan. In this experiment, the activities of monooxygenase (MO), glutathione-S-transferase (GST), acetylcholinesterase (AchE) as well as the concentration of vitellogenin (Vg) in the liver were measured. Results show that activities of MO, GST and AchE, and Vg levels in normal frogs (male/female) were 0.09 +/- 0.02/0.09+/-0.01 deltaA min(-1) mg(-1) protein, 0.12 +/- 0.04/0.13 +/- 0.04 deltaA min(-1) mg(-1) protein, 6.13 +/- 2.69/6.01 +/- 2.09 U mg(-1) protein and 0.87 +/- 0.42/2.18 +/- 0.50 microg mg(-1) protein, respectively. Activities of MO, GST and AchE, and Vg levels in malformed frogs (male/female) were 0.15 +/- 0.04/0.21 +/- 0.07 deltaA min(-1) mg(-1) protein, 0.27 +/- 0.08/0.30 +/- 0.12 deltaA min(-1) mg(-1) protein, 4.59 +/- 2.71/5.19 +/- 3.74 U mg(-1) protein and 1.46 +/- 0.61/3.15 +/- 0.88 microg mg(-1) protein, respectively in KP site, and were 0.16 +/- 0.69/0.1 +/- 80.07 deltaA min(-1) mg(-1) protein, 0.21 +/- 0.07/0.24 +/- 0.08 deltaA min(-1) mg(-1) protein, 5.13 +/- 4.58/3.94 +/- 1.33 U mg(-1) protein and 2.23 +/- 1.47/4.11 +/- 1.63 microg mg(-1) protein, respectively in T site. These results indicate that male and female malformed frogs in both rivers upstream are found with higher activities. No significant difference in AchE activity was found between normal and malformed frogs in this investigation. It is therefore reasonable to speculate that the organic chemicals released from agricultural activities are presumable the main factors that lead to the malformation of frogs.     

Effects of the interactions between selenium and phosphorus on the growth and selenium accumulation in rice (Oryza sativa)

The solution culture, paddy soil culture and the simulation experiments in the laboratory were conducted to clarify the interactions between selenium and phosphorus, and its effects on the growth and selenium accumulation in rice. Results revealed that a suitable supply of selenium could promote rice growth and excessive selenium could injure rice plant, causing lower biomass, especially in the roots. The supply of selenite could enhance the selenium contents of rice shoots and roots in solution culture and in soil culture. The selenium concentrations in roots were much higher than those in shoots supplied with the same rates of selenium and phosphorus. The interaction between selenium and phosphorus was evident. When the phosphorus supply increased to meet the needs of plant growth, phosphorus could promote absorption and accumulation of selenium in the shoots. If the phosphorus supply was excessive, phosphorus could inhibit the accumulation of selenium in the shoots at the lower selenite level (2 micromol l(-1)), but could not at the higher selenite level (10 micromol l(-1)). With the supply of phosphate increased, the selenium concentrations in the roots decreased significantly at both selenite levels. The presence of phosphate could decrease Se sorption on the soil surface and increase the selenium concentration in the soil solution. The concentrations of selenium in shoots and roots supplied with 0.08 g kg(-1) phosphorus were lower than those with no phosphorus supplied. With the increase of phosphorus added to 0.4 g kg(-1), the selenium concentration in shoots and roots increased. The effect of phosphorus on the concentration was statistically significant at all three selenium levels.     

Seasonal changes in plasma calcium and inorganic phosphate levels in relation to parathyroid structure of the grey quail, Coturnix coturnix coturnix Linnaeus

Plasma Ca concentration (annual mean) in males Coturnix cotumix coturnix was 10.27 +/- 0.14 mg/100 ml while it was slightly higher (11.85 +/- 0.15 mg/100 ml) among females. Plasma Pi levels (annual mean) in males and females were 5.62 +/- 0.12 mg/100 ml and 6.52 +/- 0.20 mg/100 ml, respectively. While the males did not exhibit marked fluctuation in plasma Ca and Pi levels either in winter or summer, the females did record significant elevation in the levels of both these electrolytes during breeding season. The peak values of plasma Ca (17.66 +/- 0.38 mg/100 ml) and Pi (8.64 +/- 0.22 mg/100 ml) in females were observed during June. Parathyroid gland of the grey quail exhibited hyperactivity (hypertrophy and hyperplasia) during breeding season, however, the activity was more conspicuous among females than in males. The maximum increase in cell and nuclear diameters were observed in females during May-July. The follicles were also filled with AF- and PAS-positive materials during these months. The glands depicted signs of hypoactivity and degeneration during peak winter season (November-December) as evident by decrease in cell and nuclear diameters as well as vacuolation in the chief cells.     

