To compare the soil remediation effectiveness of saltsof weak organic acids with strongchelating agents, three soils of different textures,all polluted by heavy metals, were washed in a column,at optimum pH, with salts of weak organic acids,namely, citrate, tartarate or oxalate + citrate orchelating agents (EDTA or DTPA). For the clay loam,Cr, Mn, Hg and Pb were removed by citrate andtartarate at levels of 43 to 45, 37 to 41, 91 to 92and 75%, respectively. EDTA and DTPA effectivelyleached only Pb after 20 pore volumes. For the loam,citrate leached 98 and 89% of Cd and Pb after 20 porevolumes, respectively, while tartarate leached out 91and 87% of Cd and Pb. EDTA and DTPA removed 93 to97% of these metals after 20 pore volumes. For thesandy clay loam, 84 to 91, 73 to 84, 56 to 70 and 72to 81% of Cd, Cu, Pb and Zn were removedrespectively, by citrate and tartarate. EDTA and DTPAremoved 93 to 97% of these metals after 20 porevolumes. An in situ soil remediation simulation wasalso tested using the sandy clay loam in a tub. After12 hr of retention, the citrate solution washed 81, 82,73 and 90%, of Cd, Cu, Pb and Zn, respectively, aftersix pore volumes. EDTA and DTPA effectively removedall heavy metals, except for Hg, but also extractedlarge quantities of soil nutrients and pollute thesoil by being adsorbed on the soil particles. Thesalts of citrate and tartarate effectively removed theheavy metals from the three polluted soils whileleaching little macro-nutrients and improving soilstructure. Each soil reached C and B levels ofsoil-clean-up criteria after 10 to 20 pore volumes andwithin 10 to 15 hr of flushing.

Atmospheric emission of volatilepesticides can be a significant source of airpollution. A field study was conducted to reduce1,3-dichloropropene (1,3-D) emission by applying thechemical via subsurface drip irrigation with a reduceddosage (4.7 g m⁻² or 47 kg ha⁻¹). Comparisons were made between ashallow drip application with the plot covered with apolyethylene film, a deep drip application and aconventional shank injection (at 11.2 g m⁻²) withthe plots left as bare soil surface. For eachtreatment, seven replicated active flux chambers wereused continuously to measure 1,3-D loss until nomeasurable emission was found. Results indicated thattotal 1,3-D emission loss was over 90% for the shankinjection, and 66 and 57% for the shallow and deepdrip plots, respectively. The emission loss wasextremely high for shank injection since about 80%were lost from the bed furrows where the slantedshanks left uncompacted fractures. On mass basis, theshank plot lost 10.4 g m⁻², whereas the shallow-and deep-drip plots lost 3.1 and 2.7 g m⁻²,respectively. Applying 1,3-D using subsurface dripirrigation with reduced dosage has a great potentialfor emission reduction.

Laboratory and field experiments werecarried out with 2,4-D herbicide(2,4-Dichlorophenoxyacetic acid) to evaluate itstransformation and migration in the coastal waterprotection zones of the Oka river, Russia. In thefirst laboratory experiment, the transformation of2,4-D was studied in various soil samples from coastalslopes (1–0°) of 480 m length soil-geochemicalcatena on the right side of the Oka river incomparison with watershed and floodplain soils. Thetransformation of 2,4-D was the lowest in soil sampleswith minimal pH values and was independent of eitherslope values or vicinity to the Oka river channel.Using indirect estimates, the surface runoff potentialwas calculated for this herbicide. In the second fieldexperiment, the vertical migration and transformationof 2,4-D was carried out in soddy sand soil (EutricArenosol) placed in the left side of the Oka river(0-100 cm) under `soft' (40 mm 2 hr⁻¹) and `hard'(40 mm 15 min⁻¹) irrigation regimes. Furthermore, thetransformation of this herbicide was studied in 0–20and 40–50 cm soil layers under various temperature andmoisture regimes. After 1 day of irrigation, the mainherbicide quantity was found in the 0–30 cm layerunder both irrigation regimes. The transformation ofthe herbicide was faster in the surface, 0–20 cmlayer, than in the deeper, 40–50 cm layer.

