Seasonal Variations and Chemical Forms of Heavy Metals in Soils and Dusts from the Satellite Cities of Seoul, Korea

This research investigated heavy metal pollution of soils and dusts in two representative satellite cities of Seoul, Korea and studied the seasonal variations in metal concentrations through the rainy season and the chemical forms of metals using a sequential extraction analysis. The metal dispersion pattern was illustrated to match with urban structure. Soil and dust samples were collected from the cities of Uijeongbu and Koyang, which are the northern and northwestern satellite cities of Seoul (the capital), before and after rainy season. Concentrations of Cu, Pb and Zn were higher than those of the world averages for soils, and their levels decreased after rain, particularly in highly contaminated samples. Relatively high pH values were found in roadside soils, but no seasonal variation was found after the rainy season. The three metals (Cu, Pb and Zn) in soils and dusts were associated with various chemical fractions of soils and dusts as distinguished by the sequential extraction scheme, and a strong similarity of metal association between soils and dusts was found, which indicates that airborne dust may be a principle source of soil contamination. Copper is uniformly distributed, and Pb is largely associated with the reducible phase. There is an appreciable proportion of total Zn in the exchangeable/water-acid soluble fraction. After the rainy season, the most soluble fractions in soils and dusts were leached away. In terms of mobility and bioavailability of metals in soils and dusts, the order Zn >> Cu > Pb is suggested. Geographical variations of total metals corresponded well with urbanised areas of cities, especially the industrial complex and major motorways.     

广东省不同水库底泥理化性质对内源氮磷释放影响

采用分级浸取分离方法,分析了广东省10个典型水库底泥的氮磷营养形态分布和污染状况;并通过模拟覆水试验,研究了不同水库底泥氮磷形态及理化性质对内源氮磷释放的影响。结果表明：广东省10个水库底泥氮磷污染较为严重,全氮含量为0.33~3.31 g.kg^-1,平均值为1.70 g.kg^-1;全磷含量为0.14~2.63 g.kg^-1,平均值为1.31 g.kg^-1。底泥氮磷主要以可转化态形式存在,可转化态氮磷含量占总氮磷含量百分比分别为41.2%~71.4%和53.6%~93.2%。底泥内源氮磷的释放主要受氮磷的赋存形态和含量的影响,水库底泥总氮的释放量与离子交换态氮（IEF-N）、碳酸盐结合态氮（WAEF-N）、铁锰氧化物结合态氮（SAEF-N）呈极显著正相关关系,相关系数分别为0.931、0.814、0.807;总磷的释放量与碳酸盐结合态磷（WAEF-P）、铁锰氧化物结合态磷（SAEF-P）呈极显著正相关,相关系数分别为0.960、0.957;这几种氮磷形态是上覆水体中氮磷的重要来源。同时底泥内源氮磷释放还与底泥机械组成有关,其中总氮和总磷释放量与底泥黏粒质量分数呈显著正相关,相关系数分别为0.738、0.638;而总氮的释放量与底泥砂粒质量分数呈显著负相关,相关系数为-0.685。这可能与可转化态氮磷更多的分布在细粒级底泥中有关,细颗粒底泥氮磷释放是上覆水体氮磷的主要来源。     

稻季田面水不同形态氮素变化及氮肥减量研究

通过氮肥减量田间小区试验,研究了稻季3次施肥后田面水不同形态氮素的变化特征、水稻产量与氮肥农学效率和环境效应的关系。结果表明：施氮显著增加了田面水的氮素质量浓度,且氮素质量浓度随施氮量的减少而降低。田面水总氮,有机氮在施氮后1 d达到最大,随后快速下降;铵态氮和无机氮在基肥和分蘖肥施用1 d后也达到最大,而在穗肥施用后经历了一个先升后降的变化过程;无机氮是田面水氮素的主要形态,应将无机氮作为农田排水污染检测的主要指标;施氮后1周是防止稻田田面水氮素大量流失的关键时期;随着施氮量的增加,氮肥农学效率不断下降,氮素径流损失不断增大,综合水稻产量、农学效率和环境效应,试验区氮肥减量50%是可行的,但其产量持续性仍需进一步验证。     

乌江渡沉积物磷的污染特征及其对河流筑坝的响应

受息烽河输入的影响,乌江渡水库的磷污染问题一直备受关注,但水库上游水体磷的释放以及河流筑坝对水库磷污染的影响却没有引起太多的重视。本文通过对表层沉积物和沉积物柱芯中磷及其形态的分析,研究乌江渡沉积物磷的污染现状和历史变化趋势及其对河流筑坝的响应。结果表明:1)乌江渡水库沉积物磷污染现已非常严重,远高于国内其他湖库;2)乌江渡沉积物磷含量从上游至下游有递增的趋势,且主要由NaOH-P的增加所致;3)乌江渡沉积物磷的空间变化可能源于不同粒径颗粒物或藻类的沿程沉降,也可能源于水体中Fe²⁺被氧化后引起磷的沿程沉降,但真实原因还需要进一步的证实。这说明上游水库滞留在沉积物中的磷部分可能重新释放出来,导致乌江渡水库中上游沉积物磷的污染也相当严重。     

Catchment soils as a factor of trace metal accumulation in sediments of the reservoir Klingenberg (eastern Ore Mountains, Germany)