Experimental warming, not grazing, decreases rangeland quality on the Tibetan Plateau.

We investigated experimental warming and simulated grazing (clipping) effects on rangeland quality, as indicated by vegetation production and nutritive quality, in winter-grazed meadows and summer-grazed shrublands on the Tibetan Plateau, a rangeland system experiencing climatic and pastoral land use changes. Warming decreased total aboveground net primary productivity (ANPP) by 40 g x m(-2) x yr(-1) at the meadow habitats and decreased palatable ANPP (total ANPP minus non-palatable forb ANPP) by 10 g x m(-2) x yr(-1) at both habitats. The decreased production of the medicinal forb Gentiana straminea and the increased production of the non-palatable forb Stellera chamaejasme with warming also reduced rangeland quality. At the shrubland habitats, warming resulted in less digestible shrubs, whose foliage contains 25% digestible dry matter (DDM), replacing more digestible graminoids, whose foliage contains 60% DDM. This shift from graminoids to shrubs not only results in lower-quality forage, but could also have important consequences for future domestic herd composition. Although warming extended the growing season in non-clipped plots, the reduced rangeland quality due to decreased vegetative production and nutritive quality will likely overwhelm the improved rangeland quality associated with an extended growing season. Grazing maintained or improved rangeland quality by increasing total ANPP by 20-40 g x m(-2) x yr(-1) with no effect on palatable ANPP. Grazing effects on forage nutritive quality, as measured by foliar nitrogen and carbon content and by shifts in plant group ANPP, resulted in improved forage quality. Grazing extended the growing season at both habitats, and it advanced the growing season at the meadows. Synergistic interactions between warming and grazing were present, such that grazing mediated the warming-induced declines in vegetation production and nutritive quality. Moreover, combined treatment effects were nonadditive, suggesting that we cannot predict the combined effect of global changes and human activities from single-factor studies. Our findings suggest that the rangelands on the Tibetan Plateau, and the pastoralists who depend on them, may be vulnerable to future climate changes. Grazing can mitigate the negative warming effects on rangeland quality. For example, grazing management may be an important tool to keep warming-induced shrub expansion in check. Moreover, flexible and opportunistic grazing management will be required in a warmer future.     

Imidacloprid residues in fruits,vegetables and water samples from Palestine

The aim of this work was to report on imidacloprid [IUPAC name 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] residues in some vegetables, fruits, and water samples collected from the West Bank, Palestine, in 1998 and 1999. Imidacloprid and its derivatives in the study samples were extracted by methanol/water and oxidized into 6-chloronicotinic acid and subsequently derivatized into 6-chloronicotinic acid trimethylsilyl ester before being determined by GC/MS. Imidacloprid residues were detected in more than half of the analyzed samples. The highest and lowest imidacloprid concentrations were found in eggplant (0.46 mg/kg) and green beans (0.08 mg/kg), respectively. An increase of 11–120% in imidacloprid concentration in the 1999 samples was observed when compared with those of 1998. This may suggest imidacloprid accumulation in the soil and/or increased use by local farmers. The imidacloprid residue concentrations in several crops were found to exceed the CODEX maximum residue limit.     