The cement industry has been one of the major sources of air pollution in the past and the Turkish Air Quality Protection Regulation has issued limits also to trace elementemissions to minimise the polluting effects of this industrialsector. In the present study, dust samples were obtained isokinetically from 18 main stacks of 10 cement plants locatedin different geographical areas of Turkey. The samples were analysed for trace elements Hg, Cd, Cr, Pb, Ni, Se, Te, TI, V, Sb, Ba, Zn, Co, Sr, Cu, Bi, Mo, Be, and As. The results are presented both as concentration in the dust samples as well as emissions per unit production, and concentration inthe stack gas. The trace element emissions of the main stacksagree to great extent with the values given in the literature. On the other hand, the trace element emissions of the plants considered are well below the limits set in the Turkish Air Quality Protection Regulation.

Soil erosion has both on-farm and off-farm impacts. Reduction ofsoil depth can impair the land's productivity, and the transportof sediments can degrade streams, lakes, and estuaries. Since1933, soil conservation policies have existed in the UnitedStates. Originally they focused on the on-farm benefits ofkeeping soil on the land and increasing net farm income.Beginning in the 1980s, however, policy goals increasinglyincluded reductions in off-site impacts of erosion. As aconsequence of conservation efforts associated with explicitU.S. government policies, total soil erosion between 1982 and1992 was reduced by 32% and the sheet and rill erosion ratefell from an average of 4.1 tons per acre per year in 1982 to 3.1 tons per acre in 1992. Wind erosion rate fell from anaverage of 3.3 tons per acre per year to 2.4 tons per acre peryear over the same period. Still, soil erosion is imposingsubstantial social costs. These costs are estimated to be about$37.6 billion annually. To further reduce soil erosion andthereby mitigate its social costs, there are a number of policyoptions available to induce farmers to adopt conservationpractices including education and technical assistance,financial assistance, research and development, land retirement,and regulation and taxes.

Twenty-eight volatile organic compounds have been measured in a 3-month monitoring campaign. The sampling point is locatedin the urban centre of La Coruña, a medium-size town in theNorthwest of Spain. Only a petrol refinery can be consideredas an important point VOCs source in its surrounding area.The municipal landfill collapsed in September 1996, and rebuilding works caused strong odour episodes at the urbancentre. We tried to check how this problem affected urban airquality. Samples were taken with Tenax-TA tubes and analysedby thermal desorption-GC-MS. From the results obtained, traffic emissions were recognised as the main VOCs source inthe sampling zone. On November 9th a contaminationepisode took place. Aromatic and aliphatic compounds levelswere probably affected by emissions from fuel treatmentprocesses in a nearby petrol refinery. No influence onquantified VOCs concentrations from the remaking landfillworks was observed. Several compounds (organosulphurs, estersand alcohols) were recognised as the cause of odour problems.

Roads play a major role intransporting sediment associated nonpoint sourcepollutants to urban stream networks via storm drains. In urban areas the relationship of erodible soil toroads may be of critical importance in controllingmetal contributions to roads. Two 50-m transects(Park and School) were investigated perpendicular toroads in Manoa basin, Oahu, Hawaii. Concentrations ofnine elements were compared to background control soillocations and to five supplemental samples from nearbyrecreational parks. Sediment from curbside areas ofroads (road deposited sediment) was collected as thestarting point of each transect, and subsequently soilwas sampled from two depths (0–2.5 cm and 7.5–10.0 cm)along the transects. Total and 0.5 M HCl extractableconcentrations were determined for aluminum (Al),calcium (Ca), chromium (Cr), copper (Cu), iron (Fe),manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn)using either inductively coupled plasma-atomicemission spectroscopy (ICP-AES) or flame atomicemission spectroscopy (FAAS). Ca, Cu, Pb and Znexhibited anthropogenic enhancement, with Pb and Znhaving the greatest enrichment in road sedimentfollowed by locations nearest the road. Copperdisplayed a narrower band of contamination than eitherPb or Zn, and this may reflect larger aerosolassociations and more rapid fall velocities. Lead andZn exhibited substantial decay in concentration at 50 m compared to the road sediment, but enrichment wasstill apparent. The positioning of a band of soilbetween the road-curb area and the sidewalk for thePark transect facilitated deposition and storage oftrace metals, and with subsequent erosion by splash orconcentrated flow this area can account for continuedtransport of contaminated sediment to adjacent roadsurfaces. On the other hand the School transect hadno soil directly beside the road, and the nearestsample from the road (5 m) displayed enrichment butsubstantially lower than the Park transect. Thesepreliminary data suggest that remobilization of soilstored metals in close proximity to roads cansignificantly prolong the environmental contaminationof urban road systems and eventually stream sediments.