The release and accumulation dynamics of trace metals in soils and aquatic sediments were exemplarily investigated in the catchment area of the Reservoir Klingenberg(Germany). Catchment soils were examined for mobilizable and total concentrations of arsenic(As), cadmium(Cd), chrome(Cr), iron(Fe), manganese(Mn), nickel(Ni), lead(Pb),and zinc(Zn) and compared with trace metal quantities accumulated in riverbed and reservoir sediments. The comparison of all samples showed relatively small variations of Cr(7.96–46.0 mg/kg), Fe(7.79–40.4 g/kg), and Ni(6.06–56.5 mg/kg), while stronger differences were found for As(11.2–164 mg/kg), Cd(0.14–30.5 mg/kg), Mn(0.08–1.84 g/kg), Pb(20.7–183 mg/kg), and Zn(69.1–916 mg/kg). The catchment soils were slightly enriched by Cd, Pb, and Zn. Especially Cd and Zn were characterized by large mobilizable proportions.The mean trace metal concentrations in riverbed sediments were higher than in catchment soils, while reservoir sediments accumulated the highest amounts of the analyzed elements. The enrichment of trace metals in reservoir sediments was generally determined by the sedimentation of fine particles, while the distribution of As, Fe, and Mn was additionally impacted by redox conditions. For Cd and Zn, which in comparison were most enriched in riverbed and reservoir sediments, a significant release from soils by leaching processes was observed. The accumulation of As and Pb in reservoir sediments was influenced to a greater extent by soil erosion and by anthropogenic or chalcogen sources in the catchment.     

外源铅铜镉在长三角和珠三角农业土壤中的转化

选择了我国经济发达地区的长江三角洲和珠江三角洲10个代表性农业土壤，采用室内培养和化学分级方法研究了加入外源铅、铜、镉在土壤中的动态变化及转化趋势，探讨了碳酸钙、粉煤灰、猪粪和钢渣等土壤改良剂对土壤重金属形态的影响。结果表明，随着土壤重金属负荷的提高，土壤中交换态重金属的比例增大，残余态比例下降，有效性提高，对环境威胁增大。当重金属加入最较低时，重金属优先向氧化物结合态、有机质结合态转化；而当加入最较高时，向交换态和碳酸盐结合态转化的比例明皿增加。pH和土壤组分对重金属在土壤中的转化有显著的影响，土壤pH下降可使交换态Cd、Cu、Pb的比例递增。加入碳酸钙、粉煤灰、猪粪和钢渣等改良剂可显著地降低土壤中交换态重金属比例，增加其它形态的重金属比例。     

蚯蚓生态滤池对生活污水中氮的去除作用

研究了单级蚯蚓生态滤池对生活污水中不同形态氮的去除效果,并对其机制进行了探讨.结果表明,处理前进水总氮以氨氮为主,占83.88%,出水总氮以硝态氮为主,占76.46%,氮素的形态在处理前后发生了很大的改变;系统对总氮和氨氮的平均去除率分别为28.08%和90.44%,硝态氮大量积累,亚硝态氮少量积累;系统硝化作用强,反硝化作用受到抑制,总体脱氮能力较差,可采取提高湿干比、改进滤池构造、多级滤池串联、后接人工湿地和提高进水碳氮比等手段强化反硝化,以提高滤池总氮的去除效果.     

滇池与红枫湖沉积物中磷的地球化学特征比较研究

对比研究了滇池与红枫湖表层沉积物中磷的形态含量及其生物有效性.结果表明,两湖沉积物总磷含量相当,分别为1373.8～ 4616.3mg·kg-1、1194.4 ～4324.3 mg·kg-1.HCl-P、Res-P为滇池沉积物中主要的磷形态,占总磷的62.9％ ～86.4％;而红枫湖中磷形态顺序为NaOH-P＞ Res-P＞ HCl-P＞ BD-P＞ NH4Cl-P;两湖沉积物中有机磷均以低活性态为主.红枫湖沉积物中NH4Cl-P、BD-P、NaOH-rP及生物有效磷等平均含量明显高于滇池,表明其内源磷释放对上覆水体富营养化的贡献更大.Olsen-P与NH4Cl-P、BD-P、NaOH-rP等活性磷形态呈显著正相关,而与NaOH-nrP、HCl-P、Res-P、TP等相关性不显著,因此,可作为评价两湖沉积物释磷能力及其潜在环境风险的重要指标.     

中国市政污泥中磷的含量与形态分布

于2016年采集了全国46个城市的市政污泥样品,运用SMT法测定了污泥中不同形态磷的含量.结果表明,我国市政污泥中总磷（TP）、无机磷（IP）、非磷灰石态无机磷（NAIP）、磷灰石态无机磷（AP）、有机磷（OP）和生物有效磷（NAIP+OP）的平均含量分别为（17.32±5.13）、（11.71±4.01）、（9.18±3.44）、（3.03±2.74）、（4.54±4.23）和（13.72±4.36）g·kg^-1.其中IP是污泥中磷的主要存在形态,占TP含量的60%以上;NAIP是主要的无机磷形态,占IP含量的66%以上.污泥中生物有效磷占TP含量的比例介于66.8%~96.1%之间,二者呈现极显著正相关关系（r=0.942,P<0.01）.市政污泥磷含量和排放量总体上呈现东高西低的空间分布规律.2016年随污泥处置排放入环境的磷达到了1.04×10⁵ t,其中1.95×10⁴ t随污泥农用进入土壤,4.69×10⁴ t进入填埋场,1.47×10⁴ t进入建筑材料中,2.34×10⁴ t经垃圾焚烧进入焚烧灰,4.50t被直接倾倒丢弃.与历史数据对比发现,我国市政污泥中总磷的含量呈现先升高、后降低的变化趋势.     

工业含氨污染处理技术的经济价值分析

揭示了氨污染处理的成本效益,提出氨作为废物与资源的临界点浓度与氨的经济价值模型,并探讨了不同形态及介质中氨污染处理技术的成本差异.结果表明,在废水中氨氮浓度接近于10％时,通过资源化利用基本能够达到净现值为0,即收支平衡.相同进水浓度时,氨氮在碱性条件下单位处理成本最低,为0.19～0.41元/kg NH3,在离子态、...