皆伐对青藏高原东部银露梅种群生长与繁殖的影响

调查了青藏高原东部川西云杉原始林下优势灌木银露梅及其在皆伐7 a后迹地上的种群结构、生长与繁殖状况,并进行了对比研究.发现(1)皆伐迹地生境中的银露梅灌丛年龄结构、萌生株年龄结构、萌生株数大小结构和冠幅结构与原始林下相比均存在着较大的差异;(2)在皆伐生境中,与林下同龄的银露梅丛冠幅、基径总和以及株高总和均显著增加,皆伐显著促进了银露梅的无性萌生能力和结实数量的增加.综合分析表明,银露梅能有效适应迹地退化形成的阳性生境,因此可作为高海拔地区皆伐迹地植被恢复中先锋灌木种.图2表1参21     

Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and freshwater fish (Tilapia)

Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 mug/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 mug/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 mug/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 mug Cd/g creatinine and in asymptomatic persons UCd was 11.62 mug Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.     

Effects of different concentrations of tetracycline and oxytetracycline on the growth and ecotoxicity in lettuce北大核心CSCD

四环素类抗生素(TCs)是目前我国应用广泛、用量最大的一类抗生素,畜禽粪便和土壤中存在TCs残留,影响蔬菜作物的生长发育. TCs因水溶性较高更容易被植物转运和积累,植物对TCs耐受性机理研究仍不足.为更全面探究土壤TCs对蔬菜的毒性作用,研究不同浓度四环素(TC)和土霉素(OTC)分别对生菜的抗生素残留、生长特征及抗氧化酶系统的影响.结果显示,在0(对照)、2、10、50、250 mg/kg 5个施用水平下,生菜叶片抗生素含量逐渐增加,且土霉素含量始终大于四环素含量.与对照相比,抗生素浓度在50 mg/kg以上时对生菜生长具有显著抑制作用,其中,株高、根长、地上部和地下部鲜重与叶片TC残留量具显著负相关.生菜叶片的脯氨酸含量随浓度增加呈先增加后降低的趋势,在10 mg/kg时达到最大.并且低浓度(2 mg/kg)促进抗氧化酶基因SOD、POD21和CAT的表达,高浓度抗生素(50、250 mg/kg)对其产生抑制作用,10 mg/kg的抗生素处理对SOD、POD21和CAT基因表达的影响在抗生素种类上存在差异.本研究表明抗生素浓度超过50 mg/kg对生菜生长产生抑制作用,脯氨酸和抗氧化酶SOD、POD、CAT的转录水平及其酶活性能快速响应抗生素胁迫,可作为生菜对抗生素抗性的辅助评价指标.(图8表3参19)     

竹银水库库底氮磷营养盐释放潜力研究

竹银水库是珠海新建的目前最大的对澳门供水水库,总库容达4500×104 m3。氮和磷是浮游植物生长繁殖的主要限制性营养元素,氮、磷的供应很大程度决定着水生生态系统的初级生产力和有机质的微生物循环,而水体氮、磷营养盐的一个重要来源就是沉积物,即底泥。以竹银水库蓄水前库内不同区域的底泥为对象,对水库内代表不同区域的10个位点底泥进行采样,通过水库蓄水模型装置,模拟无氧条件下各区域底泥在蓄水后短期内向上覆水体释放氮、磷营养盐的情况,并对释放到水体中的总氮、总磷进行2天一次的定期监测,评估该水库底泥氮、磷营养盐的释放潜力。结果表明：竹银水库库底氮、磷营养盐的释放存在空间差异,农业种植区和畜牧养殖区附近的采样点具有较大的总氮和总磷释放潜力;各采样点的总氮平均释放潜力达15 g·m-3,总磷平均释放潜力达30 mg·m-3,磷释放的风险远低于氮,磷仍将是竹银水库最主要的限制性营养元素;预计该水库在蓄水后10 d内最多可释放近1.7×105 kg的氮和1.5×103 kg左右的磷,按满库容计算,则底泥营养盐的释放使水库水体氮、磷营养盐质量浓度分别提高4.25 mg·L^-1和0.038 mg·L^-1。建议对不同区域性质的底泥采取具有针对性的处理措施：对农业种植区与牲畜养殖场区域的底泥应以清淤为主,对于其他区域可采取底泥覆盖等技术降低其营养盐释放风险。     

Effects of selenium on activity of glutathione peroxidase and expression of selenium metabolism-related genes in Brassica