This study is focussed on evaluation of temperature effectduring frozen storage on movement of trace elements in differenttissues (exoskeleton, carapace and abdominal muscle) of twocommercially important shrimp species (Penaeusmerguiensis and Metapenaues affinis). Moreoverrelationships between total length and sex of specimens with concentration of trace elements in selected tissues were assessed. Concentrations of Cd, Cr, Cu, Fe, Mn, Ni and Znin samples were determined by ICP-AES. Only in the case of Niand Zn sex related differences could be observed. With theexception of Cu, the trace metals distributed significantlydifferent between the tissues. The only significant differencesbetween species were found in bioaccumulation of Mn. Sizedependent relationship was observed only for Ni. Associationsbetween Mn and Fe were positively and highly significant in allthe cases. The levels of all the metals in muscle of the shrimpsfrom the studied region were comparable to other world areas. MeanCu and Zn levels in edible parts of M. affinis stored at–10 °C exceeded some existing guidelines, while the concentrations at –30 °C were somewhat lower than them.

A fish canning facility processes 1900–2000 tons of mackerel and sardine annually at arate of 10–15 tons per day for a total of 200 days yr⁻¹. This factory generates an average of 20 m³ of industrial wastewaters per day. The objective of our study, which was carried out on a bimonthly basisfrom December 1995 to November 1996, was to determine the overall pollutant load associated with this effluent in relation to the applicable Egyptian Standards and to propose methods for pollutant load reduction before discharging it to the local sewer. The methods were to benefit through the recovery of wasted organic load and transform it into an environmentally safe residue amenable for either immediate reuse or final disposal thereafter. Five chemical coagulation/flocculation treatments were tried using ferric chloride, alum, lime, ferric chloride and lime, and alum and lime. The best method involved the use of FeCl₃ and Ca(OH)₂ (0.4 g Fe L⁻¹ and 0.2 g Ca L⁻¹, respectively) which reduced the average influent BOD₅ from 989 to 204 mg L⁻¹, the COD from 1324 to 320 mg L⁻¹, TSS from 4485 to 206 mg L⁻¹, total protein content from 812 to 66 mg L⁻¹ and oil and grease from 320 to 66 mg L⁻¹. The separated dried precipitate averaged 50 g L⁻¹ which was found to contain 40% by weight recovered protein and 20% recovered fat. The solid was ideal for on-site reprocessing as animal feed. As well, the final effluent, if not discharged to the area sewer, was safe for controlled use in some irrigation applications or forestry projects at the desert area surrounding the factory.

Seven sediment cores were collected along a transect about20 km off from the mouth of the Po River, in the northernAdriatic Sea (Italy). Cores were characterised by differentdepositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, aswell as for total organic matter. Metal distributiongenerally showed vertical and spatial variability ascribed tograin size effects with no significant anthropogenicperturbation. Conversely, mercury showed vertical profilescharacterised by surface enrichment, with concentrations inthe upper layer (50–230 ng g⁻¹) exceeding 3–11 times the background value of 20 ng g⁻¹ determined in bottomcores. Surface maxima were attributed to anthropogenic mercurydelivered mainly by the Po River.