Inorganic selenium (Se) is absorbed and enriched by plants and converted into a stable and nutritionally important organic form, which subsequently when consumed by humans or animals results in increased Se tissue levels. Brassica is one of the most potent Se-enriched plants. The aim of this study was to compare differences in Se enrichment between two predominant Brassica plants namely Brassica rapa Linn L. and Brassica tumida Tsenet Lee L. on Se metabolic parameters. Plants exposed to soil Se levels (0, 0.5, 1, 2.5 or 5?mg/kg) were examined on the activity of glutathione peroxidase (GSH-Px), Se levels and expression of Se metabolism related genes using soil pots. Data showed that activities of GSH-Px in leaf and root of the two Brassica species were significantly increased in the presence of Se at 2.5?mg/kg. Se concentrations of leaf, stem and root in B. tumida Tsenet Lee L. and B. rapa Linn L. rose from 0.31 to 21.84-fold (leaf), 1.15 to 15.16-fold (stem) and 2.11 to 15.26-fold (root) in the presence of metal in a concentration-dependent manner. The highest expression levels of adenosine triphosphate (ATP), ATP sulfurylase (APS), selenocysteine methyltransferase (SMT), serine acetyltransferase (SAT), cysteine desulfurase (CysD) and S-adenosyl-l-Met:l-Met S-methyltransferase (MMT) in leaf of B. rapa Linn L. were found at 1?mg/kg Se. The highest expression levels of ATP, APS, SMT, SAT, CysD and MMT in leaf of B. tumida Tsenet Lee L. were observed at 2.5?mg/kg Se. The Se concentrations in leaf, stem and root of B. rapa Linn L. were higher than in B. tumida Tsenet Lee L. under the same soil Se level conditions. At the same Se level, differences in the expression of Se-related genes were observed between these two Brassica species. Our observations may be used to optimize the utilization of Brassica as a nutritional source of Se by growing this plant under certain soil conditions.     

不同磷水平对不同种源尾叶桉的生长和养分吸收的影响

选定4个尾叶桉种源在不同的施P水平下盆栽，研究它们之间在生长和P、N吸收上的遗传差异．结果显示：施P肥对尾叶桉4个种源的生长高度、生物量积累、P及N吸收有着明显的作用，种源之间在上述指标上也有着明显的差异．在低P和高P施肥条件下，这种差异不明显，最大差异出现在土壤P的临界供给范围内（每kg土壤施15－20mg的P）．施P肥还会改变苗木地上部分和地下部分的干重之比、地上部分和地下部分的P、N吸收量之比．     

Assessment of human health risks from heavy metals in outdoor dust samples in a coal mining area

Jharia (India) a coal mining town has been affected by the consequences of mining and associated activities. Samples of outdoor fallen dust were collected at different locations of Jharia covering four different zones: commercial, petrol pump, high traffic, and residential areas. The dust samples were analysed for different trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, and Zn). The highest concentration of the elements in the dust samples are Mn (658 mg/kg), Zn (163.6 mg/kg), Cr (75.4 mg/kg), Pb (67.8 mg/kg), Ni (66 mg/kg), Cu (56.8 mg/kg), Co (16.9 mg/kg), As (4.1 mg/kg), and Cd (0.78 mg/kg). The concentration of selenium was below detection limit. Except Cd, contents of all the other elements in the dust samples were significantly lower in the residential area. High amount of Ni (145 mg/kg) and Pb (102 mg/kg) was observed in the high traffic and petrol pump areas, respectively. The exposure risk assessment strategies are helpful in predicting the potential health risk of the trace elements in the street dust. Selected receptors for risk assessment were infants, toddlers, children, teens, and adults. The calculated hazard quotient (HQ) for lifetime exposure was <1.0 for all the elements studied, indicating no risks from these elements for adults Among the receptors, toddlers were found to be more vulnerable, with HQ for Co, Cr, and Pb > 0.1. The finding predicts potential health risk to toddlers and children.     

Assessment of deposition of MEMC (seed dressing fungicide) in exposed rice grain through study of seedling growth parameters

Rice seed grains exposed to 240 ppm of seed dressing fungicide, MEMC showed increase in deposition of mercury with increase in period of observation (0h to 48h) in 765+/-5 mg of intact endosperm. The gradual increase in mercury deposition in intact endosperm caused simultaneous decrease in mercury content of the seed coat. Exposure periods of 5 to 20 min with 240 ppm of MEMC showed 5.5 to 8.72 microg of mercury deposition in 765+/-5 mg of intact endosperm. Increase in period of exposure (3 to 20 min) to 240 ppm of MEMC and also increase in chronic treatment to lower concentrations (1.5 ppm to 24 ppm) to seed grains have shown similar results in seedling growth parameters. Lower period of exposure or exposure to lower concentrations, both showed a significant inhibition of root growth, however the shoot growth showed stimulation. But higher exposure period or exposure to higher concentrations brought inhibition of both root and shoot growth. The exposure period showing 50% of root growth inhibition of 72h old seedling was calculated to be 10 min So also the chronic treatment showing the 50% of root growth inhibition was calculated to be 9 ppm. Ten min exposure of rice grain to 240 ppm of MEMC showed deposition of 7.11 microg of mercury in 765+/-5 mg of intact endosperm at 48h of observation (optimal phase of germinating process). Regression analysis indicated that by the time of 72h the intact endosperm and developing seedling might have acquired with a minimum amount of 10.23 microg of mercury from the seed coat. Finally it can be said that 10.23 microg of MEMC might be bringing 50% root growth inhibition in 72h old seedlings and 16.71 microg of mercury causing 50% inhibition of both root and shoot growth of 120h old seedlings.     

EDTA and citric acid mediated phytoextraction of Zn, Cu, Pb and Cd through marigold (Tagetes erecta)

Phytoextraction is an emerging cost-effective solution for remediation of contaminated soils which involves the removal of toxins, especially heavy metals and metalloids, by the roots of the plants with subsequent transport to aerial plant organs. The aim of the present investigation is to study the effects of EDTA and citric acid on accumulation potential of marigold (Tagetes erecta) to Zn, Cu, Pb, and Cd and also to evaluate the impacts of these chelators (EDTA and citric acid) in combination with all the four heavy metals on the growth of marigold. The plants were grown in pots and treated with Zn (7.3 mg l(-1)), Cu (7.5 mg I(-1)), Pb (3.7 mg l(-1)) and Cd (0.2 mg l(-1)) alone and in combination with different doses of EDTA i.e., 10, 20 and 30 mg l(-1). All the three doses of EDTA i.e., 10, 20 and 30 mg l(-1) significantly increased the accumulation of Zn, Cu, Pb and Cd by roots, stems and leaves as compared to control treatments. The 30 mg l(-1) concentration of citric acid showed reduced accumulation of these metals by root, stem and leaves as compared to lower doses i.e., 10 and 20 mg l(-1). Among the four heavy metals, Zn accumulated in the great amount (526.34 mg kg(-1) DW) followed by Cu (443.14 mg kg(-1) DW), Pb (393.16 mg kg(-1) DW) and Cd (333.62 mg kg(-1) DW) in leaves with 30 mg l(-1) EDTA treatment. The highest concentration of EDTA and citric acid (30 mg l(-1)) caused significant reduction in growth of marigold in terms of plant height, fresh weight of plant, total chlorophyll, carbohydrate content and protein content. Thus EDTA and citric acid efficiently increased the phytoextractability of marigold which can be used to remediate the soil contaminated with these metals.     

狼尾草根系对阿特拉津长期胁迫的氧化应激响应

通过盆栽实验研究了抗性植物狼尾草根部丙二醛(MDA)、脯氨酸(Pro)、抗坏血酸(As A)含量及超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)等氧化应激生理指标对不同浓度阿特拉津长期(48 d)胁迫的响应规律。结果表明:当阿特拉津胁迫浓度分别高于20 mg·kg~(-1)和50 mg·kg~(-1)时,狼尾草根系的MDA与Pro含量较对照组显著升高(P0.05);随着阿特拉津胁迫浓度的增加,狼尾草根部SOD和GR活性呈先升高后降低的趋势,其中当阿特拉津胁迫浓度为20 mg·kg~(-1)时,SOD和GR活性达到最大值;供试植物根系中As A含量与阿特拉津胁迫浓度呈正相关。综上,中低浓度(≤20 mg·kg~(-1))阿特拉津处理没有对狼尾草的根系产生明显的氧化胁迫效应,狼尾草根系的上述抗氧化应激生理指标对于发挥阿特拉津抗性起着重要的作用。     

Inconsistent definitions of "urban" result in different conclusions about the size of urban carbon and nitrogen stocks

There is conflicting evidence about the importance of urban soils and vegetation in regional C budgets that is caused, in part, by inconsistent definitions of "urban" land use. We quantified urban ecosystem contributions to C stocks in the Boston (Massachusetts, USA) Metropolitan Statistical Area (MSA) using several alternative urban definitions. Development altered aboveground and belowground C and N stocks, and the sign and magnitude of these changes varied by land use and development intensity. Aboveground biomass (live trees, dbh > or = 5 cm) for the MSA was 7.2 +/- 0.4 kg C/m2 (mean +/- SE), reflecting a high proportion of forest cover. Vegetation C was highest in forest (11.6 +/- 0.5 kg C/m2), followed by residential (4.6 +/- 0.5 kg C/m2), and then other developed (2.0 +/- 0.4 kg C/m2) land uses. Soil C (0-10 cm depth) followed the same pattern of decreasing C concentration from forest, to residential, to other developed land uses (4.1 +/- 0.1, 4.0 +/- 0.2, and 3.3 +/- 0.2 kg C/m2, respectively). Within a land use type, urban areas (which we defined as > 25% impervious surface area [ISA] within a 1-km(2) moving window) generally contained less vegetation C, but slightly more soil C, than nonurban areas. Soil N concentrations were higher in urban areas than nonurban areas of the same land use type, except for residential areas, which had similarly high soil N concentrations. When we compared our definition of urban to other commonly used urban extents (U.S. Census Bureau, Global Rural-Urban Mapping Project [GRUMP], and the MSA itself), we found that urban soil (1 m depth) and vegetation C stocks spanned a wide range, from 14.4 +/- 0.8 to 54.5 +/- 3.4 Tg C and from 4.2 +/- 0.4 to 27.3 +/- 3.2 Tg C, respectively. Conclusions about the importance of urban soils and vegetation to regional C and N stocks are very sensitive to the definition of urban used by the investigators. Urban areas, regardless of definition, are rapidly expanding in their extent; a systematic understanding of how our development patterns influence ecosystems is necessary to inform future development choices.     

组合施肥技术对黑土肥力影响的研究

采取定位试验的方法研究了组合施肥技术对土壤有机质、氮、磷的影响。结果表明,组合施肥较单施化肥土壤有机质含量增加1.8～3.3g/kg;土壤全氮增加0.05g/kg,速效氮(除Ⅱ处理外)增加6.6～44.6mg/kg;土壤全磷增加0.15～0.29g/kg.速效磷增加15.68～37.21mg/kg。土壤有机质增量为0.6～23g/kg;土壤氮素增量全氮增加0.002～0.25g/kg,速效氮增加11.6～39.4mg/kg;土壤磷素增量全磷增加0.09～0.24g/kg,速效磷增加23.59～57.28mg/kg。在保持土壤肥力有所提高的情况下,玉米大豆两年平均产量提高7.7％～17.3％,净收入提高19.4％～37.3％,由此可见,组合施肥技术应用前景广阔。     

3种抗生素对黑麦草种子萌发的生态毒性效应

为探明四环素、环丙沙星和磺胺嘧啶3种抗生素对黑麦草种子萌发的影响,为评价抗生素污染的生态影响提供科学依据,采用保湿培养法研究了它们对黑麦草种子萌发的影响,比较分析了抗生素的生态毒性差异和相对敏感的指标。结果表明,在种子萌发期,一定浓度范围的抗生素胁迫会引发植物种子抵抗逆境的应激反应,因此,3种抗生素在1 mg·L~(-1)处理水平下均能促进种子发芽。超过该浓度,四环素对黑麦草种子发芽仍有一定的促进作用,而环丙沙星和磺胺嘧啶则表现为抑制作用。四环素对种子发芽率的最大无作用浓度(NOEC)为5 mg·L~(-1),而环丙沙星和磺胺嘧啶对种子发芽率的NOEC为1 mg·L~(-1)。实验结束时,3种抗生素在1 mg·L~(-1)处理水平下的种子发芽率最高。3种抗生素浓度超过0.1 mg·L~(-1)时,种子根长和芽长即受到抑制,因此,它们对种子根长和芽长的NOEC均为0～0.1 mg·L~(-1)。其中,磺胺嘧啶的抑制作用最为显著。根长受到抑制的程度强于芽长。黑麦草种子萌发受3种抗生素影响程度依次为磺胺嘧啶环丙沙星四环素。     

Chemical changes in agricultural soils of Korea: data review and suggested countermeasures

The monitoring of chemical properties, including heavy metals, in soils is necessary if better management and remediation practices are to be established for polluted soils. The National Institute of Agricultural Science and Technology initiated a monitoring study that investigated fertility and heavy metal contents of the benchmarked soils. The study covered paddy soils, upland soils, and horticultural soils in the plastic film houses, and orchard soils throughout the Korea from 1990 to 1998. Likewise, 4047 samples of paddy and 2534 samples of plastic house in 1999 and 2000 were analyzed through the Soil Environment Conservation Act. Soil chemical properties such as pH, organic matter, available phosphate and extractable calcium, magnesium and potassium contents, and heavy metal contents such as cadmium, copper, lead, zinc, arsenic, mercury, and cobalt contents were analyzed. The study showed that the average contents of organic matter, available phosphate, and extractable potassium rapidly increased in plastic house soils than in upland or paddy soils. Two kinds of fertilizer recommendation systems were established for the study: the standard levels by national soil average data for 77 crops and the recommendation by soil test for 70 crops. Standard nitrogen fertilizer application levels for cereal crops changed from 94 kg/ha in 1960s, 99 kg/ha in 1970s, 110 kg/ha in 1980s to 90 kg/ha in 1990s. The K2O-fertilizer also changed from 67 kg/ha in 1960s, 76 kg/ha in 1970s, 92 kg/ha in 1980s, and only 44 kg/ha in 1990s. In rice paddy fields, the average contents of Cd, Cu, Pb, and Zn in surface soils (0-15 cm depth) were 0.11 mg kg(-1) (ranged from 0 to 1.01), 4.70 mg kg(-1) (0-41.59), 4.84 mg kg(-1) (0-66.44), and 4.47 mg kg(-1) (0-96.70), respectively. In the uplands, the average contents of Cd, Cu, Pb, Zn, and As in surface soils (0-15 cm depth) were 0.135 mg kg(-1) (ranged from 0 to 0.660), 2.77 mg kg(-1) (0.07-78.24), 3.47 mg kg(-1) (0-43.00), 10.70 mg kg(-1) (0.30-65.10), and 0.57 mg kg(-1) (0.21-2.90), respectively. In plastic film houses, the average contents of Cd, Cu, Pb, Zn, and As in surface soil were 0.12 mg kg(-1) (ranging from 0 to 1.28), 4.82 mg kg(-1) (0-46.50), 2.68 mg kg(-1) (0-46.50), 31.19 mg kg(-1) (0.19-252.0), and 0.36 mg kg(-1) (0-4.98), respectively. In orchard fields, the average contents of Cd, Cu, Pb, Zn, As, and Hg in surface soils (0-20 cm depth) were 0.11 mg kg(-1) (ranged from 0-0.49), 3.62 mg kg(-1) (0.03-45.30), 2.30 mg kg(-1) (0-27.80), 16.60 mg kg(-1) (0.33-105.50), 0.44 mg kg(-1) (0-4.14), and 0.05 mg kg(-1) (0.01-0.54), respectively. For polluted soils with over the warning content levels of heavy metals, fine red earth application, land reconsolidation and soil amelioration such as lime, phosphate, organic manure, and submerging were recommended. For the countermeasure areas, cultivation of non-edible crops such as garden trees, flowers, and fiber crops; land reformation; and heavy application of fine red earth (up to 30 cm) were strongly recommended. Land use techniques should be changed to be harmonious with the environment to increase yield and income. Soil function characteristics should be taken into account.